OutputStream
public
abstract
class
OutputStream
extends Object
implements
Closeable,
Flushable
java.lang.Object | |
↳ | java.io.OutputStream |
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.
See also:
Summary
Public constructors | |
---|---|
OutputStream()
Constructor for subclasses to call. |
Public methods | |
---|---|
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 |
void
|
write(byte[] b)
Writes |
void
|
write(byte[] b, int off, int len)
Writes |
abstract
void
|
write(int b)
Writes the specified byte to this output stream. |
Inherited methods | |
---|---|
Public constructors
Public methods
close
public void close ()
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.
Throws | |
---|---|
IOException |
if an I/O error occurs. |
flush
public void flush ()
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.
Throws | |
---|---|
IOException |
if an I/O error occurs. |
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 | |
---|---|
OutputStream |
an OutputStream which discards all bytes |
write
public void write (byte[] b)
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 |
byte : the data. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |
See also:
write
public void write (byte[] b, int off, int len)
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 |
byte : the data. |
off |
int : the start offset in the data. |
len |
int : 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. |
write
public abstract void write (int b)
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 |
int : the byte . |
Throws | |
---|---|
IOException |
if an I/O error occurs. In particular,
an IOException may be thrown if the
output stream has been closed. |