/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.io;
import java.util.Arrays;
/**
* A specialized {@link Writer} that writes characters to a {@code StringBuffer}
* in a sequential manner, appending them in the process. The result can later
* be queried using the {@link #StringWriter(int)} or {@link #toString()}
* methods.
*
* @see StringReader
*/
public class StringWriter extends Writer {
private StringBuffer buf;
/**
* Constructs a new {@code StringWriter} which has a {@link StringBuffer}
* allocated with the default size of 16 characters. The {@code
* StringBuffer} is also the {@code lock} used to synchronize access to this
* writer.
*/
public StringWriter() {
buf = new StringBuffer(16);
lock = buf;
}
/**
* Constructs a new {@code StringWriter} which has a {@link StringBuffer}
* allocated with a size of {@code initialSize} characters. The {@code
* StringBuffer} is also the {@code lock} used to synchronize access to this
* writer.
*
* @param initialSize
* the intial size of the target string buffer.
*/
public StringWriter(int initialSize) {
if (initialSize < 0) {
throw new IllegalArgumentException();
}
buf = new StringBuffer(initialSize);
lock = buf;
}
/**
* Calling this method has no effect. In contrast to most {@code Writer} subclasses,
* the other methods in {@code StringWriter} do not throw an {@code IOException} if
* {@code close()} has been called.
*
* @throws IOException
* if an error occurs while closing this writer.
*/
@Override
public void close() throws IOException {
/* empty */
}
/**
* Calling this method has no effect.
*/
@Override
public void flush() {
/* empty */
}
/**
* Gets a reference to this writer's internal {@link StringBuffer}. Any
* changes made to the returned buffer are reflected in this writer.
*
* @return a reference to this writer's internal {@code StringBuffer}.
*/
public StringBuffer getBuffer() {
return buf;
}
/**
* Gets a copy of the contents of this writer as a string.
*
* @return this writer's contents as a string.
*/
@Override
public String toString() {
return buf.toString();
}
/**
* Writes {@code count} characters starting at {@code offset} in {@code buf}
* to this writer's {@code StringBuffer}.
*
* @param chars
* the non-null character array to write.
* @param offset
* the index of the first character in {@code chars} to write.
* @param count
* the maximum number of characters to write.
* @throws IndexOutOfBoundsException
* if {@code offset < 0} or {@code count < 0}, or if {@code
* offset + count} is greater than the size of {@code buf}.
*/
@Override
public void write(char[] chars, int offset, int count) {
Arrays.checkOffsetAndCount(chars.length, offset, count);
if (count == 0) {
return;
}
buf.append(chars, offset, count);
}
/**
* Writes one character to this writer's {@code StringBuffer}. Only the two
* least significant bytes of the integer {@code oneChar} are written.
*
* @param oneChar
* the character to write to this writer's {@code StringBuffer}.
*/
@Override
public void write(int oneChar) {
buf.append((char) oneChar);
}
/**
* Writes the characters from the specified string to this writer's {@code
* StringBuffer}.
*
* @param str
* the non-null string containing the characters to write.
*/
@Override
public void write(String str) {
buf.append(str);
}
/**
* Writes {@code count} characters from {@code str} starting at {@code
* offset} to this writer's {@code StringBuffer}.
*
* @param str
* the non-null string containing the characters to write.
* @param offset
* the index of the first character in {@code str} to write.
* @param count
* the number of characters from {@code str} to write.
* @throws StringIndexOutOfBoundsException
* if {@code offset < 0} or {@code count < 0}, or if {@code
* offset + count} is greater than the length of {@code str}.
*/
@Override
public void write(String str, int offset, int count) {
String sub = str.substring(offset, offset + count);
buf.append(sub);
}
/**
* Appends the character {@code c} to this writer's {@code StringBuffer}.
* This method works the same way as {@link #write(int)}.
*
* @param c
* the character to append to the target stream.
* @return this writer.
*/
@Override
public StringWriter append(char c) {
write(c);
return this;
}
/**
* Appends the character sequence {@code csq} to this writer's {@code
* StringBuffer}. This method works the same way as {@code
* StringWriter.write(csq.toString())}. If {@code csq} is {@code null}, then
* the string "null" is written to the target stream.
*
* @param csq
* the character sequence appended to the target.
* @return this writer.
*/
@Override
public StringWriter append(CharSequence csq) {
if (csq == null) {
csq = "null";
}
write(csq.toString());
return this;
}
/**
* Appends a subsequence of the character sequence {@code csq} to this
* writer's {@code StringBuffer}. This method works the same way as {@code
* StringWriter.writer(csq.subsequence(start, end).toString())}. If {@code
* csq} is {@code null}, then the specified subsequence of the string "null"
* will be written to the target.
*
* @param csq
* the character sequence appended to the target.
* @param start
* the index of the first char in the character sequence appended
* to the target.
* @param end
* the index of the character following the last character of the
* subsequence appended to the target.
* @return this writer.
* @throws IndexOutOfBoundsException
* if {@code start > end}, {@code start < 0}, {@code end < 0} or
* either {@code start} or {@code end} are greater or equal than
* the length of {@code csq}.
*/
@Override
public StringWriter append(CharSequence csq, int start, int end) {
if (csq == null) {
csq = "null";
}
String output = csq.subSequence(start, end).toString();
write(output, 0, output.length());
return this;
}
}