The java.io.OutputStream class sends raw bytes of data
to a target such as the console or a network server. Like InputStream, OutputStream is an abstract class.
However, many methods in the class library are only specified to
return OutputStream rather than the more specific
subclass.
public abstract void write(int b) throws IOException
public void write(byte[] data) throws IOException
public void write(byte[] data, int offset, int length)
throws IOException
public void flush() throws IOException
public void close() throws IOException
The write() methods send raw bytes of data to whomever
is listening to this stream.
Sometimes output streams are buffered by the operating system
for performance. In other words, rather than writing each byte as
it's written, the bytes are accumulated in a buffer ranging from
several bytes to several thousand bytes. Then, when the buffer
fills up, all the data is written at once. The flush()
method forces the data to be written whether or not the buffer is
full.
This is not the same as the buffering performed by a
BufferedOutputStream. That buffering is handled by the
Java runtime. This buffering is at the native OS level. However, a
call to flush() should empty both buffers.
The close() method closes the stream and releases
any resources associated with the stream. After the stream is closed,
attempts to write to it throw IOExceptions.