PushbackReader

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

所有已实现的接口:

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

从以下版本开始:

JDK1.1

字段概要
- 从类继承的字段 java.io.FilterReader
  in
- 从类继承的字段 java.io.Reader
  lock

构造器概要

构造器
构造器	说明
`PushbackReader(Reader in)`	Creates a new pushback reader with a one-character pushback buffer.
`PushbackReader(Reader in, int size)`	Creates a new pushback reader with a pushback buffer of the given size.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`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)`	Pushes back an array of characters by copying it to the front of the pushback buffer.
`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(int c)`	Pushes back a single character by copying it to the front of the pushback buffer.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从类继承的方法 java.io.Reader
read, read

- 构造器详细资料
  - PushbackReader
```
public PushbackReader(Reader in,
                      int size)
```
    Creates a new pushback reader with a pushback buffer of the given size.
    
    参数:
    
    in - The reader from which characters will be read
    
    size - The size of the pushback buffer
    
    抛出:
    
    IllegalArgumentException - if size <= 0
  - PushbackReader
```
public PushbackReader(Reader in)
```
    Creates a new pushback reader with a one-character pushback buffer.
    
    参数:
    
    in - The reader from which characters will be read
- 方法详细资料
  - read
```
public int read()
         throws IOException
```
    Reads a single character.
    
    覆盖:
    
    read 在类中 FilterReader
    
    返回:
    
    The character read, or -1 if the end of the stream has been reached
    
    抛出:
    
    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.
    
    覆盖:
    
    read 在类中 FilterReader
    
    参数:
    
    cbuf - Destination buffer
    
    off - Offset at which to start writing characters
    
    len - Maximum number of characters to read
    
    返回:
    
    The number of characters read, or -1 if the end of the stream has been reached
    
    抛出:
    
    IOException - If an 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.
    
    参数:
    
    c - The int value representing a character to be pushed back
    
    抛出:
    
    IOException - If the pushback buffer is full, 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.
    
    参数:
    
    cbuf - Character array
    
    off - Offset of first character to push back
    
    len - Number of characters to push back
    
    抛出:
    
    IOException - If there is insufficient room in the pushback buffer, or if some other 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.
    
    参数:
    
    cbuf - Character array to push back
    
    抛出:
    
    IOException - If there is insufficient room in the pushback buffer, or if some other I/O error occurs
  - ready
```
public boolean ready()
              throws IOException
```
    Tells whether this stream is ready to be read.
    
    覆盖:
    
    ready 在类中 FilterReader
    
    返回:
    
    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.
    
    抛出:
    
    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.
    
    覆盖:
    
    mark 在类中 FilterReader
    
    参数:
    
    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.
    
    抛出:
    
    IOException - Always, since mark is not supported
  - reset
```
public void reset()
           throws IOException
```
    Resets the stream. The reset method of PushbackReader always throws an exception.
    
    覆盖:
    
    reset 在类中 FilterReader
    
    抛出:
    
    IOException - Always, since reset is not supported
  - markSupported
```
public boolean markSupported()
```
    Tells whether this stream supports the mark() operation, which it does not.
    
    覆盖:
    
    markSupported 在类中 FilterReader
    
    返回:
    
    true if and only if this stream supports the mark operation.
  - 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.
    
    指定者:
    
    close 在接口中 AutoCloseable
    
    指定者:
    
    close 在接口中 Closeable
    
    覆盖:
    
    close 在类中 FilterReader
    
    抛出:
    
    IOException - If an I/O error occurs
  - 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.
    
    覆盖:
    
    skip 在类中 FilterReader
    
    参数:
    
    n - The number of characters to skip
    
    返回:
    
    The number of characters actually skipped
    
    抛出:
    
    IllegalArgumentException - If n is negative.
    
    IOException - If an I/O error occurs

类 PushbackReader

字段概要

从类继承的字段 java.io.FilterReader

从类继承的字段 java.io.Reader

构造器概要

方法概要

从类继承的方法 java.lang.Object

从类继承的方法 java.io.Reader

构造器详细资料

PushbackReader

PushbackReader

方法详细资料

read

read

unread

unread

unread

ready

mark

reset

markSupported

close

skip