Run only in system tray with no dock/taskbar icon in Java

Question

Is it possible for a Java application, a .jar one to be exact, to run only in the SystemTray without the user seeing anything on his taskbar/dock but having visible components like a JWindow ?
An example would be Dropbox's app for MacOS, which has the following window appear from the SystemTray while still having no visible icon at the dock.

If so then how can that be done?

Answer 1

Yes it can be done. Here is some sample code that adds a menu to a tray icon and adds a listener to a menu item in that menu which creates a dialog with the user clicks the item. When I create a runnable jar with this code it does not display an icon on the taskbar, it only shows the icon in the system tray.

import java.awt.AWTException;
import java.awt.Image;
import java.awt.SystemTray;
import java.awt.TrayIcon;
import java.awt.Menu;
import java.awt.MenuItem;
import java.awt.PopupMenu;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JOptionPane;

public class SystemTrayExample {
    private static final SystemTray tray = SystemTray.getSystemTray();
    private static final PopupMenu popup = new PopupMenu();
    private static TrayIcon trayIcon;

    public static void main(String[] args) {

        if (!SystemTray.isSupported()) {
            // SystemTray is not supported
        }

        trayIcon = new TrayIcon(createImage("icon.jpg", "tray icon"));
        trayIcon.setImageAutoSize(true);

        ActionListener listener = new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                MenuItem item = (MenuItem) e.getSource();

                String s = (String) JOptionPane.showInputDialog(null, "Report "
                        + item.getLabel(), "Create Report",
                        JOptionPane.PLAIN_MESSAGE, null, null, "");

                // Do something with the string...
            }
        };
        MenuItem exitItem = new MenuItem("Exit");
        exitItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                tray.remove(trayIcon);
                System.exit(0);
            }
        });


        Menu reportMenu = new Menu("Report");
        MenuItem menuItem = new MenuItem("Item");
        reportMenu.add(menuItem);
        menuItem.addActionListener(listener);
        popup.add(reportMenu);
        popup.add(exitItem);
        trayIcon.setPopupMenu(popup);

        try {
            tray.add(trayIcon);
        } catch (AWTException e) {
            // TrayIcon could not be added
        }

    }

    // Obtain the image URL
    protected static Image createImage(String path, String description) {
        URL imageURL = SystemTrayExample.class.getResource(path);

        if (imageURL == null) {
            System.err.println("Resource not found: " + path);
            return null;
        } else {
            return (new ImageIcon(imageURL, description)).getImage();
        }
    }
}

Answer 2

Sure it can be done (for Windows anyways). Here is a runnable example with a popup menu. The icon displayed in the tray is retrieved from a URL (use whatever Icon you want:

import java.awt.AWTException;
import java.awt.CheckboxMenuItem;
import java.awt.Image;
import java.awt.Menu;
import java.awt.MenuItem;
import java.awt.PopupMenu;
import java.awt.SystemTray;
import java.awt.TrayIcon;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;


public class TrayIconDemo2 {

    public TrayIconDemo2() throws Exception {
        initComponents();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    new TrayIconDemo2();
                } catch (Exception ex) { System.out.println("Error - " + ex.getMessage()); }
            }
        });
    }

    private void initComponents() throws Exception {
        createAndShowTray();
    }

    private void createAndShowTray() throws Exception {
        //Check the SystemTray is supported
        if (!SystemTray.isSupported()) {
            System.out.println("SystemTray is not supported");
            return;
        }

        PopupMenu popup = new PopupMenu();
        //retrieve icon form url and scale it to 32 x 32
        final TrayIcon trayIcon = new TrayIcon(ImageIO.read(
                new URL("http://www.optical-illusions.com/thumb/ec665b8dfcc248da272224972e9eaf92.jpg"))
                .getScaledInstance(32, 32, Image.SCALE_SMOOTH), null);

        //get the system tray
        final SystemTray tray = SystemTray.getSystemTray();

        // Create a pop-up menu components
        MenuItem aboutItem = new MenuItem("About");
        aboutItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                JOptionPane.showMessageDialog(null, "About");
            }
        });

        final  CheckboxMenuItem cb1 = new CheckboxMenuItem("Show Tooltip");
        cb1.addItemListener(new ItemListener() {
            @Override
            public void itemStateChanged(ItemEvent ie) {
                if(cb1.getState()==true) {
                trayIcon.setToolTip("Hello, world");
                }else {
                trayIcon.setToolTip("");
                }
            }
        });

        Menu displayMenu = new Menu("Display");

        MenuItem infoItem = new MenuItem("Info");
        //add actionlistner to Info menu item
        infoItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                JOptionPane.showMessageDialog(null, "Display Info of some sort :D");
            }
        });

        MenuItem exitItem = new MenuItem("Exit");
        //add actionlistner to Exit menu item
        exitItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                System.exit(0);
            }
        });

        //Add components to pop-up menu
        popup.add(aboutItem);
        popup.addSeparator();
        popup.add(cb1);
        popup.addSeparator();
        popup.add(displayMenu);
        displayMenu.add(infoItem);
        popup.add(exitItem);

        trayIcon.setPopupMenu(popup);

        try {
            tray.add(trayIcon);
        } catch (AWTException e) {
            System.out.println("TrayIcon could not be added.");
        }
    }
}

You can display whatever you like from your system tray icon but you should do it via a popup menu.

Answer 3

Put this line:

System.setProperty("apple.awt.UIElement", "true");

as first statement in your main:

public static void main(String[] args) {
    System.setProperty("apple.awt.UIElement", "true");
    // Your stuff...
}

I have succesfully tried it with "TrayIconDemo2" example by @DevilsHnd that you can find as another answer in this page.

By the way I'll add something more giving credits to this answer by @Muhammad Usman. I have pasted all the answer that I have checked as correct below:

According to JavaFX you cannot hide dock icon in JavaFX application. Please view this link .

There are two ways to hide dock icon.

• Apple standard way, just modify *.app/Contents/Info.plist and add <key>LSUIElement</key> <string>1</string> .
• Start your application as AWT application and hide dock icon using system property. After setting system property call the JavaFX main method and JavaFX application will take over now with no dock icon. Please see the sample code snippet below.

 /** - This class is intended to start application as AWT application before initializing - JavaFX application. JavaFX does not support dock-icon-less application so we are - creating JavaFX application from AWT application so that we can achieve the desired - functionality. - */ public class AWTMain { public static void main(String[] args) { // This is awt property which enables dock-icon-less // applications System.setProperty("apple.awt.UIElement", "true"); java.awt.Toolkit.getDefaultToolkit(); // This is a call to JavaFX application main method. // From now on we are transferring control to FX application. FXMain.main(args); } } 

Here FXMain is referred as previous class with main method.

You will also need to modify your .pom file if you are using maven and other places too where you have mentioned main class for application.