Background is not painted

Question

I want to create a simple game menue for the game pong. In the background there is a ball that bounces of the edges just to look nice. Now I want to add Buttons to this menue screen. But then the Background isn't painted anymore. So i want to draw a live Background but the buttons should still stay in the front. This live Background is implemented with a loop. In the following are the GUI class and the DrawStartMenueClass.

I heard about Layers but everybody uses them with some kind of tool in NetBeans and I got eclipse so I don't have that opportunity. I guess you can put the buttons and the background in different containers but then again I am not sure how that would. Every help is welcome.

public class GUI {



    public GUI() {

        //Frame erzeugen
        Var.frame = new JFrame("Pong");
        Var.frame.setSize(Var.dimension);
        Var.frame.setVisible(true);
        Var.frame.setResizable(true);
        Var.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Var.frame.setLocationRelativeTo(null);

        //Komponenten erzeugen
        Var.start = new JButton("Start");
        Var.optionen = new JButton("Optionen");
        Var.modus = new JButton("Modus");
        Var.skins = new JButton("Skins");
        Var.beenden = new JButton("Beenden");

        //Komponenten anpassen
        Var.start.setBounds((Var.screenWidth / 2) - (Var.buttonWidth / 2), 400, Var.buttonWidth, 50);
        Var.optionen.setBounds((Var.screenWidth / 2) - (Var.buttonWidth / 2), 500, Var.buttonWidth, 50);
        Var.modus.setBounds((Var.screenWidth / 2) - (Var.buttonWidth / 2), 600, Var.buttonWidth, 50);
        Var.skins.setBounds((Var.screenWidth / 2) - (Var.buttonWidth / 2), 700, Var.buttonWidth, 50);
        Var.beenden.setBounds((Var.screenWidth / 2) - (Var.buttonWidth / 2), 800, Var.buttonWidth, 50);

        //Komponenten hinzufügen
        Var.frame.getContentPane().add(new DrawStartMenue());
        Var.frame.add(Var.start);
        Var.frame.add(Var.optionen);
        Var.frame.add(Var.modus);
        Var.frame.add(Var.skins);
        Var.frame.add(Var.beenden);

    }

}

package main;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.RenderingHints;

import javax.swing.JPanel;


public class DrawStartMenue extends JPanel{

    private static final long serialVersionUID = 1L;
    private GridLayout experimentLayout = new GridLayout(6,1);


    public Graphics2D g2d;

    public void paint(Graphics g) {

        //Objekt g zum Zeichnen erzeugen
        super.paintComponent(g);
        g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);


        //Hintergrund
        g2d.setColor(Color.BLACK);
        g2d.fillRect(0,  0,  Var.screenWidth,  Var.screenHeight);
        g2d.setColor(Color.WHITE);
        g2d.setStroke(new BasicStroke(8));
        g2d.drawRect(Var.whiteRectX1, Var.whiteRectY1 , Var.whiteRectWidth, Var.whiteRectHeight);

        //Ball im Hintergrund
        for(int i = 0; i < Var.ballList.size(); i++) {
            g2d.fillOval(Var.ballList.get(i).ballX, Var.ballList.get(i).ballY,
                         Var.ballList.get(i).ballWidth, Var.ballList.get(i).ballHeight);
        }

        //Schriftzug
        drawCenteredString(g, "PONG", Var.rect, new Font("NO CONTINUE", Font.PLAIN, 230));
        repaint();


    }

Answer 1

    Var.frame.getContentPane().add(new DrawStartMenue());
    Var.frame.add(Var.start);
    Var.frame.add(Var.optionen);
    Var.frame.add(Var.modus);
    Var.frame.add(Var.skins);
    Var.frame.add(Var.beenden);

The default layout for a JFrame is the BorderLayout. When you add a component to the frame without specifying a constraint the component is added to the CENTER. Only one component can be added to the CENTER. So only the last one added is visible.

If you want the button on the background then you need to add the buttons to background panel, not the frame:

    JPanel background = new DrawStartMenue();
    Var.frame.add(background, BorderLayout.CENTER);
    background.add(Var.start);
    background.add(Var.optionen);
    background.add(Var.modus);
    background.add(Var.skins);
    background .add(Var.beenden);

Other problems with the code:

1. custom painting is done by overriding paintComopnent(...) not paint(...).
2. Never invoke repaint() in a painting method. Swing will determine when the component should be repainted.
3. components should be added to the frame BEFORE the frame is made visible.
4. don't attempt to setBounds(...) components. Swing was designed to be used with layout managers. Use the appropriate layout manager for your desired layout.

Edit:

So you know how to:

1. add components to a panel
2. do custom painting on a panel.

So to combine both concepts you modify the SwingPaintDemo2 code as follow:

//f.add(new MyPanel());
JPanel panel = new MyPanel();
panel.add( new JButton("Testing") );
f.add(panel);

So know that you know the basics, you use the knowledge on your real code.

And don't forget, you should NEVER invoke repaint in a painting method. I already showed you how to use a Swing Timer for the animation.

Next if you don't like the location of the buttons, then you use a different layout manager on the MyPanel class. If you need help with layout manager, then the Swing tutorial also has a section on layout manager with working example for you to download and test.

Answer 2

Here is the MRE. I finally got it to work. However it doesn't work in my project.

package main;

import java.awt.Color;

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

public class GUI {

    static JFrame frame;
    static JPanel buttons;
    static JPanel background;
    static JButton test1;
    static JButton test2;

    public static void main(String[] args) {

        frame = new JFrame();
        frame.setResizable(false);
        frame.setSize(600,  400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


        //Initzialize Components
        buttons = new JPanel();
        buttons.setBackground(Color.BLACK);

        background = new JPanel();
        background.setBackground(Color.BLACK);

        test1 = new JButton("Test1");
        test2 = new JButton("Test2");


        //Adding the Buttons
        buttons.add(test1);
        buttons.add(test2);

        //Adding panels to JFrame
        frame.add(background);
        //frame.add(buttons);

        background.add(buttons);

        frame.setVisible(true);




    }

}