Class BufferedOutputStream

java.io.BufferedOutputStream

All Implemented Interfaces:: Closeable, Flushable, AutoCloseable

public class BufferedOutputStream extends FilterOutputStream

The class implements a buffered output stream. By setting up such an output stream, an application can write bytes to the underlying output stream without necessarily causing a call to the underlying system for each byte written.

API Note:: Once wrapped in a BufferedOutputStream, the underlying OutputStream should not be used directly nor wrapped with another stream.
Since:: 1.0

Field Summary

Modifier and Type	Field	Description
`protected byte[]`	`buf`	The internal buffer where data is stored.
`protected int`	`count`	The number of valid bytes in the buffer.

Fields declared in class FilterOutputStream

out

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

Constructor Summary

Constructor	Description
`BufferedOutputStream(OutputStream out)`	Creates a new buffered output stream to write data to the specified underlying output stream.
`BufferedOutputStream(OutputStream out, int size)`	Creates a new buffered output stream to write data to the specified underlying output stream with the specified buffer size.

Method Summary

Modifier and Type	Method	Description
`void`	`flush()`	Flushes this buffered output stream.
`void`	`write(byte[] b, int off, int len)`	Writes `len` bytes from the specified byte array starting at offset `off` to this buffered output stream.
`void`	`write(int b)`	Writes the specified byte to this buffered output stream.

Methods declared in class FilterOutputStream

close, write

Modifier and Type	Method	Description
`void`	`close()`	Closes this output stream and releases any system resources associated with the stream.
`void`	`write(byte[] b)`	Writes `b.length` bytes to this output stream.

Methods declared in class OutputStream

nullOutputStream

Modifier and Type	Method	Description
`static OutputStream`	`nullOutputStream()`	Returns a new `OutputStream` which discards all bytes.

Methods declared in class Object

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

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this 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()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`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(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.

Field Details

buf

protected byte[] buf

The internal buffer where data is stored.

count

protected int count

The number of valid bytes in the buffer. This value is always in the range 0 through buf.length; elements buf[0] through buf[count-1] contain valid byte data.

Constructor Details

BufferedOutputStream

public BufferedOutputStream(OutputStream out)

Creates a new buffered output stream to write data to the specified underlying output stream.

Parameters:: out - the underlying output stream.

BufferedOutputStream

public BufferedOutputStream(OutputStream out, int size)

Creates a new buffered output stream to write data to the specified underlying output stream with the specified buffer size.

Parameters:: out - the underlying output stream.; size - the buffer size.
Throws:: IllegalArgumentException - if size <= 0.

Method Details

write

public void write(int b) throws IOException

Writes the specified byte to this buffered output stream.

Overrides:: write in class FilterOutputStream
Parameters:: b - the byte to be written.
Throws:: IOException - if an I/O error occurs.

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 buffered output stream.

Ordinarily this method stores bytes from the given array into this stream's buffer, flushing the buffer to the underlying output stream as needed. If the requested length is at least as large as this stream's buffer, however, then this method will flush the buffer and write the bytes directly to the underlying output stream. Thus redundant BufferedOutputStreams will not copy data unnecessarily.

Overrides:

write in class FilterOutputStream

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:

flush

public void flush() throws IOException

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

Specified by:

flush in interface Flushable

Overrides:

flush in class FilterOutputStream

Throws:

IOException - if an I/O error occurs.

See Also:

© 1993, 2025, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.