Module java.base

Package java.io

Class FilterOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

Direct Known Subclasses:

BufferedOutputStream, CheckedOutputStream, CipherOutputStream, DataOutputStream, DeflaterOutputStream, DigestOutputStream, InflaterOutputStream, PrintStream

public class FilterOutputStream
extends OutputStream

This class is the superclass of all classes that filter output streams. These streams sit on top of an already existing output stream (the underlying output stream) which it uses as its basic sink of data, but possibly transforming the data along the way or providing additional functionality.

The class FilterOutputStream itself simply overrides all methods of OutputStream with versions that pass all requests to the underlying output stream. Subclasses of FilterOutputStream may further override some of these methods as well as provide additional methods and fields.

Since:

1.0

Field Summary

Fields

Modifier and Type	Field	Description
protected OutputStream	out	The underlying output stream to be filtered.

Constructor Summary

Constructors

Constructor	Description
FilterOutputStream(OutputStream out)	Creates an output stream filter built on top of the specified underlying output stream.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this output stream and releases any system resources associated with the stream.
void	flush()	Flushes this output stream and forces any buffered output bytes to be written out to the stream.
void	write(byte[] b)	Writes b.length bytes to this output stream.
void	write(byte[] b, int off, int len)	Writes len bytes from the specified byte array starting at offset off to this output stream.
void	write(int b)	Writes the specified byte to this output stream.

Methods declared in class java.io.OutputStream

nullOutputStream

Methods declared in class java.lang.Object

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

Field Details

out

protected OutputStream out

The underlying output stream to be filtered.

Constructor Details

FilterOutputStream

public FilterOutputStream(OutputStream out)

Creates an output stream filter built on top of the specified underlying output stream.

Parameters:

out - the underlying output stream to be assigned to the field this.out for later use, or null if this instance is to be created without an underlying stream.

Method Details

write

public void write(int b)
           throws IOException

Writes the specified byte to this output stream.

The write method of FilterOutputStream calls the write method of its underlying output stream, that is, it performs out.write(b).

Implements the abstract write method of OutputStream.

Specified by:

write in class OutputStream

Parameters:

b - the byte.

Throws:

IOException - if an I/O error occurs.

write

public void write(byte[] b)
           throws IOException

Writes b.length bytes to this output stream.

Overrides:

write in class OutputStream

Implementation Requirements:

The write method of FilterOutputStream calls its write method of three arguments with the arguments b, 0, and b.length.

Implementation Note:

Note that this method does not call the one-argument write method of its underlying output stream with the single argument b.

Parameters:

b - the data to be written.

Throws:

IOException - if an I/O error occurs.

See Also:

• write(byte[], int, int)

write

public void write(byte[] b,
 int off,
 int len)
           throws IOException

Writes len bytes from the specified byte array starting at offset off to this output stream.

Overrides:

write in class OutputStream

Implementation Requirements:

The write method of FilterOutputStream calls the write method of one argument on each byte to output.

Implementation Note:

Note that this method does not call the write method of its underlying output stream with the same arguments. Subclasses of FilterOutputStream should provide a more efficient implementation of this method.

Parameters:

b - the data.

off - the start offset in the data.

len - the number of bytes to write.

Throws:

IOException - if an I/O error occurs.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

See Also:

• write(int)

flush

public void flush()
           throws IOException

Flushes this output stream and forces any buffered output bytes to be written out to the stream.

Specified by:

flush in interface Flushable

Overrides:

flush in class OutputStream

Implementation Requirements:

The flush method of FilterOutputStream calls the flush method of its underlying output stream.

Throws:

IOException - if an I/O error occurs.

See Also:

• out

close

public void close()
           throws IOException

Closes this output stream and releases any system resources associated with the stream.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class OutputStream

Implementation Requirements:

When not already closed, the close method of FilterOutputStream calls its flush method, and then calls the close method of its underlying output stream.

Throws:

IOException - if an I/O error occurs.

See Also:

• flush()
• out