Class CharArrayWriter

java.lang.Object
java.io.Writer
java.io.CharArrayWriter
All Implemented Interfaces:
Closeable, Flushable, Appendable, AutoCloseable 
public class CharArrayWriter extends Writer
This class implements a character buffer that can be used as an Writer. The buffer automatically grows when data is written to the stream. The data can be retrieved using toCharArray() and toString().

Note: Invoking close() on this class has no effect, and methods of this class can be called after the stream has closed without generating an IOException.

Since:
1.1

Field Summary

Modifier and Type Field Description
protected char[] buf
The buffer where data is stored.
protected int count
The number of chars in the buffer.

Fields declared in class java.io.Writer

lock

Constructor Summary

Constructor Description
CharArrayWriter()
Creates a new CharArrayWriter.
CharArrayWriter(int initialSize)
Creates a new CharArrayWriter with the specified initial size.

Method Summary

Modifier and Type Method Description
CharArrayWriter append(char c)
Appends the specified character to this writer.
CharArrayWriter append(CharSequence csq)
Appends the specified character sequence to this writer.
CharArrayWriter append(CharSequence csq, int start, int end)
Appends a subsequence of the specified character sequence to this writer.
void close()
Close the stream.
void flush()
Flush the stream.
void reset()
Resets the buffer so that you can use it again without throwing away the already allocated buffer.
int size()
Returns the current size of the buffer.
char[] toCharArray()
Returns a copy of the input data.
String toString()
Converts input data to a string.
void write(char[] c, int off, int len)
Writes characters to the buffer.
void write(int c)
Writes a character to the buffer.
void write(String str, int off, int len)
Write a portion of a string to the buffer.
void writeTo(Writer out)
Writes the contents of the buffer to another character stream.

Methods declared in class java.io.Writer

nullWriter, write, write

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

buf

protected char[] buf
The buffer where data is stored.

count

protected int count
The number of chars in the buffer.

Constructor Details

CharArrayWriter

public CharArrayWriter()
Creates a new CharArrayWriter.

CharArrayWriter

public CharArrayWriter(int initialSize)
Creates a new CharArrayWriter with the specified initial size.
Parameters:
initialSize - an int specifying the initial buffer size.
Throws:
IllegalArgumentException - if initialSize is negative

Method Details

write

public void write(int c)
Writes a character to the buffer.
Overrides:
write in class Writer
Parameters:
c - int specifying a character to be written

write

public void write(char[] c, int off, int len)
Writes characters to the buffer.
Specified by:
write in class Writer
Parameters:
c - the data to be written
off - the start offset in the data
len - the number of chars that are written
Throws:
IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given array

write

public void write(String str, int off, int len)
Write a portion of a string to the buffer.
Overrides:
write in class Writer
Parameters:
str - String to be written from
off - Offset from which to start reading characters
len - Number of characters to be written
Throws:
IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given string

writeTo

public void writeTo(Writer out) throws IOException
Writes the contents of the buffer to another character stream.
Parameters:
out - the output stream to write to
Throws:
IOException - If an I/O error occurs.

append

public CharArrayWriter append(CharSequence csq)
Appends the specified character sequence to this writer.

An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation 

     out.write(csq.toString())

Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.
Returns:
This writer
Since:
1.5

append

public CharArrayWriter append(CharSequence csq, int start, int end)
Appends a subsequence of the specified character sequence to this writer.

An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation 

     out.write(csq.subSequence(start, end).toString())
Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
start - The index of the first character in the subsequence
end - The index of the character following the last character in the subsequence
Returns:
This writer
Throws:
IndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
Since:
1.5

append

public CharArrayWriter append(char c)
Appends the specified character to this writer.

An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation 

     out.write(c)
Specified by:
append in interface Appendable
Overrides:
append in class Writer
Parameters:
c - The 16-bit character to append
Returns:
This writer
Since:
1.5

reset

public void reset()
Resets the buffer so that you can use it again without throwing away the already allocated buffer.

toCharArray

public char[] toCharArray()
Returns a copy of the input data.
Returns:
an array of chars copied from the input data.

size

public int size()
Returns the current size of the buffer.
Returns:
an int representing the current size of the buffer.

toString

public String toString()
Converts input data to a string.
Overrides:
toString in class Object
Returns:
the string.

flush

public void flush()
Flush the stream.

The flush method of CharArrayWriter does nothing.

Specified by:
flush in interface Flushable
Specified by:
flush in class Writer

close

public void close()
Close the stream. This method does not release the buffer, since its contents might still be required. Note: Invoking this method in this class will have no effect.
Specified by:
close in interface AutoCloseable
Specified by:
close in interface Closeable
Specified by:
close in class Writer

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/CharArrayWriter.html