Class OutputStream

All Implemented Interfaces:
Closeable, Flushable, AutoCloseable
Direct Known Subclasses:
ByteArrayOutputStream, FileOutputStream, FilterOutputStream, ObjectOutputStream, PipedOutputStream 
public abstract class OutputStream
extends Object
implements Closeable, Flushable

This abstract class is the superclass of all classes representing an output stream of bytes. An output stream accepts output bytes and sends them to some sink.

Applications that need to define a subclass of OutputStream must always provide at least a method that writes one byte of output.

Since:
1.0
See Also:
BufferedOutputStream, ByteArrayOutputStream, DataOutputStream, FilterOutputStream, InputStream, write(int)

Constructors

Constructor Description
OutputStream()

Methods

Modifier and Type Method Description
void close()

Closes this output stream and releases any system resources associated with this stream.
void flush()

Flushes this output stream and forces any buffered output bytes to be written out.
static OutputStream nullOutputStream()

Returns a new OutputStream which discards all bytes.
void write​(byte[] b)

Writes b.length bytes from the specified byte array 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.
abstract void write​(int b)

Writes the specified byte to this output stream.

Methods declared in class java.lang.Object

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

Constructors

OutputStream

public OutputStream()

Methods

nullOutputStream

public static OutputStream nullOutputStream()

Returns a new OutputStream which discards all bytes. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect.

While the stream is open, the write(int), write(byte[]), and write(byte[], int, int) methods do nothing. After the stream has been closed, these methods all throw IOException.

The flush() method does nothing.

Returns:
an OutputStream which discards all bytes
Since:
11

write

public abstract void write(int b)
                    throws IOException

Writes the specified byte to this output stream. The general contract for write is that one byte is written to the output stream. The byte to be written is the eight low-order bits of the argument b. The 24 high-order bits of b are ignored.

Subclasses of OutputStream must provide an implementation for this method.

Parameters:
b - the byte.
Throws:
IOException - if an I/O error occurs. In particular, an IOException may be thrown if the output stream has been closed.

write

public void write(byte[] b)
           throws IOException

Writes b.length bytes from the specified byte array to this output stream. The general contract for write(b) is that it should have exactly the same effect as the call write(b, 0, b.length).

Parameters:
b - the data.
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. The general contract for write(b, off, len) is that some of the bytes in the array b are written to the output stream in order; element b[off] is the first byte written and b[off+len-1] is the last byte written by this operation.

The write method of OutputStream calls the write method of one argument on each of the bytes to be written out. Subclasses are encouraged to override this method and provide a more efficient implementation.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

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. In particular, an IOException is thrown if the output stream is closed.

flush

public void flush()
           throws IOException

Flushes this output stream and forces any buffered output bytes to be written out. The general contract of flush is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.

If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.

The flush method of OutputStream does nothing.

Specified by:
flush in interface Flushable
Throws:
IOException - if an I/O error occurs.

close

public void close()
           throws IOException

Closes this output stream and releases any system resources associated with this stream. The general contract of close is that it closes the output stream. A closed stream cannot perform output operations and cannot be reopened.

The close method of OutputStream does nothing.

Specified by:
close in interface AutoCloseable
Specified by:
close in interface Closeable
Throws:
IOException - if an I/O error occurs.

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/OutputStream.html