java - 在 JFrame MessageBox 中给出计算结果

Question

我希望我的程序执行带有文本字段的 JFrame:名字、姓氏、帐户状态和提款金额，向用户询问该信息，然后显示这样的消息框:“你好约翰·史密斯，提款后，你当前的帐户状态是:(提款后的状态)。我做了我能做的唯一方法(起初我想创建一个单独的类，我将在其中解析状态和提款金额，然后进行计算，但我有问题)。所以我在 Card 类中做到了。问题是(这就是我想问你的)程序不仅不进行计算，而且根本不编译。当我从我的程序中删除计算代码，它可以编译，但显而易见的是，仅在消息框中返回“HellofirstNamelastName”。

public class Card extends JFrame {

    private JTextField firstName;
    private JTextField lastName;
    private JTextField state;
    private JTextField withdrawal;
    private JButton accept;


    public Card() {
        super("Cash Machine");
        setLayout(new FlowLayout());

        firstName = new JTextField("First name");
        add(firstName);

        lastName = new JTextField("Last name");
        add(lastName);

        state = new JTextField("Current account state");
        add(state);

        withdrawal = new JTextField("Amount of withdrawal");
        add(withdrawal);

        accept = new JButton("Accept");
        add(accept);


        newHandler handler = new newHandler();
        accept.addActionListener(handler);

    }
    String state1 = state.getText();
    int state2 = Integer.parseInt(state1);
    String withdrawal1 = withdrawal.getText();
    int withdrawal2 = Integer.parseInt(withdrawal1);
    int finalState = state2 - withdrawal2;



    private class newHandler implements ActionListener {

        ArrayList<String> first_names = new ArrayList<String>();
        ArrayList<String> last_names = new ArrayList<String>();
        public void actionPerformed(ActionEvent event) {


            // SHOWING THE FINAL MESSAGE BOX
            if(event.getSource()==accept)

                JOptionPane.showMessageDialog(null, "Hello " + firstName.getText() + " " + lastName.getText() + " " + state.getText() + " .Your current account state is: " + finalState);
            }
            }       
        }

Answer 1

对不起，是我的错。您在类里面发表的所有陈述都是赋值语句，因此技术上它们是允许的，但它们的位置仍然给您带来问题。

您的问题是您已经在类中将计算作为赋值语句的一部分进行了，因此您在用户有机会输入数据之前进行计算。

相反，在 handler 类中进行计算，以便文本字段中包含一些数据。

像这样:

//   String state1 = state.getText();
//   int state2 = Integer.parseInt(state1);
//   String withdrawal1 = withdrawal.getText();
//   int withdrawal2 = Integer.parseInt(withdrawal1);
//   int finalState = state2 - withdrawal2;


private class newHandler implements ActionListener {
  ArrayList<String> first_names = new ArrayList<String>();
  ArrayList<String> last_names = new ArrayList<String>();

  public void actionPerformed(ActionEvent event) {

     // SHOWING THE FINAL MESSAGE BOX
     if (event.getSource() == accept) {

        String state1 = state.getText();
        int state2 = Integer.parseInt(state1);
        String withdrawal1 = withdrawal.getText();
        int withdrawal2 = Integer.parseInt(withdrawal1);
        int finalState = state2 - withdrawal2;

        JOptionPane.showMessageDialog(null, "Hello " + firstName.getText()
              + " " + lastName.getText() + " " + state.getText()
              + " .Your current account state is: " + finalState);
     }
  }
}