Java tutorial
import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.RandomAccessFile; import java.nio.ByteBuffer; import java.nio.channels.FileChannel; public class MainClass { private static final int BSIZE = 1024; public static void main(String[] args) throws Exception { FileChannel fc = new RandomAccessFile("data.txt", "rw").getChannel(); fc.position(fc.size()); fc.write(ByteBuffer.wrap("Some more".getBytes())); fc.close(); } }