I am using Java 11 on Debian 4. I am trying to build a very basic Java GUI. To start with I have the following code:

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;

public class BasicSwing extends JFrame {
    JPanel p = new JPanel();
    JButton b = new JButton("Hello");

    public static void main (String[] args) {
       new BasicSwing();
    }
    
    public BasicSwing() {
        super("Basic Swing");
        setSize(400,300);
        setResizable(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        p.add(b);
        add(p);
        setVisible(true);
    }
}

I have the X11 server running. The code does not fail but the GUI does not show up. I am not using Netbeans and I compile and run the code just as I would run and compile any other java code, ie with javac and java commands.The code does not stop and does not throw any error. Am I missing something very basic? I have seen a lot of discussion on the GUI not showing up but I am unable to find a solution to this problem given my specific development environment.

CodePudding user response：

Instead of calling the setVisible method inside of your JFrame extended class's constructor, You should make a call on it in your main function.

Do it this way:

public static void main (String[] args) {
       EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    BasicSwing mySwingApp = new BasicSwing();
                    mySwingApp.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
}

Please read more about why I use a java.awt.EventQueue here.

Update:

It's not good practice to directly create a class that extends JFrame. Also, please read this too, for more clarification.