如何使 JFrame 真正全屏?

In my Java application I try to make a JFrame really fullscreen by using this code:

public class MainFrame extends JFrame {

    private static final long serialVersionUID = 1L;

    public MainFrame() {
        super();
        this.setTitle();
        this.setUndecorated(true);

        this.setExtendedState(JFrame.MAXIMIZED_BOTH);

        this.setVisible(true);
        //this.pack();
    }
}

但在我的 Mac 上，我仍然可以看到 Dock 和 OSX 的顶部工具栏.那么如何创建一个真正占用整个屏幕的 JFrame?