java - 如何在不双重实例化 JFrame 的情况下更改图像？

Question

所以我想更改每次按下滚动按钮时显示的图像，但每当我尝试这样做时，我都会双重实例化JFrame。如果可能的话，我想以这种方式使用 ActionListener。

这是我的代码:

import javax.swing.JFrame;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JTextArea;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class DiceFrame extends JFrame{

ImageIcon[] dice_images = new ImageIcon[7]; 
String score = "This is a test";
JPanel mainPanel;
JPanel scorePanel;
JPanel buttonPanel;
JLabel picLabel;
JTextArea scoreField;
JButton roll;
JButton save;
ActionListener action;
ActionListener output;

public DiceFrame(){
  super();

  mainPanel = new JPanel();
  scorePanel = new JPanel();
  buttonPanel = new JPanel();
  roll = new JButton("Roll");
  save = new JButton("Save");
  picLabel = new JLabel();
  scoreField = new JTextArea();

  setSize(400,300);
  setTitle("Dice Program");
  loadImage();

  getContentPane().add(mainPanel, BorderLayout.CENTER);
  getContentPane().add(scorePanel, BorderLayout.EAST);
  getContentPane().add(buttonPanel, BorderLayout.SOUTH);

  mainPanel.add(picLabel);
  picLabel.setIcon(dice_images[0]);
  buttonPanel.add(roll);
  buttonPanel.add(save);
  scorePanel.add(scoreField);
  scoreField.setText(score);
  roll.addActionListener(action);
  save.addActionListener(output);
}

private void loadImage()
{
  dice_images [0] = new ImageIcon("res/dice_img/die_01_sm.gif");
  dice_images [1] = new ImageIcon("res/dice_img/die_02_sm.gif");
  dice_images [2] = new ImageIcon("res/dice_img/die_03_sm.gif");
  dice_images [3] = new ImageIcon("res/dice_img/die_04_sm.gif");
  dice_images [4] = new ImageIcon("res/dice_img/die_05_sm.gif");
  dice_images [5] = new ImageIcon("res/dice_img/die_06_sm.gif");
  dice_images [6] = new ImageIcon("res/dice_img/die_01_sm.gif");
}


public static void main(String [] args){
  DiceFrame frame = new DiceFrame();

  frame.setDefaultLookAndFeelDecorated(true);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setResizable(false);
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);

 }


}

class DiceActionListener implements ActionListener{

 @Override
 public void actionPerformed(ActionEvent e){}
}


class SaveActionListener implements ActionListener{

@Override
public void actionPerformed(ActionEvent e){}
}

我不知道要在 actionPerformed 方法中放入什么内容，以免创建另一个 JFrame 实例。

Answer 1

执行类似以下代码的操作。创建一个可以更改图像图标的方法。然后在单击按钮时调用它。看看评论。

import javax.swing.JFrame;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JTextArea;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class DiceFrame extends JFrame {

    ImageIcon[] dice_images = new ImageIcon[7]; 
    String score = "This is a test";
    JPanel mainPanel, scorePanel, buttonPanel;
    JLabel picLabel;
    JTextArea scoreField;
    JButton roll, save;

    public DiceFrame(){

        super();
        mainPanel = new JPanel();
        scorePanel = new JPanel();
        buttonPanel = new JPanel();
        roll = new JButton("Roll");
        save = new JButton("Save");
        picLabel = new JLabel();
        scoreField = new JTextArea();

        setSize(400,300);
        setTitle("Dice Program");
        loadImage();

        getContentPane().add(mainPanel, BorderLayout.CENTER);
        getContentPane().add(scorePanel, BorderLayout.EAST);
        getContentPane().add(buttonPanel, BorderLayout.SOUTH);

        mainPanel.add(picLabel);
        picLabel.setIcon(dice_images[0]);
        buttonPanel.add(roll);
        buttonPanel.add(save);
        scorePanel.add(scoreField);
        scoreField.setText(score);

        save.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) {
            System.out.println("You clicked save");
        }
        });

        roll.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) {
            //call your icon change method with the index you want to change it to
            changeIcon(3);
        }
        });
    }

    private void loadImage() {

        //use a loop insted of repeting the add, but becareful if i < 10 because your file names need to match :)
        for(int i = 0; i < 7; i++) {

            dice_images [i] = new ImageIcon("res/dice_img/die_0" + i + "_sm.gif");
        }
    }

    public static void main(String [] args) {

        DiceFrame frame = new DiceFrame();
        frame.setDefaultLookAndFeelDecorated(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    //create a method to change your icon
    public void changeIcon(int imageIndex) {

        picLabel.setIcon(this.dice_images[imageIndex]);
    }
}