Writer

public abstract class Writer extends Object
implements Appendable Closeable Flushable

Known Direct Subclasses BufferedWriter, CharArrayWriter, FilterWriter, OutputStreamWriter, PipedWriter, PrintWriter, StringWriter BufferedWriter Writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.  CharArrayWriter This class implements a character buffer that can be used as an Writer.  FilterWriter Abstract class for writing filtered character streams.  OutputStreamWriter A class for turning a character stream into a byte stream.  PipedWriter Piped character-output streams.  PrintWriter Prints formatted representations of objects to a text-output stream.  StringWriter A character stream that collects its output in a string buffer, which can then be used to construct a string.

Known Indirect Subclasses FileWriter FileWriter Convenience class for writing character files.

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 Also

• Writer
• BufferedWriter
• CharArrayWriter
• FilterWriter
• OutputStreamWriter
• FileWriter
• PipedWriter
• PrintWriter
• StringWriter
• Reader

Field Summary

protected Object

lock

The object used to synchronize operations on this stream.

Protected Constructor Summary

	Writer() Creates a new character-stream writer whose critical sections will synchronize on the writer itself.
	Writer(Object lock) Creates a new character-stream writer whose critical sections will synchronize on the given object.

Public Method Summary

Writer	append(char c) Appends the specified character to this writer.
Writer	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this writer.
Writer	append(CharSequence csq) Appends the specified character sequence to this writer.
abstract void	close() Closes the stream, flushing it first.
abstract void	flush() Flushes the stream.
void	write(String str) Writes a string.
void	write(int c) Writes a single character.
void	write(String str, int off, int len) Writes a portion of a string.
abstract void	write(char[] cbuf, int off, int len) Writes a portion of an array of characters.
void	write(char[] cbuf) Writes an array of characters.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.lang.Appendable

abstract Appendable	append(char c) Appends the specified character to this Appendable.
abstract Appendable	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this Appendable.
abstract Appendable	append(CharSequence csq) Appends the specified character sequence to this Appendable.

From interface java.io.Closeable

abstract void

close() Closes this stream and releases any system resources associated with it.

From interface java.io.Flushable

abstract void

flush() Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Fields

protected Object lock

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 this or a synchronized method.

Protected Constructors

protected Writer ()

Creates a new character-stream writer whose critical sections will synchronize on the writer itself.

protected Writer (Object lock)

Creates a new character-stream writer whose critical sections will synchronize on the given object.

Parameters

lock	Object to synchronize on

Public Methods

public Writer 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) 

Parameters

c	The 16-bit character to append

Returns

• This writer

Throws

IOException	If an I/O error occurs

public Writer append (CharSequence csq, int start, int end)

Appends a subsequence of the specified character sequence to this writer. Appendable.

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()) 

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()
IOException	If an I/O error occurs

public Writer 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.

Parameters

csq	The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.

Returns

• This writer

Throws

IOException	If an I/O error occurs

public abstract void close ()

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

public abstract void flush ()

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.

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

public void write (String str)

Writes a string.

Parameters

str	String to be written

Throws

IOException	If an I/O error occurs

public void write (int c)

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.

Subclasses that intend to support efficient single-character output should override this method.

Parameters

c	int specifying a character to be written

Throws

IOException	If an I/O error occurs

public void write (String str, int off, int len)

Writes a portion of a string.

Parameters

str	A String
off	Offset from which to start writing characters
len	Number of characters to write

Throws

IndexOutOfBoundsException	If off is negative, or len is negative, or off+len is negative or greater than the length of the given string
IOException	If an I/O error occurs

public abstract void write (char[] cbuf, int off, int len)

Writes a portion of an array of characters.

Parameters

cbuf	Array of characters
off	Offset from which to start writing characters
len	Number of characters to write

Throws

IOException	If an I/O error occurs

public void write (char[] cbuf)

Writes an array of characters.

Parameters

cbuf	Array of characters to be written

Throws

IOException	If an I/O error occurs