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Java example source code file (CharArrayReader.java)
The CharArrayReader.java Java example source code/*
* Copyright (c) 1996, 2005, 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;
/**
* This class implements a character buffer that can be used as a
* character-input stream.
*
* @author Herb Jellinek
* @since JDK1.1
*/
public class CharArrayReader extends Reader {
/** The character buffer. */
protected char buf[];
/** The current buffer position. */
protected int pos;
/** The position of mark in buffer. */
protected int markedPos = 0;
/**
* The index of the end of this buffer. There is not valid
* data at or beyond this index.
*/
protected int count;
/**
* Creates a CharArrayReader from the specified array of chars.
* @param buf Input buffer (not copied)
*/
public CharArrayReader(char buf[]) {
this.buf = buf;
this.pos = 0;
this.count = buf.length;
}
/**
* Creates a CharArrayReader from the specified array of chars.
*
* <p> The resulting reader will start reading at the given
* <tt>offset. The total number of char values that can be
* read from this reader will be either <tt>length or
* <tt>buf.length-offset, whichever is smaller.
*
* @throws IllegalArgumentException
* If <tt>offset is negative or greater than
* <tt>buf.length, or if length is negative, or if
* the sum of these two values is negative.
*
* @param buf Input buffer (not copied)
* @param offset Offset of the first char to read
* @param length Number of chars to read
*/
public CharArrayReader(char buf[], int offset, int length) {
if ((offset < 0) || (offset > buf.length) || (length < 0) ||
((offset + length) < 0)) {
throw new IllegalArgumentException();
}
this.buf = buf;
this.pos = offset;
this.count = Math.min(offset + length, buf.length);
this.markedPos = offset;
}
/** Checks to make sure that the stream has not been closed */
private void ensureOpen() throws IOException {
if (buf == null)
throw new IOException("Stream closed");
}
/**
* Reads a single character.
*
* @exception IOException If an I/O error occurs
*/
public int read() throws IOException {
synchronized (lock) {
ensureOpen();
if (pos >= count)
return -1;
else
return buf[pos++];
}
}
/**
* Reads characters into a portion of an array.
* @param b Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
* @return The actual number of characters read, or -1 if
* the end of the stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public int read(char b[], int off, int len) throws IOException {
synchronized (lock) {
ensureOpen();
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
if (pos >= count) {
return -1;
}
if (pos + len > count) {
len = count - pos;
}
if (len <= 0) {
return 0;
}
System.arraycopy(buf, pos, b, off, len);
pos += len;
return len;
}
}
/**
* Skips characters. Returns the number of characters that were skipped.
*
* <p>The
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