4 Replies Latest reply on Jan 27, 2008 6:46 AM by 843802

    How to use singleinstance service with a JWS application


      I have a Swing application and i am using Java web start to deploy on the user machines.
      I want to know how to implement the single instance service. so that only one instance os the application is running.

      Where should i use the singleinstance class provided by JNLP api.

      for ex:

      package test;

      import java.awt.BorderLayout;

      import javax.swing.JFrame;
      import javax.swing.JOptionPane;
      import javax.swing.JPanel;
      import javax.swing.JScrollPane;
      import javax.swing.JTextArea;

      import javax.swing.border.EmptyBorder;
      import java.util.Date;

      // classes of the web-start API, used in this example.
      import javax.jnlp.SingleInstanceListener;
      import javax.jnlp.SingleInstanceService;
      import javax.jnlp.ServiceManager;
      import javax.jnlp.UnavailableServiceException;

      /** A test of the SingleInstanceService using the web-start API.
      @author Andrew Thompson
      @version 2007/1/8
      public class SingleInstanceApplication
      extends JFrame
      implements SingleInstanceListener {

      /** A simple editing area. */
      JTextArea document;

      /** Assemble the GUI. */
      SingleInstanceApplication() {
      super("JNLP API single instance service");

      try {
      SingleInstanceService singleInstanceService =
      // add the listener to this application!
      (SingleInstanceListener)this );
      } catch(UnavailableServiceException use) {


      document = new JTextArea(
      "Try openning another version of this application\n");

      JPanel main = new JPanel(new BorderLayout());
      main.add(new JScrollPane(document));
      main.setBorder( new EmptyBorder(8,8,8,8) );



      /** Specified by the SingleInstanceListener interface
      @param args The command line parameters used for this invocation */
      public void newActivation(String[] args) {
      StringBuffer sb = new StringBuffer();
      for (int ii=0; ii<args.length; ii++) {
      sb.append("'" + args[ii] + "' ");
      String message = "Got new args: " + sb.toString();
      // this usually serves to alert the user the app.
      // wants attention. On Win. it will flash the
      // apps. icon in the task bar.
      JOptionPane.showMessageDialog(this, message);
      // also add the new args and time to the document.
      document.append( new Date() + "\t" + message + "\n" );

      /** Construct the GUI and display it. If the user double clicked
      a file to start the application, begin measures to load that file. */
      public static void main(String[] args) {
      SingleInstanceApplication app =
      new SingleInstanceApplication();

      in my progrma there are many clasess where should i use this.

      Pls help new bie!!

      Thanks and Regards