author | forax |
Sun, 19 Feb 2012 16:51:35 +0000 | |
changeset 11907 | c021db66251d |
parent 11016 | e2665f4ac6d2 |
child 14342 | 8435a30053c1 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package java.io; |
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/** |
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* Abstract class for writing to character streams. The only methods that a |
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* subclass must implement are write(char[], int, int), flush(), and close(). |
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* Most subclasses, however, will override some of the methods defined here in |
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* order to provide higher efficiency, additional functionality, or both. |
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* |
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* @see Writer |
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* @see BufferedWriter |
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* @see CharArrayWriter |
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* @see FilterWriter |
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* @see OutputStreamWriter |
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* @see FileWriter |
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* @see PipedWriter |
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* @see PrintWriter |
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* @see StringWriter |
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* @see Reader |
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* |
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* @author Mark Reinhold |
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* @since JDK1.1 |
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*/ |
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public abstract class Writer implements Appendable, Closeable, Flushable { |
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/** |
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* Temporary buffer used to hold writes of strings and single characters |
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*/ |
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private char[] writeBuffer; |
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/** |
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* Size of writeBuffer, must be >= 1 |
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*/ |
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private static final int WRITE_BUFFER_SIZE = 1024; |
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/** |
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* The object used to synchronize operations on this stream. For |
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* efficiency, a character-stream object may use an object other than |
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* itself to protect critical sections. A subclass should therefore use |
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* the object in this field rather than <tt>this</tt> or a synchronized |
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* method. |
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*/ |
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protected Object lock; |
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/** |
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* Creates a new character-stream writer whose critical sections will |
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* synchronize on the writer itself. |
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*/ |
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protected Writer() { |
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this.lock = this; |
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} |
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/** |
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* Creates a new character-stream writer whose critical sections will |
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* synchronize on the given object. |
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* |
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* @param lock |
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* Object to synchronize on |
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*/ |
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protected Writer(Object lock) { |
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if (lock == null) { |
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throw new NullPointerException(); |
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} |
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this.lock = lock; |
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} |
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/** |
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* Writes a single character. The character to be written is contained in |
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* the 16 low-order bits of the given integer value; the 16 high-order bits |
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* are ignored. |
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* |
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* <p> Subclasses that intend to support efficient single-character output |
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* should override this method. |
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* |
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* @param c |
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* int specifying a character to be written |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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public void write(int c) throws IOException { |
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synchronized (lock) { |
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if (writeBuffer == null){ |
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writeBuffer = new char[WRITE_BUFFER_SIZE]; |
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} |
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writeBuffer[0] = (char) c; |
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write(writeBuffer, 0, 1); |
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} |
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} |
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/** |
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* Writes an array of characters. |
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* |
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* @param cbuf |
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* Array of characters to be written |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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public void write(char cbuf[]) throws IOException { |
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write(cbuf, 0, cbuf.length); |
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} |
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/** |
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* Writes a portion of an array of characters. |
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* |
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* @param cbuf |
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* Array of characters |
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* |
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* @param off |
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* Offset from which to start writing characters |
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* |
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* @param len |
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* Number of characters to write |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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abstract public void write(char cbuf[], int off, int len) throws IOException; |
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/** |
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* Writes a string. |
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* |
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* @param str |
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* String to be written |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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public void write(String str) throws IOException { |
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write(str, 0, str.length()); |
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} |
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/** |
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* Writes a portion of a string. |
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* |
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* @param str |
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* A String |
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* |
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* @param off |
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* Offset from which to start writing characters |
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* |
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* @param len |
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* Number of characters to write |
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* |
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* @throws IndexOutOfBoundsException |
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* If <tt>off</tt> is negative, or <tt>len</tt> is negative, |
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* or <tt>off+len</tt> is negative or greater than the length |
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* of the given string |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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public void write(String str, int off, int len) throws IOException { |
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synchronized (lock) { |
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char cbuf[]; |
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if (len <= WRITE_BUFFER_SIZE) { |
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if (writeBuffer == null) { |
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writeBuffer = new char[WRITE_BUFFER_SIZE]; |
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} |
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cbuf = writeBuffer; |
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} else { // Don't permanently allocate very large buffers. |
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cbuf = new char[len]; |
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} |
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str.getChars(off, (off + len), cbuf, 0); |
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write(cbuf, 0, len); |
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} |
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} |
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/** |
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* Appends the specified character sequence to this writer. |
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* |
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* <p> An invocation of this method of the form <tt>out.append(csq)</tt> |
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* behaves in exactly the same way as the invocation |
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* |
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* <pre> |
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* out.write(csq.toString()) </pre> |
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* |
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* <p> Depending on the specification of <tt>toString</tt> for the |
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* character sequence <tt>csq</tt>, the entire sequence may not be |
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* appended. For instance, invoking the <tt>toString</tt> method of a |
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* character buffer will return a subsequence whose content depends upon |
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* the buffer's position and limit. |
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* |
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* @param csq |
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* The character sequence to append. If <tt>csq</tt> is |
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* <tt>null</tt>, then the four characters <tt>"null"</tt> are |
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* appended to this writer. |
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* |
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* @return This writer |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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* |
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* @since 1.5 |
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*/ |
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public Writer append(CharSequence csq) throws IOException { |
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if (csq == null) |
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write("null"); |
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else |
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write(csq.toString()); |
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return this; |
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} |
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/** |
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* Appends a subsequence of the specified character sequence to this writer. |
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* <tt>Appendable</tt>. |
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* |
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* <p> An invocation of this method of the form <tt>out.append(csq, start, |
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* end)</tt> when <tt>csq</tt> is not <tt>null</tt> behaves in exactly the |
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* same way as the invocation |
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* |
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* <pre> |
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* out.write(csq.subSequence(start, end).toString()) </pre> |
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* |
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* @param csq |
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* The character sequence from which a subsequence will be |
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* appended. If <tt>csq</tt> is <tt>null</tt>, then characters |
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* will be appended as if <tt>csq</tt> contained the four |
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* characters <tt>"null"</tt>. |
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* |
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* @param start |
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* The index of the first character in the subsequence |
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* |
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* @param end |
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* The index of the character following the last character in the |
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* subsequence |
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* |
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* @return This writer |
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* |
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* @throws IndexOutOfBoundsException |
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* If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt> |
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* is greater than <tt>end</tt>, or <tt>end</tt> is greater than |
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* <tt>csq.length()</tt> |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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* |
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* @since 1.5 |
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*/ |
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public Writer append(CharSequence csq, int start, int end) throws IOException { |
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CharSequence cs = (csq == null ? "null" : csq); |
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write(cs.subSequence(start, end).toString()); |
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return this; |
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} |
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/** |
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* Appends the specified character to this writer. |
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* |
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* <p> An invocation of this method of the form <tt>out.append(c)</tt> |
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* behaves in exactly the same way as the invocation |
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* |
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* <pre> |
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* out.write(c) </pre> |
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* |
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* @param c |
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* The 16-bit character to append |
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* |
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* @return This writer |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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* |
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* @since 1.5 |
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*/ |
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public Writer append(char c) throws IOException { |
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write(c); |
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return this; |
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} |
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/** |
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* Flushes the stream. If the stream has saved any characters from the |
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* various write() methods in a buffer, write them immediately to their |
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* intended destination. Then, if that destination is another character or |
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* byte stream, flush it. Thus one flush() invocation will flush all the |
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* buffers in a chain of Writers and OutputStreams. |
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* |
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* <p> If the intended destination of this stream is an abstraction provided |
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* by the underlying operating system, for example a file, then flushing the |
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* stream guarantees only that bytes previously written to the stream are |
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* passed to the operating system for writing; it does not guarantee that |
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* they are actually written to a physical device such as a disk drive. |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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abstract public void flush() throws IOException; |
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/** |
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* Closes the stream, flushing it first. Once the stream has been closed, |
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* further write() or flush() invocations will cause an IOException to be |
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* thrown. Closing a previously closed stream has no effect. |
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* |
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* @throws IOException |
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* If an I/O error occurs |
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*/ |
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abstract public void close() throws IOException; |
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} |