import java.io.*;

public class WriteByteToFile
{
   public static void main(String[] args) throws Exception
   {
      RandomAccessFile f = new RandomAccessFile( "output", "rw" );
      f.setLength(0);  // Erase file

      byte x;

      f.writeByte( (byte) 65 );
      f.writeByte( (byte) 66 );
      f.writeByte( (byte) 8 );     // backspace
   }
}