content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.lang;
  
  import dalvik.annotation.optimization.FastNative;
  import java.io.ObjectStreamField;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.Charset;
  import java.nio.ByteBuffer;
  import java.util.Comparator;
  import java.util.Formatter;
  import java.util.Locale;
  import java.util.Objects;
  import java.util.StringJoiner;
  import java.util.regex.Pattern;
  import java.util.regex.PatternSyntaxException;
  
  import libcore.util.CharsetUtils;
  
  /**
   * The {@code String} class represents character strings. All
   * string literals in Java programs, such as {@code "abc"}, are
   * implemented as instances of this class.
   * <p>
   * Strings are constant; their values cannot be changed after they
   * are created. String buffers support mutable strings.
   * Because String objects are immutable they can be shared. For example:
   * <blockquote><pre>
   *     String str = "abc";
   * </pre></blockquote><p>
   * is equivalent to:
   * <blockquote><pre>
   *     char data[] = {'a', 'b', 'c'};
   *     String str = new String(data);
   * </pre></blockquote><p>
   * Here are some more examples of how strings can be used:
   * <blockquote><pre>
   *     System.out.println("abc");
   *     String cde = "cde";
   *     System.out.println("abc" + cde);
   *     String c = "abc".substring(2,3);
   *     String d = cde.substring(1, 2);
   * </pre></blockquote>
   * <p>
   * The class {@code String} includes methods for examining
   * individual characters of the sequence, for comparing strings, for
   * searching strings, for extracting substrings, and for creating a
   * copy of a string with all characters translated to uppercase or to
   * lowercase. Case mapping is based on the Unicode Standard version
   * specified by the {@link Character Character} class.
   * <p>
   * The Java language provides special support for the string
   * concatenation operator (&nbsp;+&nbsp;), and for conversion of
   * other objects to strings. String concatenation is implemented
   * through the {@code StringBuilder}(or {@code StringBuffer})
   * class and its {@code append} method.
   * String conversions are implemented through the method
   * {@code toString}, defined by {@code Object} and
   * inherited by all classes in Java. For additional information on
   * string concatenation and conversion, see Gosling, Joy, and Steele,
   * <i>The Java Language Specification</i>.
   *
   * <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
   * or method in this class will cause a {@link NullPointerException} to be
   * thrown.
   *
   * <p>A {@code String} represents a string in the UTF-16 format
   * in which <em>supplementary characters</em> are represented by <em>surrogate
   * pairs</em> (see the section <a href="Character.html#unicode">Unicode
   * Character Representations</a> in the {@code Character} class for
   * more information).
   * Index values refer to {@code char} code units, so a supplementary
   * character uses two positions in a {@code String}.
   * <p>The {@code String} class provides methods for dealing with
   * Unicode code points (i.e., characters), in addition to those for
   * dealing with Unicode code units (i.e., {@code char} values).
   *
   * @author  Lee Boynton
   * @author  Arthur van Hoff
   * @author  Martin Buchholz
   * @author  Ulf Zibis
   * @see     Object#toString()
   * @see     StringBuffer
   * @see     StringBuilder
   * @see     Charset
   * @since   JDK1.0
   */
  
  public final class String
      implements java.io.Serializable, Comparable<String>, CharSequence {
  
      // BEGIN Android-changed: The character data is managed by the runtime.
      // We only keep track of the length here and compression here. This has several consequences
      // throughout this class:
      //  - References to value[i] are replaced by charAt(i).
      //  - References to value.length are replaced by calls to length().
      //  - Sometimes the result of length() is assigned to a local variable to avoid repeated calls.
      //  - We skip several attempts at optimization where the values field was assigned to a local
      //    variable to avoid the getfield opcode.
      // These changes are not all marked individually.
      //
      // private final char value[];
      //
      // If STRING_COMPRESSION_ENABLED, count stores the length shifted one bit to the left with the
      // lowest bit used to indicate whether or not the bytes are compressed (see GetFlaggedCount in
      // the native code).
      private final int count;
      // END Android-changed: The character data is managed by the runtime.
  
      // Android-changed: We make use of new StringIndexOutOfBoundsException constructor signatures.
      // These improve some error messages. These changes are not all marked individually.
  
      /** Cache the hash code for the string */
      private int hash; // Default to 0
  
      /** use serialVersionUID from JDK 1.0.2 for interoperability */
      private static final long serialVersionUID = -6849794470754667710L;
  
      /**
       * Class String is special cased within the Serialization Stream Protocol.
       *
       * A String instance is written into an ObjectOutputStream according to
       * <a href="{@docRoot}/../platform/serialization/spec/output.html">
       * Object Serialization Specification, Section 6.2, "Stream Elements"</a>
       */
      private static final ObjectStreamField[] serialPersistentFields =
          new ObjectStreamField[0];
  
      /**
       * Initializes a newly created {@code String} object so that it represents
       * an empty character sequence.  Note that use of this constructor is
       * unnecessary since Strings are immutable.
       */
      public String() {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Initializes a newly created {@code String} object so that it represents
       * the same sequence of characters as the argument; in other words, the
       * newly created string is a copy of the argument string. Unless an
       * explicit copy of {@code original} is needed, use of this constructor is
       * unnecessary since Strings are immutable.
       *
       * @param  original
       *         A {@code String}
       */
      public String(String original) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new {@code String} so that it represents the sequence of
       * characters currently contained in the character array argument. The
       * contents of the character array are copied; subsequent modification of
       * the character array does not affect the newly created string.
       *
       * @param  value
       *         The initial value of the string
       */
      public String(char value[]) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new {@code String} that contains characters from a subarray
       * of the character array argument. The {@code offset} argument is the
       * index of the first character of the subarray and the {@code count}
       * argument specifies the length of the subarray. The contents of the
       * subarray are copied; subsequent modification of the character array does
       * not affect the newly created string.
       *
       * @param  value
       *         Array that is the source of characters
       *
       * @param  offset
       *         The initial offset
       *
       * @param  count
       *         The length
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} and {@code count} arguments index
       *          characters outside the bounds of the {@code value} array
       */
      public String(char value[], int offset, int count) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new {@code String} that contains characters from a subarray
       * of the <a href="Character.html#unicode">Unicode code point</a> array
       * argument.  The {@code offset} argument is the index of the first code
       * point of the subarray and the {@code count} argument specifies the
       * length of the subarray.  The contents of the subarray are converted to
       * {@code char}s; subsequent modification of the {@code int} array does not
       * affect the newly created string.
       *
       * @param  codePoints
       *         Array that is the source of Unicode code points
       *
       * @param  offset
       *         The initial offset
       *
       * @param  count
       *         The length
       *
       * @throws  IllegalArgumentException
       *          If any invalid Unicode code point is found in {@code
       *          codePoints}
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} and {@code count} arguments index
       *          characters outside the bounds of the {@code codePoints} array
       *
       * @since  1.5
       */
      public String(int[] codePoints, int offset, int count) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new {@code String} constructed from a subarray of an array
       * of 8-bit integer values.
       *
       * <p> The {@code offset} argument is the index of the first byte of the
       * subarray, and the {@code count} argument specifies the length of the
       * subarray.
       *
       * <p> Each {@code byte} in the subarray is converted to a {@code char} as
       * specified in the method above.
       *
       * @deprecated This method does not properly convert bytes into characters.
       * As of JDK&nbsp;1.1, the preferred way to do this is via the
       * {@code String} constructors that take a {@link
       * Charset}, charset name, or that use the platform's
       * default charset.
       *
       * @param  ascii
       *         The bytes to be converted to characters
       *
       * @param  hibyte
       *         The top 8 bits of each 16-bit Unicode code unit
       *
       * @param  offset
       *         The initial offset
       * @param  count
       *         The length
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} or {@code count} argument is invalid
       *
       * @see  #String(byte[], int)
       * @see  #String(byte[], int, int, String)
       * @see  #String(byte[], int, int, Charset)
       * @see  #String(byte[], int, int)
       * @see  #String(byte[], String)
       * @see  #String(byte[], Charset)
       * @see  #String(byte[])
       */
      @Deprecated
      public String(byte ascii[], int hibyte, int offset, int count) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new {@code String} containing characters constructed from
       * an array of 8-bit integer values. Each character <i>c</i>in the
       * resulting string is constructed from the corresponding component
       * <i>b</i> in the byte array such that:
       *
       * <blockquote><pre>
       *     <b><i>c</i></b> == (char)(((hibyte &amp; 0xff) &lt;&lt; 8)
       *                         | (<b><i>b</i></b> &amp; 0xff))
       * </pre></blockquote>
       *
       * @deprecated  This method does not properly convert bytes into
       * characters.  As of JDK&nbsp;1.1, the preferred way to do this is via the
       * {@code String} constructors that take a {@link
       * Charset}, charset name, or that use the platform's
       * default charset.
       *
       * @param  ascii
       *         The bytes to be converted to characters
       *
       * @param  hibyte
       *         The top 8 bits of each 16-bit Unicode code unit
       *
       * @see  #String(byte[], int, int, String)
       * @see  #String(byte[], int, int, Charset)
       * @see  #String(byte[], int, int)
       * @see  #String(byte[], String)
       * @see  #String(byte[], Charset)
       * @see  #String(byte[])
       */
      @Deprecated
      public String(byte ascii[], int hibyte) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified subarray of
       * bytes using the specified charset.  The length of the new {@code String}
       * is a function of the charset, and hence may not be equal to the length
       * of the subarray.
       *
       * <p> The behavior of this constructor when the given bytes are not valid
       * in the given charset is unspecified.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @param  offset
       *         The index of the first byte to decode
       *
       * @param  length
       *         The number of bytes to decode
  
       * @param  charsetName
       *         The name of a supported {@linkplain Charset
       *         charset}
       *
       * @throws  UnsupportedEncodingException
       *          If the named charset is not supported
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} and {@code length} arguments index
       *          characters outside the bounds of the {@code bytes} array
       *
       * @since  JDK1.1
       */
      public String(byte bytes[], int offset, int length, String charsetName)
              throws UnsupportedEncodingException {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified subarray of
       * bytes using the specified {@linkplain Charset charset}.
       * The length of the new {@code String} is a function of the charset, and
       * hence may not be equal to the length of the subarray.
       *
       * <p> This method always replaces malformed-input and unmappable-character
       * sequences with this charset's default replacement string.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @param  offset
       *         The index of the first byte to decode
       *
       * @param  length
       *         The number of bytes to decode
       *
       * @param  charset
       *         The {@linkplain Charset charset} to be used to
       *         decode the {@code bytes}
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} and {@code length} arguments index
       *          characters outside the bounds of the {@code bytes} array
       *
       * @since  1.6
       */
      public String(byte bytes[], int offset, int length, Charset charset) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified array of bytes
       * using the specified {@linkplain Charset charset}.  The
       * length of the new {@code String} is a function of the charset, and hence
       * may not be equal to the length of the byte array.
       *
       * <p> The behavior of this constructor when the given bytes are not valid
       * in the given charset is unspecified.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @param  charsetName
       *         The name of a supported {@linkplain Charset
       *         charset}
       *
       * @throws  UnsupportedEncodingException
       *          If the named charset is not supported
       *
       * @since  JDK1.1
       */
      public String(byte bytes[], String charsetName)
              throws UnsupportedEncodingException {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified array of
       * bytes using the specified {@linkplain Charset charset}.
       * The length of the new {@code String} is a function of the charset, and
       * hence may not be equal to the length of the byte array.
       *
       * <p> This method always replaces malformed-input and unmappable-character
       * sequences with this charset's default replacement string.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @param  charset
       *         The {@linkplain Charset charset} to be used to
       *         decode the {@code bytes}
       *
       * @since  1.6
       */
      public String(byte bytes[], Charset charset) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified subarray of
       * bytes using the platform's default charset.  The length of the new
       * {@code String} is a function of the charset, and hence may not be equal
       * to the length of the subarray.
       *
       * <p> The behavior of this constructor when the given bytes are not valid
       * in the default charset is unspecified.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @param  offset
       *         The index of the first byte to decode
       *
       * @param  length
       *         The number of bytes to decode
       *
       * @throws  IndexOutOfBoundsException
       *          If the {@code offset} and the {@code length} arguments index
       *          characters outside the bounds of the {@code bytes} array
       *
       * @since  JDK1.1
       */
      public String(byte bytes[], int offset, int length) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Constructs a new {@code String} by decoding the specified array of bytes
       * using the platform's default charset.  The length of the new {@code
       * String} is a function of the charset, and hence may not be equal to the
       * length of the byte array.
       *
       * <p> The behavior of this constructor when the given bytes are not valid
       * in the default charset is unspecified.  The {@link
       * java.nio.charset.CharsetDecoder} class should be used when more control
       * over the decoding process is required.
       *
       * @param  bytes
       *         The bytes to be decoded into characters
       *
       * @since  JDK1.1
       */
      public String(byte bytes[]) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new string that contains the sequence of characters
       * currently contained in the string buffer argument. The contents of the
       * string buffer are copied; subsequent modification of the string buffer
       * does not affect the newly created string.
       *
       * @param  buffer
       *         A {@code StringBuffer}
       */
      public String(StringBuffer buffer) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      /**
       * Allocates a new string that contains the sequence of characters
       * currently contained in the string builder argument. The contents of the
       * string builder are copied; subsequent modification of the string builder
       * does not affect the newly created string.
       *
       * <p> This constructor is provided to ease migration to {@code
       * StringBuilder}. Obtaining a string from a string builder via the {@code
       * toString} method is likely to run faster and is generally preferred.
       *
       * @param   builder
       *          A {@code StringBuilder}
       *
       * @since  1.5
       */
      public String(StringBuilder builder) {
          // Android-changed: Constructor unsupported as all calls are intercepted by the runtime.
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
  
      // Android-removed: Unused package-private constructor String(char[] value, boolean share).
  
      // BEGIN Android-added: Constructor for internal use.
      // Not implemented in java as all calls are intercepted by the runtime.
      /**
       * Package private constructor
       *
       * @deprecated Use {@link #String(char[],int,int)} instead.
       */
      @Deprecated
      String(int offset, int count, char[] value) {
          throw new UnsupportedOperationException("Use StringFactory instead.");
      }
      // END Android-added: Constructor for internal use.
  
      /**
       * Returns the length of this string.
       * The length is equal to the number of <a href="Character.html#unicode">Unicode
       * code units</a> in the string.
       *
       * @return  the length of the sequence of characters represented by this
       *          object.
       */
      public int length() {
          // BEGIN Android-changed: Get length from count field rather than value array (see above).
          // return value.length;
          final boolean STRING_COMPRESSION_ENABLED = true;
          if (STRING_COMPRESSION_ENABLED) {
              // For the compression purposes (save the characters as 8-bit if all characters
              // are ASCII), the least significant bit of "count" is used as the compression flag.
              return (count >>> 1);
          } else {
              return count;
          }
          // END Android-changed: Get length from count field rather than value array (see above).
      }
  
      /**
       * Returns {@code true} if, and only if, {@link #length()} is {@code 0}.
       *
       * @return {@code true} if {@link #length()} is {@code 0}, otherwise
       * {@code false}
       *
       * @since 1.6
       */
      public boolean isEmpty() {
          // Android-changed: Get length from count field rather than value array (see above).
          // Empty string has {@code count == 0} with or without string compression enabled.
          // return value.length == 0;
          return count == 0;
      }
  
      /**
       * Returns the {@code char} value at the
       * specified index. An index ranges from {@code 0} to
       * {@code length() - 1}. The first {@code char} value of the sequence
       * is at index {@code 0}, the next at index {@code 1},
       * and so on, as for array indexing.
       *
       * <p>If the {@code char} value specified by the index is a
       * <a href="Character.html#unicode">surrogate</a>, the surrogate
       * value is returned.
       *
       * @param      index   the index of the {@code char} value.
       * @return     the {@code char} value at the specified index of this string.
       *             The first {@code char} value is at index {@code 0}.
       * @exception  IndexOutOfBoundsException  if the {@code index}
       *             argument is negative or not less than the length of this
       *             string.
       */
      // BEGIN Android-changed: Replace with implementation in runtime to access chars (see above).
      @FastNative
      public native char charAt(int index);
      // END Android-changed: Replace with implementation in runtime to access chars (see above).
  
      /**
       * Returns the character (Unicode code point) at the specified
       * index. The index refers to {@code char} values
       * (Unicode code units) and ranges from {@code 0} to
       * {@link #length()}{@code  - 1}.
       *
       * <p> If the {@code char} value specified at the given index
       * is in the high-surrogate range, the following index is less
       * than the length of this {@code String}, and the
       * {@code char} value at the following index is in the
       * low-surrogate range, then the supplementary code point
       * corresponding to this surrogate pair is returned. Otherwise,
       * the {@code char} value at the given index is returned.
       *
       * @param      index the index to the {@code char} values
       * @return     the code point value of the character at the
       *             {@code index}
       * @exception  IndexOutOfBoundsException  if the {@code index}
       *             argument is negative or not less than the length of this
       *             string.
       * @since      1.5
       */
      public int codePointAt(int index) {
          if ((index < 0) || (index >= length())) {
              throw new StringIndexOutOfBoundsException(index);
          }
          // Android-changed: Skip codePointAtImpl optimization that needs access to java chars.
          return Character.codePointAt(this, index);
      }
  
      /**
       * Returns the character (Unicode code point) before the specified
       * index. The index refers to {@code char} values
       * (Unicode code units) and ranges from {@code 1} to {@link
       * CharSequence#length() length}.
       *
       * <p> If the {@code char} value at {@code (index - 1)}
       * is in the low-surrogate range, {@code (index - 2)} is not
       * negative, and the {@code char} value at {@code (index -
       * 2)} is in the high-surrogate range, then the
       * supplementary code point value of the surrogate pair is
       * returned. If the {@code char} value at {@code index -
       * 1} is an unpaired low-surrogate or a high-surrogate, the
       * surrogate value is returned.
       *
       * @param     index the index following the code point that should be returned
       * @return    the Unicode code point value before the given index.
       * @exception IndexOutOfBoundsException if the {@code index}
       *            argument is less than 1 or greater than the length
       *            of this string.
       * @since     1.5
       */
      public int codePointBefore(int index) {
          int i = index - 1;
          if ((i < 0) || (i >= length())) {
              throw new StringIndexOutOfBoundsException(index);
          }
          // Android-changed: Skip codePointBeforeImpl optimization that needs access to java chars.
          return Character.codePointBefore(this, index);
      }
  
      /**
       * Returns the number of Unicode code points in the specified text
       * range of this {@code String}. The text range begins at the
       * specified {@code beginIndex} and extends to the
       * {@code char} at index {@code endIndex - 1}. Thus the
       * length (in {@code char}s) of the text range is
       * {@code endIndex-beginIndex}. Unpaired surrogates within
       * the text range count as one code point each.
       *
       * @param beginIndex the index to the first {@code char} of
       * the text range.
       * @param endIndex the index after the last {@code char} of
       * the text range.
       * @return the number of Unicode code points in the specified text
       * range
       * @exception IndexOutOfBoundsException if the
       * {@code beginIndex} is negative, or {@code endIndex}
       * is larger than the length of this {@code String}, or
       * {@code beginIndex} is larger than {@code endIndex}.
       * @since  1.5
       */
      public int codePointCount(int beginIndex, int endIndex) {
          if (beginIndex < 0 || endIndex > length() || beginIndex > endIndex) {
              throw new IndexOutOfBoundsException();
          }
          // Android-changed: Skip codePointCountImpl optimization that needs access to java chars.
          return Character.codePointCount(this, beginIndex, endIndex);
      }
  
      /**
       * Returns the index within this {@code String} that is
       * offset from the given {@code index} by
       * {@code codePointOffset} code points. Unpaired surrogates
       * within the text range given by {@code index} and
       * {@code codePointOffset} count as one code point each.
       *
       * @param index the index to be offset
       * @param codePointOffset the offset in code points
       * @return the index within this {@code String}
       * @exception IndexOutOfBoundsException if {@code index}
       *   is negative or larger then the length of this
       *   {@code String}, or if {@code codePointOffset} is positive
       *   and the substring starting with {@code index} has fewer
       *   than {@code codePointOffset} code points,
       *   or if {@code codePointOffset} is negative and the substring
       *   before {@code index} has fewer than the absolute value
       *   of {@code codePointOffset} code points.
       * @since 1.5
       */
      public int offsetByCodePoints(int index, int codePointOffset) {
          if (index < 0 || index > length()) {
              throw new IndexOutOfBoundsException();
          }
          // Android-changed: Skip offsetByCodePointsImpl optimization that needs access to java chars
          return Character.offsetByCodePoints(this, index, codePointOffset);
      }
  
      /**
       * Copy characters from this string into dst starting at dstBegin.
       * This method doesn't perform any range checking.
       */
      void getChars(char dst[], int dstBegin) {
          // Android-changed: Replace arraycopy with native call since chars are managed by runtime.
          getCharsNoCheck(0, length(), dst, dstBegin);
      }
  
      /**
       * Copies characters from this string into the destination character
       * array.
       * <p>
       * The first character to be copied is at index {@code srcBegin};
       * the last character to be copied is at index {@code srcEnd-1}
       * (thus the total number of characters to be copied is
       * {@code srcEnd-srcBegin}). The characters are copied into the
       * subarray of {@code dst} starting at index {@code dstBegin}
       * and ending at index:
       * <blockquote><pre>
       *     dstBegin + (srcEnd-srcBegin) - 1
       * </pre></blockquote>
       *
       * @param      srcBegin   index of the first character in the string
       *                        to copy.
       * @param      srcEnd     index after the last character in the string
       *                        to copy.
       * @param      dst        the destination array.
       * @param      dstBegin   the start offset in the destination array.
       * @exception IndexOutOfBoundsException If any of the following
       *            is true:
       *            <ul><li>{@code srcBegin} is negative.
       *            <li>{@code srcBegin} is greater than {@code srcEnd}
       *            <li>{@code srcEnd} is greater than the length of this
       *                string
       *            <li>{@code dstBegin} is negative
       *            <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than
       *                {@code dst.length}</ul>
       */
      public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
          // BEGIN Android-changed: Implement in terms of length() and native getCharsNoCheck method.
          if (dst == null) {
              throw new NullPointerException("dst == null");
          }
  
          if (srcBegin < 0) {
              throw new StringIndexOutOfBoundsException(this, srcBegin);
          }
          if (srcEnd > length()) {
              throw new StringIndexOutOfBoundsException(this, srcEnd);
          }
  
          int n = srcEnd - srcBegin;
          if (srcEnd < srcBegin) {
              throw new StringIndexOutOfBoundsException(this, srcBegin, n);
          }
  
          if (dstBegin < 0) {
              throw new ArrayIndexOutOfBoundsException("dstBegin < 0. dstBegin=" + dstBegin);
          }
          // dstBegin can be equal to dst.length, but only in the case where zero chars are to be
          // copied.
          if (dstBegin > dst.length) {
              throw new ArrayIndexOutOfBoundsException(
                      "dstBegin > dst.length. dstBegin=" + dstBegin + ", dst.length=" + dst.length);
          }
          if (n > dst.length - dstBegin) {
              throw new ArrayIndexOutOfBoundsException(
                      "n > dst.length - dstBegin. n=" + n + ", dst.length=" + dst.length
                              + "dstBegin=" + dstBegin);
          }
  
          getCharsNoCheck(srcBegin, srcEnd, dst, dstBegin);
          // END Android-changed: Implement in terms of length() and native getCharsNoCheck method.
      }
  
      // BEGIN Android-added: Native method to access char storage managed by runtime.
      /**
       * getChars without bounds checks, for use by other classes
       * within the java.lang package only.  The caller is responsible for
       * ensuring that start >= 0 && start <= end && end <= count.
       */
      @FastNative
      native void getCharsNoCheck(int start, int end, char[] buffer, int index);
      // END Android-added: Native method to access char storage managed by runtime.
  
      /**
       * Copies characters from this string into the destination byte array. Each
       * byte receives the 8 low-order bits of the corresponding character. The
       * eight high-order bits of each character are not copied and do not
       * participate in the transfer in any way.
       *
       * <p> The first character to be copied is at index {@code srcBegin}; the
       * last character to be copied is at index {@code srcEnd-1}.  The total
       * number of characters to be copied is {@code srcEnd-srcBegin}. The
       * characters, converted to bytes, are copied into the subarray of {@code
       * dst} starting at index {@code dstBegin} and ending at index:
       *
       * <blockquote><pre>
       *     dstBegin + (srcEnd-srcBegin) - 1
       * </pre></blockquote>
       *
       * @deprecated  This method does not properly convert characters into
       * bytes.  As of JDK&nbsp;1.1, the preferred way to do this is via the
       * {@link #getBytes()} method, which uses the platform's default charset.
       *
       * @param  srcBegin
       *         Index of the first character in the string to copy
       *
       * @param  srcEnd
       *         Index after the last character in the string to copy
       *
       * @param  dst
       *         The destination array
       *
       * @param  dstBegin
       *         The start offset in the destination array
       *
       * @throws  IndexOutOfBoundsException
       *          If any of the following is true:
       *          <ul>
       *            <li> {@code srcBegin} is negative
       *            <li> {@code srcBegin} is greater than {@code srcEnd}
       *            <li> {@code srcEnd} is greater than the length of this String
       *            <li> {@code dstBegin} is negative
       *            <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
       *                 dst.length}
       *          </ul>
       */
      @Deprecated
      public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
          if (srcBegin < 0) {
              throw new StringIndexOutOfBoundsException(this, srcBegin);
          }
          if (srcEnd > length()) {
              throw new StringIndexOutOfBoundsException(this, srcEnd);
          }
          if (srcBegin > srcEnd) {
              throw new StringIndexOutOfBoundsException(this, srcEnd - srcBegin);
          }
  
          int j = dstBegin;
          int n = srcEnd;
          int i = srcBegin;
  
          while (i < n) {
              dst[j++] = (byte)charAt(i++);
          }
      }
  
      /**
       * Encodes this {@code String} into a sequence of bytes using the named
       * charset, storing the result into a new byte array.
       *
       * <p> The behavior of this method when this string cannot be encoded in
       * the given charset is unspecified.  The {@link
       * java.nio.charset.CharsetEncoder} class should be used when more control
       * over the encoding process is required.
       *
       * @param  charsetName
       *         The name of a supported {@linkplain Charset
       *         charset}
       *
       * @return  The resultant byte array
       *
       * @throws  UnsupportedEncodingException
       *          If the named charset is not supported
       *
       * @since  JDK1.1
       */
      public byte[] getBytes(String charsetName)
              throws UnsupportedEncodingException {
          if (charsetName == null) throw new NullPointerException();
          // Android-changed: Skip StringCoding optimization that needs access to java chars.
          // return StringCoding.encode(charsetName, value, 0, value.length);
          return getBytes(Charset.forNameUEE(charsetName));
      }
  
      /**
       * Encodes this {@code String} into a sequence of bytes using the given
       * {@linkplain Charset charset}, storing the result into a
       * new byte array.
       *
       * <p> This method always replaces malformed-input and unmappable-character
       * sequences with this charset's default replacement byte array.  The
       * {@link java.nio.charset.CharsetEncoder} class should be used when more
       * control over the encoding process is required.
       *
       * @param  charset
       *         The {@linkplain Charset} to be used to encode
       *         the {@code String}
       *
       * @return  The resultant byte array
       *
       * @since  1.6
       */
      public byte[] getBytes(Charset charset) {
          // BEGIN Android-changed: Skip StringCoding optimization that needs access to java chars.
          // if (charset == null) throw new NullPointerException();
          // return StringCoding.encode(charset, value, 0, value.length);
          if (charset == null) {
              throw new NullPointerException("charset == null");
          }
  
          final int len = length();
          final String name = charset.name();
          if ("UTF-8".equals(name)) {
              return CharsetUtils.toUtf8Bytes(this, 0, len);
          } else if ("ISO-8859-1".equals(name)) {
              return CharsetUtils.toIsoLatin1Bytes(this, 0, len);
          } else if ("US-ASCII".equals(name)) {
              return CharsetUtils.toAsciiBytes(this, 0, len);
          } else if ("UTF-16BE".equals(name)) {
              return CharsetUtils.toBigEndianUtf16Bytes(this, 0, len);
          }
  
          ByteBuffer buffer = charset.encode(this);
          byte[] bytes = new byte[buffer.limit()];
          buffer.get(bytes);
          return bytes;
          // END Android-changed: Skip StringCoding optimization that needs access to java chars.
      }
  
      /**
       * Encodes this {@code String} into a sequence of bytes using the
       * platform's default charset, storing the result into a new byte array.
       *
       * <p> The behavior of this method when this string cannot be encoded in
       * the default charset is unspecified.  The {@link
       * java.nio.charset.CharsetEncoder} class should be used when more control
       * over the encoding process is required.
       *
       * @return  The resultant byte array
       *
       * @since      JDK1.1
       */
      public byte[] getBytes() {
          // Android-changed: Skip StringCoding optimization that needs access to java chars.
          // return StringCoding.encode(value, 0, value.length);
          return getBytes(Charset.defaultCharset());
      }
  
      /**
       * Compares this string to the specified object.  The result is {@code
       * true} if and only if the argument is not {@code null} and is a {@code
       * String} object that represents the same sequence of characters as this
       * object.
       *
       * @param  anObject
       *         The object to compare this {@code String} against
       *
       * @return  {@code true} if the given object represents a {@code String}
       *          equivalent to this string, {@code false} otherwise
       *
       * @see  #compareTo(String)
       * @see  #equalsIgnoreCase(String)
       */
      public boolean equals(Object anObject) {
          if (this == anObject) {
              return true;
          }
          if (anObject instanceof String) {
              String anotherString = (String)anObject;
              int n = length();
              if (n == anotherString.length()) {
                  int i = 0;
                  while (n-- != 0) {
                      if (charAt(i) != anotherString.charAt(i))
                              return false;
                      i++;
                  }
                  return true;
              }
          }
          return false;
      }
  
      /**
       * Compares this string to the specified {@code StringBuffer}.  The result
       * is {@code true} if and only if this {@code String} represents the same
       * sequence of characters as the specified {@code StringBuffer}. This method
       * synchronizes on the {@code StringBuffer}.
       *
       * @param  sb
       *         The {@code StringBuffer} to compare this {@code String} against
       *
       * @return  {@code true} if this {@code String} represents the same
       *          sequence of characters as the specified {@code StringBuffer},
       *          {@code false} otherwise
       *
       * @since  1.4
       */
      public boolean contentEquals(StringBuffer sb) {
          return contentEquals((CharSequence)sb);
      }
  
      private boolean nonSyncContentEquals(AbstractStringBuilder sb) {
          char v2[] = sb.getValue();
          int n = length();
          if (n != sb.length()) {
              return false;
          }
          for (int i = 0; i < n; i++) {
              if (charAt(i) != v2[i]) {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * Compares this string to the specified {@code CharSequence}.  The
       * result is {@code true} if and only if this {@code String} represents the
       * same sequence of char values as the specified sequence. Note that if the
       * {@code CharSequence} is a {@code StringBuffer} then the method
       * synchronizes on it.
       *
       * @param  cs
       *         The sequence to compare this {@code String} against
       *
       * @return  {@code true} if this {@code String} represents the same
       *          sequence of char values as the specified sequence, {@code
       *          false} otherwise
       *
       * @since  1.5
       */
      public boolean contentEquals(CharSequence cs) {
          // Argument is a StringBuffer, StringBuilder
          if (cs instanceof AbstractStringBuilder) {
              if (cs instanceof StringBuffer) {
                  synchronized(cs) {
                     return nonSyncContentEquals((AbstractStringBuilder)cs);
                  }
              } else {
                  return nonSyncContentEquals((AbstractStringBuilder)cs);
              }
          }
          // Argument is a String
          if (cs instanceof String) {
              return equals(cs);
          }
          // Argument is a generic CharSequence
          int n = length();
          if (n != cs.length()) {
              return false;
          }
          for (int i = 0; i < n; i++) {
              if (charAt(i) != cs.charAt(i)) {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * Compares this {@code String} to another {@code String}, ignoring case
       * considerations.  Two strings are considered equal ignoring case if they
       * are of the same length and corresponding characters in the two strings
       * are equal ignoring case.
       *
       * <p> Two characters {@code c1} and {@code c2} are considered the same
       * ignoring case if at least one of the following is true:
       * <ul>
       *   <li> The two characters are the same (as compared by the
       *        {@code ==} operator)
       *   <li> Applying the method {@link
       *        Character#toUpperCase(char)} to each character
       *        produces the same result
       *   <li> Applying the method {@link
       *        Character#toLowerCase(char)} to each character
       *        produces the same result
       * </ul>
       *
       * @param  anotherString
       *         The {@code String} to compare this {@code String} against
       *
       * @return  {@code true} if the argument is not {@code null} and it
       *          represents an equivalent {@code String} ignoring case; {@code
       *          false} otherwise
       *
       * @see  #equals(Object)
       */
      public boolean equalsIgnoreCase(String anotherString) {
          final int len = length();
          return (this == anotherString) ? true
                  : (anotherString != null)
                  && (anotherString.length() == len)
                  && regionMatches(true, 0, anotherString, 0, len);
      }
  
      /**
       * Compares two strings lexicographically.
       * The comparison is based on the Unicode value of each character in
       * the strings. The character sequence represented by this
       * {@code String} object is compared lexicographically to the
       * character sequence represented by the argument string. The result is
       * a negative integer if this {@code String} object
       * lexicographically precedes the argument string. The result is a
       * positive integer if this {@code String} object lexicographically
       * follows the argument string. The result is zero if the strings
       * are equal; {@code compareTo} returns {@code 0} exactly when
       * the {@link #equals(Object)} method would return {@code true}.
       * <p>
       * This is the definition of lexicographic ordering. If two strings are
       * different, then either they have different characters at some index
       * that is a valid index for both strings, or their lengths are different,
       * or both. If they have different characters at one or more index
       * positions, let <i>k</i> be the smallest such index; then the string
       * whose character at position <i>k</i> has the smaller value, as
       * determined by using the &lt; operator, lexicographically precedes the
       * other string. In this case, {@code compareTo} returns the
       * difference of the two character values at position {@code k} in
       * the two string -- that is, the value:
       * <blockquote><pre>
       * this.charAt(k)-anotherString.charAt(k)
       * </pre></blockquote>
       * If there is no index position at which they differ, then the shorter
       * string lexicographically precedes the longer string. In this case,
       * {@code compareTo} returns the difference of the lengths of the
       * strings -- that is, the value:
       * <blockquote><pre>
       * this.length()-anotherString.length()
       * </pre></blockquote>
       *
       * @param   anotherString   the {@code String} to be compared.
       * @return  the value {@code 0} if the argument string is equal to
       *          this string; a value less than {@code 0} if this string
       *          is lexicographically less than the string argument; and a
       *          value greater than {@code 0} if this string is
       *          lexicographically greater than the string argument.
       */
      // BEGIN Android-changed: Replace with implementation in runtime to access chars (see above).
      @FastNative
      public native int compareTo(String anotherString);
      // END Android-changed: Replace with implementation in runtime to access chars (see above).
  
      /**
       * A Comparator that orders {@code String} objects as by
       * {@code compareToIgnoreCase}. This comparator is serializable.
       * <p>
       * Note that this Comparator does <em>not</em> take locale into account,
       * and will result in an unsatisfactory ordering for certain locales.
       * The java.text package provides <em>Collators</em> to allow
       * locale-sensitive ordering.
       *
       * @see     java.text.Collator#compare(String, String)
       * @since   1.2
       */
      public static final Comparator<String> CASE_INSENSITIVE_ORDER
                                           = new CaseInsensitiveComparator();
      private static class CaseInsensitiveComparator
              implements Comparator<String>, java.io.Serializable {
          // use serialVersionUID from JDK 1.2.2 for interoperability
          private static final long serialVersionUID = 8575799808933029326L;
  
          public int compare(String s1, String s2) {
              int n1 = s1.length();
              int n2 = s2.length();
              int min = Math.min(n1, n2);
              for (int i = 0; i < min; i++) {
                  char c1 = s1.charAt(i);
                  char c2 = s2.charAt(i);
                  if (c1 != c2) {
                      c1 = Character.toUpperCase(c1);
                      c2 = Character.toUpperCase(c2);
                      if (c1 != c2) {
                          c1 = Character.toLowerCase(c1);
                          c2 = Character.toLowerCase(c2);
                          if (c1 != c2) {
                              // No overflow because of numeric promotion
                              return c1 - c2;
                          }
                      }
                  }
              }
              return n1 - n2;
          }
  
          /** Replaces the de-serialized object. */
          private Object readResolve() { return CASE_INSENSITIVE_ORDER; }
      }
  
      /**
       * Compares two strings lexicographically, ignoring case
       * differences. This method returns an integer whose sign is that of
       * calling {@code compareTo} with normalized versions of the strings
       * where case differences have been eliminated by calling
       * {@code Character.toLowerCase(Character.toUpperCase(character))} on
       * each character.
       * <p>
       * Note that this method does <em>not</em> take locale into account,
       * and will result in an unsatisfactory ordering for certain locales.
       * The java.text package provides <em>collators</em> to allow
       * locale-sensitive ordering.
       *
       * @param   str   the {@code String} to be compared.
       * @return  a negative integer, zero, or a positive integer as the
       *          specified String is greater than, equal to, or less
       *          than this String, ignoring case considerations.
       * @see     java.text.Collator#compare(String, String)
       * @since   1.2
       */
      public int compareToIgnoreCase(String str) {
          return CASE_INSENSITIVE_ORDER.compare(this, str);
      }
  
      /**
       * Tests if two string regions are equal.
       * <p>
       * A substring of this {@code String} object is compared to a substring
       * of the argument other. The result is true if these substrings
       * represent identical character sequences. The substring of this
       * {@code String} object to be compared begins at index {@code toffset}
       * and has length {@code len}. The substring of other to be compared
       * begins at index {@code ooffset} and has length {@code len}. The
       * result is {@code false} if and only if at least one of the following
       * is true:
       * <ul><li>{@code toffset} is negative.
       * <li>{@code ooffset} is negative.
       * <li>{@code toffset+len} is greater than the length of this
       * {@code String} object.
       * <li>{@code ooffset+len} is greater than the length of the other
       * argument.
       * <li>There is some nonnegative integer <i>k</i> less than {@code len}
       * such that:
       * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + }
       * <i>k</i>{@code )}
       * </ul>
       *
       * @param   toffset   the starting offset of the subregion in this string.
       * @param   other     the string argument.
       * @param   ooffset   the starting offset of the subregion in the string
       *                    argument.
       * @param   len       the number of characters to compare.
       * @return  {@code true} if the specified subregion of this string
       *          exactly matches the specified subregion of the string argument;
       *          {@code false} otherwise.
       */
      public boolean regionMatches(int toffset, String other, int ooffset,
              int len) {
          int to = toffset;
          int po = ooffset;
          // Note: toffset, ooffset, or len might be near -1>>>1.
          if ((ooffset < 0) || (toffset < 0)
                  || (toffset > (long)length() - len)
                  || (ooffset > (long)other.length() - len)) {
              return false;
          }
          while (len-- > 0) {
              if (charAt(to++) != other.charAt(po++)) {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * Tests if two string regions are equal.
       * <p>
       * A substring of this {@code String} object is compared to a substring
       * of the argument {@code other}. The result is {@code true} if these
       * substrings represent character sequences that are the same, ignoring
       * case if and only if {@code ignoreCase} is true. The substring of
       * this {@code String} object to be compared begins at index
       * {@code toffset} and has length {@code len}. The substring of
       * {@code other} to be compared begins at index {@code ooffset} and
       * has length {@code len}. The result is {@code false} if and only if
       * at least one of the following is true:
       * <ul><li>{@code toffset} is negative.
       * <li>{@code ooffset} is negative.
       * <li>{@code toffset+len} is greater than the length of this
       * {@code String} object.
       * <li>{@code ooffset+len} is greater than the length of the other
       * argument.
       * <li>{@code ignoreCase} is {@code false} and there is some nonnegative
       * integer <i>k</i> less than {@code len} such that:
       * <blockquote><pre>
       * this.charAt(toffset+k) != other.charAt(ooffset+k)
       * </pre></blockquote>
       * <li>{@code ignoreCase} is {@code true} and there is some nonnegative
       * integer <i>k</i> less than {@code len} such that:
       * <blockquote><pre>
       * Character.toLowerCase(this.charAt(toffset+k)) !=
       Character.toLowerCase(other.charAt(ooffset+k))
       * </pre></blockquote>
       * and:
       * <blockquote><pre>
       * Character.toUpperCase(this.charAt(toffset+k)) !=
       *         Character.toUpperCase(other.charAt(ooffset+k))
       * </pre></blockquote>
       * </ul>
       *
       * @param   ignoreCase   if {@code true}, ignore case when comparing
       *                       characters.
       * @param   toffset      the starting offset of the subregion in this
       *                       string.
       * @param   other        the string argument.
       * @param   ooffset      the starting offset of the subregion in the string
       *                       argument.
       * @param   len          the number of characters to compare.
       * @return  {@code true} if the specified subregion of this string
       *          matches the specified subregion of the string argument;
       *          {@code false} otherwise. Whether the matching is exact
       *          or case insensitive depends on the {@code ignoreCase}
       *          argument.
       */
      public boolean regionMatches(boolean ignoreCase, int toffset,
              String other, int ooffset, int len) {
          int to = toffset;
          int po = ooffset;
          // Note: toffset, ooffset, or len might be near -1>>>1.
          if ((ooffset < 0) || (toffset < 0)
                  || (toffset > (long)length() - len)
                  || (ooffset > (long)other.length() - len)) {
              return false;
          }
          while (len-- > 0) {
              char c1 = charAt(to++);
              char c2 = other.charAt(po++);
              if (c1 == c2) {
                  continue;
              }
              if (ignoreCase) {
                  // If characters don't match but case may be ignored,
                  // try converting both characters to uppercase.
                  // If the results match, then the comparison scan should
                  // continue.
                  char u1 = Character.toUpperCase(c1);
                  char u2 = Character.toUpperCase(c2);
                  if (u1 == u2) {
                      continue;
                  }
                  // Unfortunately, conversion to uppercase does not work properly
                  // for the Georgian alphabet, which has strange rules about case
                  // conversion.  So we need to make one last check before
                  // exiting.
                  if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
                      continue;
                  }
              }
              return false;
          }
          return true;
      }
  
      /**
       * Tests if the substring of this string beginning at the
       * specified index starts with the specified prefix.
       *
       * @param   prefix    the prefix.
       * @param   toffset   where to begin looking in this string.
       * @return  {@code true} if the character sequence represented by the
       *          argument is a prefix of the substring of this object starting
       *          at index {@code toffset}; {@code false} otherwise.
       *          The result is {@code false} if {@code toffset} is
       *          negative or greater than the length of this
       *          {@code String} object; otherwise the result is the same
       *          as the result of the expression
       *          <pre>
       *          this.substring(toffset).startsWith(prefix)
       *          </pre>
       */
      public boolean startsWith(String prefix, int toffset) {
          int to = toffset;
          int po = 0;
          int pc = prefix.length();
          // Note: toffset might be near -1>>>1.
          if ((toffset < 0) || (toffset > length() - pc)) {
              return false;
          }
          while (--pc >= 0) {
              if (charAt(to++) != prefix.charAt(po++)) {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * Tests if this string starts with the specified prefix.
       *
       * @param   prefix   the prefix.
       * @return  {@code true} if the character sequence represented by the
       *          argument is a prefix of the character sequence represented by
       *          this string; {@code false} otherwise.
       *          Note also that {@code true} will be returned if the
       *          argument is an empty string or is equal to this
       *          {@code String} object as determined by the
       *          {@link #equals(Object)} method.
       * @since   1. 0
       */
      public boolean startsWith(String prefix) {
          return startsWith(prefix, 0);
      }
  
      /**
       * Tests if this string ends with the specified suffix.
       *
       * @param   suffix   the suffix.
       * @return  {@code true} if the character sequence represented by the
       *          argument is a suffix of the character sequence represented by
       *          this object; {@code false} otherwise. Note that the
       *          result will be {@code true} if the argument is the
       *          empty string or is equal to this {@code String} object
       *          as determined by the {@link #equals(Object)} method.
       */
      public boolean endsWith(String suffix) {
          return startsWith(suffix, length() - suffix.length());
      }
  
      /**
       * Returns a hash code for this string. The hash code for a
       * {@code String} object is computed as
       * <blockquote><pre>
       * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
       * </pre></blockquote>
       * using {@code int} arithmetic, where {@code s[i]} is the
       * <i>i</i>th character of the string, {@code n} is the length of
       * the string, and {@code ^} indicates exponentiation.
       * (The hash value of the empty string is zero.)
       *
       * @return  a hash code value for this object.
       */
      public int hashCode() {
          int h = hash;
          final int len = length();
          if (h == 0 && len > 0) {
              for (int i = 0; i < len; i++) {
                  h = 31 * h + charAt(i);
              }
              hash = h;
          }
          return h;
      }
  
      /**
       * Returns the index within this string of the first occurrence of
       * the specified character. If a character with value
       * {@code ch} occurs in the character sequence represented by
       * this {@code String} object, then the index (in Unicode
       * code units) of the first such occurrence is returned. For
       * values of {@code ch} in the range from 0 to 0xFFFF
       * (inclusive), this is the smallest value <i>k</i> such that:
       * <blockquote><pre>
       * this.charAt(<i>k</i>) == ch
       * </pre></blockquote>
       * is true. For other values of {@code ch}, it is the
       * smallest value <i>k</i> such that:
       * <blockquote><pre>
       * this.codePointAt(<i>k</i>) == ch
       * </pre></blockquote>
       * is true. In either case, if no such character occurs in this
       * string, then {@code -1} is returned.
       *
       * @param   ch   a character (Unicode code point).
       * @return  the index of the first occurrence of the character in the
       *          character sequence represented by this object, or
       *          {@code -1} if the character does not occur.
       */
      public int indexOf(int ch) {
          return indexOf(ch, 0);
      }
  
      /**
       * Returns the index within this string of the first occurrence of the
       * specified character, starting the search at the specified index.
       * <p>
       * If a character with value {@code ch} occurs in the
       * character sequence represented by this {@code String}
       * object at an index no smaller than {@code fromIndex}, then
       * the index of the first such occurrence is returned. For values
       * of {@code ch} in the range from 0 to 0xFFFF (inclusive),
       * this is the smallest value <i>k</i> such that:
       * <blockquote><pre>
       * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &gt;= fromIndex)
       * </pre></blockquote>
       * is true. For other values of {@code ch}, it is the
       * smallest value <i>k</i> such that:
       * <blockquote><pre>
       * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &gt;= fromIndex)
       * </pre></blockquote>
       * is true. In either case, if no such character occurs in this
       * string at or after position {@code fromIndex}, then
       * {@code -1} is returned.
       *
       * <p>
       * There is no restriction on the value of {@code fromIndex}. If it
       * is negative, it has the same effect as if it were zero: this entire
       * string may be searched. If it is greater than the length of this
       * string, it has the same effect as if it were equal to the length of
       * this string: {@code -1} is returned.
       *
       * <p>All indices are specified in {@code char} values
       * (Unicode code units).
       *
       * @param   ch          a character (Unicode code point).
       * @param   fromIndex   the index to start the search from.
       * @return  the index of the first occurrence of the character in the
       *          character sequence represented by this object that is greater
       *          than or equal to {@code fromIndex}, or {@code -1}
       *          if the character does not occur.
       */
      public int indexOf(int ch, int fromIndex) {
          final int max = length();
          if (fromIndex < 0) {
              fromIndex = 0;
          } else if (fromIndex >= max) {
              // Note: fromIndex might be near -1>>>1.
              return -1;
          }
  
          if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
              // handle most cases here (ch is a BMP code point or a
              // negative value (invalid code point))
              for (int i = fromIndex; i < max; i++) {
                  if (charAt(i) == ch) {
                      return i;
                  }
              }
              return -1;
          } else {
              return indexOfSupplementary(ch, fromIndex);
          }
      }
  
      /**
       * Handles (rare) calls of indexOf with a supplementary character.
       */
      private int indexOfSupplementary(int ch, int fromIndex) {
          if (Character.isValidCodePoint(ch)) {
              final char hi = Character.highSurrogate(ch);
              final char lo = Character.lowSurrogate(ch);
              final int max = length() - 1;
              for (int i = fromIndex; i < max; i++) {
                  if (charAt(i) == hi && charAt(i + 1) == lo) {
                      return i;
                  }
              }
          }
          return -1;
      }
  
      /**
       * Returns the index within this string of the last occurrence of
       * the specified character. For values of {@code ch} in the
       * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
       * units) returned is the largest value <i>k</i> such that:
       * <blockquote><pre>
       * this.charAt(<i>k</i>) == ch
       * </pre></blockquote>
       * is true. For other values of {@code ch}, it is the
       * largest value <i>k</i> such that:
       * <blockquote><pre>
       * this.codePointAt(<i>k</i>) == ch
       * </pre></blockquote>
       * is true.  In either case, if no such character occurs in this
       * string, then {@code -1} is returned.  The
       * {@code String} is searched backwards starting at the last
       * character.
       *
       * @param   ch   a character (Unicode code point).
       * @return  the index of the last occurrence of the character in the
       *          character sequence represented by this object, or
       *          {@code -1} if the character does not occur.
       */
      public int lastIndexOf(int ch) {
          return lastIndexOf(ch, length() - 1);
      }
  
      /**
       * Returns the index within this string of the last occurrence of
       * the specified character, searching backward starting at the
       * specified index. For values of {@code ch} in the range
       * from 0 to 0xFFFF (inclusive), the index returned is the largest
       * value <i>k</i> such that:
       * <blockquote><pre>
       * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &lt;= fromIndex)
       * </pre></blockquote>
       * is true. For other values of {@code ch}, it is the
       * largest value <i>k</i> such that:
       * <blockquote><pre>
       * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &lt;= fromIndex)
       * </pre></blockquote>
       * is true. In either case, if no such character occurs in this
       * string at or before position {@code fromIndex}, then
       * {@code -1} is returned.
       *
       * <p>All indices are specified in {@code char} values
       * (Unicode code units).
       *
       * @param   ch          a character (Unicode code point).
       * @param   fromIndex   the index to start the search from. There is no
       *          restriction on the value of {@code fromIndex}. If it is
       *          greater than or equal to the length of this string, it has
       *          the same effect as if it were equal to one less than the
       *          length of this string: this entire string may be searched.
       *          If it is negative, it has the same effect as if it were -1:
       *          -1 is returned.
       * @return  the index of the last occurrence of the character in the
       *          character sequence represented by this object that is less
       *          than or equal to {@code fromIndex}, or {@code -1}
       *          if the character does not occur before that point.
       */
      public int lastIndexOf(int ch, int fromIndex) {
          if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
              // handle most cases here (ch is a BMP code point or a
              // negative value (invalid code point))
              int i = Math.min(fromIndex, length() - 1);
              for (; i >= 0; i--) {
                  if (charAt(i) == ch) {
                      return i;
                  }
              }
              return -1;
          } else {
              return lastIndexOfSupplementary(ch, fromIndex);
          }
      }
  
      /**
       * Handles (rare) calls of lastIndexOf with a supplementary character.
       */
      private int lastIndexOfSupplementary(int ch, int fromIndex) {
          if (Character.isValidCodePoint(ch)) {
              char hi = Character.highSurrogate(ch);
              char lo = Character.lowSurrogate(ch);
              int i = Math.min(fromIndex, length() - 2);
              for (; i >= 0; i--) {
                  if (charAt(i) == hi && charAt(i + 1) == lo) {
                      return i;
                  }
              }
          }
          return -1;
      }
  
      /**
       * Returns the index within this string of the first occurrence of the
       * specified substring.
       *
       * <p>The returned index is the smallest value <i>k</i> for which:
       * <blockquote><pre>
       * this.startsWith(str, <i>k</i>)
       * </pre></blockquote>
       * If no such value of <i>k</i> exists, then {@code -1} is returned.
       *
       * @param   str   the substring to search for.
       * @return  the index of the first occurrence of the specified substring,
       *          or {@code -1} if there is no such occurrence.
       */
      public int indexOf(String str) {
          return indexOf(str, 0);
      }
  
      /**
       * Returns the index within this string of the first occurrence of the
       * specified substring, starting at the specified index.
       *
       * <p>The returned index is the smallest value <i>k</i> for which:
       * <blockquote><pre>
       * <i>k</i> &gt;= fromIndex {@code &&} this.startsWith(str, <i>k</i>)
       * </pre></blockquote>
       * If no such value of <i>k</i> exists, then {@code -1} is returned.
       *
       * @param   str         the substring to search for.
       * @param   fromIndex   the index from which to start the search.
       * @return  the index of the first occurrence of the specified substring,
       *          starting at the specified index,
       *          or {@code -1} if there is no such occurrence.
       */
      public int indexOf(String str, int fromIndex) {
          // Android-changed: Delegate to the static indexOf method below.
          return indexOf(this, str, fromIndex);
      }
  
      // BEGIN Android-added: Private static indexOf method that takes String parameters.
      // The use of length(), charAt(), etc. makes it more efficient for compressed strings.
      /**
       * The source is the string being searched, and the target is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   target       the characters being searched for.
       * @param   fromIndex    the index to begin searching from.
       */
      private static int indexOf(String source, String target, int fromIndex) {
          final int sourceLength = source.length();
          final int targetLength = target.length();
          if (fromIndex >= sourceLength) {
              return (targetLength == 0 ? sourceLength : -1);
          }
          if (fromIndex < 0) {
              fromIndex = 0;
          }
          if (targetLength == 0) {
              return fromIndex;
          }
  
          char first = target.charAt(0);
          int max = (sourceLength - targetLength);
  
          for (int i = fromIndex; i <= max; i++) {
              /* Look for first character. */
              if (source.charAt(i)!= first) {
                  while (++i <= max && source.charAt(i) != first);
              }
  
              /* Found first character, now look at the rest of v2 */
              if (i <= max) {
                  int j = i + 1;
                  int end = j + targetLength - 1;
                  for (int k = 1; j < end && source.charAt(j)
                           == target.charAt(k); j++, k++);
  
                  if (j == end) {
                      /* Found whole string. */
                      return i;
                  }
              }
          }
          return -1;
      }
      // END Android-added: Private static indexOf method that takes String parameters.
  
      /**
       * Code shared by String and AbstractStringBuilder to do searches. The
       * source is the character array being searched, and the target
       * is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   sourceOffset offset of the source string.
       * @param   sourceCount  count of the source string.
       * @param   target       the characters being searched for.
       * @param   fromIndex    the index to begin searching from.
       */
      static int indexOf(char[] source, int sourceOffset, int sourceCount,
              String target, int fromIndex) {
          return indexOf(source, sourceOffset, sourceCount,
                         target.toCharArray(), 0, target.length(),
                         fromIndex);
      }
  
      /**
       * Code shared by String and StringBuffer to do searches. The
       * source is the character array being searched, and the target
       * is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   sourceOffset offset of the source string.
       * @param   sourceCount  count of the source string.
       * @param   target       the characters being searched for.
       * @param   targetOffset offset of the target string.
       * @param   targetCount  count of the target string.
       * @param   fromIndex    the index to begin searching from.
       */
      static int indexOf(char[] source, int sourceOffset, int sourceCount,
              char[] target, int targetOffset, int targetCount,
              int fromIndex) {
          if (fromIndex >= sourceCount) {
              return (targetCount == 0 ? sourceCount : -1);
          }
          if (fromIndex < 0) {
              fromIndex = 0;
          }
          if (targetCount == 0) {
              return fromIndex;
          }
  
          char first = target[targetOffset];
          int max = sourceOffset + (sourceCount - targetCount);
  
          for (int i = sourceOffset + fromIndex; i <= max; i++) {
              /* Look for first character. */
              if (source[i] != first) {
                  while (++i <= max && source[i] != first);
              }
  
              /* Found first character, now look at the rest of v2 */
              if (i <= max) {
                  int j = i + 1;
                  int end = j + targetCount - 1;
                  for (int k = targetOffset + 1; j < end && source[j]
                          == target[k]; j++, k++);
  
                  if (j == end) {
                      /* Found whole string. */
                      return i - sourceOffset;
                  }
              }
          }
          return -1;
      }
  
      /**
       * Returns the index within this string of the last occurrence of the
       * specified substring.  The last occurrence of the empty string ""
       * is considered to occur at the index value {@code this.length()}.
       *
       * <p>The returned index is the largest value <i>k</i> for which:
       * <blockquote><pre>
       * this.startsWith(str, <i>k</i>)
       * </pre></blockquote>
       * If no such value of <i>k</i> exists, then {@code -1} is returned.
       *
       * @param   str   the substring to search for.
       * @return  the index of the last occurrence of the specified substring,
       *          or {@code -1} if there is no such occurrence.
       */
      public int lastIndexOf(String str) {
          return lastIndexOf(str, length());
      }
  
      /**
       * Returns the index within this string of the last occurrence of the
       * specified substring, searching backward starting at the specified index.
       *
       * <p>The returned index is the largest value <i>k</i> for which:
       * <blockquote><pre>
       * <i>k</i> {@code <=} fromIndex {@code &&} this.startsWith(str, <i>k</i>)
       * </pre></blockquote>
       * If no such value of <i>k</i> exists, then {@code -1} is returned.
       *
       * @param   str         the substring to search for.
       * @param   fromIndex   the index to start the search from.
       * @return  the index of the last occurrence of the specified substring,
       *          searching backward from the specified index,
       *          or {@code -1} if there is no such occurrence.
       */
      public int lastIndexOf(String str, int fromIndex) {
          // Android-changed: Change parameters to static lastIndexOf to match new signature below.
          return lastIndexOf(this, str, fromIndex);
      }
  
      // BEGIN Android-added: Private static lastIndexOf method that takes String parameters.
      // The use of length(), charAt(), etc. makes it more efficient for compressed strings.
      /**
       * The source is the string being searched, and the target is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   target       the characters being searched for.
       * @param   fromIndex    the index to begin searching from.
       */
      private static int lastIndexOf(String source, String target, int fromIndex) {
          /*
           * Check arguments; return immediately where possible. For
           * consistency, don't check for null str.
           */
          final int sourceLength = source.length();
          final int targetLength = target.length();
          int rightIndex = sourceLength - targetLength;
          if (fromIndex < 0) {
              return -1;
          }
          if (fromIndex > rightIndex) {
              fromIndex = rightIndex;
          }
          /* Empty string always matches. */
          if (targetLength == 0) {
              return fromIndex;
          }
  
          int strLastIndex = targetLength - 1;
          char strLastChar = target.charAt(strLastIndex);
          int min = targetLength - 1;
          int i = min + fromIndex;
  
          startSearchForLastChar:
          while (true) {
              while (i >= min && source.charAt(i) != strLastChar) {
                  i--;
              }
              if (i < min) {
                  return -1;
              }
              int j = i - 1;
              int start = j - (targetLength - 1);
              int k = strLastIndex - 1;
  
              while (j > start) {
                  if (source.charAt(j--) != target.charAt(k--)) {
                      i--;
                      continue startSearchForLastChar;
                  }
              }
              return start + 1;
          }
      }
      // END Android-added: Private static lastIndexOf method that takes String parameters.
  
      /**
       * Code shared by String and AbstractStringBuilder to do searches. The
       * source is the character array being searched, and the target
       * is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   sourceOffset offset of the source string.
       * @param   sourceCount  count of the source string.
       * @param   target       the characters being searched for.
       * @param   fromIndex    the index to begin searching from.
       */
      static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
              String target, int fromIndex) {
          return lastIndexOf(source, sourceOffset, sourceCount,
                         target.toCharArray(), 0, target.length(),
                         fromIndex);
      }
  
      /**
       * Code shared by String and StringBuffer to do searches. The
       * source is the character array being searched, and the target
       * is the string being searched for.
       *
       * @param   source       the characters being searched.
       * @param   sourceOffset offset of the source string.
       * @param   sourceCount  count of the source string.
       * @param   target       the characters being searched for.
       * @param   targetOffset offset of the target string.
       * @param   targetCount  count of the target string.
       * @param   fromIndex    the index to begin searching from.
       */
      static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
              char[] target, int targetOffset, int targetCount,
              int fromIndex) {
          /*
           * Check arguments; return immediately where possible. For
           * consistency, don't check for null str.
           */
          int rightIndex = sourceCount - targetCount;
          if (fromIndex < 0) {
              return -1;
          }
          if (fromIndex > rightIndex) {
              fromIndex = rightIndex;
          }
          /* Empty string always matches. */
          if (targetCount == 0) {
              return fromIndex;
          }
  
          int strLastIndex = targetOffset + targetCount - 1;
          char strLastChar = target[strLastIndex];
          int min = sourceOffset + targetCount - 1;
          int i = min + fromIndex;
  
      startSearchForLastChar:
          while (true) {
              while (i >= min && source[i] != strLastChar) {
                  i--;
              }
              if (i < min) {
                  return -1;
              }
              int j = i - 1;
              int start = j - (targetCount - 1);
              int k = strLastIndex - 1;
  
              while (j > start) {
                  if (source[j--] != target[k--]) {
                      i--;
                      continue startSearchForLastChar;
                  }
              }
              return start - sourceOffset + 1;
          }
      }
  
      /**
       * Returns a string that is a substring of this string. The
       * substring begins with the character at the specified index and
       * extends to the end of this string. <p>
       * Examples:
       * <blockquote><pre>
       * "unhappy".substring(2) returns "happy"
       * "Harbison".substring(3) returns "bison"
       * "emptiness".substring(9) returns "" (an empty string)
       * </pre></blockquote>
       *
       * @param      beginIndex   the beginning index, inclusive.
       * @return     the specified substring.
       * @exception  IndexOutOfBoundsException  if
       *             {@code beginIndex} is negative or larger than the
       *             length of this {@code String} object.
       */
      public String substring(int beginIndex) {
          if (beginIndex < 0) {
              throw new StringIndexOutOfBoundsException(this, beginIndex);
          }
          int subLen = length() - beginIndex;
          if (subLen < 0) {
              throw new StringIndexOutOfBoundsException(this, beginIndex);
          }
          // Android-changed: Use native fastSubstring instead of String constructor.
          return (beginIndex == 0) ? this : fastSubstring(beginIndex, subLen);
      }
  
      /**
       * Returns a string that is a substring of this string. The
       * substring begins at the specified {@code beginIndex} and
       * extends to the character at index {@code endIndex - 1}.
       * Thus the length of the substring is {@code endIndex-beginIndex}.
       * <p>
       * Examples:
       * <blockquote><pre>
       * "hamburger".substring(4, 8) returns "urge"
       * "smiles".substring(1, 5) returns "mile"
       * </pre></blockquote>
       *
       * @param      beginIndex   the beginning index, inclusive.
       * @param      endIndex     the ending index, exclusive.
       * @return     the specified substring.
       * @exception  IndexOutOfBoundsException  if the
       *             {@code beginIndex} is negative, or
       *             {@code endIndex} is larger than the length of
       *             this {@code String} object, or
       *             {@code beginIndex} is larger than
       *             {@code endIndex}.
       */
      public String substring(int beginIndex, int endIndex) {
          if (beginIndex < 0) {
              throw new StringIndexOutOfBoundsException(this, beginIndex);
          }
          if (endIndex > length()) {
              throw new StringIndexOutOfBoundsException(this, endIndex);
          }
          int subLen = endIndex - beginIndex;
          if (subLen < 0) {
              throw new StringIndexOutOfBoundsException(subLen);
          }
  
          // Android-changed: Use native fastSubstring instead of String constructor.
          return ((beginIndex == 0) && (endIndex == length())) ? this
                  : fastSubstring(beginIndex, subLen);
      }
  
      // BEGIN Android-added: Native method to access char storage managed by runtime.
      @FastNative
      private native String fastSubstring(int start, int length);
      // END Android-added: Native method to access char storage managed by runtime.
  
      /**
       * Returns a character sequence that is a subsequence of this sequence.
       *
       * <p> An invocation of this method of the form
       *
       * <blockquote><pre>
       * str.subSequence(begin,&nbsp;end)</pre></blockquote>
       *
       * behaves in exactly the same way as the invocation
       *
       * <blockquote><pre>
       * str.substring(begin,&nbsp;end)</pre></blockquote>
       *
       * @apiNote
       * This method is defined so that the {@code String} class can implement
       * the {@link CharSequence} interface.
       *
       * @param   beginIndex   the begin index, inclusive.
       * @param   endIndex     the end index, exclusive.
       * @return  the specified subsequence.
       *
       * @throws  IndexOutOfBoundsException
       *          if {@code beginIndex} or {@code endIndex} is negative,
       *          if {@code endIndex} is greater than {@code length()},
       *          or if {@code beginIndex} is greater than {@code endIndex}
       *
       * @since 1.4
       * @spec JSR-51
       */
      public CharSequence subSequence(int beginIndex, int endIndex) {
          return this.substring(beginIndex, endIndex);
      }
  
      /**
       * Concatenates the specified string to the end of this string.
       * <p>
       * If the length of the argument string is {@code 0}, then this
       * {@code String} object is returned. Otherwise, a
       * {@code String} object is returned that represents a character
       * sequence that is the concatenation of the character sequence
       * represented by this {@code String} object and the character
       * sequence represented by the argument string.<p>
       * Examples:
       * <blockquote><pre>
       * "cares".concat("s") returns "caress"
       * "to".concat("get").concat("her") returns "together"
       * </pre></blockquote>
       *
       * @param   str   the {@code String} that is concatenated to the end
       *                of this {@code String}.
       * @return  a string that represents the concatenation of this object's
       *          characters followed by the string argument's characters.
       */
      // BEGIN Android-changed: Replace with implementation in runtime to access chars (see above).
      @FastNative
      public native String concat(String str);
      // END Android-changed: Replace with implementation in runtime to access chars (see above).
  
      /**
       * Returns a string resulting from replacing all occurrences of
       * {@code oldChar} in this string with {@code newChar}.
       * <p>
       * If the character {@code oldChar} does not occur in the
       * character sequence represented by this {@code String} object,
       * then a reference to this {@code String} object is returned.
       * Otherwise, a {@code String} object is returned that
       * represents a character sequence identical to the character sequence
       * represented by this {@code String} object, except that every
       * occurrence of {@code oldChar} is replaced by an occurrence
       * of {@code newChar}.
       * <p>
       * Examples:
       * <blockquote><pre>
       * "mesquite in your cellar".replace('e', 'o')
       *         returns "mosquito in your collar"
       * "the war of baronets".replace('r', 'y')
       *         returns "the way of bayonets"
       * "sparring with a purple porpoise".replace('p', 't')
       *         returns "starring with a turtle tortoise"
       * "JonL".replace('q', 'x') returns "JonL" (no change)
       * </pre></blockquote>
       *
       * @param   oldChar   the old character.
       * @param   newChar   the new character.
       * @return  a string derived from this string by replacing every
       *          occurrence of {@code oldChar} with {@code newChar}.
       */
      public String replace(char oldChar, char newChar) {
          // BEGIN Android-changed: Replace with implementation using native doReplace method.
          if (oldChar != newChar) {
              final int len = length();
              for (int i = 0; i < len; ++i) {
                  if (charAt(i) == oldChar) {
                      return doReplace(oldChar, newChar);
                  }
              }
          }
          // END Android-changed: Replace with implementation using native doReplace method.
          return this;
      }
  
      // BEGIN Android-added: Native method to access char storage managed by runtime.
      // Implementation of replace(char oldChar, char newChar) called when we found a match.
      @FastNative
      private native String doReplace(char oldChar, char newChar);
      // END Android-added: Native method to access char storage managed by runtime.
  
      /**
       * Tells whether or not this string matches the given <a
       * href="../util/regex/Pattern.html#sum">regular expression</a>.
       *
       * <p> An invocation of this method of the form
       * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the
       * same result as the expression
       *
       * <blockquote>
       * {@link Pattern}.{@link Pattern#matches(String,CharSequence)
       * matches(<i>regex</i>, <i>str</i>)}
       * </blockquote>
       *
       * @param   regex
       *          the regular expression to which this string is to be matched
       *
       * @return  {@code true} if, and only if, this string matches the
       *          given regular expression
       *
       * @throws  PatternSyntaxException
       *          if the regular expression's syntax is invalid
       *
       * @see Pattern
       *
       * @since 1.4
       * @spec JSR-51
       */
      public boolean matches(String regex) {
          return Pattern.matches(regex, this);
      }
  
      /**
       * Returns true if and only if this string contains the specified
       * sequence of char values.
       *
       * @param s the sequence to search for
       * @return true if this string contains {@code s}, false otherwise
       * @since 1.5
       */
      public boolean contains(CharSequence s) {
          return indexOf(s.toString()) > -1;
      }
  
      /**
       * Replaces the first substring of this string that matches the given <a
       * href="../util/regex/Pattern.html#sum">regular expression</a> with the
       * given replacement.
       *
       * <p> An invocation of this method of the form
       * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
       * yields exactly the same result as the expression
       *
       * <blockquote>
       * <code>
       * {@link Pattern}.{@link
       * Pattern#compile compile}(<i>regex</i>).{@link
       * Pattern#matcher(CharSequence) matcher}(<i>str</i>).{@link
       * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>)
       * </code>
       * </blockquote>
       *
       *<p>
       * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
       * replacement string may cause the results to be different than if it were
       * being treated as a literal replacement string; see
       * {@link java.util.regex.Matcher#replaceFirst}.
       * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
       * meaning of these characters, if desired.
       *
       * @param   regex
       *          the regular expression to which this string is to be matched
       * @param   replacement
       *          the string to be substituted for the first match
       *
       * @return  The resulting {@code String}
       *
       * @throws  PatternSyntaxException
       *          if the regular expression's syntax is invalid
       *
       * @see Pattern
       *
       * @since 1.4
       * @spec JSR-51
       */
      public String replaceFirst(String regex, String replacement) {
          return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
      }
  
      /**
       * Replaces each substring of this string that matches the given <a
       * href="../util/regex/Pattern.html#sum">regular expression</a> with the
       * given replacement.
       *
       * <p> An invocation of this method of the form
       * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
       * yields exactly the same result as the expression
       *
       * <blockquote>
       * <code>
       * {@link Pattern}.{@link
       * Pattern#compile compile}(<i>regex</i>).{@link
       * Pattern#matcher(CharSequence) matcher}(<i>str</i>).{@link
       * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>)
       * </code>
       * </blockquote>
       *
       *<p>
       * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
       * replacement string may cause the results to be different than if it were
       * being treated as a literal replacement string; see
       * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
       * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
       * meaning of these characters, if desired.
       *
       * @param   regex
       *          the regular expression to which this string is to be matched
       * @param   replacement
       *          the string to be substituted for each match
       *
       * @return  The resulting {@code String}
       *
       * @throws  PatternSyntaxException
       *          if the regular expression's syntax is invalid
       *
       * @see Pattern
       *
       * @since 1.4
       * @spec JSR-51
       */
      public String replaceAll(String regex, String replacement) {
          return Pattern.compile(regex).matcher(this).replaceAll(replacement);
      }
  
      /**
       * Replaces each substring of this string that matches the literal target
       * sequence with the specified literal replacement sequence. The
       * replacement proceeds from the beginning of the string to the end, for
       * example, replacing "aa" with "b" in the string "aaa" will result in
       * "ba" rather than "ab".
       *
       * @param  target The sequence of char values to be replaced
       * @param  replacement The replacement sequence of char values
       * @return  The resulting string
       * @since 1.5
       */
      public String replace(CharSequence target, CharSequence replacement) {
          // BEGIN Android-changed: Replace regex-based implementation with a bespoke one.
          if (target == null) {
              throw new NullPointerException("target == null");
          }
  
          if (replacement == null) {
              throw new NullPointerException("replacement == null");
          }
  
          String replacementStr = replacement.toString();
          String targetStr = target.toString();
  
          // Special case when target == "". This is a pretty nonsensical transformation and nobody
          // should be hitting this.
          //
          // See commit 870b23b3febc85 and http://code.google.com/p/android/issues/detail?id=8807
          // An empty target is inserted at the start of the string, the end of the string and
          // between all characters.
          final int len = length();
          if (targetStr.isEmpty()) {
              // Note that overallocates by |replacement.size()| if |this| is the empty string, but
              // that should be a rare case within an already nonsensical case.
              StringBuilder sb = new StringBuilder(replacementStr.length() * (len + 2) + len);
              sb.append(replacementStr);
              for (int i = 0; i < len; ++i) {
                  sb.append(charAt(i));
                  sb.append(replacementStr);
              }
  
              return sb.toString();
          }
  
          // This is the "regular" case.
          int lastMatch = 0;
          StringBuilder sb = null;
          for (;;) {
              int currentMatch = indexOf(this, targetStr, lastMatch);
              if (currentMatch == -1) {
                  break;
              }
  
              if (sb == null) {
                  sb = new StringBuilder(len);
              }
  
              sb.append(this, lastMatch, currentMatch);
              sb.append(replacementStr);
              lastMatch = currentMatch + targetStr.length();
          }
  
          if (sb != null) {
              sb.append(this, lastMatch, len);
              return sb.toString();
          } else {
              return this;
          }
          // END Android-changed: Replace regex-based implementation with a bespoke one.
      }
  
      /**
       * Splits this string around matches of the given
       * <a href="../util/regex/Pattern.html#sum">regular expression</a>.
       *
       * <p> The array returned by this method contains each substring of this
       * string that is terminated by another substring that matches the given
       * expression or is terminated by the end of the string.  The substrings in
       * the array are in the order in which they occur in this string.  If the
       * expression does not match any part of the input then the resulting array
       * has just one element, namely this string.
       *
       * <p> When there is a positive-width match at the beginning of this
       * string then an empty leading substring is included at the beginning
       * of the resulting array. A zero-width match at the beginning however
       * never produces such empty leading substring.
       *
       * <p> The {@code limit} parameter controls the number of times the
       * pattern is applied and therefore affects the length of the resulting
       * array.  If the limit <i>n</i> is greater than zero then the pattern
       * will be applied at most <i>n</i>&nbsp;-&nbsp;1 times, the array's
       * length will be no greater than <i>n</i>, and the array's last entry
       * will contain all input beyond the last matched delimiter.  If <i>n</i>
       * is non-positive then the pattern will be applied as many times as
       * possible and the array can have any length.  If <i>n</i> is zero then
       * the pattern will be applied as many times as possible, the array can
       * have any length, and trailing empty strings will be discarded.
       *
       * <p> The string {@code "boo:and:foo"}, for example, yields the
       * following results with these parameters:
       *
       * <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result">
       * <tr>
       *     <th>Regex</th>
       *     <th>Limit</th>
       *     <th>Result</th>
       * </tr>
       * <tr><td align=center>:</td>
       *     <td align=center>2</td>
       *     <td>{@code { "boo", "and:foo" }}</td></tr>
       * <tr><td align=center>:</td>
       *     <td align=center>5</td>
       *     <td>{@code { "boo", "and", "foo" }}</td></tr>
       * <tr><td align=center>:</td>
       *     <td align=center>-2</td>
       *     <td>{@code { "boo", "and", "foo" }}</td></tr>
       * <tr><td align=center>o</td>
       *     <td align=center>5</td>
       *     <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
       * <tr><td align=center>o</td>
       *     <td align=center>-2</td>
       *     <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
       * <tr><td align=center>o</td>
       *     <td align=center>0</td>
       *     <td>{@code { "b", "", ":and:f" }}</td></tr>
       * </table></blockquote>
       *
       * <p> An invocation of this method of the form
       * <i>str.</i>{@code split(}<i>regex</i>{@code ,}&nbsp;<i>n</i>{@code )}
       * yields the same result as the expression
       *
       * <blockquote>
       * <code>
       * {@link Pattern}.{@link
       * Pattern#compile compile}(<i>regex</i>).{@link
       * Pattern#split(CharSequence,int) split}(<i>str</i>,&nbsp;<i>n</i>)
       * </code>
       * </blockquote>
       *
       *
       * @param  regex
       *         the delimiting regular expression
       *
       * @param  limit
       *         the result threshold, as described above
       *
       * @return  the array of strings computed by splitting this string
       *          around matches of the given regular expression
       *
       * @throws  PatternSyntaxException
       *          if the regular expression's syntax is invalid
       *
       * @see Pattern
       *
       * @since 1.4
       * @spec JSR-51
       */
      public String[] split(String regex, int limit) {
          // BEGIN Android-changed: Replace custom fast-path with use of new Pattern.fastSplit method.
          // Try fast splitting without allocating Pattern object
          String[] fast = Pattern.fastSplit(regex, this, limit);
          if (fast != null) {
              return fast;
          }
          // END Android-changed: Replace custom fast-path with use of new Pattern.fastSplit method.
          return Pattern.compile(regex).split(this, limit);
      }
  
      /**
       * Splits this string around matches of the given <a
       * href="../util/regex/Pattern.html#sum">regular expression</a>.
       *
       * <p> This method works as if by invoking the two-argument {@link
       * #split(String, int) split} method with the given expression and a limit
       * argument of zero.  Trailing empty strings are therefore not included in
       * the resulting array.
       *
       * <p> The string {@code "boo:and:foo"}, for example, yields the following
       * results with these expressions:
       *
       * <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result">
       * <tr>
       *  <th>Regex</th>
       *  <th>Result</th>
       * </tr>
       * <tr><td align=center>:</td>
       *     <td>{@code { "boo", "and", "foo" }}</td></tr>
       * <tr><td align=center>o</td>
       *     <td>{@code { "b", "", ":and:f" }}</td></tr>
       * </table></blockquote>
       *
       *
       * @param  regex
       *         the delimiting regular expression
       *
       * @return  the array of strings computed by splitting this string
       *          around matches of the given regular expression
       *
       * @throws  PatternSyntaxException
       *          if the regular expression's syntax is invalid
       *
       * @see Pattern
       *
       * @since 1.4
       * @spec JSR-51
       */
      public String[] split(String regex) {
          return split(regex, 0);
      }
  
      /**
       * Returns a new String composed of copies of the
       * {@code CharSequence elements} joined together with a copy of
       * the specified {@code delimiter}.
       *
       * <blockquote>For example,
       * <pre>{@code
       *     String message = String.join("-", "Java", "is", "cool");
       *     // message returned is: "Java-is-cool"
       * }</pre></blockquote>
       *
       * Note that if an element is null, then {@code "null"} is added.
       *
       * @param  delimiter the delimiter that separates each element
       * @param  elements the elements to join together.
       *
       * @return a new {@code String} that is composed of the {@code elements}
       *         separated by the {@code delimiter}
       *
       * @throws NullPointerException If {@code delimiter} or {@code elements}
       *         is {@code null}
       *
       * @see StringJoiner
       * @since 1.8
       */
      public static String join(CharSequence delimiter, CharSequence... elements) {
          Objects.requireNonNull(delimiter);
          Objects.requireNonNull(elements);
          // Number of elements not likely worth Arrays.stream overhead.
          StringJoiner joiner = new StringJoiner(delimiter);
          for (CharSequence cs: elements) {
              joiner.add(cs);
          }
          return joiner.toString();
      }
  
      /**
       * Returns a new {@code String} composed of copies of the
       * {@code CharSequence elements} joined together with a copy of the
       * specified {@code delimiter}.
       *
       * <blockquote>For example,
       * <pre>{@code
       *     List<String> strings = new LinkedList<>();
       *     strings.add("Java");strings.add("is");
       *     strings.add("cool");
       *     String message = String.join(" ", strings);
       *     //message returned is: "Java is cool"
       *
       *     Set<String> strings = new LinkedHashSet<>();
       *     strings.add("Java"); strings.add("is");
       *     strings.add("very"); strings.add("cool");
       *     String message = String.join("-", strings);
       *     //message returned is: "Java-is-very-cool"
       * }</pre></blockquote>
       *
       * Note that if an individual element is {@code null}, then {@code "null"} is added.
       *
       * @param  delimiter a sequence of characters that is used to separate each
       *         of the {@code elements} in the resulting {@code String}
       * @param  elements an {@code Iterable} that will have its {@code elements}
       *         joined together.
       *
       * @return a new {@code String} that is composed from the {@code elements}
       *         argument
       *
       * @throws NullPointerException If {@code delimiter} or {@code elements}
       *         is {@code null}
       *
       * @see    #join(CharSequence,CharSequence...)
       * @see    StringJoiner
       * @since 1.8
       */
      public static String join(CharSequence delimiter,
              Iterable<? extends CharSequence> elements) {
          Objects.requireNonNull(delimiter);
          Objects.requireNonNull(elements);
          StringJoiner joiner = new StringJoiner(delimiter);
          for (CharSequence cs: elements) {
              joiner.add(cs);
          }
          return joiner.toString();
      }
  
      /**
       * Converts all of the characters in this {@code String} to lower
       * case using the rules of the given {@code Locale}.  Case mapping is based
       * on the Unicode Standard version specified by the {@link Character Character}
       * class. Since case mappings are not always 1:1 char mappings, the resulting
       * {@code String} may be a different length than the original {@code String}.
       * <p>
       * Examples of lowercase  mappings are in the following table:
       * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description">
       * <tr>
       *   <th>Language Code of Locale</th>
       *   <th>Upper Case</th>
       *   <th>Lower Case</th>
       *   <th>Description</th>
       * </tr>
       * <tr>
       *   <td>tr (Turkish)</td>
       *   <td>&#92;u0130</td>
       *   <td>&#92;u0069</td>
       *   <td>capital letter I with dot above -&gt; small letter i</td>
       * </tr>
       * <tr>
       *   <td>tr (Turkish)</td>
       *   <td>&#92;u0049</td>
       *   <td>&#92;u0131</td>
       *   <td>capital letter I -&gt; small letter dotless i </td>
       * </tr>
       * <tr>
       *   <td>(all)</td>
       *   <td>French Fries</td>
       *   <td>french fries</td>
       *   <td>lowercased all chars in String</td>
       * </tr>
       * <tr>
       *   <td>(all)</td>
       *   <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi">
       *       <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil">
       *       <img src="doc-files/capsigma.gif" alt="capsigma"></td>
       *   <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi">
       *       <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon">
       *       <img src="doc-files/sigma1.gif" alt="sigma"></td>
       *   <td>lowercased all chars in String</td>
       * </tr>
       * </table>
       *
       * @param locale use the case transformation rules for this locale
       * @return the {@code String}, converted to lowercase.
       * @see     String#toLowerCase()
       * @see     String#toUpperCase()
       * @see     String#toUpperCase(Locale)
       * @since   1.1
       */
      public String toLowerCase(Locale locale) {
          // Android-changed: Replace custom code with call to new CaseMapper class.
          return CaseMapper.toLowerCase(locale, this);
      }
  
      /**
       * Converts all of the characters in this {@code String} to lower
       * case using the rules of the default locale. This is equivalent to calling
       * {@code toLowerCase(Locale.getDefault())}.
       * <p>
       * <b>Note:</b> This method is locale sensitive, and may produce unexpected
       * results if used for strings that are intended to be interpreted locale
       * independently.
       * Examples are programming language identifiers, protocol keys, and HTML
       * tags.
       * For instance, {@code "TITLE".toLowerCase()} in a Turkish locale
       * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the
       * LATIN SMALL LETTER DOTLESS I character.
       * To obtain correct results for locale insensitive strings, use
       * {@code toLowerCase(Locale.ROOT)}.
       * <p>
       * @return  the {@code String}, converted to lowercase.
       * @see     String#toLowerCase(Locale)
       */
      public String toLowerCase() {
          return toLowerCase(Locale.getDefault());
      }
  
      /**
       * Converts all of the characters in this {@code String} to upper
       * case using the rules of the given {@code Locale}. Case mapping is based
       * on the Unicode Standard version specified by the {@link Character Character}
       * class. Since case mappings are not always 1:1 char mappings, the resulting
       * {@code String} may be a different length than the original {@code String}.
       * <p>
       * Examples of locale-sensitive and 1:M case mappings are in the following table.
       *
       * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.">
       * <tr>
       *   <th>Language Code of Locale</th>
       *   <th>Lower Case</th>
       *   <th>Upper Case</th>
       *   <th>Description</th>
       * </tr>
       * <tr>
       *   <td>tr (Turkish)</td>
       *   <td>&#92;u0069</td>
       *   <td>&#92;u0130</td>
       *   <td>small letter i -&gt; capital letter I with dot above</td>
       * </tr>
       * <tr>
       *   <td>tr (Turkish)</td>
       *   <td>&#92;u0131</td>
       *   <td>&#92;u0049</td>
       *   <td>small letter dotless i -&gt; capital letter I</td>
       * </tr>
       * <tr>
       *   <td>(all)</td>
       *   <td>&#92;u00df</td>
       *   <td>&#92;u0053 &#92;u0053</td>
       *   <td>small letter sharp s -&gt; two letters: SS</td>
       * </tr>
       * <tr>
       *   <td>(all)</td>
       *   <td>Fahrvergn&uuml;gen</td>
       *   <td>FAHRVERGN&Uuml;GEN</td>
       *   <td></td>
       * </tr>
       * </table>
       * @param locale use the case transformation rules for this locale
       * @return the {@code String}, converted to uppercase.
       * @see     String#toUpperCase()
       * @see     String#toLowerCase()
       * @see     String#toLowerCase(Locale)
       * @since   1.1
       */
      public String toUpperCase(Locale locale) {
          // Android-changed: Replace custom code with call to new CaseMapper class.
          return CaseMapper.toUpperCase(locale, this, length());
      }
  
      /**
       * Converts all of the characters in this {@code String} to upper
       * case using the rules of the default locale. This method is equivalent to
       * {@code toUpperCase(Locale.getDefault())}.
       * <p>
       * <b>Note:</b> This method is locale sensitive, and may produce unexpected
       * results if used for strings that are intended to be interpreted locale
       * independently.
       * Examples are programming language identifiers, protocol keys, and HTML
       * tags.
       * For instance, {@code "title".toUpperCase()} in a Turkish locale
       * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the
       * LATIN CAPITAL LETTER I WITH DOT ABOVE character.
       * To obtain correct results for locale insensitive strings, use
       * {@code toUpperCase(Locale.ROOT)}.
       * <p>
       * @return  the {@code String}, converted to uppercase.
       * @see     String#toUpperCase(Locale)
       */
      public String toUpperCase() {
          return toUpperCase(Locale.getDefault());
      }
  
      /**
       * Returns a string whose value is this string, with any leading and trailing
       * whitespace removed.
       * <p>
       * If this {@code String} object represents an empty character
       * sequence, or the first and last characters of character sequence
       * represented by this {@code String} object both have codes
       * greater than {@code '\u005Cu0020'} (the space character), then a
       * reference to this {@code String} object is returned.
       * <p>
       * Otherwise, if there is no character with a code greater than
       * {@code '\u005Cu0020'} in the string, then a
       * {@code String} object representing an empty string is
       * returned.
       * <p>
       * Otherwise, let <i>k</i> be the index of the first character in the
       * string whose code is greater than {@code '\u005Cu0020'}, and let
       * <i>m</i> be the index of the last character in the string whose code
       * is greater than {@code '\u005Cu0020'}. A {@code String}
       * object is returned, representing the substring of this string that
       * begins with the character at index <i>k</i> and ends with the
       * character at index <i>m</i>-that is, the result of
       * {@code this.substring(k, m + 1)}.
       * <p>
       * This method may be used to trim whitespace (as defined above) from
       * the beginning and end of a string.
       *
       * @return  A string whose value is this string, with any leading and trailing white
       *          space removed, or this string if it has no leading or
       *          trailing white space.
       */
      public String trim() {
          int len = length();
          int st = 0;
  
          while ((st < len) && (charAt(st) <= ' ')) {
              st++;
          }
          while ((st < len) && (charAt(len - 1) <= ' ')) {
              len--;
          }
          return ((st > 0) || (len < length())) ? substring(st, len) : this;
      }
  
      /**
       * This object (which is already a string!) is itself returned.
       *
       * @return  the string itself.
       */
      public String toString() {
          return this;
      }
  
      /**
       * Converts this string to a new character array.
       *
       * @return  a newly allocated character array whose length is the length
       *          of this string and whose contents are initialized to contain
       *          the character sequence represented by this string.
       */
      // BEGIN Android-changed: Replace with implementation in runtime to access chars (see above).
      @FastNative
      public native char[] toCharArray();
      // END Android-changed: Replace with implementation in runtime to access chars (see above).
  
  
      /**
       * Returns a formatted string using the specified format string and
       * arguments.
       *
       * <p> The locale always used is the one returned by {@link
       * Locale#getDefault() Locale.getDefault()}.
       *
       * @param  format
       *         A <a href="../util/Formatter.html#syntax">format string</a>
       *
       * @param  args
       *         Arguments referenced by the format specifiers in the format
       *         string.  If there are more arguments than format specifiers, the
       *         extra arguments are ignored.  The number of arguments is
       *         variable and may be zero.  The maximum number of arguments is
       *         limited by the maximum dimension of a Java array as defined by
       *         <cite>The Java&trade; Virtual Machine Specification</cite>.
       *         The behaviour on a
       *         {@code null} argument depends on the <a
       *         href="../util/Formatter.html#syntax">conversion</a>.
       *
       * @throws  java.util.IllegalFormatException
       *          If a format string contains an illegal syntax, a format
       *          specifier that is incompatible with the given arguments,
       *          insufficient arguments given the format string, or other
       *          illegal conditions.  For specification of all possible
       *          formatting errors, see the <a
       *          href="../util/Formatter.html#detail">Details</a> section of the
       *          formatter class specification.
       *
       * @return  A formatted string
       *
       * @see  Formatter
       * @since  1.5
       */
      public static String format(String format, Object... args) {
          return new Formatter().format(format, args).toString();
      }
  
      /**
       * Returns a formatted string using the specified locale, format string,
       * and arguments.
       *
       * @param  l
       *         The {@linkplain Locale locale} to apply during
       *         formatting.  If {@code l} is {@code null} then no localization
       *         is applied.
       *
       * @param  format
       *         A <a href="../util/Formatter.html#syntax">format string</a>
       *
       * @param  args
       *         Arguments referenced by the format specifiers in the format
       *         string.  If there are more arguments than format specifiers, the
       *         extra arguments are ignored.  The number of arguments is
       *         variable and may be zero.  The maximum number of arguments is
       *         limited by the maximum dimension of a Java array as defined by
       *         <cite>The Java&trade; Virtual Machine Specification</cite>.
       *         The behaviour on a
       *         {@code null} argument depends on the
       *         <a href="../util/Formatter.html#syntax">conversion</a>.
       *
       * @throws  java.util.IllegalFormatException
       *          If a format string contains an illegal syntax, a format
       *          specifier that is incompatible with the given arguments,
       *          insufficient arguments given the format string, or other
       *          illegal conditions.  For specification of all possible
       *          formatting errors, see the <a
       *          href="../util/Formatter.html#detail">Details</a> section of the
       *          formatter class specification
       *
       * @return  A formatted string
       *
       * @see  Formatter
       * @since  1.5
       */
      public static String format(Locale l, String format, Object... args) {
          return new Formatter(l).format(format, args).toString();
      }
  
      /**
       * Returns the string representation of the {@code Object} argument.
       *
       * @param   obj   an {@code Object}.
       * @return  if the argument is {@code null}, then a string equal to
       *          {@code "null"}; otherwise, the value of
       *          {@code obj.toString()} is returned.
       * @see     Object#toString()
       */
      public static String valueOf(Object obj) {
          return (obj == null) ? "null" : obj.toString();
      }
  
      /**
       * Returns the string representation of the {@code char} array
       * argument. The contents of the character array are copied; subsequent
       * modification of the character array does not affect the returned
       * string.
       *
       * @param   data     the character array.
       * @return  a {@code String} that contains the characters of the
       *          character array.
       */
      public static String valueOf(char data[]) {
          return new String(data);
      }
  
      /**
       * Returns the string representation of a specific subarray of the
       * {@code char} array argument.
       * <p>
       * The {@code offset} argument is the index of the first
       * character of the subarray. The {@code count} argument
       * specifies the length of the subarray. The contents of the subarray
       * are copied; subsequent modification of the character array does not
       * affect the returned string.
       *
       * @param   data     the character array.
       * @param   offset   initial offset of the subarray.
       * @param   count    length of the subarray.
       * @return  a {@code String} that contains the characters of the
       *          specified subarray of the character array.
       * @exception IndexOutOfBoundsException if {@code offset} is
       *          negative, or {@code count} is negative, or
       *          {@code offset+count} is larger than
       *          {@code data.length}.
       */
      public static String valueOf(char data[], int offset, int count) {
          return new String(data, offset, count);
      }
  
      /**
       * Equivalent to {@link #valueOf(char[], int, int)}.
       *
       * @param   data     the character array.
       * @param   offset   initial offset of the subarray.
       * @param   count    length of the subarray.
       * @return  a {@code String} that contains the characters of the
       *          specified subarray of the character array.
       * @exception IndexOutOfBoundsException if {@code offset} is
       *          negative, or {@code count} is negative, or
       *          {@code offset+count} is larger than
       *          {@code data.length}.
       */
      public static String copyValueOf(char data[], int offset, int count) {
          return new String(data, offset, count);
      }
  
      /**
       * Equivalent to {@link #valueOf(char[])}.
       *
       * @param   data   the character array.
       * @return  a {@code String} that contains the characters of the
       *          character array.
       */
      public static String copyValueOf(char data[]) {
          return new String(data);
      }
  
      /**
       * Returns the string representation of the {@code boolean} argument.
       *
       * @param   b   a {@code boolean}.
       * @return  if the argument is {@code true}, a string equal to
       *          {@code "true"} is returned; otherwise, a string equal to
       *          {@code "false"} is returned.
       */
      public static String valueOf(boolean b) {
          return b ? "true" : "false";
      }
  
      /**
       * Returns the string representation of the {@code char}
       * argument.
       *
       * @param   c   a {@code char}.
       * @return  a string of length {@code 1} containing
       *          as its single character the argument {@code c}.
       */
      public static String valueOf(char c) {
          // Android-changed: Replace constructor call with call to StringFactory class.
          // There is currently no String(char[], boolean) on Android to call. http://b/79902155
          // char data[] = {c};
          // return new String(data, true);
          return StringFactory.newStringFromChars(0, 1, new char[] { c });
      }
  
      /**
       * Returns the string representation of the {@code int} argument.
       * <p>
       * The representation is exactly the one returned by the
       * {@code Integer.toString} method of one argument.
       *
       * @param   i   an {@code int}.
       * @return  a string representation of the {@code int} argument.
       * @see     Integer#toString(int, int)
       */
      public static String valueOf(int i) {
          return Integer.toString(i);
      }
  
      /**
       * Returns the string representation of the {@code long} argument.
       * <p>
       * The representation is exactly the one returned by the
       * {@code Long.toString} method of one argument.
       *
       * @param   l   a {@code long}.
       * @return  a string representation of the {@code long} argument.
       * @see     Long#toString(long)
       */
      public static String valueOf(long l) {
          return Long.toString(l);
      }
  
      /**
       * Returns the string representation of the {@code float} argument.
       * <p>
       * The representation is exactly the one returned by the
       * {@code Float.toString} method of one argument.
       *
       * @param   f   a {@code float}.
       * @return  a string representation of the {@code float} argument.
       * @see     Float#toString(float)
       */
      public static String valueOf(float f) {
          return Float.toString(f);
      }
  
      /**
       * Returns the string representation of the {@code double} argument.
       * <p>
       * The representation is exactly the one returned by the
       * {@code Double.toString} method of one argument.
       *
       * @param   d   a {@code double}.
       * @return  a  string representation of the {@code double} argument.
       * @see     Double#toString(double)
       */
      public static String valueOf(double d) {
          return Double.toString(d);
      }
  
      /**
       * Returns a canonical representation for the string object.
       * <p>
       * A pool of strings, initially empty, is maintained privately by the
       * class {@code String}.
       * <p>
       * When the intern method is invoked, if the pool already contains a
       * string equal to this {@code String} object as determined by
       * the {@link #equals(Object)} method, then the string from the pool is
       * returned. Otherwise, this {@code String} object is added to the
       * pool and a reference to this {@code String} object is returned.
       * <p>
       * It follows that for any two strings {@code s} and {@code t},
       * {@code s.intern() == t.intern()} is {@code true}
       * if and only if {@code s.equals(t)} is {@code true}.
       * <p>
       * All literal strings and string-valued constant expressions are
       * interned. String literals are defined in section 3.10.5 of the
       * <cite>The Java&trade; Language Specification</cite>.
       *
       * @return  a string that has the same contents as this string, but is
       *          guaranteed to be from a pool of unique strings.
       */
      // BEGIN Android-changed: Annotate native method as @FastNative.
      @FastNative
      // END Android-changed: Annotate native method as @FastNative.
      public native String intern();
  }
  