Java GUI：按鈕控件不可見

Question

我在屏幕上顯示我的主菜單時出現問題。我看不出問題在哪裏。它正在顯示的是一個空白的JFrame窗口。它沒有顯示我的面板上的按鈕。

主類：

public class Main { 

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

} 
} 

GUIView類別：

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); 

} 

}

MainMenu的類別：

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

你從來沒有創建的MainMenu一個實例。要修復，你可以這樣做：

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

Answer 2

嘗試這種方式............

public class Test1 extends JFrame { 



    int count; 

    public Test1(){ 

     this.setSize(400,400); 
     MyCompo m = new MyCompo(); 
     this.add(BorderLayout.CENTER,m); 
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    } 





    class MyCompo extends JPanel{ 


     public MyCompo() { 
      this.setSize(300,300); 
      setComponents(); 
      //setHandlers(); 

     } 

     public void paintComponent(Graphics g) { 

      //setComponents(); 

     } 
     public void setComponents() { 

      this.setLayout(new GridLayout(5,4)); 
      this.add(new Button("1")); 
      this.add(new Button("2")); 
      this.add(new Button("3")); 
      this.add(new Button("4")); 
      this.add(new Button("5")); 
      this.add(new Button("6")); 
      this.add(new Button("7")); 
      this.add(new Button("8")); 
     } 

    } 

    public static void main(String[] args){ 

     EventQueue.invokeLater(new Runnable() { 

      public void run() { 
       Test1 t = new Test1(); 

       t.setVisible(true); 

      } 

     }); 

    } 

}