Java tutorial
import java.io.File; import java.io.RandomAccessFile; public class Main { public static void main(String[] argv) throws Exception { File f = new File("filename"); RandomAccessFile raf = new RandomAccessFile(f, "rw"); // Read a character char ch = raf.readChar(); // Seek to end of file raf.seek(f.length()); // Append to the end raf.writeChars("aString"); raf.close(); } }