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How to use singleinstance service with a JWS application

843802Dec 14 2007 — edited Jan 27 2008

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
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Post Details
Locked on Feb 24 2008
Added on Dec 14 2007