Java-JButton没有出现在JFrame中

Question

I want to make a title screen for my game which involves a title screen. Having just a jframe works and lets me use absolute positioning(i know its not great but its what i intend to use unless i can work out how to reposition jbuttons on a layout). However, when i add a jpanel so that i can repaint and revalidate, the buttons dont show up and i dont know why. In summary, i want to know why my jbuttons arent showing and how i could fix it(and it would be GREAT if you could tell me how to reposition jbuttons on a flowlayout or any other layout!!!) This is my code. Thanks! :)

public class Launcher extends JFrame{

private static final long serialVersionUID = 1L;

public static final int WIDTH = 800;
public static final int HEIGHT = 600;
public static final String TITLE = "Field of the Dead Pre-Release 0.1";
protected static JButton b3;
protected static JButton b4;
protected static JButton b5;
protected static JButton b6;
protected static JButton b7;
protected static JButton b8;
protected static JButton b9;
protected static JButton b10;
protected static JButton b11;
JFrame frame = new JFrame("Field of the Dead");
JPanel panel = new JPanel();

public Launcher() {

    JFrame.setDefaultLookAndFeelDecorated(false);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(null);
    frame.setSize(WIDTH, HEIGHT);
    frame.setVisible(true);
    frame.setResizable(false);
    frame.add(panel);
    panel.setLayout(null);
    b3 = new JButton("Quit Game");
    b3.setBounds(600, 500, 150, 30);
    panel.add(b3);
    b4 = new JButton("Options");
    b4.setBounds(600, 450, 150, 30);
    panel.add(b4);
    b5 = new JButton("Officer Store");
    b5.setBounds(600, 50, 150, 30);
    panel.add(b5);
    b6 = new JButton("Offline Campaign");
    b6.setBounds(50, 50, 150, 30);
    panel.add(b6);
    b7 = new JButton("Offline Training");
    b7.setBounds(50, 200, 150, 30);
    panel.add(b7);
    b8 = new JButton("Online Campaign");
    b8.setBounds(50, 350, 150, 30);
    panel.add(b8);
    b9 = new JButton("Online PvP Games");
    b9.setBounds(50, 500, 150, 30);
    panel.add(b9);
    b10 = new JButton("Bonus Store");
    b10.setBounds(600, 100, 150, 30);
    panel.add(b10);
    b11 = new JButton("Screen Resolution");

    b3HandlerClass b3handler = new b3HandlerClass();
    b4HandlerClass b4handler = new b4HandlerClass();
    b5HandlerClass b5handler = new b5HandlerClass();
    b6HandlerClass b6handler = new b6HandlerClass();
    b7HandlerClass b7handler = new b7HandlerClass();
    b8HandlerClass b8handler = new b8HandlerClass();
    b9HandlerClass b9handler = new b9HandlerClass();

    b3.addActionListener(b3handler);
    b4.addActionListener(b4handler);
    b5.addActionListener(b5handler);
    b6.addActionListener(b6handler);
    b7.addActionListener((ActionListener) b7handler);
    b8.addActionListener(b8handler);
    b9.addActionListener(b9handler);
}

private class b3HandlerClass implements ActionListener{
    public void actionPerformed(ActionEvent event) {
        System.exit(0);
    }
}

private class b4HandlerClass implements ActionListener{
    public void actionPerformed(ActionEvent event) {
        panel.remove(b3);
        panel.remove(b4);
        panel.remove(b5);
        panel.remove(b6);
        panel.remove(b7);
        panel.remove(b8);
        panel.remove(b9);
        panel.remove(b10);

        b11 = new JButton("Screen Resolution");

        panel.add(b11);
        panel.revalidate();
        panel.repaint();
    }

}

Answer 1

You are setting the JFrame visible before adding your components, so it makes sense that they won't show. solution: set visible after adding components.

Other issues:

• Over use of static: Your components are static and none of them should be since overuse of static makes for inflexible classes that are difficult to re-use.
• Use of null layout and setBounds(...) : This leads to physically inflexible GUI's that look terrible on all platforms but your own and that are hard if not impossible to enhance or change. Instead learn about and use the layout the managers.
• Removing and adding components: You're better off using a CardLayout and swapping JPanels.

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Addendum:
You comment:

Didn't work, still doesn't show the JBUttons

Yep, you shot yourself in the foot with the null layout. Because your JFrame's layout is null, the JPanel defaults to a size of [0, 0]. Solution: don't have it use a null layout .