File I/O - Absolute Java - page 585

Display 10.2 Some Methods of the Class PrintWriter (part 2 of 2)

public void close()

Closes the stream's connection to a file. The following method calls flush before closing the file:

public void flush()

Flushes the output stream. This forces an actual physical write to the file of any data that has been
buffered and not yet physically written to the file. Normally, you should not need to invoke flush .

When your program is finished writing to a file, it should close the stream connected
to that file. In Display 10.1, the stream connected to the file stuff.txt is closed with
the statement

outputStream.close();
The class PrintWriter , and every other class for file output or file input streams, has a
method named close . When this method is invoked, the system releases any resources
used to connect the stream to the file and does any other housekeeping that is needed.
If your program does not close a file before the program ends, Java will close it for you
when the program ends, but it is safest to close the file with an explicit call to close .
Output streams connected to files are often buffered , which means that, rather than
physically writing every instance of output data as soon as possible, the data is saved
in a temporary location, known as a buffer ; when enough data is accumulated in this
temporary location, it is physically written to the file. This can add to efficiency, since
physical writes to a file can be slow. The method flush causes a physical write to the file
of any buffered data. The method close includes an invocation of the method flush .

buffered

buffer

Closing a File
When your program is finished writing to a file or reading from a file, it should close the
stream connected to that file by invoking the method named close .
SYNTAX
Stream_Object .close();
EXAMPLE
outputStream.close();
inputStream.close();

It may seem like there is no reason to use the method close to close a file. If your
program ends normally but without closing a file, the system will automatically close
it for you. So why should you bother to close files with an explicit call to the method
close ? There are at least two reasons. First, if your program ends abnormally, then