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package java.io;
import java.util.Objects;
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.
Author: Arthur van Hoff See Also: Since: 1.0
/**
* 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.
* <p>
* Applications that need to define a subclass of
* <code>OutputStream</code> must always provide at least a method
* that writes one byte of output.
*
* @author Arthur van Hoff
* @see java.io.BufferedOutputStream
* @see java.io.ByteArrayOutputStream
* @see java.io.DataOutputStream
* @see java.io.FilterOutputStream
* @see java.io.InputStream
* @see java.io.OutputStream#write(int)
* @since 1.0
*/
public abstract class OutputStream implements Closeable, Flushable {
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
/**
* Returns a new {@code OutputStream} which discards all bytes. The
* returned stream is initially open. The stream is closed by calling
* the {@code close()} method. Subsequent calls to {@code close()} have
* no effect.
*
* <p> While the stream is open, the {@code write(int)}, {@code
* write(byte[])}, and {@code write(byte[], int, int)} methods do nothing.
* After the stream has been closed, these methods all throw {@code
* IOException}.
*
* <p> The {@code flush()} method does nothing.
*
* @return an {@code OutputStream} which discards all bytes
*
* @since 11
*/
public static OutputStream nullOutputStream() {
return new OutputStream() {
private volatile boolean closed;
private void ensureOpen() throws IOException {
if (closed) {
throw new IOException("Stream closed");
}
}
@Override
public void write(int b) throws IOException {
ensureOpen();
}
@Override
public void write(byte b[], int off, int len) throws IOException {
Objects.checkFromIndexSize(off, len, b.length);
ensureOpen();
}
@Override
public void close() {
closed = true;
}
};
}
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.
Params: - 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.
/**
* Writes the specified byte to this output stream. The general
* contract for <code>write</code> is that one byte is written
* to the output stream. The byte to be written is the eight
* low-order bits of the argument <code>b</code>. The 24
* high-order bits of <code>b</code> are ignored.
* <p>
* Subclasses of <code>OutputStream</code> must provide an
* implementation for this method.
*
* @param b the <code>byte</code>.
* @exception IOException if an I/O error occurs. In particular,
* an <code>IOException</code> may be thrown if the
* output stream has been closed.
*/
public abstract void write(int 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).
Params: - b – the data.
Throws: - IOException – if an I/O error occurs.
See Also:
/**
* Writes <code>b.length</code> bytes from the specified byte array
* to this output stream. The general contract for <code>write(b)</code>
* is that it should have exactly the same effect as the call
* <code>write(b, 0, b.length)</code>.
*
* @param b the data.
* @exception IOException if an I/O error occurs.
* @see java.io.OutputStream#write(byte[], int, int)
*/
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}
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.
Params: - 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.
/**
* Writes <code>len</code> bytes from the specified byte array
* starting at offset <code>off</code> to this output stream.
* The general contract for <code>write(b, off, len)</code> is that
* some of the bytes in the array <code>b</code> are written to the
* output stream in order; element <code>b[off]</code> is the first
* byte written and <code>b[off+len-1]</code> is the last byte written
* by this operation.
* <p>
* The <code>write</code> method of <code>OutputStream</code> 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.
* <p>
* If <code>b</code> is <code>null</code>, a
* <code>NullPointerException</code> is thrown.
* <p>
* If <code>off</code> is negative, or <code>len</code> is negative, or
* <code>off+len</code> is greater than the length of the array
* {@code b}, then an {@code IndexOutOfBoundsException} is thrown.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @exception IOException if an I/O error occurs. In particular,
* an <code>IOException</code> is thrown if the output
* stream is closed.
*/
public void write(byte b[], int off, int len) throws IOException {
Objects.checkFromIndexSize(off, len, b.length);
// len == 0 condition implicitly handled by loop bounds
for (int i = 0 ; i < len ; i++) {
write(b[off + i]);
}
}
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.
/**
* Flushes this output stream and forces any buffered output bytes
* to be written out. The general contract of <code>flush</code> 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.
* <p>
* 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.
* <p>
* The <code>flush</code> method of <code>OutputStream</code> does nothing.
*
* @exception IOException if an I/O error occurs.
*/
public void flush() 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.
Throws: - IOException – if an I/O error occurs.
/**
* Closes this output stream and releases any system resources
* associated with this stream. The general contract of <code>close</code>
* is that it closes the output stream. A closed stream cannot perform
* output operations and cannot be reopened.
* <p>
* The <code>close</code> method of <code>OutputStream</code> does nothing.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
}
}