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java.io
class FilterInputStream

java.lang.Object extended by java.io.InputStream extended by java.io.FilterInputStream
All Implemented Interfaces:
Closeable
Direct Known Subclasses:
BufferedInputStream, CheckedInputStream, CipherInputStream, DataInputStream, DeflaterInputStream, DigestInputStream, InflaterInputStream, LineNumberInputStream, ProgressMonitorInputStream, PushbackInputStream

public class FilterInputStream
extends InputStream

A FilterInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. The class FilterInputStream itself simply overrides all methods of InputStream with versions that pass all requests to the contained input stream. Subclasses of FilterInputStream may further override some of these methods and may also provide additional methods and fields.

See Also (auto-generated):

InputStream

BufferedInputStream

Thread


Field Summary
protected InputStream in
          The input stream to be filtered.
 
Constructor Summary
protected

          Creates a FilterInputStream by assigning the argument in to the field this.in so as to remember it for later use.
 
Method Summary
 int

          Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
 void

          Closes this input stream and releases any system resources associated with the stream.
 void
mark(int readlimit)

          Marks the current position in this input stream.
 boolean

          Tests if this input stream supports the mark and reset methods.
 int

          Reads the next byte of data from this input stream.
 int
read(byte[] b)

          Reads up to byte.length bytes of data from this input stream into an array of bytes.
 int
read(byte[] b, int off, int len)

          Reads up to len bytes of data from this input stream into an array of bytes.
 void

          Repositions this stream to the position at the time the mark method was last called on this input stream.
 long
skip(long n)

          Skips over and discards n bytes of data from this input stream.
 
Methods inherited from class java.io.InputStream
available, close, mark, markSupported, read, read, read, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

in

protected volatile InputStream in
The input stream to be filtered.
Constructor Detail

FilterInputStream

protected FilterInputStream(InputStream in)
Creates a FilterInputStream by assigning the argument in to the field this.in so as to remember it for later use.

Parameters:
in - the underlying input stream, or null if this instance is to be created without an underlying stream.
Method Detail

available

public int available()
              throws IOException
Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

This method returns the result of {@link #in in}.available().

Overrides:
available in class InputStream
Returns:
an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking.
Throws:
IOException - if an I/O error occurs.

close

public void close()
           throws IOException
Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

Overrides:
close in class InputStream
Throws:
IOException - if an I/O error occurs.

mark

public synchronized void mark(int readlimit)
Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit argument tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

This method simply performs in.mark(readlimit).

Overrides:
mark in class InputStream
Parameters:
readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

markSupported

public boolean markSupported()
Tests if this input stream supports the mark and reset methods. This method simply performs in.markSupported().

Overrides:
markSupported in class InputStream
Returns:
true if this stream type supports the mark and reset method; false otherwise.

read

public int read()
         throws IOException
Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

This method simply performs in.read() and returns the result.

Overrides:
read in class InputStream
Returns:
the next byte of data, or -1 if the end of the stream is reached.
Throws:
IOException - if an I/O error occurs.

read

public int read(byte[] b)
         throws IOException
Reads up to byte.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

This method simply performs the call read(b, 0, b.length) and returns the result. It is important that it does not do in.read(b) instead; certain subclasses of FilterInputStream depend on the implementation strategy actually used.

Overrides:
read in class InputStream
Parameters:
b - the buffer into which the data is read.
Returns:
the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
IOException - if an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException
Reads up to len bytes of data from this input stream into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

This method simply performs in.read(b, off, len) and returns the result.

Overrides:
read in class InputStream
Parameters:
b - the buffer into which the data is read.
off - the start offset in the destination array b
len - the maximum number of bytes read.
Returns:
the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
IOException - if an I/O error occurs.

reset

public synchronized void reset()
                        throws IOException
Repositions this stream to the position at the time the mark method was last called on this input stream.

This method simply performs in.reset().

Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.

Overrides:
reset in class InputStream
Throws:
IOException - if the stream has not been marked or if the mark has been invalidated.

skip

public long skip(long n)
          throws IOException
{@inheritDoc}

This method simply performs in.skip(n).

Overrides:
skip in class InputStream
Parameters:
n
Throws:
IOException


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.