我不知道为什么 JLabel 没有显示

Question

I have a main class that creates the instance of the JFrame and JPanel and I set the JPanel as public so I can access it from another class to add more things into it (I don't know if this is how it works, that's just my logic).

public class Main {

   private JFrame obj; 
   public Gameplay gamePlay; 

   public Main() {
      obj = new JFrame();
      gamePlay = new Gameplay();
   }

   public void execute() {
      //properties of the jframe
      obj.setBounds(10, 10, 700, 600);
      obj.setTitle("Brick breaker");
      obj.setResizable(false);
      obj.setVisible(true);
      obj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      //add the jpanel inside the jframe
      obj.add(gamePlay);
   }

   public static void main(String[] args) {
      Main main = new Main();
      main.execute();
   }
}

Then, I have another class named Gameplay which extends JPanel . One of the methods inside has to draw things inside the JPanel and add a label when a condition is true.

Note that the commented region at the end where "GAME OVER" is drawn by with graphics g it does work correctly, but I want to put a label instead because I want to use custom font. The label never shows up. All the other things that the method pait() has to paint also work fine.

public void paint(Graphics g) {
    //background
    g.setColor(Color.black);
    g.fillRect(1, 1, 692, 592);
    
    //more code of drawing things
    //...
    
    if(ballposY > 570) {
        play = false;
        ballXdir = 0;
        ballYdir = 0;
        
        lblGameOver = new JLabel("GAME OVER");
        lblGameOver.setForeground(Color.green);
        lblGameOver.setFont(pixels);//custom font
        Main main = new Main();
        main.gamePlay.add(lblGameOver);

        //g.setColor(Color.green);
        //g.setFont(new Font("serif", Font.BOLD, 30));
        //g.drawString("GAME OVER", 250, 300);
    }
    g.dispose();
}

Answer 1

You are need to add this line to your code:

lblGameOver.setOpaque(true); It's will add your BackGroud and make that methode works well lblGameOver.setForeground(Color.green);