Hi friend,

FileWriter
The FileWriter is a class used for writing character files.
This constructor simply overwrite the contents in the file by the specified string but if you put the boolean value as true with the file name (argument of the constructor)
then the constructor append the specified data to the file i.e. the pre-exist data in a file is not overwritten and
the new data is appended after the pre-exist data.

BufferedWriter

The BufferWriter class is used to write text to a character-output stream,
buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.


import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.IOException;

public class BufferedWriterExample
{
public static void main( String [] args )
{
try
{
FileWriter fwo = new FileWriter( "output.txt", false );
// false means we will be writing to the file
BufferedWriter bwObj = new BufferedWriter( fwo );

// write four lines
bwObj.write( "Hello World 1" );
bwObj.newLine( );
bwObj.write( "Hello World 2" );
bwObj.newLine( );
bwObj.write( "Hello World 3" );
bwObj.newLine( );
bwObj.write( "Hello World 4 );
bwObj.newLine( );


bwObj.close( );
System.out.println( "File is Write" );
}

catch( IOException ioexception )
{
ioexception.printStackTrace( );
}
}
}


For read more information :


http://www.roseindia.net/java/example/java/io/java-append-to-file.shtml

Thanks