content: /*
   * Copyright (c) 1996, 2011, 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;
  
  
  /**
   * Abstract class for writing to character streams.  The only methods that a
   * subclass must implement are write(char[], int, int), flush(), and close().
   * Most subclasses, however, will override some of the methods defined here in
   * order to provide higher efficiency, additional functionality, or both.
   *
   * @see Writer
   * @see   BufferedWriter
   * @see   CharArrayWriter
   * @see   FilterWriter
   * @see   OutputStreamWriter
   * @see     FileWriter
   * @see   PipedWriter
   * @see   PrintWriter
   * @see   StringWriter
   * @see Reader
   *
   * @author      Mark Reinhold
   * @since       JDK1.1
   */
  
  public abstract class Writer implements Appendable, Closeable, Flushable {
  
      /**
       * Temporary buffer used to hold writes of strings and single characters
       */
      private char[] writeBuffer;
  
      /**
       * Size of writeBuffer, must be >= 1
       */
      private static final int WRITE_BUFFER_SIZE = 1024;
  
      /**
       * The object used to synchronize operations on this stream.  For
       * efficiency, a character-stream object may use an object other than
       * itself to protect critical sections.  A subclass should therefore use
       * the object in this field rather than <tt>this</tt> or a synchronized
       * method.
       */
      protected Object lock;
  
      /**
       * Creates a new character-stream writer whose critical sections will
       * synchronize on the writer itself.
       */
      protected Writer() {
          this.lock = this;
      }
  
      /**
       * Creates a new character-stream writer whose critical sections will
       * synchronize on the given object.
       *
       * @param  lock
       *         Object to synchronize on
       */
      protected Writer(Object lock) {
          if (lock == null) {
              throw new NullPointerException();
          }
          this.lock = lock;
      }
  
      /**
       * Writes a single character.  The character to be written is contained in
       * the 16 low-order bits of the given integer value; the 16 high-order bits
       * are ignored.
       *
       * <p> Subclasses that intend to support efficient single-character output
       * should override this method.
       *
       * @param  c
       *         int specifying a character to be written
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public void write(int c) throws IOException {
          synchronized (lock) {
              if (writeBuffer == null){
                  writeBuffer = new char[WRITE_BUFFER_SIZE];
              }
              writeBuffer[0] = (char) c;
              write(writeBuffer, 0, 1);
          }
      }
  
      /**
       * Writes an array of characters.
       *
       * @param  cbuf
       *         Array of characters to be written
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public void write(char cbuf[]) throws IOException {
          write(cbuf, 0, cbuf.length);
      }
  
      /**
       * Writes a portion of an array of characters.
       *
       * @param  cbuf
       *         Array of characters
       *
       * @param  off
       *         Offset from which to start writing characters
       *
       * @param  len
       *         Number of characters to write
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      abstract public void write(char cbuf[], int off, int len) throws IOException;
  
      /**
       * Writes a string.
       *
       * @param  str
       *         String to be written
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public void write(String str) throws IOException {
          write(str, 0, str.length());
      }
  
      /**
       * Writes a portion of a string.
       *
       * @param  str
       *         A String
       *
       * @param  off
       *         Offset from which to start writing characters
       *
       * @param  len
       *         Number of characters to write
       *
       * @throws  IndexOutOfBoundsException
       *          If <tt>off</tt> is negative, or <tt>len</tt> is negative,
       *          or <tt>off+len</tt> is negative or greater than the length
       *          of the given string
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public void write(String str, int off, int len) throws IOException {
          synchronized (lock) {
              char cbuf[];
              if (len <= WRITE_BUFFER_SIZE) {
                  if (writeBuffer == null) {
                      writeBuffer = new char[WRITE_BUFFER_SIZE];
                  }
                  cbuf = writeBuffer;
              } else {    // Don't permanently allocate very large buffers.
                  cbuf = new char[len];
              }
              str.getChars(off, (off + len), cbuf, 0);
              write(cbuf, 0, len);
          }
      }
  
      /**
       * 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
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @since  1.5
       */
      public Writer append(CharSequence csq) throws IOException {
          if (csq == null)
              write("null");
          else
              write(csq.toString());
          return this;
      }
  
      /**
       * Appends a subsequence of the specified character sequence to this writer.
       * <tt>Appendable</tt>.
       *
       * <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>
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @since  1.5
       */
      public Writer append(CharSequence csq, int start, int end) throws IOException {
          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
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @since 1.5
       */
      public Writer append(char c) throws IOException {
          write(c);
          return this;
      }
  
      /**
       * Flushes the stream.  If the stream has saved any characters from the
       * various write() methods in a buffer, write them immediately to their
       * intended destination.  Then, if that destination is another character or
       * byte stream, flush it.  Thus one flush() invocation will flush all the
       * buffers in a chain of Writers and OutputStreams.
       *
       * <p> If the intended destination of this stream is an abstraction provided
       * by the underlying operating system, for example a file, then flushing the
       * stream guarantees only that bytes previously written to the stream are
       * passed to the operating system for writing; it does not guarantee that
       * they are actually written to a physical device such as a disk drive.
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      abstract public void flush() throws IOException;
  
      /**
       * Closes the stream, flushing it first. Once the stream has been closed,
       * further write() or flush() invocations will cause an IOException to be
       * thrown. Closing a previously closed stream has no effect.
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      abstract public void close() throws IOException;
  
  }
  