Appending til en txt fil

Hej Jeg opretter en txt fil, hvergang jeg køre dette program. Txt filen skal ikke slættes, men der skal appendes til denne txt fil hvergang istedet.

Hvordan klare jeg dette??



package klient;

import java.util.Vector;
import java.net.UnknownHostException;
import java.io.IOException;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.text.DateFormat;
import java.util.Date;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.util.Enumeration;
import java.net.DatagramSocket;
import java.net.DatagramPacket;
import java.net.*;


public class LogFil extends Thread //Arver fra tråden.
{
  static String LokalIP ="";
  static InetAddress localMachine = null;
  static String LokalName = "";
  static DatagramPacket packet = null;
  static DatagramSocket socket = null;
  //static int UdpPort = 1026;
  //static String UdpIP = "192.168.1.196";
  static InetAddress address;
  PrintWriter ud = null;

  public LogFil()
  {
      /*-------------------------------------------------------------------------*/
    /*Finder Lokal IP Adresse*/

      try {
        localMachine = java.net.InetAddress.getLocalHost();
      }
      catch (UnknownHostException ex4) {
      }
  LokalIP = localMachine.getHostAddress();
      LokalName = localMachine.getHostName();
  /*Finder Lokal IP Adresse*/

  /*Opretter en LogFil Starter*/
  Date time = new Date();
  DateFormat df1 = new SimpleDateFormat("yyyy-MM-dd");
  DateFormat df2 = new SimpleDateFormat("HH-mm-ss");
  FileWriter fil = null;

  try {
  //fil = new FileWriter("Klient " + df1.format(time) + " " + df2.format(time) + ".txt");
  fil = new FileWriter("C:/SunKlient/Klient.txt");
  }
  catch (IOException ex3)
  {
  }

    ud = new PrintWriter(fil, true);


    try {
      jbInit();
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
    //ud.println("Sun klient Startet: " + time);
//ud.flush();
  /*Opretter en LogFil Slutter*/
  /*-------------------------------------------------------------------------*/

  }

private static Vector logging = new Vector();

  static public void SkrivLog(String SkrivTilVector)
  {
    logging.addElement(SkrivTilVector);
  }

  public void run()
  {


while(true)
    {
    while (logging.size() > 0)
    {
   
      ud.println((String)logging.elementAt(0));
      logging.removeElementAt(0);

    }

  }
}

  private void jbInit() throws Exception {
  }
}