java - 我的 JButton 的 ActionListener 如何访问另一个类中的变量？

Question

我正在为一个项目做老虎机。我无法让我的 JButton 从我的 ArrayList 生成新的随机数。我可以在程序启动时随机化数字并设置 actionlistener，但它无法满足我的需要。它仅用于测试目的。

我的 Actionlistener 在不同的 Java 文件中。一切正常，我只是不知道如何在按钮按下时在 plc1、plc2 和 plc3 的占位符中生成新的随机数点击。

我最近才真正开始编写代码，大约 3 周前。请不要讨厌，这是我的第一个项目。

package GGCGuiLotto;

import java.util.ArrayList;
import java.awt.Color;
import java.awt.Image;
import java.awt.BorderLayout; 
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Icon;
import javax.swing.JOptionPane;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextField;

import java.util.Random;


public class GGCGuiLotto {

public static void main(String[] args) {    

//Arraylist of images

ImageIcon pic0 = new ImageIcon("pics/pic1.png");
ImageIcon pic1 = new ImageIcon("pics/pic2.png");
ImageIcon pic2 = new ImageIcon("pics/pic3.png");
ImageIcon pic3 = new ImageIcon("pics/pic4.png");
ImageIcon pic4 = new ImageIcon("pics/pic5.png");
ImageIcon pic5 = new ImageIcon("pics/pic6.png");
ImageIcon pic6 = new ImageIcon("pics/pic7.png");

final ArrayList<ImageIcon> slotlist = new ArrayList<ImageIcon>();   
    slotlist.add(pic0);
    slotlist.add(pic1);
    slotlist.add(pic2);
    slotlist.add(pic3);
    slotlist.add(pic4);
    slotlist.add(pic5);
    slotlist.add(pic6);

    Random ran = new Random();

    int plc1 = ran.nextInt(4);
    int plc2 = ran.nextInt(4);
    int plc3 = ran.nextInt(4);

    //generates the frame and the labels are added.

    JFrame frame = new JFrame();
    frame.setSize (400,275);
    frame.setTitle("GGC Lotto Slots Rcorbin");
    frame.setResizable(false);
    frame.setVisible(true);

    JPanel pnlReels = new JPanel();
    frame.add(pnlReels);

    JPanel aReel1 = new JPanel();
    aReel1.setBackground(new Color(25,25,112));
    aReel1.setBounds(15,10,100,100);

    JPanel bReel2 = new JPanel();
    bReel2.setBackground(new Color(25,25,112));
    bReel2.setBounds(145,10,100,100);

    JPanel cReel3 = new JPanel();
    cReel3.setBackground(new Color(25,25,112));
    cReel3.setBounds(275,10,100,100);   

        pnlReels.add(aReel1);
    pnlReels.add(bReel2);
    pnlReels.add(cReel3);   

    JLabel aReel1lbl = new JLabel();
    JLabel bReel2lbl = new JLabel();
    JLabel cReel3lbl = new JLabel();

    aReel1.add(aReel1lbl);
    bReel2.add(bReel2lbl);
    cReel3.add(cReel3lbl);  

    aReel1lbl.setIcon(slotlist.get(plc1));
    bReel2lbl.setIcon(slotlist.get(plc2));
    cReel3lbl.setIcon(slotlist.get(plc3));  

    //jbutton 
    JButton slotbtn1 = new JButton();
    slotbtn1.setText("GGC LOTTO Click ME");
    pnlReels.add(slotbtn1);
    slotbtn1.setBounds(145,50,100,75);
    //FirstGuiListener act = new FirstGuiListener();
    //slotbtn1.addActionListener((ActionListener) act); 

GenPLCListener genPLC = new GenPLCListener();
slotbtn1.addActionListener((genPLC));
    {}
    if (plc1 == plc2 && plc1 == plc3 && plc2 == plc3)
    {
        JOptionPane.showConfirmDialog(null,"Winner! Play Again? ","GGC Lotto Slots RCorbin ",JOptionPane.YES_NO_OPTION);
        //System.out.println("Winner");
    }
    else
    {
        //JOptionPane.showMessageDialog(null,"No Winner Winner Chicken Dinner ! ");
        System.out.println("Crazy");    }

}
}

---

package GGCGuiLotto;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;

import javax.swing.JOptionPane;

class GenPLCListener extends GGCGuiLotto implements ActionListener{
public void actionPerformed(ActionEvent event){
        System.out.println("Works");

JOptionPane.showConfirmDialog(null,"Choose Wisely. ","Click If you Trust!",JOptionPane.YES_NO_OPTION);
}
}

Answer 1

尝试扩展 GGCGuiLotto 不会做您认为应该做的事情，也就是让您访问相同 实例变量。所以摆脱它。相反，您可以按引用传递，GGCGuiLotto 的当前实例给您的监听器。并有一些 getter 和 setter 来从 GGCGuiLotto 类访问您需要的变量。我的意思可能是这样的(不完全确定你想要完成什么，所以这只是一个例子)。

public class GenPLCListener implements ActionListener {
    private GGCGuiLotto lotto;

    public GenPLCListener(GGCGuiLotto lotto) {
        this.lotto = lotto;
    }

    @Override
    public void actionPerfomred(ActionEvent e) {
        List<ImageIcon> slotList = lotto.getSlotList();
        Collections.shuffle(slotList);  // shuffle the list
        // do something else if need be.
    }
}

当您创建监听器时，将 this 传递给它。 this 是 GGCGuiLotto

的实例

---

一些旁注

• Swing 程序不像控制台程序。您不想在 main 方法中执行所有操作。对于初学者，您可以将 main 方法中的代码放入构造函数中。然后在 main 方法中创建一个 GGCGuiLotto 的实例。

• Swing 应用程序应该在事件调度线程上运行。参见 Initial Threads

---

编辑

对于您的问题，也许更合适的解决方案是使用 pullSlot 方法创建一个 interface，您可以在 GGCGuiLotto 类中覆盖该方法只需将 interface 传递给监听器并在 actionPerformed 中调用 pullSlot 方法。像这样

public interface PullInterface {
    public void pullSlot();
}

public class GGCGuiLotto implements PullInterface {
    ArrayList<ImageIcon> slotList = new ArrayList<>();  // global scope.
    JLabel aReel1lbl = new JLabel();
    JLabel bReel2lbl = new JLabel();
    JLabel cReel3lbl = new JLabel();
    Random rand = new Random();

    public GGCGuiLotto() {
        GenPLCListener listener = new GenPLCListener(this);
    }

    @Override
    public void pullSlot() {
        // do what you need to do here to implement a pulling of the lever
        int r1 = rand.nextInt(slotList.size());
        int r2 = rand.nextInt(slotList.size());
        int r3 = rand.nextInt(slotList.size());

        reel1lbl.setIcon(slotList.get(r1));
    }
}

public class GenPLCListener implement ActionListener {
    private PullInterface pull;

    public GenPLCListener(PullInterface pull) {
        this.pull = pull;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        pull.pullSlot();
    }
}