Added in API level 1

Summary: Inherited Fields | Ctors | Methods | Inherited Methods

PushbackReader

public class PushbackReader
extends FilterReader

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

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

Summary

Inherited fields

From class java.io.FilterReader


    protected
    
    
    Reader

in

The underlying character-input stream.

From class java.io.Reader


    protected
    
    
    Object

lock

The object used to synchronize operations on this stream.

Public constructors
`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.

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

From class


        
          java.io.FilterReader

`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.
`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.

From class


        
          java.io.Reader

`abstract 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.
`static Reader`	`nullReader()` Returns a new `Reader` that reads no characters.
`int`	`read()` Reads a single character.
`abstract int`	`read(char[] cbuf, int off, int len)` Reads characters into a portion of an array.
`int`	`read(char[] cbuf)` Reads characters into an array.
`int`	`read(CharBuffer target)` Attempts to read characters into the specified character buffer.
`boolean`	`ready()` Tells whether this stream is ready to be read.
`void`	`reset()` Resets the stream.
`long`	`skip(long n)` Skips characters.
`long`	`transferTo(Writer out)` Reads all characters from this reader and writes the characters to the given writer in the order that they are read.

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          java.io.Closeable


      close()

Closes this stream and releases any system resources associated with it.

From interface


        
          java.lang.Readable


      read(CharBuffer cb)

Attempts to read characters into the specified character buffer.

From interface


        
          java.lang.AutoCloseable


      close()

Closes this resource, relinquishing any underlying resources.

Public constructors

PushbackReader

Added in API level 1

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

PushbackReader

Added in API level 1

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

Throws
`IllegalArgumentException`	if `size <= 0`

Public methods

close

Added in API level 1

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

Throws
`IOException`	If an I/O error occurs

mark

Added in API level 1

public void mark (int readAheadLimit)

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

Parameters
`readAheadLimit`	`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.

Throws
`IOException`	Always, since mark is not supported

markSupported

Added in API level 1

public boolean markSupported ()

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

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

read

Added in API level 1

public int read ()

Reads a single character.

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

Throws
`IOException`	If an I/O error occurs

read

Added in API level 1

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

Reads characters into a portion of an array.

Parameters
`cbuf`	`char`: Destination buffer
`off`	`int`: Offset at which to start writing characters
`len`	`int`: Maximum number of characters to read

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

Throws
`IOException`	If an I/O error occurs
`IndexOutOfBoundsException`

ready

Added in API level 1

public boolean ready ()

Tells whether this stream is ready to be read.

Returns
`boolean`	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

reset

Added in API level 1

public void reset ()

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

Throws
`IOException`	Always, since reset is not supported

skip

Added in API level 1

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`	`long`: The number of characters to skip

Returns
`long`	The number of characters actually skipped

Throws
`IllegalArgumentException`	If `n` is negative.
`IOException`	If an I/O error occurs

unread

Added in API level 1

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`	`char`: Character array
`off`	`int`: Offset of first character to push back
`len`	`int`: 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

unread

Added in API level 1

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`	`char`: Character array to push back

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

unread

Added in API level 1

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`	`int`: 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