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java.io
Class PushbackReader

java.lang.Object
 |
 +--java.io.Reader
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 +--java.io.FilterReader
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 +--java.io.PushbackReader

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public class PushbackReader

extends FilterReader

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

Since:

JDK1.1

Version:

1.15, 01/12/03

Author:

Mark Reinhold

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buf

private char[] buf

Pushback buffer

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pos

private int pos

Current position in buffer

PushbackReader

public PushbackReader(Reader in,
 int size)

Enabled: Create 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

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PushbackReader

public PushbackReader(Reader in)

Enabled: Create a new pushback reader with a one-character pushback buffer.

Parameters:

in - The reader from which characters will be read

ensureOpen

private void ensureOpen()
 throws IOException

Check to make sure that the stream has not been closed.

IOException

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read

public int read()
 throws IOException

Enabled: Read a single character.

Overrides:

read in class FilterReader

Returns:

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

IOException

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read

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

Enabled: Read 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

IOException

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unread

public void unread(int c)
 throws IOException

Enabled: Push back a single character.

Parameters:

c - The character to push back

IOException

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unread

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

Enabled: Push 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

IOException

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unread

public void unread(char[] cbuf)
 throws IOException

Enabled: Push 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

IOException

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ready

public boolean ready()
 throws IOException

Enabled: Tell whether this stream is ready to be read.

Overrides:

ready in class FilterReader

Returns:

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.

IOException

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mark

public void mark(int readAheadLimit)
 throws IOException

Enabled: Mark the present position in the stream. The mark for class PushbackReader always throws an exception.

Overrides:

mark in class FilterReader

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.

IOException

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reset

public void reset()
 throws IOException

Enabled: Reset the stream. The reset method of PushbackReader always throws an exception.

Overrides:

reset in class FilterReader

IOException

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markSupported

public boolean markSupported()

Enabled: Tell whether this stream supports the mark() operation, which it does not.

Overrides:

markSupported in class FilterReader

Returns:

true if and only if this stream supports the mark operation.

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close

public void close()
 throws IOException

Enabled: Close the stream.

Overrides:

close in class FilterReader

IOException

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