当对JFrame使用PaintComponent时，除非使用pack，否则必须调整窗口大小才能显示它。 我该如何补救？

Question

I am creating a Blackjack game, and I'm trying to get cards to show up on top of the table image when the hit button is hit. However, they keep showing up to the side of the table image, and only either show up a. when I use the pack() method in the ActionListener, or if I don't use pack(), when I resize the window.

My Code:

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;


public class BlackjackTable3 extends JFrame {


  JButton stayButton = new JButton("STAY");
  JButton hitButton = new JButton("HIT");
  JPanel mainPanel = new JPanel();

  public BlackjackTable3() {
    this.setTitle("Blackjack Test Table");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel tablePanel = new JPanel();
    ImageIcon pic = new ImageIcon("blackjackTableCanvas.jpg");
    mainPanel.add(new JLabel(pic), BorderLayout.NORTH);




    this.add(mainPanel);
    this.setSize(1600,1600);
    this.setVisible(true);

    JPanel buttonPanel = new JPanel();
    ActionListener pressChoice = new DecisionListener();
    hitButton.addActionListener(pressChoice);
    stayButton.addActionListener(pressChoice);

    buttonPanel.setSize(300,150);
    buttonPanel.add(hitButton,BorderLayout.WEST);
   buttonPanel.add(stayButton,BorderLayout.EAST);
    buttonPanel.setVisible(true);
    this.add(buttonPanel, BorderLayout.SOUTH);

  }



  class DecisionListener implements ActionListener{

    public void actionPerformed(ActionEvent a){
      //code for hit/stay to go here

      if(a.getSource() == hitButton){
        System.out.println("YOU CHOSE HIT!");
        CardRender2 c = new CardRender2(new Card());

        mainPanel.add(c, BorderLayout.CENTER);
        pack();
      }
      else if(a.getSource() == stayButton){
        System.out.println("YOU CHOSE STAY!");
      }

    }
  }



  public static void main(String[] args){
    BlackjackTable3 b = new BlackjackTable3();

  }

}

My CardRender2 code:

public class CardRender2 extends JComponent{ 
public CardRender2(Card card) {
  this.val = card.value.face;
    this.suit = card.suit.toString();
    String filename = this.fetchCardFileLabel();
    try {
        image = ImageIO.read(new File("card deck\\" + filename + ".png"));
    } catch (IOException e) {
        e.printStackTrace();
    }
    JLabel j = new JLabel();
    j.add(this);

}

@Override
protected void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D) g;
    super.paintComponent(g2);
    g2.drawImage(image, 0, 0, null);

}
...}

I tried using repaint(), and I can't use paint bc I get a compiler error. How can I fix this issue?

Answer 1

how can I place these cards OVER, ON TOP OF, the table image?

You need a hierarchy of components something like:

• JFrame
  • background component with image
    • card component with image

One way is to use labels to contain your images:

JLabel card = new JLabel(...);
JLabel background = new JLabel(...);
background.setLayout( new FlowLayout() );
background.add( card );
frame.add(background, BorderLayout.CENTER);

This will only work if the background image is bigger than your card component.