Runtime class behaving erratic

Question

hi all,
I am writing a simple network shell in java...it runs well for any dos commands but it doesn't executes a .exe file (using runtime class) while the program is active but when i quit the program the .exe file called before runs.
what's the problem...

Answer 1

                        else if(array.length == 2 && array[1] == ':'&& array[2] == '\\')
                               for (int index = 0; index < roots.length; index++)
                                    if(string1.equals(roots[index].toString()))
                                        System.setProperty("user.dir", string1);
                                        pwd = System.getProperty("user.dir");
                                        output.println(pwd);
                                        output.flush();
                        else if(array[0] == 'c' && array[1] == 'd' && array.length > 2)
                                   System.setProperty("user.dir", string1.substring(3));
                            //System.out.println(string1.substring(3));
                            pwd = System.getProperty("user.dir");
                            output.println(pwd);
                            //output.flush();
                        else if(string1.endsWith(".exe") || string1.endsWith(".avi"))
                            System.out.println(pwd+"\\"+string1);
                                   String run1 = pwd+"\\"+string1;
                                   /* Thread t = new Thread(new Run(run1));
                                   t.start(); */
                                   rtime.exec(run1);////******* HERE LIES THE PROBLEM @run1 path of the .exe file
                                   continue;
                              else
                                   commands[2] = string1;
                            p = rtime.exec(commands);                           
                            Scanner scan = new Scanner(p.getInputStream());
                                   String out = "";
                            while(scan.hasNextLine())
                                        out = out + scan.nextLine()+"~";
                                        //output.flush();
                            output.println(out);
                                   output.flush();
                              output.println("end");
                              output.flush();
        catch (IOException ex)
            ex.printStackTrace();
     public void run()
          try
               Runtime.getRuntime().exec(string);
          catch(IOException e)
    private static DatagramSocket clientSocket;
     private static MulticastSocket multiSocket;
    private static int boundPort = 8000;
    private static int multiPort = 5678;
     private static InetAddress group;
     private static String string = "active";
    private static String pwd;
     private static PrintWriter output;
    private static Scanner input;
    private static Process p;
    private static DatagramPacket packet;
}