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Class java.io.PushbackReader - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.io.PushbackReader

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

public class PushbackReader
extends FilterReader
A character-stream reader that allows characters to be pushed back into the stream.


Constructor Index

 o PushbackReader(Reader)
Create a new pushback reader with a one-character pushback buffer.
 o PushbackReader(Reader, int)
Create a new pushback reader with a pushback buffer of the given size.

Method Index

 o close()
Close the stream.
 o markSupported()
Tell whether this stream supports the mark() operation, which it does not.
 o read()
Read a single character.
 o read(char[], int, int)
Read characters into a portion of an array.
 o ready()
Tell whether this stream is ready to be read.
 o unread(char[])
Push back an array of characters by copying it to the front of the pushback buffer.
 o unread(char[], int, int)
Push back a portion of an array of characters by copying it to the front of the pushback buffer.
 o unread(int)
Push back a single character.

Constructors

 o PushbackReader
 public PushbackReader(Reader in,
                       int size)
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
 o PushbackReader
 public PushbackReader(Reader in)
Create a new pushback reader with a one-character pushback buffer.

Parameters:
in - The reader from which characters will be read

Methods

 o read
 public int read() throws IOException
Read 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
Overrides:
read in class FilterReader
 o read
 public int read(char cbuf[],
                 int off,
                 int len) throws IOException
Read 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
Overrides:
read in class FilterReader
 o unread
 public void unread(int c) throws IOException
Push back a single character.

Parameters:
c - The character to push back
Throws: IOException
If the pushback buffer is full, or if some other I/O error occurs
 o unread
 public void unread(char cbuf[],
                    int off,
                    int len) throws IOException
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
Throws: IOException
If there is insufficient room in the pushback buffer, or if some other I/O error occurs
 o unread
 public void unread(char cbuf[]) throws IOException
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
Throws: IOException
If there is insufficient room in the pushback buffer, or if some other I/O error occurs
 o ready
 public boolean ready() throws IOException
Tell whether this stream is ready to be read.

Throws: IOException
If an I/O error occurs
Overrides:
ready in class FilterReader
 o markSupported
 public boolean markSupported()
Tell whether this stream supports the mark() operation, which it does not.

Overrides:
markSupported in class FilterReader
 o close
 public void close() throws IOException
Close the stream.

Throws: IOException
If an I/O error occurs
Overrides:
close in class FilterReader

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