Java Reference
In-Depth Information
To open a file for output, create a
FileOutputStream
object. Here are two commonly used
constructors:
FileOutputStream(String
fileName
) throws FileNotFoundException
FileOutputStream(String
fileName
, boolean
append
)
throws FileNotFoundException
If the file cannot be created, then
FileNotFoundException
is thrown. In the first form,
when an output file is opened, any preexisting file by the same name is destroyed. In the
second form, if
append
is
true
, then output is appended to the end of the file. Otherwise,
the file is overwritten.
To write to a file, you will use the
write( )
method. Its simplest form is shown here:
void write(int
byteval
) throws IOException
This method writes the byte specified by
byteval
to the file. Although
byteval
is declared as
an integer, only the low-order 8 bits are written to the file. If an error occurs during writing,
an
IOException
is thrown.
Once you are done with an output file, you must close it using
close( )
, shown here:
void close( ) throws IOException
Closing a file releases the system resources allocated to the file, allowing them to be used
by another file. It also ensures that any output remaining in an output buffer is actually
written to the physical device.
The following example copies a text file. The names of the source and destination files
are specified on the command line.
