OpenJDK 1.22 · java.io.PushbackReader · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private char[]	buf Pushback buffer
private int	pos Current position in buffer

Access	Constructor and Description
public	PushbackReader(Reader The reader from which characters will be read in, int The size of the pushback buffer size) Creates a new pushback reader with a pushback buffer of the given size.
public	PushbackReader(Reader The reader from which characters will be read in) Creates a new pushback reader with a one-character pushback buffer.

Method Summary

Modifier and Type	Method and Description
public void	close() Overrides java.io.FilterReader.close. Implements java.io.Closeable.close. Closes the stream and releases any system resources associated with it.
private void	ensureOpen() Checks to make sure that the stream has not been closed.
public void	mark(int 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. readAheadLimit) Overrides java.io.FilterReader.mark. Marks the present position in the stream.
public boolean	markSupported() Overrides java.io.FilterReader.markSupported. Tells whether this stream supports the mark() operation, which it does not.
public int	Returns: The character read, or -1 if the end of the stream has been reached read() Overrides java.io.FilterReader.read. Reads a single character.
public int	read(char[] Destination buffer cbuf, int Offset at which to start storing characters off, int Maximum number of characters to read len) Overrides java.io.FilterReader.read. Reads characters into a portion of an array.
public boolean	ready() Overrides java.io.FilterReader.ready. Tells whether this stream is ready to be read.
public void	reset() Overrides java.io.FilterReader.reset. Resets the stream.
public long	skip(long The number of characters to skip n) Overrides java.io.FilterReader.skip. Skips characters.
public void	unread(int The int value representing a character to be pushed back c) Pushes back a single character by copying it to the front of the pushback buffer.
public void	unread(char[] Character array cbuf, int Offset of first character to push back off, int Number of characters to push back len) Pushes back a portion of an array of characters by copying it to the front of the pushback buffer.
public void	unread(char[] Character array to push back cbuf) Pushes back an array of characters by copying it to the front of the pushback buffer.

buf	back to summary
private char[] buf Pushback buffer

pos	back to summary
private int pos Current position in buffer

PushbackReader	back to summary
public PushbackReader(Reader in, int size) Creates a new pushback reader with a pushback buffer of the given size. Parameters in:Reader The reader from which characters will be read size:int The size of the pushback buffer Exceptions IllegalArgumentException: if `size <= 0`

PushbackReader	back to summary
public PushbackReader(Reader in) Creates a new pushback reader with a one-character pushback buffer. Parameters in:Reader The reader from which characters will be read

Method Detail

close	back to summary
public void close() throws IOException Overrides java.io.FilterReader.close. Implements java.io.Closeable.close. 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. This method will block while there is another thread blocking on the reader. Exceptions IOException: If an I/O error occurs

back to summary

public void close() throws IOException

Overrides java.io.FilterReader.close.

Implements java.io.Closeable.close.

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. This method will block while there is another thread blocking on the reader.

Exceptions

IOException:: If an I/O error occurs

ensureOpen	back to summary
private void ensureOpen() throws IOException Checks to make sure that the stream has not been closed.

mark back to summary

mark	back to summary
public void mark(int readAheadLimit) throws IOException Overrides java.io.FilterReader.mark. Marks the present position in the stream. The `mark` for class `PushbackReader` always throws an exception. Parameters readAheadLimit:int Doc from java.io.Reader.mark. 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. Exceptions IOException: Always, since mark is not supported

public void mark(int readAheadLimit) throws IOException

Overrides java.io.FilterReader.mark.

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

Parameters

readAheadLimit:int

Doc from java.io.Reader.mark.

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.

Exceptions

IOException:: Always, since mark is not supported

markSupported	back to summary
public boolean markSupported() Overrides java.io.FilterReader.markSupported. Tells whether this stream supports the mark() operation, which it does not. Returns:boolean Doc from java.io.Reader.markSupported. true if and only if this stream supports the mark operation.

markSupported

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public boolean markSupported()

Overrides java.io.FilterReader.markSupported.

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

Returns:boolean

Doc from java.io.Reader.markSupported.

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

read	back to summary
public int read() throws IOException Overrides java.io.FilterReader.read. Reads a single character. Returns:int The character read, or -1 if the end of the stream has been reached Exceptions IOException: If an I/O error occurs

read

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public int read() throws IOException

Overrides java.io.FilterReader.read.

Reads a single character.

Returns:int

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

Exceptions

IOException:: If an I/O error occurs

read back to summary

read	back to summary
public int read(char[] cbuf, int off, int len) throws IOException Overrides java.io.FilterReader.read. Doc from java.io.FilterReader.read. Reads 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. If `len` is zero, then no characters are read and `0` is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value `-1` is returned; otherwise, at least one character is read and stored into `cbuf`. Parameters cbuf:char[] Doc from java.io.Reader.read. Destination buffer off:int Doc from java.io.Reader.read. Offset at which to start storing characters len:int Doc from java.io.Reader.read. Maximum number of characters to read Returns:int Doc from java.io.Reader.read. The number of characters read, or -1 if the end of the stream has been reached Exceptions IOException: Doc from java.io.Reader.read. If an I/O error occurs

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

Overrides java.io.FilterReader.read.

Doc from java.io.FilterReader.read.

Reads 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.

If len is zero, then no characters are read and 0 is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value -1 is returned; otherwise, at least one character is read and stored into cbuf.

Parameters

cbuf:char[]

Doc from java.io.Reader.read.

Destination buffer

off:int

Doc from java.io.Reader.read.

Offset at which to start storing characters

len:int

Doc from java.io.Reader.read.

Maximum number of characters to read

Returns:int

Doc from java.io.Reader.read.

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

Exceptions

IOException:

Doc from java.io.Reader.read.

If an I/O error occurs

ready	back to summary
public boolean ready() throws IOException Overrides java.io.FilterReader.ready. Tells whether this stream is ready to be read. Returns:boolean Doc from java.io.Reader.ready. 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. Exceptions IOException: If an I/O error occurs

ready

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public boolean ready() throws IOException

Overrides java.io.FilterReader.ready.

Tells whether this stream is ready to be read.

Returns:boolean

Doc from java.io.Reader.ready.

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.

Exceptions

IOException:: If an I/O error occurs

reset back to summary

reset	back to summary
public void reset() throws IOException Overrides java.io.FilterReader.reset. Resets the stream. The `reset` method of `PushbackReader` always throws an exception. Exceptions IOException: Always, since reset is not supported

public void reset() throws IOException

Overrides java.io.FilterReader.reset.

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

Exceptions

IOException:: Always, since reset is not supported

skip	back to summary
public long skip(long n) throws IOException Overrides java.io.FilterReader.skip. Doc from java.io.FilterReader.skip. Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned. Parameters n:long Doc from java.io.Reader.skip. The number of characters to skip Returns:long Doc from java.io.Reader.skip. The number of characters actually skipped Exceptions IOException: Doc from java.io.Reader.skip. If an I/O error occurs

skip

back to summary

public long skip(long n) throws IOException

Overrides java.io.FilterReader.skip.

Doc from java.io.FilterReader.skip.

Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned.

Parameters

n:long

Doc from java.io.Reader.skip.

The number of characters to skip

Returns:long

Doc from java.io.Reader.skip.

The number of characters actually skipped

Exceptions

IOException:

Doc from java.io.Reader.skip.

If an I/O error occurs

unread back to summary

unread	back to summary
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:int The int value representing a character to be pushed back Exceptions IOException: If the pushback buffer is full, or if some other I/O error occurs

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:int: The int value representing a character to be pushed back

Exceptions

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

unread back to summary

unread	back to summary
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:char[] Character array off:int Offset of first character to push back len:int Number of characters to push back Exceptions IOException: If there is insufficient room in the pushback buffer, or if some other I/O error occurs

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:char[]: Character array
off:int: Offset of first character to push back
len:int: Number of characters to push back

Exceptions

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

unread back to summary

unread	back to summary
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:char[] Character array to push back Exceptions IOException: If there is insufficient room in the pushback buffer, or if some other I/O error occurs

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:char[]: Character array to push back

Exceptions

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

public Class PushbackReader

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