content: /*
   * Copyright (c) 1996, 2012, 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.io;
  
  import java.util.Objects;
  import java.util.Formatter;
  import java.util.Locale;
  import java.nio.charset.Charset;
  import java.nio.charset.IllegalCharsetNameException;
  import java.nio.charset.UnsupportedCharsetException;
  
  /**
   * Prints formatted representations of objects to a text-output stream.  This
   * class implements all of the <tt>print</tt> methods found in {@link
   * PrintStream}.  It does not contain methods for writing raw bytes, for which
   * a program should use unencoded byte streams.
   *
   * <p> Unlike the {@link PrintStream} class, if automatic flushing is enabled
   * it will be done only when one of the <tt>println</tt>, <tt>printf</tt>, or
   * <tt>format</tt> methods is invoked, rather than whenever a newline character
   * happens to be output.  These methods use the platform's own notion of line
   * separator rather than the newline character.
   *
   * <p> Methods in this class never throw I/O exceptions, although some of its
   * constructors may.  The client may inquire as to whether any errors have
   * occurred by invoking {@link #checkError checkError()}.
   *
   * @author      Frank Yellin
   * @author      Mark Reinhold
   * @since       JDK1.1
   */
  
  public class PrintWriter extends Writer {
  
      /**
       * The underlying character-output stream of this
       * <code>PrintWriter</code>.
       *
       * @since 1.2
       */
      protected Writer out;
  
      private final boolean autoFlush;
      private boolean trouble = false;
      private Formatter formatter;
      private PrintStream psOut = null;
  
      /**
       * Line separator string.  This is the value of the line.separator
       * property at the moment that the stream was created.
       */
      private final String lineSeparator;
  
      /**
       * Returns a charset object for the given charset name.
       * @throws NullPointerException          is csn is null
       * @throws UnsupportedEncodingException  if the charset is not supported
       */
      private static Charset toCharset(String csn)
          throws UnsupportedEncodingException
      {
          Objects.requireNonNull(csn, "charsetName");
          try {
              return Charset.forName(csn);
          } catch (IllegalCharsetNameException|UnsupportedCharsetException unused) {
              // UnsupportedEncodingException should be thrown
              throw new UnsupportedEncodingException(csn);
          }
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing.
       *
       * @param  out        A character-output stream
       */
      public PrintWriter (Writer out) {
          this(out, false);
      }
  
      /**
       * Creates a new PrintWriter.
       *
       * @param  out        A character-output stream
       * @param  autoFlush  A boolean; if true, the <tt>println</tt>,
       *                    <tt>printf</tt>, or <tt>format</tt> methods will
       *                    flush the output buffer
       */
      public PrintWriter(Writer out,
                         boolean autoFlush) {
          super(out);
          this.out = out;
          this.autoFlush = autoFlush;
          lineSeparator = java.security.AccessController.doPrivileged(
              new sun.security.action.GetPropertyAction("line.separator"));
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing, from an
       * existing OutputStream.  This convenience constructor creates the
       * necessary intermediate OutputStreamWriter, which will convert characters
       * into bytes using the default character encoding.
       *
       * @param  out        An output stream
       *
       * @see OutputStreamWriter#OutputStreamWriter(OutputStream)
       */
      public PrintWriter(OutputStream out) {
          this(out, false);
      }
  
      /**
       * Creates a new PrintWriter from an existing OutputStream.  This
       * convenience constructor creates the necessary intermediate
       * OutputStreamWriter, which will convert characters into bytes using the
       * default character encoding.
       *
       * @param  out        An output stream
       * @param  autoFlush  A boolean; if true, the <tt>println</tt>,
       *                    <tt>printf</tt>, or <tt>format</tt> methods will
       *                    flush the output buffer
       *
       * @see OutputStreamWriter#OutputStreamWriter(OutputStream)
       */
      public PrintWriter(OutputStream out, boolean autoFlush) {
          this(new BufferedWriter(new OutputStreamWriter(out)), autoFlush);
  
          // save print stream for error propagation
          if (out instanceof PrintStream) {
              psOut = (PrintStream) out;
          }
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing, with the
       * specified file name.  This convenience constructor creates the necessary
       * intermediate {@link OutputStreamWriter OutputStreamWriter},
       * which will encode characters using the {@linkplain
       * Charset#defaultCharset() default charset} for this
       * instance of the Java virtual machine.
       *
       * @param  fileName
       *         The name of the file to use as the destination of this writer.
       *         If the file exists then it will be truncated to zero size;
       *         otherwise, a new file will be created.  The output will be
       *         written to the file and is buffered.
       *
       * @throws  FileNotFoundException
       *          If the given string does not denote an existing, writable
       *          regular file and a new regular file of that name cannot be
       *          created, or if some other error occurs while opening or
       *          creating the file
       *
       * @throws  SecurityException
       *          If a security manager is present and {@link
       *          SecurityManager#checkWrite checkWrite(fileName)} denies write
       *          access to the file
       *
       * @since  1.5
       */
      public PrintWriter(String fileName) throws FileNotFoundException {
          this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))),
               false);
      }
  
      /* Private constructor */
      private PrintWriter(Charset charset, File file)
          throws FileNotFoundException
      {
          this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset)),
               false);
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing, with the
       * specified file name and charset.  This convenience constructor creates
       * the necessary intermediate {@link OutputStreamWriter
       * OutputStreamWriter}, which will encode characters using the provided
       * charset.
       *
       * @param  fileName
       *         The name of the file to use as the destination of this writer.
       *         If the file exists then it will be truncated to zero size;
       *         otherwise, a new file will be created.  The output will be
       *         written to the file and is buffered.
       *
       * @param  csn
       *         The name of a supported {@linkplain Charset
       *         charset}
       *
       * @throws  FileNotFoundException
       *          If the given string does not denote an existing, writable
       *          regular file and a new regular file of that name cannot be
       *          created, or if some other error occurs while opening or
       *          creating the file
       *
       * @throws  SecurityException
       *          If a security manager is present and {@link
       *          SecurityManager#checkWrite checkWrite(fileName)} denies write
       *          access to the file
       *
       * @throws  UnsupportedEncodingException
       *          If the named charset is not supported
       *
       * @since  1.5
       */
      public PrintWriter(String fileName, String csn)
          throws FileNotFoundException, UnsupportedEncodingException
      {
          this(toCharset(csn), new File(fileName));
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing, with the
       * specified file.  This convenience constructor creates the necessary
       * intermediate {@link OutputStreamWriter OutputStreamWriter},
       * which will encode characters using the {@linkplain
       * Charset#defaultCharset() default charset} for this
       * instance of the Java virtual machine.
       *
       * @param  file
       *         The file to use as the destination of this writer.  If the file
       *         exists then it will be truncated to zero size; otherwise, a new
       *         file will be created.  The output will be written to the file
       *         and is buffered.
       *
       * @throws  FileNotFoundException
       *          If the given file object does not denote an existing, writable
       *          regular file and a new regular file of that name cannot be
       *          created, or if some other error occurs while opening or
       *          creating the file
       *
       * @throws  SecurityException
       *          If a security manager is present and {@link
       *          SecurityManager#checkWrite checkWrite(file.getPath())}
       *          denies write access to the file
       *
       * @since  1.5
       */
      public PrintWriter(File file) throws FileNotFoundException {
          this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))),
               false);
      }
  
      /**
       * Creates a new PrintWriter, without automatic line flushing, with the
       * specified file and charset.  This convenience constructor creates the
       * necessary intermediate {@link OutputStreamWriter
       * OutputStreamWriter}, which will encode characters using the provided
       * charset.
       *
       * @param  file
       *         The file to use as the destination of this writer.  If the file
       *         exists then it will be truncated to zero size; otherwise, a new
       *         file will be created.  The output will be written to the file
       *         and is buffered.
       *
       * @param  csn
       *         The name of a supported {@linkplain Charset
       *         charset}
       *
       * @throws  FileNotFoundException
       *          If the given file object does not denote an existing, writable
       *          regular file and a new regular file of that name cannot be
       *          created, or if some other error occurs while opening or
       *          creating the file
       *
       * @throws  SecurityException
       *          If a security manager is present and {@link
       *          SecurityManager#checkWrite checkWrite(file.getPath())}
       *          denies write access to the file
       *
       * @throws  UnsupportedEncodingException
       *          If the named charset is not supported
       *
       * @since  1.5
       */
      public PrintWriter(File file, String csn)
          throws FileNotFoundException, UnsupportedEncodingException
      {
          this(toCharset(csn), file);
      }
  
      /** Checks to make sure that the stream has not been closed */
      private void ensureOpen() throws IOException {
          if (out == null)
              throw new IOException("Stream closed");
      }
  
      /**
       * Flushes the stream.
       * @see #checkError()
       */
      public void flush() {
          try {
              synchronized (lock) {
                  ensureOpen();
                  out.flush();
              }
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /**
       * Closes the stream and releases any system resources associated
       * with it. Closing a previously closed stream has no effect.
       *
       * @see #checkError()
       */
      public void close() {
          try {
              synchronized (lock) {
                  if (out == null)
                      return;
                  out.close();
                  out = null;
              }
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /**
       * Flushes the stream if it's not closed and checks its error state.
       *
       * @return <code>true</code> if the print stream has encountered an error,
       *          either on the underlying output stream or during a format
       *          conversion.
       */
      public boolean checkError() {
          if (out != null) {
              flush();
          }
          if (out instanceof PrintWriter) {
              PrintWriter pw = (PrintWriter) out;
              return pw.checkError();
          } else if (psOut != null) {
              return psOut.checkError();
          }
          return trouble;
      }
  
      /**
       * Indicates that an error has occurred.
       *
       * <p> This method will cause subsequent invocations of {@link
       * #checkError()} to return <tt>true</tt> until {@link
       * #clearError()} is invoked.
       */
      protected void setError() {
          trouble = true;
      }
  
      /**
       * Clears the error state of this stream.
       *
       * <p> This method will cause subsequent invocations of {@link
       * #checkError()} to return <tt>false</tt> until another write
       * operation fails and invokes {@link #setError()}.
       *
       * @since 1.6
       */
      protected void clearError() {
          trouble = false;
      }
  
      /*
       * Exception-catching, synchronized output operations,
       * which also implement the write() methods of Writer
       */
  
      /**
       * Writes a single character.
       * @param c int specifying a character to be written.
       */
      public void write(int c) {
          try {
              synchronized (lock) {
                  ensureOpen();
                  out.write(c);
              }
          }
          catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /**
       * Writes A Portion of an array of characters.
       * @param buf Array of characters
       * @param off Offset from which to start writing characters
       * @param len Number of characters to write
       */
      public void write(char buf[], int off, int len) {
          try {
              synchronized (lock) {
                  ensureOpen();
                  out.write(buf, off, len);
              }
          }
          catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /**
       * Writes an array of characters.  This method cannot be inherited from the
       * Writer class because it must suppress I/O exceptions.
       * @param buf Array of characters to be written
       */
      public void write(char buf[]) {
          write(buf, 0, buf.length);
      }
  
      /**
       * Writes a portion of a string.
       * @param s A String
       * @param off Offset from which to start writing characters
       * @param len Number of characters to write
       */
      public void write(String s, int off, int len) {
          try {
              synchronized (lock) {
                  ensureOpen();
                  out.write(s, off, len);
              }
          }
          catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /**
       * Writes a string.  This method cannot be inherited from the Writer class
       * because it must suppress I/O exceptions.
       * @param s String to be written
       */
      public void write(String s) {
          write(s, 0, s.length());
      }
  
      private void newLine() {
          try {
              synchronized (lock) {
                  ensureOpen();
                  out.write(lineSeparator);
                  if (autoFlush)
                      out.flush();
              }
          }
          catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          }
          catch (IOException x) {
              trouble = true;
          }
      }
  
      /* Methods that do not terminate lines */
  
      /**
       * Prints a boolean value.  The string produced by <code>{@link
       * String#valueOf(boolean)}</code> is translated into bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link
       * #write(int)}</code> method.
       *
       * @param      b   The <code>boolean</code> to be printed
       */
      public void print(boolean b) {
          write(b ? "true" : "false");
      }
  
      /**
       * Prints a character.  The character is translated into one or more bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link
       * #write(int)}</code> method.
       *
       * @param      c   The <code>char</code> to be printed
       */
      public void print(char c) {
          write(c);
      }
  
      /**
       * Prints an integer.  The string produced by <code>{@link
       * String#valueOf(int)}</code> is translated into bytes according
       * to the platform's default character encoding, and these bytes are
       * written in exactly the manner of the <code>{@link #write(int)}</code>
       * method.
       *
       * @param      i   The <code>int</code> to be printed
       * @see        Integer#toString(int)
       */
      public void print(int i) {
          write(String.valueOf(i));
      }
  
      /**
       * Prints a long integer.  The string produced by <code>{@link
       * String#valueOf(long)}</code> is translated into bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link #write(int)}</code>
       * method.
       *
       * @param      l   The <code>long</code> to be printed
       * @see        Long#toString(long)
       */
      public void print(long l) {
          write(String.valueOf(l));
      }
  
      /**
       * Prints a floating-point number.  The string produced by <code>{@link
       * String#valueOf(float)}</code> is translated into bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link #write(int)}</code>
       * method.
       *
       * @param      f   The <code>float</code> to be printed
       * @see        Float#toString(float)
       */
      public void print(float f) {
          write(String.valueOf(f));
      }
  
      /**
       * Prints a double-precision floating-point number.  The string produced by
       * <code>{@link String#valueOf(double)}</code> is translated into
       * bytes according to the platform's default character encoding, and these
       * bytes are written in exactly the manner of the <code>{@link
       * #write(int)}</code> method.
       *
       * @param      d   The <code>double</code> to be printed
       * @see        Double#toString(double)
       */
      public void print(double d) {
          write(String.valueOf(d));
      }
  
      /**
       * Prints an array of characters.  The characters are converted into bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link #write(int)}</code>
       * method.
       *
       * @param      s   The array of chars to be printed
       *
       * @throws  NullPointerException  If <code>s</code> is <code>null</code>
       */
      public void print(char s[]) {
          write(s);
      }
  
      /**
       * Prints a string.  If the argument is <code>null</code> then the string
       * <code>"null"</code> is printed.  Otherwise, the string's characters are
       * converted into bytes according to the platform's default character
       * encoding, and these bytes are written in exactly the manner of the
       * <code>{@link #write(int)}</code> method.
       *
       * @param      s   The <code>String</code> to be printed
       */
      public void print(String s) {
          if (s == null) {
              s = "null";
          }
          write(s);
      }
  
      /**
       * Prints an object.  The string produced by the <code>{@link
       * String#valueOf(Object)}</code> method is translated into bytes
       * according to the platform's default character encoding, and these bytes
       * are written in exactly the manner of the <code>{@link #write(int)}</code>
       * method.
       *
       * @param      obj   The <code>Object</code> to be printed
       * @see        Object#toString()
       */
      public void print(Object obj) {
          write(String.valueOf(obj));
      }
  
      /* Methods that do terminate lines */
  
      /**
       * Terminates the current line by writing the line separator string.  The
       * line separator string is defined by the system property
       * <code>line.separator</code>, and is not necessarily a single newline
       * character (<code>'\n'</code>).
       */
      public void println() {
          newLine();
      }
  
      /**
       * Prints a boolean value and then terminates the line.  This method behaves
       * as though it invokes <code>{@link #print(boolean)}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x the <code>boolean</code> value to be printed
       */
      public void println(boolean x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints a character and then terminates the line.  This method behaves as
       * though it invokes <code>{@link #print(char)}</code> and then <code>{@link
       * #println()}</code>.
       *
       * @param x the <code>char</code> value to be printed
       */
      public void println(char x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints an integer and then terminates the line.  This method behaves as
       * though it invokes <code>{@link #print(int)}</code> and then <code>{@link
       * #println()}</code>.
       *
       * @param x the <code>int</code> value to be printed
       */
      public void println(int x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints a long integer and then terminates the line.  This method behaves
       * as though it invokes <code>{@link #print(long)}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x the <code>long</code> value to be printed
       */
      public void println(long x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints a floating-point number and then terminates the line.  This method
       * behaves as though it invokes <code>{@link #print(float)}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x the <code>float</code> value to be printed
       */
      public void println(float x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints a double-precision floating-point number and then terminates the
       * line.  This method behaves as though it invokes <code>{@link
       * #print(double)}</code> and then <code>{@link #println()}</code>.
       *
       * @param x the <code>double</code> value to be printed
       */
      public void println(double x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints an array of characters and then terminates the line.  This method
       * behaves as though it invokes <code>{@link #print(char[])}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x the array of <code>char</code> values to be printed
       */
      public void println(char x[]) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints a String and then terminates the line.  This method behaves as
       * though it invokes <code>{@link #print(String)}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x the <code>String</code> value to be printed
       */
      public void println(String x) {
          synchronized (lock) {
              print(x);
              println();
          }
      }
  
      /**
       * Prints an Object and then terminates the line.  This method calls
       * at first String.valueOf(x) to get the printed object's string value,
       * then behaves as
       * though it invokes <code>{@link #print(String)}</code> and then
       * <code>{@link #println()}</code>.
       *
       * @param x  The <code>Object</code> to be printed.
       */
      public void println(Object x) {
          String s = String.valueOf(x);
          synchronized (lock) {
              print(s);
              println();
          }
      }
  
      /**
       * A convenience method to write a formatted string to this writer using
       * the specified format string and arguments.  If automatic flushing is
       * enabled, calls to this method will flush the output buffer.
       *
       * <p> An invocation of this method of the form <tt>out.printf(format,
       * args)</tt> behaves in exactly the same way as the invocation
       *
       * <pre>
       *     out.format(format, args) </pre>
       *
       * @param  format
       *         A format string as described in <a
       *         href="../util/Formatter.html#syntax">Format string syntax</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
       *         <tt>null</tt> 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.
       *
       * @throws  NullPointerException
       *          If the <tt>format</tt> is <tt>null</tt>
       *
       * @return  This writer
       *
       * @since  1.5
       */
      public PrintWriter printf(String format, Object ... args) {
          return format(format, args);
      }
  
      /**
       * A convenience method to write a formatted string to this writer using
       * the specified format string and arguments.  If automatic flushing is
       * enabled, calls to this method will flush the output buffer.
       *
       * <p> An invocation of this method of the form <tt>out.printf(l, format,
       * args)</tt> behaves in exactly the same way as the invocation
       *
       * <pre>
       *     out.format(l, format, args) </pre>
       *
       * @param  l
       *         The {@linkplain Locale locale} to apply during
       *         formatting.  If <tt>l</tt> is <tt>null</tt> then no localization
       *         is applied.
       *
       * @param  format
       *         A format string as described in <a
       *         href="../util/Formatter.html#syntax">Format string syntax</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
       *         <tt>null</tt> 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.
       *
       * @throws  NullPointerException
       *          If the <tt>format</tt> is <tt>null</tt>
       *
       * @return  This writer
       *
       * @since  1.5
       */
      public PrintWriter printf(Locale l, String format, Object ... args) {
          return format(l, format, args);
      }
  
      /**
       * Writes a formatted string to this writer using the specified format
       * string and arguments.  If automatic flushing is enabled, calls to this
       * method will flush the output buffer.
       *
       * <p> The locale always used is the one returned by {@link
       * Locale#getDefault() Locale.getDefault()}, regardless of any
       * previous invocations of other formatting methods on this object.
       *
       * @param  format
       *         A format string as described in <a
       *         href="../util/Formatter.html#syntax">Format string syntax</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
       *         <tt>null</tt> 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.
       *
       * @throws  NullPointerException
       *          If the <tt>format</tt> is <tt>null</tt>
       *
       * @return  This writer
       *
       * @since  1.5
       */
      public PrintWriter format(String format, Object ... args) {
          try {
              synchronized (lock) {
                  ensureOpen();
                  if ((formatter == null)
                      || (formatter.locale() != Locale.getDefault()))
                      formatter = new Formatter(this);
                  formatter.format(Locale.getDefault(), format, args);
                  if (autoFlush)
                      out.flush();
              }
          } catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          } catch (IOException x) {
              trouble = true;
          }
          return this;
      }
  
      /**
       * Writes a formatted string to this writer using the specified format
       * string and arguments.  If automatic flushing is enabled, calls to this
       * method will flush the output buffer.
       *
       * @param  l
       *         The {@linkplain Locale locale} to apply during
       *         formatting.  If <tt>l</tt> is <tt>null</tt> then no localization
       *         is applied.
       *
       * @param  format
       *         A format string as described in <a
       *         href="../util/Formatter.html#syntax">Format string syntax</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
       *         <tt>null</tt> 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.
       *
       * @throws  NullPointerException
       *          If the <tt>format</tt> is <tt>null</tt>
       *
       * @return  This writer
       *
       * @since  1.5
       */
      public PrintWriter format(Locale l, String format, Object ... args) {
          try {
              synchronized (lock) {
                  ensureOpen();
                  if ((formatter == null) || (formatter.locale() != l))
                      formatter = new Formatter(this, l);
                  formatter.format(l, format, args);
                  if (autoFlush)
                      out.flush();
              }
          } catch (InterruptedIOException x) {
              Thread.currentThread().interrupt();
          } catch (IOException x) {
              trouble = true;
          }
          return this;
      }
  
      /**
       * Appends the specified character sequence to this writer.
       *
       * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
       * behaves in exactly the same way as the invocation
       *
       * <pre>
       *     out.write(csq.toString()) </pre>
       *
       * <p> Depending on the specification of <tt>toString</tt> for the
       * character sequence <tt>csq</tt>, the entire sequence may not be
       * appended. For instance, invoking the <tt>toString</tt> method of a
       * character buffer will return a subsequence whose content depends upon
       * the buffer's position and limit.
       *
       * @param  csq
       *         The character sequence to append.  If <tt>csq</tt> is
       *         <tt>null</tt>, then the four characters <tt>"null"</tt> are
       *         appended to this writer.
       *
       * @return  This writer
       *
       * @since  1.5
       */
      public PrintWriter append(CharSequence csq) {
          if (csq == null)
              write("null");
          else
              write(csq.toString());
          return this;
      }
  
      /**
       * Appends a subsequence of the specified character sequence to this writer.
       *
       * <p> An invocation of this method of the form <tt>out.append(csq, start,
       * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
       * exactly the same way as the invocation
       *
       * <pre>
       *     out.write(csq.subSequence(start, end).toString()) </pre>
       *
       * @param  csq
       *         The character sequence from which a subsequence will be
       *         appended.  If <tt>csq</tt> is <tt>null</tt>, then characters
       *         will be appended as if <tt>csq</tt> contained the four
       *         characters <tt>"null"</tt>.
       *
       * @param  start
       *         The index of the first character in the subsequence
       *
       * @param  end
       *         The index of the character following the last character in the
       *         subsequence
       *
       * @return  This writer
       *
       * @throws  IndexOutOfBoundsException
       *          If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
       *          is greater than <tt>end</tt>, or <tt>end</tt> is greater than
       *          <tt>csq.length()</tt>
       *
       * @since  1.5
       */
      public PrintWriter append(CharSequence csq, int start, int end) {
          CharSequence cs = (csq == null ? "null" : csq);
          write(cs.subSequence(start, end).toString());
          return this;
      }
  
      /**
       * Appends the specified character to this writer.
       *
       * <p> An invocation of this method of the form <tt>out.append(c)</tt>
       * behaves in exactly the same way as the invocation
       *
       * <pre>
       *     out.write(c) </pre>
       *
       * @param  c
       *         The 16-bit character to append
       *
       * @return  This writer
       *
       * @since 1.5
       */
      public PrintWriter append(char c) {
          write(c);
          return this;
      }
  }
  