java.io
Class InputStreamReader

java.lang.Object
  |
  +--java.io.Reader
        |
        +--java.io.InputStreamReader

Direct Known Subclasses:

FileReader

public class InputStreamReader

extends Reader

An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and translates them into characters according to a specified character encoding. The encoding that it uses may be specified by name, or the platform's default encoding 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. For top efficiency, consider wrapping an InputStreamReader within a BufferedReader; for example,

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

Since:

JDK1.1

See Also:

BufferedReader, InputStream

Field Summary

private byte[]	bb
private sun.io.ByteToCharConverter	btc
private static int	defaultByteBufferSize
private InputStream	in
private int	nBytes
private int	nextByte

Fields inherited from class java.io.Reader

lock, maxSkipBufferSize, skipBuffer

Constructor Summary

	InputStreamReader(InputStream in) Create an InputStreamReader that uses the default character encoding.
private	InputStreamReader(InputStream in, sun.io.ByteToCharConverter btc) Create an InputStreamReader that uses the specified byte-to-character converter.
	InputStreamReader(InputStream in, String enc) Create an InputStreamReader that uses the named character encoding.

Method Summary

void	close() Close the stream.
private int	convertInto(char[] cbuf, int off, int end)
private void	ensureOpen() Check to make sure that the stream has not been closed
private int	fill(char[] cbuf, int off, int end)
private int	flushInto(char[] cbuf, int off, int end)
String	getEncoding() Returns the canonical name of the character encoding being used by this stream.
private boolean	inReady() Tell whether the underlying byte stream is ready to be read.
private void	malfunction()
int	read() Read a single character.
int	read(char[] cbuf, int off, int len) Read characters into a portion of an array.
boolean	ready() Tell whether this stream is ready to be read.

Methods inherited from class java.io.Reader

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait

Field Detail

btc

private sun.io.ByteToCharConverter btc

in

private InputStream in

defaultByteBufferSize

private static final int defaultByteBufferSize

bb

private byte[] bb

nBytes

private int nBytes

nextByte

private int nextByte

Constructor Detail

InputStreamReader

public InputStreamReader(InputStream in)

Create an InputStreamReader that uses the default character encoding.

Parameters:

in - An InputStream

InputStreamReader

public InputStreamReader(InputStream in,
                         String enc)
                  throws UnsupportedEncodingException

Create an InputStreamReader that uses the named character encoding.

Parameters:

in - An InputStream

enc - Name of encoding to be used

Throws:

UnsupportedEncodingException - If the named encoding is not supported

InputStreamReader

private InputStreamReader(InputStream in,
                          sun.io.ByteToCharConverter btc)

Create an InputStreamReader that uses the specified byte-to-character converter. The converter is assumed to have been reset.

Parameters:

in - An InputStream

btc - A ByteToCharConverter

Method Detail

getEncoding

public String getEncoding()

Returns the canonical name of the character encoding being used by this stream. If this InputStreamReader was created with the InputStreamReader(InputStream, String) constructor, the returned encoding name, being canonical, may differ from the encoding name passed to the constructor. May return null if the stream has been closed.

malfunction

private void malfunction()

convertInto

private int convertInto(char[] cbuf,
                        int off,
                        int end)
                 throws IOException

flushInto

private int flushInto(char[] cbuf,
                      int off,
                      int end)
               throws IOException

fill

private int fill(char[] cbuf,
                 int off,
                 int end)
          throws IOException

inReady

private boolean inReady()

Tell whether the underlying byte stream is ready to be read. Return false for those streams that do not support available(), such as the Win32 console stream.

ensureOpen

private void ensureOpen()
                 throws IOException

Check to make sure that the stream has not been closed

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 Reader

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 storing 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 Reader

ready

public boolean ready()
              throws IOException

Tell 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

Overrides:

ready in class Reader

close

public void close()
           throws IOException

Close the stream.

Throws:

IOException - If an I/O error occurs

Overrides:

close in class Reader