Question

我正在尝试使用分层窗格为我正在处理的程序创建一个菜单，但该按钮不会显示。我似乎无法弄清楚它是什么......

public class FlashcardGUI {

public static void main(String[] args) 
{
    JFrame projectFrame = new JFrame("StudyFast Flashcard");
    projectFrame.setName("StudyFast Flashcards");
    projectFrame.setSize(1000,600);
    projectFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    projectFrame.setVisible(true);


    JLayeredPane projectLayeredPane = new JLayeredPane();
    projectFrame.setContentPane(projectLayeredPane);

    JPanel projectMenu1 = new JPanel();
    projectLayeredPane.setLayer(projectMenu1, 0);

    final JButton startNow = new JButton();
    startNow.setText("Exit");
    startNow.addActionListener(new ActionListener() 
        {
            public void actionPerformed(ActionEvent e) 
                {
                    System.exit(0);
                }
        });



    projectFrame.add(projectLayeredPane);
    projectLayeredPane.add(projectMenu1);
    projectMenu1.add(startNow);
    }
}

Answer 1

将这两行放在main方法的末尾。为了使按钮显示，顺序很重要。

projectFrame.pack();
projectFrame.setVisible(true);

（确保删除第9行已有的projectFrame.setVisible(true);。）

Answer 2

我已更新您的代码，现在正在运行。请在代码中查看问题的内联注释。希望这会有所帮助。

public class FlashcardGUI2 {

public static void main(String[] args) {
    JFrame projectFrame = new JFrame("StudyFast Flashcard");
    projectFrame.setName("StudyFast Flashcards");
    projectFrame.setSize(1000,600);
    projectFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    projectFrame.setVisible(true);
    JLayeredPane projectLayeredPane = new JLayeredPane();
    LayoutManager layout = new FlowLayout();   //creating a FlowLayout object
    projectLayeredPane.setLayout(layout);   //adding the layout to JLayeredPane
                                            //because JLayeredPane do not have default layout of
                                            //its own. The reason you were not 
                                            //getting the button displayed
    projectLayeredPane.setPreferredSize(new Dimension(300, 310));
    JPanel projectMenu1 = new JPanel();
    final JButton startNow = new JButton();
    startNow.setText("Exit");
    startNow.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                    System.exit(0);
                }
        });
    projectLayeredPane.add(projectMenu1,new Integer(50));
    projectLayeredPane.add(startNow,new Integer(10));
    projectFrame.add(projectLayeredPane);
    projectFrame.pack();
    }
}

为什么不显示我的按钮？

2 个答案: