如何将 JMenuBar 移动到 Mac OS X 上的屏幕菜单栏？

Question

When I move my JMenuBar to the screen menu bar on Mac OS X, it leaves some blank space where the menu would be in my window; I need to remove that space. I am using

System.setProperty("apple.laf.useScreenMenuBar", "true")

to move my JMenuBar to the screen menu bar. My friend who uses a Mac reports that this leaves some ugly vertical space where the menu would reside if I did not set that property. What is the best way to resolve this issue?

EDIT: Here is an example from my source:

public static void main(String[] args) {
    System.setProperty("apple.laf.useScreenMenuBar", "true");
    System.setProperty("com.apple.mrj.application.apple.menu.about.name", "Name");

    JFrame frame = new JFrame("Gabby");
    final DesktopMain dm = new DesktopMain();

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(dm);
    frame.setSize(160, 144);
    frame.setLocationRelativeTo(null);
    frame.setIgnoreRepaint(true);

    JMenuBar menuBar = new JMenuBar();
    JMenu fileMenu = new JMenu("File");
    menuBar.add(fileMenu);

    // Populating the menu bar code goes here

    frame.setJMenuBar(menuBar);
    frame.setVisible(true);
}

Answer 1

Depending on when it's done, setting the property after your program launches may be too late to be effective. Instead, add the setting at launch time.

java -Dapple.laf.useScreenMenuBar=true -jar MyApplication.jar

Alternatively, set the property in your application bundle's Info.plist , as discussed in Java Deployment Options for Mac OS X , Java Dictionary Info.plist Keys , About Info.plist Keys and Java Runtime System Properties .

<key>Properties</key>
<dict>
    <key>apple.laf.useScreenMenuBar</key>
    <string>true</string>
    ...
</dict>

Addendum: As shown below, the problem does not appear using the approach suggested by @Urs Reupke or myself. Your (missing) DesktopMain may be at fault.

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;

/** @see http://stackoverflow.com/questions/8955638 */
public class NewMain {

    public static void main(String[] args) {
        System.setProperty("apple.laf.useScreenMenuBar", "true");
        System.setProperty(
            "com.apple.mrj.application.apple.menu.about.name", "Name");
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {

                JFrame frame = new JFrame("Gabby");
                final JPanel dm = new JPanel() {

                    @Override
                    public Dimension getPreferredSize() {
                        return new Dimension(320, 240);
                    }
                };
                dm.setBorder(BorderFactory.createLineBorder(Color.blue, 10));

                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(dm);
                frame.pack();
                frame.setLocationByPlatform(true);

                JMenuBar menuBar = new JMenuBar();
                JMenu fileMenu = new JMenu("File");
                menuBar.add(fileMenu);
                frame.setJMenuBar(menuBar);
                frame.setVisible(true);
            }
        });
    }
}

Answer 2

As an alternative to what trashgod suggests, do what you're doing - but do it very early, before you initialize your UI.

Also, you might consider using this to display your application's name in the bar:

    System.setProperty("com.apple.mrj.application.apple.menu.about.name", "MyApplication");

Answer 3

I know this question is old, but what worked for me is I created a new class called Main, and then set the system property like

System.setProperty("apple.laf.useScreenMenuBar", "true");
System.setProperty("apple.awt.application.name", "My app");

Works in JDK15.

Answer 4

对于 Java 8 使用这个

System.setProperty("apple.awt.application.name", "My app");