Question

我正在尝试使用动作侦听器来更新ATM类程序中的“Balance”值。我目前仍然坚持一旦更改完成后更新Balance的原始值的方法。许多不同的动作听众也可以改变这个值，例如。提取5英镑，存入£X等。

这是我在界面中添加按钮的地方：

protected void buildGUI(){
    int balance = 10; //sets the initial balance of the user
...
JButton withdraw5 = new JButton("Withdraw \u00a35");
    Withdraw5Listener w5 = new Withdraw5Listener(screen,balance);
    withdraw5.addActionListener(w5);

    JButton withdraw10 = new JButton("Withdraw \u00a310");
    Withdraw10Listener w10 = new Withdraw10Listener(screen,balance);
    withdraw10.addActionListener(w10);

    JButton withdraw20 = new JButton("Withdraw \u00a320");
    Withdraw20Listener w20 = new Withdraw20Listener(screen,balance);
    withdraw20.addActionListener(w20);

    //adds action listener to the deposit button
    JButton deposit = new JButton("Deposit");
    DepositListener dl = new DepositListener(screen, inputLabel,balance, withdraw5, withdraw10, withdraw20);
    deposit.addActionListener(dl);

这里是我制作动作监听器类的地方（除了一些小细节之外，它们几乎相互重复，所以这里只是其中之一）。

import javax.swing.*;
import java.awt.event.*;

public class Withdraw5Listener implements ActionListener {

private int balance;
private JTextArea screen;

public Withdraw5Listener(JTextArea display, int money){
    balance = money;
    screen = display;
}

public void actionPerformed(ActionEvent e){
    if (balance > 5){
        balance = balance - 5;
        screen.setText("You have withdrawn \u00a35 \n" + "Your balance is " + balance);
        System.out.println("Withdrawn \u00a35");
    }
}
}

当然，这些类中的每一个都只使用10的原始余额值，那么如何才能让它改变原始值呢？

谢谢大家的帮助！

如何使用动作侦听器更新其他类的变量

0 个答案: