java - 如何使 txPanel 仅在单击 'enter pin ok' 按钮后才可见？

Question

public class ATMgui extends JFrame implements ActionListener {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public static final int WIDTH = 500;
    public static final int HEIGHT = 200;
    private ATMbizlogic theBLU;// short for the Business Logic Unit
    public JLabel totalBalanceLabel;
    public JTextField withdrawTextField;
    public JTextField depositTextField;
    public JTextField pinTextField;

    /**
     * Creates a new instance of ATMgui
     */
    public ATMgui() {
        setTitle("ATM Transactions");
        setSize(WIDTH, HEIGHT);
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        Container contentPane = getContentPane();
        contentPane.setBackground(Color.BLACK);
        contentPane.setLayout(new BorderLayout());


        // Do the panel for the rest stop
        JLabel start = new JLabel("Welcome To Your Account", JLabel.CENTER);
        Font curFont = start.getFont();
        start.setFont(new Font(curFont.getFontName(), curFont.getStyle(), 25));
        start.setForeground(Color.BLUE);
        start.setOpaque(true);
        start.setBackground(Color.BLACK);


        pinTextField = new JTextField();
        JLabel pinLabel = new JLabel("Enter your PIN below:", JLabel.CENTER);
        pinLabel.setForeground(Color.RED);
        pinLabel.setOpaque(true);
        pinLabel.setBackground(Color.WHITE);



        JButton pinButton = new JButton("Enter Pin OK");
        pinButton.addActionListener(this);
        pinButton.setBackground(Color.red);

        JPanel pinPanel = new JPanel();
        pinPanel.setLayout(new GridLayout(3, 1, 100, 0));

        pinPanel.add(pinLabel);
        pinPanel.add(pinTextField);
        pinPanel.add(pinButton);

        contentPane.add(pinPanel, BorderLayout.WEST);


        JPanel headingPanel = new JPanel();
        headingPanel.setLayout(new GridLayout());
        headingPanel.add(start);

        contentPane.add(headingPanel, BorderLayout.NORTH);


        // Do the panel for the amount & type of transactions
        withdrawTextField = new JTextField();
        JLabel withdrawLabel = new JLabel("Withdraw (0.00)", JLabel.CENTER);
        withdrawLabel.setForeground(Color.RED);
        withdrawLabel.setOpaque(true);
        withdrawLabel.setBackground(Color.WHITE);



        depositTextField = new JTextField();
        JLabel depositLabel = new JLabel("Deposit (0.00)", JLabel.CENTER);
        depositLabel.setForeground(Color.RED);
        depositLabel.setOpaque(true);
        depositLabel.setBackground(Color.WHITE);



        JButton txButton = new JButton("Transactions OK");
        txButton.addActionListener(this);
        txButton.setBackground(Color.red);




        JPanel txPanel = new JPanel();
        txPanel.setLayout(new GridLayout(5, 1, 30, 0));

        txPanel.add(withdrawLabel);
        txPanel.add(withdrawTextField);
        txPanel.add(depositLabel);
        txPanel.add(depositTextField);
        txPanel.add(txButton);

        contentPane.add(txPanel, BorderLayout.EAST);
        txPanel.setVisible(true);


        totalBalanceLabel = new JLabel("Your balance after transactions: ", JLabel.CENTER);
        totalBalanceLabel.setForeground(Color.BLUE);
        totalBalanceLabel.setOpaque(true);
        totalBalanceLabel.setBackground(Color.BLACK);


        contentPane.add(totalBalanceLabel, BorderLayout.SOUTH);


        theBLU = new ATMbizlogic();
    }

    public void actionPerformed(ActionEvent e) {
        String actionCommand = e.getActionCommand();

        // Container contentPane = getContentPane();

        if (actionCommand.equals("Transactions OK")) {
            try {
                double deposit = Double.parseDouble(depositTextField.getText().trim());
                double withdraw = Double.parseDouble(withdrawTextField.getText().trim());
                theBLU.computeBalance(withdraw, deposit);
                totalBalanceLabel.setText("Your balance after transactions: " + theBLU.getBalance());

            } catch (ATMexception ex) {
                totalBalanceLabel.setText("Error: " + ex.getMessage());
            } catch (Exception ex) {
                totalBalanceLabel.setText("Error in deposit or withdraw amount: " + ex.getMessage());
            }
        } else if (actionCommand.equals("Enter Pin OK")) {

            try {

                double pin = Double.parseDouble(pinTextField.getText().trim());
                theBLU.checkPin(pin);

                totalBalanceLabel.setText("Your balance after transactions: " + theBLU.getBalance());



            } catch (ATMexception ex) {
                totalBalanceLabel.setText("Error: " + ex.getMessage());
            } catch (Exception ex) {
                totalBalanceLabel.setText("Error in pin: " + ex.getMessage());

            }
        } else {
            System.out.println("Error in button interface.");
        }
    }

    public static void main(String[] args) {
        ATMgui gui = new ATMgui();
        gui.setVisible(true);
    }
}

Answer 1

我不认为这是为按钮实现 ActionListeners 的正确方法。

public void actionPerformed(ActionEvent e) 
    {   
       String actionCommand = e.getActionCommand();

      // Container contentPane = getContentPane();
        if (actionCommand.equals("Transactions OK"))
        else ...
    }

在方法 actionPerformed 中使用 if-else stamements，每次按下任何按钮时，您的程序都必须检查要调用的监听器，这样一来，您的代码就不容易编辑和重用。此外，GUI 容器充当事件的接收者，那么你应该避免

pinButton.addActionListener(this);

尝试为每个按钮实现自己的内部类，如下所示:

JButton pinButton = new JButton("Enter Pin OK");
        pinButton.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent ae){
                    //enter here your action
                                     txPanel.setVisible(true);
                }
            });

通过这种方式，您不需要为您的类实现 ActionListener 接口(interface)，因为您正在为您的 pinButton 实现接口(interface)的内部实例。检查 SO 的 this old question。此外，您应该避免在类构造函数中实现所有 GUI 元素，最好在单独的方法中实现 GUI，例如 createAndShowGui()，并在构造函数中调用它，以尊重 Java Swing conventions并在与应用程序主线程不同的名为 Event Dispatch Thread 的不同线程中运行 Swing 组件。读取 this question 。

然后在 createAndShowGui() 方法中包含 txPanel.setVisible(false);。

请记住，Swing 组件不是线程安全的。