Question

我的存款和取款按钮出现问题。点击它们时它们什么都不做我的目标是让用户存款并退出账户对不起，我是这个GUI的新手。

bankAccount文件，存款和取款计算

public class bankAccount {  
    private double balance;

    public bankAccount() {   
        balance = 0;
    }

    public bankAccount(double initialBalance) {   
        balance = initialBalance;
    }

    public void deposit(double amount) {  
        double newBalance = balance + amount;
        balance = newBalance;
    }

    public void withdraw(double amount) {   
        double newBalance = balance - amount;
        balance = newBalance;
    }

    public double getBalance() {   
        return balance;
    }
}

我在actionPerformed方法的这个文件中遇到了麻烦。

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
class AccountPanel extends JPanel implements ActionListener {  
    private JLabel amountLabel, resultLabel;
    private JTextField amountTextField;   
    private JButton depositButton, withdrawButton;
    private bankAccount account;
    double result;

    public AccountPanel() {
        JPanel displayPanel = new JPanel(); 
        displayPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

        amountLabel = new JLabel("Amount:"); 
        displayPanel.add(amountLabel);

        amountTextField = new JTextField(13); 
        displayPanel.add(amountTextField); 

        JPanel resultPanel = new JPanel(); 
        resultPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

        resultLabel = new JLabel("Balance = "); 
        resultPanel.add(resultLabel);

        //buttons
        JPanel buttonPanel = new JPanel(); 
        buttonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));

        // deposit button 
        depositButton = new JButton("Deposit"); 
        buttonPanel.add(depositButton); 

        // withdraw
        withdrawButton = new JButton("Withdraw"); 
        buttonPanel.add(withdrawButton); 

        // add panels to main panel 
        this.setLayout(new BorderLayout()); 
        this.add(displayPanel, BorderLayout.WEST);
        this.add(resultPanel, BorderLayout.SOUTH); 
        this.add(buttonPanel, BorderLayout.EAST); 
    }



    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource(); 
        if (source == depositButton) {
            double dp = Double.parseDouble(amountTextField.getText());
            double dpamount = account.getBalance() + dp;
            account.deposit(dpamount);
            result = dpamount;
            resultLabel.setText("" + result);
            depositButton.addActionListener(this); 
        }
        else if (source == withdrawButton) { 
            double wd = Double.parseDouble(amountTextField.getText());
            account.withdraw(wd);
            resultLabel.setText("" + result);
            withdrawButton.addActionListener(this); 
        } 
   }
}

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.Window;
import javax.swing.JFrame;
import javax.swing.JPanel;
class AccountFrame extends JFrame { 
    private static final int FRAME_WIDTH = 400;
    private static final int FRAME_HEIGHT = 100;

    public AccountFrame() { 
        setTitle("Bank Account"); 
        setSize(FRAME_WIDTH, FRAME_HEIGHT); 
        centerWindow(this); 
        setResizable(false); 
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
        JPanel panel = new AccountPanel(); 
        this.add(panel); 
    } 

    private void centerWindow(Window w) { 
        Toolkit tk = Toolkit.getDefaultToolkit(); 
        Dimension d = tk.getScreenSize(); 
        setLocation((d.width-w.getWidth())/2, 
        (d.height-w.getHeight())/2); 
    } 
}

import javax.swing.*; 
public class Account{ 
    public static void main(String[] args) { 
        JFrame frame = new AccountFrame(); 
        frame.setVisible(true); 
    } 
}

Answer 1

尝试执行类似这样的操作，而不是使用单个actionPerformed()方法：

首先注册事件处理程序（您错过了此步骤）：

  depositButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent evt) {
       handleDepositButtonEvent(evt);
     }
  });

为该事件实施自定义事件处理程序：

  private void handleDepositButtonEvent(ActionEvent evt){
     double dp = Double.parseDouble(amountTextField.getText());
     double dpamount = account.getBalance() + dp;
     account.deposit(dpamount);
     result = dpamount;
     resultLabel.setText("" + result);
  }

为每个要生成事件的按钮和组件执行此操作;单独的行动方法更容易阅读和维护。

顺便说一句，不要在动作监听器中添加动作监听器！这毫无意义，无论如何它都不会起作用。

if (source == depositButton) {
    double dp = Double.parseDouble(amountTextField.getText());
    ...
    depositButton.addActionListener(this); //<--- don't do this
}

Answer 2

您尚未向ActionListener或depositButton注册任何withdrawButton。

在你告诉我他们是用actionPerformed方法注册之前，你必须意识到没有任何东西在称这种方法，你不应该在这里注册你的ActionListener，或者至少不是因为你无论如何，它们应该在构造函数中添加，以便在程序运行时注册它

详细了解How to Write an Action Listener和How to Use Buttons, Check Boxes, and Radio Buttons了解详情

Answer 3

depositButton.addActionListener(this)和withdrawButton.addActionListener(this)调用需要位于AccountPanel构造函数中。现在他们永远不会被执行，因为按钮最初没有事件处理程序。

GUI银行账户Java

3 个答案: