PushbackReader - JRE Emulation | JRE Emulation
public class

PushbackReader

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

Class Overview

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

Summary

[Expand]
Inherited Fields
From class java.io.FilterReader
From class java.io.Reader
Public Constructors
PushbackReader(Reader in, int size)
Creates a new pushback reader with a pushback buffer of the given size.
PushbackReader(Reader in)
Creates a new pushback reader with a one-character pushback buffer.
Public Methods
void close()
Closes the stream and releases any system resources associated with it.
void mark(int readAheadLimit)
Marks the present position in the stream.
boolean markSupported()
Tells whether this stream supports the mark() operation, which it does not.
int read()
Reads a single character.
int read(char[] cbuf, int off, int len)
Reads characters into a portion of an array.
boolean ready()
Tells whether this stream is ready to be read.
void reset()
Resets the stream.
long skip(long n)
Skips characters.
void unread(char[] cbuf, int off, int len)
Pushes back a portion of an array of characters by copying it to the front of the pushback buffer.
void unread(char[] cbuf)
Pushes back an array of characters by copying it to the front of the pushback buffer.
void unread(int c)
Pushes back a single character by copying it to the front of the pushback buffer.
Inherited Methods
[Expand]
From class java.io.FilterReader
From class java.io.Reader
From class java.lang.Object
From interface java.lang.Readable
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Public Constructors

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
Throws
IllegalArgumentException if size is <= 0

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

Public Methods

public void 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.

Throws
IOException If an I/O error occurs

public void mark (int readAheadLimit)

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

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.
Throws
IOException Always, since mark is not supported

public boolean markSupported ()

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

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

public int read ()

Reads a single character.

Returns
  • The character read, or -1 if the end of the stream has been reached
Throws
IOException If an I/O error occurs

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

Reads characters into a portion of an array.

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

public boolean ready ()

Tells whether this stream is ready to be read.

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.
Throws
IOException If an I/O error occurs

public void reset ()

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

Throws
IOException Always, since reset is not supported

public long skip (long n)

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

Parameters
n The number of characters to skip
Returns
  • The number of characters actually skipped
Throws
IllegalArgumentException If n is negative.
IOException If an I/O error occurs

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

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

public void unread (char[] cbuf)

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

public void unread (int c)

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