InputStreamReader JDK 1.6)

java.io. InputStreamReader View Source

Author(s)

Mark Reinhold

Since

JDK1.1

Version

1.47, 05/11/17

Serial

Hierarchy

Object

Reader

InputStreamReader

Implements

Subclasses

FileReader

Quick Links: Constructors Methods Fields NestedClasses

Description

public class InputStreamReader

An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset.

An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted.

Each invocation of one of an InputStreamReader's read() methods may cause one or more bytes to be read from the underlying byte-input stream. To enable the efficient conversion of bytes to characters, more bytes may be read ahead from the underlying stream than are necessary to satisfy the current read operation.

For top efficiency, consider wrapping an InputStreamReader within a BufferedReader. For example:

 BufferedReader in
   = new BufferedReader(new InputStreamReader(System.in));

See also: BufferedReader InputStream Charset

Constructors

public InputStreamReader (InputStream in)

Creates an InputStreamReader that uses the default charset.

public InputStreamReader (InputStream in, Charset cs)

Creates an InputStreamReader that uses the given charset.

public InputStreamReader (InputStream in, CharsetDecoder dec)

Creates an InputStreamReader that uses the given charset decoder.

public InputStreamReader (InputStream in, String charsetName) throws UnsupportedEncodingException

Creates an InputStreamReader that uses the named charset.

Creates an InputStreamReader that uses the named charset.
Parameters:
- in - An InputStream
- charsetName - The name of a supported {@link java.nio.charset.Charset charset

}





Throws:


  - UnsupportedEncodingException - If the named charset is not supported



 


    
    Methods


    Hide/Show inherited methods




       

public void

 close

()

    throws
    
        IOException
    




    [Specified in Reader]




    
    







       

public String

 getEncoding

()







    
         
    
    Returns the name of the character encoding being used by this stream.


    
         
        Returns the name of the character encoding being used by this stream.

  If the encoding has an historical name then that name is returned;
 otherwise the encoding's canonical name is returned.

 
 If this instance was created with the InputStreamReader.InputStreamReader(InputStream, String) constructor then the returned
 name, being unique for the encoding, may differ from the name passed to
 the constructor. This method will return null if the
 stream has been closed.
 
        
        



Returns:

    The historical name of this encoding, or
         null if the stream has been closed 












See Also:

  Charset, 



    





    


       

public void

 mark

(int readAheadLimit)

    throws
    
        IOException
    


    [Inherited From Reader]






    
         
    
    Marks the present position in the stream.


    
         
        Marks the present position in the stream.  Subsequent calls to reset()
 will attempt to reposition the stream to this point.  Not all
 character-input streams support the mark() operation.
        
        




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 - If the stream does not support mark(),
                          or if some other I/O error occurs









    



    



    


       

public boolean

 markSupported

()


    [Inherited From Reader]






    
         
    
    Tells whether this stream supports the mark() operation.


    
         
        Tells whether this stream supports the mark() operation. The default
 implementation always returns false. Subclasses should override this
 method.
        
        



Returns:

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











    



    




       

public int

 read

()

    throws
    
        IOException
    



    [Overrides Reader]





    
         
    
    Reads a single character.


    
         
        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)

    throws
    
        IOException
    


    [Inherited From Reader]






    
         
    
    Reads characters into an array.


    
         
        Reads characters into an array.  This method will block until some input
 is available, an I/O error occurs, or the end of the stream is reached.
        
        



Returns:

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





Parameters:


 - cbuf - Destination buffer





Throws:


  - IOException - If an I/O error occurs









    



    




       

public int

 read

(char[] cbuf, int offset, int length)

    throws
    
        IOException
    




    [Specified in Reader]




    
         
    
    Reads characters into a portion of an array.


    
         
        Reads characters into a portion of an array.
        
        



Returns:

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





Parameters:


 - cbuf - Destination buffer


 - offset - Offset at which to start storing characters


 - length - Maximum number of characters to read





Throws:


  - IOException - If an I/O error occurs









    





    


       

public int

 read

(CharBuffer target)

    throws
    
        IOException
    


    [Inherited From Reader]






    
         
    
    Attempts to read characters into the specified character buffer.


    
         
        Attempts to read characters into the specified character buffer.
 The buffer is used as a repository of characters as-is: the only
 changes made are the results of a put operation. No flipping or
 rewinding of the buffer is performed.
        
        



Returns:

    The number of characters added to the buffer, or 
         -1 if this source of characters is at its end 





Parameters:


 - target - the buffer to read characters into





Throws:


  - IOException - if an I/O error occurs


  - NullPointerException - if target is null


  - ReadOnlyBufferException - if target is a read only buffer






Since:

    1.5 







    



    




       

public boolean

 ready

()

    throws
    
        IOException
    



    [Overrides Reader]





    
         
    
    Tells whether this stream is ready to be read.


    
         
        Tells whether this stream is ready to be read.  An InputStreamReader is
 ready if its input buffer is not empty, or if bytes are available to be
 read from the underlying byte stream.
        
        





Throws:


  - IOException - If an I/O error occurs









    





    


       

public void

 reset

()

    throws
    
        IOException
    


    [Inherited From Reader]






    
         
    
    Resets the stream.


    
         
        Resets the stream.  If the stream has been marked, then attempt to
 reposition it at the mark.  If the stream has not been marked, then
 attempt to reset it in some way appropriate to the particular stream,
 for example by repositioning it to its starting point.  Not all
 character-input streams support the reset() operation, and some support
 reset() without supporting mark().
        
        





Throws:


  - IOException - If the stream has not been marked,
                          or if the mark has been invalidated,
                          or if the stream does not support reset(),
                          or if some other I/O error occurs









    



    



    


       

public long

 skip

(long n)

    throws
    
        IOException
    


    [Inherited From Reader]






    
         
    
    Skips characters.


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



Returns:

    The number of characters actually skipped 





Parameters:


 - n - The number of characters to skip





Throws:


  - IllegalArgumentException - If n is negative.


  - IOException - If an I/O error occurs









    



    




 


    
    Fields


    Hide/Show inherited fields



    





protected

Object lock



    [Inherited From Reader]





    
         
    
    The object used to synchronize operations on this stream.


    
         
        The object used to synchronize operations on this stream.  For
 efficiency, a character-stream object may use an object other than
 itself to protect critical sections.  A subclass should therefore use
 the object in this field rather than this or a synchronized
 method.
        
        










    



    




 


    
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