这是我第一次使用 Swing，我在使用 JPanel 时遇到了问题

Question

I am working on a program for my school to use. It is like match.com, but for a public school. Yes there has been permission from the school to do this.

This is the first time I have ever used swing and I am having an issue with adding my JPanel to my JFrame so that I can see and use the button.

    private void Framing()
    {
    JPanel Panel = new JPanel(); 
    Panel.setLayout(new BorderLayout());
    JFrame Frame = new JFrame("Warning");
    Frame.setUndecorated(true);
    JButton OK = new JButton("EXIT");
    OK.addActionListener((ActionEvent event) -> {System.exit(0);});
    OK.setBounds(100,100,100,100);
    Panel.add(OK, BorderLayout.CENTER);
    Frame.getContentPane().add(Panel, BorderLayout.CENTER);
    Panel.setLocation((Frame.getWidth()-Panel.getWidth())/2,0);
    Frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
    Frame.setLocation(600, 300);
    Frame.setResizable(false);
    Frame.setLayout(null);
    Frame.setVisible(true);
}

What is the fastest way to fix the issue with the panel not even showing up? Any solutions are welcomed.

Answer 1

Since you are a new Swing programmer, I'll try to explain with below sample code. Here I have taken your code and done few changes. See my comments in the code.

With these changes, now the program works and shows a window with a big button. When user clicks the button program exits.

import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;

public class SwingTest
{
  private void Framing() //Better method name would be "showFrame()"
  {
    JPanel Panel = new JPanel(); //Better variable name would be "panel"
    Panel.setLayout(new BorderLayout());
    JFrame Frame = new JFrame("Warning"); //Better variable name would be "frame"
    Frame.setUndecorated(true);
    JButton OK = new JButton("EXIT"); //Better variable name would be "exitButton"
    OK.addActionListener((ActionEvent event) -> {System.exit(0);});

    //Not necessary. Layout manager will handle this.
    //OK.setBounds(100,100,100,100);

    Panel.add(OK, BorderLayout.CENTER);
    Frame.getContentPane().add(Panel, BorderLayout.CENTER);

    //Not necessary. Layout manager will handle this.
    //Panel.setLocation((Frame.getWidth()-Panel.getWidth())/2,0);

    Frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
    Frame.setLocation(600, 300);
    Frame.setResizable(false);

    //This is the main problem. You should avoid this.
    //Frame.setLayout(null);

    Frame.setVisible(true);
  }

  public static void main(String[] args)
  {
    new SwingTest().Framing();
  }
}