Added in API level 1

Summary: Fields | Protected Ctors | Methods | Inherited Methods

FilterInputStream

public class FilterInputStream
extends InputStream

java.lang.Object
↳	java.io.InputStream
	↳	java.io.FilterInputStream

Known direct subclasses

Base64InputStream, BufferedInputStream, CheckedInputStream, CipherInputStream, DataInputStream, DeflaterInputStream, DigestInputStream, InflaterInputStream, LineNumberInputStream, PushbackInputStream

Base64InputStream	An InputStream that does Base64 decoding on the data read through it.
BufferedInputStream	A `BufferedInputStream` adds functionality to another input stream-namely, the ability to buffer the input and to support the `mark` and `reset` methods.
CheckedInputStream	An input stream that also maintains a checksum of the data being read.
CipherInputStream	A CipherInputStream is composed of an InputStream and a Cipher so that read() methods return data that are read in from the underlying InputStream but have been additionally processed by the Cipher.
DataInputStream	A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way.
DeflaterInputStream	Implements an input stream filter for compressing data in the "deflate" compression format.
DigestInputStream	A transparent stream that updates the associated message digest using the bits going through the stream.
InflaterInputStream	This class implements a stream filter for uncompressing data in the "deflate" compression format.
LineNumberInputStream	This class was deprecated in API level 1. This class incorrectly assumes that bytes adequately represent characters. As of JDK 1.1, the preferred way to operate on character streams is via the new character-stream classes, which include a class for counting line numbers.
PushbackInputStream	A `PushbackInputStream` adds functionality to another input stream, namely the ability to "push back" or "unread" bytes, by storing pushed-back bytes in an internal buffer.

Known indirect subclasses

GZIPInputStream, JarInputStream, ZipInputStream

GZIPInputStream	This class implements a stream filter for reading compressed data in the GZIP file format.
JarInputStream	The `JarInputStream` class is used to read the contents of a JAR file from any input stream.
ZipInputStream	This class implements an input stream filter for reading files in the ZIP file format.

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.

Summary

Fields
`protected InputStream`	`in` The input stream to be filtered.

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

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

Inherited methods

From class


        
          java.io.InputStream

`int`	`available()` Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, which may be 0, or 0 when end of stream is detected.
`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.
`static InputStream`	`nullInputStream()` Returns a new `InputStream` that reads no bytes.
`int`	`read(byte[] b)` Reads some number of bytes from the input stream and stores them into the buffer array `b`.
`abstract int`	`read()` Reads the next byte of data from the input stream.
`int`	`read(byte[] b, int off, int len)` Reads up to `len` bytes of data from the input stream into an array of bytes.
`byte[]`	`readAllBytes()` Reads all remaining bytes from the input stream.
`int`	`readNBytes(byte[] b, int off, int len)` Reads the requested number of bytes from the input stream into the given byte array.
`byte[]`	`readNBytes(int len)` Reads up to a specified number of bytes from the input stream.
`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 this input stream.
`void`	`skipNBytes(long n)` Skips over and discards exactly `n` bytes of data from this input stream.
`long`	`transferTo(OutputStream out)` Reads all bytes from this input stream and writes the bytes to the given output stream 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.AutoCloseable


      close()

Closes this resource, relinquishing any underlying resources.

Fields

in

Added in API level 1

protected InputStream in

The input stream to be filtered.

Protected constructors

FilterInputStream

Added in API level 1

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`	`InputStream`: the underlying input stream, or `null` if this instance is to be created without an underlying stream.

Public methods

available

Added in API level 1

public 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. 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().

Returns
`int`	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

Added in API level 1

public void close ()

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

Throws
`IOException`	if an I/O error occurs.

See also:

in

mark

Added in API level 1

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).

Parameters
`readlimit`	`int`: the maximum limit of bytes that can be read before the mark position becomes invalid.

See also:

in
reset()

markSupported

Added in API level 1

public boolean markSupported ()

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

Returns
`boolean`	`true` if this stream type supports the `mark` and `reset` method; `false` otherwise.

See also:

read

Added in API level 1

public int read ()

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.

Returns
`int`	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

Added in API level 1

public int read (byte[] b, 
                int off, 
                int len)

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.

Parameters
`b`	`byte`: the buffer into which the data is read.
`off`	`int`: the start offset in the destination array `b`
`len`	`int`: the maximum number of bytes read.

Returns
`int`	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

read

Added in API level 1

public int read (byte[] b)

Reads up to b.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.

Parameters
`b`	`byte`: the buffer into which the data is read.

Returns
`int`	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)

reset

Added in API level 1

public void reset ()

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.

Throws
`IOException`	if the stream has not been marked or if the mark has been invalidated.

See also:

in
mark(int)

skip

Added in API level 1

public long skip (long n)

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).

Parameters
`n`	`long`: the number of bytes to be skipped.

Returns
`long`	the actual number of bytes skipped.

Throws
`IOException`	if `in.skip(n)` throws an IOException.