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.
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.
Reader
protected Reader()
Create a new character-stream reader whose critical sections will
synchronize on the reader itself.
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.
Parameters:
cbuf - Destination buffer
off - Offset at which to start storing characters
len - Maximum number of characters to read
Returns:
The number of characters read, or -1 if the end of the
stream has been reached
True if the next read() is guaranteed not to block for input,
false otherwise. Note that returning false does not guarantee that the
next read will block.
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.
Parameters:
readAheadLimit - Limit on the number of characters that may be
read while still preserving the mark. After
reading this many characters, attempting to
reset the stream may fail.
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().
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.
Submit a bug or feature - Version 1.1.8 of Java Platform API Specification
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