More desktop integration: the system tray

One more nice touch in the Java 6 offensive to the desktop is giving Java applications the ability to add icons to the system tray in a pretty consistent way across platforms. Of course differences exist and they will show up to some degree in the code but at least now the framework exists and the programmer’s effort is a lot smaller.
The API consists of 2 classes: java.awt.SystemTray and java.awt.TrayIcon.
The programmer cannot instantiate SystemTray but instead it has to ask for it: SystemTray.getSystemTray(). The system tray si not supported on all platforms so before trying to access and use it, its availability shall be checked: SystemTray.isSupported().
On the other hand the TrayIcon class can be instantiated as many times as needed - more than one icon can be added to the system tray from an application. The icon is obviously not just a simple image. It supports mouse events and a pop-up menu. It also allows the application to display messages to the user during its progress. But enough with the theory, let’s see how it works.

package com.littletutorials.systray;

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class SysTrayDemo
{
    protected static TrayIcon trayIcon;

    private static PopupMenu createTrayMenu()
    {
        ActionListener exitListener = new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                System.out.println("Bye from the tray");
                System.exit(0);
            }
        };

        ActionListener executeListener = new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                JOptionPane.showMessageDialog(null, "Nothing here, press the button!",
                    "User action", JOptionPane.INFORMATION_MESSAGE);
                trayIcon.displayMessage("Done", "Bravo!", TrayIcon.MessageType.INFO);
            }
        };

        PopupMenu menu = new PopupMenu();
        MenuItem execItem = new MenuItem("Execute...");
        execItem.addActionListener(executeListener);
        menu.add(execItem);

        MenuItem exitItem = new MenuItem("Exit");
        exitItem.addActionListener(exitListener);
        menu.add(exitItem);
        return menu;
    }

    private static TrayIcon createTrayIcon()
    {
        Image image = Toolkit.getDefaultToolkit().getImage("ds.jpg");
        PopupMenu popup = createTrayMenu();
        TrayIcon ti = new TrayIcon(image, "Java System Tray Demo", popup);
        ti.setImageAutoSize(true);
        return ti;
    }

    public static void main(String[] args)
    {
        if (! SystemTray.isSupported())
        {
            System.out.println("System tray not supported on this platform");
            System.exit(1);
        }

        try
        {
            SystemTray sysTray = SystemTray.getSystemTray();
            trayIcon = createTrayIcon();
            sysTray.add(trayIcon);
            trayIcon.displayMessage("Ready",
                "Tray icon started and tready", TrayIcon.MessageType.INFO);
        }
        catch (AWTException e)
        {
            System.out.println("Unable to add icon to the system tray");
            System.exit(1);
        }
    }
}

Filed under: Java API, Resources by Daniel Pietraru