java.io
Class Reader

java.lang.Object
  java.io.Reader

Direct Known Subclasses:

InputStreamReader

public abstract class Reader
extends Object

Abstract class for reading character streams. The only methods that a subclass must implement are read(char[], int, int) and close(). Most subclasses, however, will override some of the methods defined here in order to provide higher efficiency, additional functionality, or both.

Field Summary

protected Object

lock The object used to synchronize operations on this stream.

Constructor Summary

protected	Reader() Create a new character-stream reader whose critical sections will synchronize on the reader itself.
protected	Reader(Object lock) Create a new character-stream reader whose critical sections will synchronize on the given object.

Method Summary

abstract void	close() Close the stream.
void	mark(int readAheadLimit) Mark the present position in the stream.
boolean	markSupported() Tell whether this stream supports the mark() operation.
int	read() Read a single character.
int	read(char[] cbuf) Read characters into an array.
abstract int	read(char[] cbuf, int off, int len) Read characters into a portion of an array.
boolean	ready() Tell whether this stream is ready to be read.
void	reset() Reset the stream.
long	skip(long n) Skip characters.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

lock

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.

Constructor Detail

Reader

protected Reader()

Create a new character-stream reader whose critical sections will synchronize on the reader itself.

Reader

protected Reader(Object lock)

Create a new character-stream reader whose critical sections will synchronize on the given object.

Method Detail

close

public abstract void close()
                    throws IOException

Close the stream. Once a stream has been closed, further read(), ready(), mark(), or reset() invocations will throw an IOException. Closing a previously-closed stream, however, has no effect.

Throws:

IOException

mark

public void mark(int readAheadLimit)
          throws IOException

Mark the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point. Not all character-input streams support the mark() operation.

Throws:

IOException

markSupported

public boolean markSupported()

Tell whether this stream supports the mark() operation. The default implementation always returns false. Subclasses should override this method.

read

public int read()
         throws IOException

Read a single character. This method will block until a character is available, an I/O error occurs, or the end of the stream is reached. Subclasses that intend to support efficient single-character input should override this method.

Throws:

IOException

read

public int read(char[] cbuf)
         throws IOException

Read characters into an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

Throws:

IOException

read

public abstract int read(char[] cbuf,
                         int off,
                         int len)
                  throws IOException

Read characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

Throws:

IOException

ready

public boolean ready()
              throws IOException

Tell whether this stream is ready to be read.

Throws:

IOException

reset

public void reset()
           throws IOException

Reset the stream. If the stream has been marked, then attempt to reposition it at the mark. If the stream has not been marked, then attempt to reset it in some way appropriate to the particular stream, for example by repositioning it to its starting point. Not all character-input streams support the reset() operation, and some support reset() without supporting mark().

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Skip characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.

Throws:

IOException