java.io
class PushbackReader

java.lang.Object java.io.Reader java.io.FilterReader java.io.PushbackReader

All Implemented Interfaces:

Closeable, Readable

public class PushbackReader
extends FilterReader

A character-stream reader that allows characters to be pushed back into the stream.

See Also (auto-generated):

BufferedReader

FileReader

DataInputStream

PushbackReader

public PushbackReader(Reader in)

Creates a new pushback reader with a one-character pushback buffer.

Parameters:

in - The reader from which characters will be read

PushbackReader

public PushbackReader(Reader in,
                      int size)

Creates a new pushback reader with a pushback buffer of the given size.

Parameters:

in - The reader from which characters will be read

size - The size of the pushback buffer

close

public void close()
           throws IOException

Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), unread(), ready(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.

Overrides:

close in class FilterReader

Throws:

IOException - If an I/O error occurs

mark

public void mark(int readAheadLimit)
          throws IOException

Marks the present position in the stream. The mark for class PushbackReader always throws an exception.

Overrides:

mark in class FilterReader

Parameters:

readAheadLimit

Throws:

IOException - Always, since mark is not supported

markSupported

public boolean markSupported()

Tells whether this stream supports the mark() operation, which it does not.

Overrides:

markSupported in class FilterReader

read

public int read()
         throws IOException

Reads a single character.

Overrides:

read in class FilterReader

Returns:

The character read, or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

read

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

Reads characters into a portion of an array.

Overrides:

read in class FilterReader

Parameters:

cbuf - Destination buffer

off - Offset at which to start writing 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

Throws:

IOException - If an I/O error occurs

ready

public boolean ready()
              throws IOException

Tells whether this stream is ready to be read.

Overrides:

ready in class FilterReader

Throws:

IOException - If an I/O error occurs

reset

public void reset()
           throws IOException

Resets the stream. The reset method of PushbackReader always throws an exception.

Overrides:

reset in class FilterReader

Throws:

IOException - Always, since reset is not supported

skip

public long skip(long n)
          throws IOException

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

Overrides:

skip in class FilterReader

Parameters:

n - The number of characters to skip

Returns:

The number of characters actually skipped

Throws:

IOException - If an I/O error occurs

unread

public void unread(char[] cbuf)
            throws IOException

Pushes back an array of characters by copying it to the front of the pushback buffer. After this method returns, the next character to be read will have the value cbuf[0], the character after that will have the value cbuf[1], and so forth.

Parameters:

cbuf - Character array to push back

Throws:

IOException - If there is insufficient room in the pushback buffer, or if some other I/O error occurs

unread

public void unread(char[] cbuf,
                   int off,
                   int len)
            throws IOException

Pushes back a portion of an array of characters by copying it to the front of the pushback buffer. After this method returns, the next character to be read will have the value cbuf[off], the character after that will have the value cbuf[off+1], and so forth.

Parameters:

cbuf - Character array

off - Offset of first character to push back

len - Number of characters to push back

Throws:

IOException - If there is insufficient room in the pushback buffer, or if some other I/O error occurs

unread

public void unread(int c)
            throws IOException

Pushes back a single character by copying it to the front of the pushback buffer. After this method returns, the next character to be read will have the value (char)c.

Parameters:

c - The int value representing a character to be pushed back

Throws:

IOException - If the pushback buffer is full, or if some other I/O error occurs