java.lang.Object
- java.io.InputStream
- - java.io.FilterInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

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.

Since:

JDK1.0

Field Summary
Fields
Modifier and Type Field and Description

protected InputStream in
The input stream to be filtered.

FilterInputStream (Java Platform SE 7 ) Home of API Java Contents Haut

Constructor Summary

Constructors
Modifier	Constructor and Description
`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.

FilterInputStream (Java Platform SE 7 ) Home of API Java Contents Haut

Method Summary

Methods
Modifier and Type	Method and Description
`int`	`available()` 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`	`close()` 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`	`markSupported()` Tests if this input stream supports the `mark` and `reset` methods.
`int`	`read()` 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`	`reset()` 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 the input stream.

FilterInputStream (Java Platform SE 7 ) Home of API Java Contents Haut

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
  - 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.
    
    Specified by:
    
    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.
    See Also:
    in
  - 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.
    See Also:
    read(byte[], int, int)
  - 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:
    
    NullPointerException - If b is null.
    
    IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
    
    IOException - if an I/O error occurs.
    See Also:
    in
  - skip
    public long skip(long n) throws IOException
    
    Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.
    This method simply performs in.skip(n).
    
    Overrides:
    
    skip in class InputStream
    
    Parameters:
    n - the number of bytes to be skipped.
    
    Returns:
    the actual number of bytes skipped.
    
    Throws:
    
    IOException - if the stream does not support seek, or if some other I/O error occurs.
  - 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 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().
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Overrides:
    
    close in class InputStream
    
    Throws:
    
    IOException - if an I/O error occurs.
    See Also:
    in
  - mark
    public 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.
    See Also:
    in, reset()
  - reset
    public 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.
    See Also:
    in, mark(int)
  - 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.
    See Also:
    in, InputStream.mark(int), InputStream.reset()

Document created the 11/06/2005, last modified the 04/03/2020
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References

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Class FilterInputStream

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