用按钮点击将ImageIcon更改为另一张图片

Question

所以我想在每次按下按钮时替换JLabel中的ImageIcon。我将图像、标签和GridBagConstraints设置为公共的。当我试图改变它，尽管什么都没有发生。

我做错了吗?

谢谢!

package hi.low;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
import java.util.Random;
import java.util.ArrayList;

public class Card_panel extends JPanel implements ActionListener
{
   private final int WIDTH = 400, HEIGHT = 200;
   private static String[] imageList =  { 
          "images/2h.png", "images/3h.png", "images/4h.png", "images/5h.png", "images/6h.png",
          "images/7h.png", "images/8h.png", "images/9h.png", "images/th.png", "images/jh.png",
          "images/qh.png", "images/kh.png", "images/ah.png", "images/2d.png", "images/3d.png", 
          "images/4d.png", "images/5d.png", "images/6d.png", "images/7d.png", "images/8d.png", 
          "images/9d.png", "images/td.png", "images/jd.png", "images/qd.png", "images/kd.png", 
          "images/ad.png", "images/2c.png", "images/3c.png", "images/4c.png", "images/5c.png",
          "images/6c.png", "images/7c.png", "images/8c.png", "images/9c.png", "images/tc.png",
          "images/jc.png", "images/qc.png", "images/kc.png", "images/ac.png", "images/2s.png",
          "images/3s.png", "images/4s.png", "images/5s.png", "images/6s.png", "images/7s.png",
          "images/8s.png", "images/9s.png", "images/ts.png", "images/js.png", "images/qs.png",
          "images/ks.png", "images/as.png"
   };
   private static int imageNum = -1;
   GridBagConstraints gbc = new GridBagConstraints();
   GridBagConstraints c = new GridBagConstraints();
   ImageIcon image;
   JLabel label;
   private static ArrayList<Card> deck;
   private static Card tempCard, currentCard;
   public Card_panel()
   {
        deck = new ArrayList();
        char[] suits = {'h', 'd', 'c', 's'};
        char[] values = {'2', '3', '4', '5', '6', '7', '8', '9', 't', 'j', 'q', 'k', 'a'};             
        for(int a = 0; a<suits.length; a++)
        {
            for(int b = 0; b<values.length; b++)
            {
                tempCard = new Card(suits[a],values[b]);
                deck.add(tempCard);
            }
        }            
        int rand_num;
        int cards_left = 52;            
        Random generator = new Random( System.currentTimeMillis() );            
        for(int a = 0; a<52; a++)
        {
            rand_num = generator.nextInt(cards_left);
            currentCard = deck.get(rand_num);
            deck.remove(rand_num);
            cards_left -= 1;
        }
        setPreferredSize(new Dimension(WIDTH, HEIGHT));
        setBackground (Color.green.darker().darker());    
        setLayout(new GridBagLayout());
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.gridwidth = 2;
        image = new ImageIcon(imageList[0]);
        label = new JLabel("", image, JLabel.CENTER);
        add( label, gbc );
        gbc.gridx = 0;
        gbc.gridy++;
        gbc.gridwidth = 1;
        JButton higher = new JButton("Higher");
        higher.setActionCommand("higher");
        higher.addActionListener (this);
        add( higher, gbc );
        gbc.gridx++;
        JButton lower = new JButton("Lower");
        lower.setActionCommand("lower");
        lower.addActionListener (this);
        add( lower, gbc );
   }
    @Override
    public void actionPerformed(ActionEvent e)
    {
        String Action;
        Action = e.getActionCommand ();
        if (Action.equals ("higher"))
        {
            System.out.println("User chose higher!");
            //function to check if it is right if right go to next card
            image = new ImageIcon(imageList[1]);
            label = new JLabel("", image, JLabel.CENTER);
            add( label, gbc );
        }
        if (Action.equals ("lower"))
        {
            System.out.println("User chose lower!");
            //function to check if it is right if right go to next card
        }    
    }        
}

Answer 1

与其每次都创建和添加一个新标签，不如直接在标签上调用setIcon

更像是…

image = new ImageIcon(imageList[1]);
label.setIcon(image);

查看如何使用标签了解更多细节。

我可能还建议你先加载图像，这样你就不需要在每个actionPerformed上重新加载它们/创建新对象

我也推荐ImageIO而不是ImageIcon