FileOutputStream class

See OutputStream class for descriptions of the methods FileOutputStream can use. They are:

write( int b ) Writes a single byte, supplied as the low-order byte in an int.

write( byte[ ] ) Writes an array of bytes.

write( byte[ ], offset, len ) Writes a portion len of a byte array, beginning at offset

close( ) Closes the stream, flushing it first.

flush( ) Flushes all associated buffers in a stream without closing it.

plus it adds:

.finalize( ) Ensures a close( ).

.getChannel( ) Returns the FileChannel object. These aren’t discussed here.

.getFD( ) Returns the file descriptor.

■ FileOutputStream is meant for writing streams of raw bytes to files. For writing streams of human-readable characters, you should consider using the Writer class FileWriter.

■ FileOutputStream will create a file if that file does not exist. If it exists it will overwrite it. i.e.

File f = new File( "some_filename");
FileOutputStream fos = new FileOutputStream ( f);
or, the same thing:
FileOutputStream fos = new FileOutputStream ( "some_filename");

 ■  You can append to the ends of files with FileOutputStream, instead of overwriting them. It has two constructors with a second boolean argument where true means to append.
 
File f = new File( "some_filename");
FileOutputStream fos = new FileOutputStream ( f, true );
or
FileOutputStream fos = new FileOutputStream ( " some_filename ", true );

■ The following snippet uses FileOutputStream to copy a file by rewriting it a byte at a time, without buffering.

import java.util.*;
 
try {
 FileInputStream fis = new FileInputStream( "input_filename" );
 FileOutputStream fis = new FileOutputStream( "output_filename" );
 int x;
 while ( (x = fis.read( ) ) != -1 ) {
 fos.write( x );
 }
 fis.close( );
 fos.close( );
} 
catch (IOException e) { }
 

■ FileOuputStream is usually chained to other output stream classes, most notably BufferedOutputStream to provide buffering. i.e. The example above is repeated with output buffering. BufferedOutputStream's methods are used.

import java.util.*;
 
try {
 FileInputStream fis = new FileInputStream( "input_filename" );
 BufferedOutputStream bos = new BufferedOutputStream( new FileOutputStream( "output_filename" );
 int x;
 while ( (x = fis.read( ) ) != -1 ) {
 bos.write( x );
 }
 fis.close( );
 bos.close( );
} 
catch (IOException e) { }