Java 图形用户界面 : button controls not Visible

Question

我在屏幕上显示主菜单时遇到问题。我不明白问题出在哪里。它所显示的只是一个空白的 JFrame 窗口。它没有显示我的带有按钮的面板。

主类:

public class Main {

public static void main(String[] args) {
    GUIView gui = new GUIView();

}
}

GUIView类:

import javax.swing.*;
import java.awt.*;

public class GUIView {
protected JFrame frame;
    public GUIView() {


    frame = new JFrame("Test");
        frame.setVisible(true);
        frame.setSize(500,500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

}

主菜单类:

import javax.swing.*;
import java.awt.*;

public class MainMenu extends GUIView {
    private JButton b1, b2, b3;
    private JPanel panel;
    public MainMenu() {
        GridBagLayout gridbag = new GridBagLayout();
        b1 = new JButton();
        b2 = new JButton();
        b3 = new JButton();

    //Button Settings;
    b1.setText("Administrator");
    b2.setText("Program Leader");
    b3.setText("Lecturer");

    //Panel Settings
    panel = new JPanel();
    panel.setLayout(gridbag);
    panel.add(b1);
    panel.add(b2);
    panel.add(b3);
    panel.setVisible(true);
    super.frame.add(panel);
}

}

Answer 1

您永远不会创建 MainMenu 的实例。要修复，您可以这样做:

public static void main(String[] args) {
   GUIView gui = new MainMenu();
}