java - 无法解析 Integer.ParseInt 抛出的 java.lang.NumberFormatException

Question

我收到此错误，但我似乎找不到可能导致它的原因。它说错误在我初始化变量 bet 的那一行。如果我删除该行和 Integer.parseInt(betTextFieldAmount)，那么它会说错误发生在初始化上。

public class RollTheDice extends JFrame implements ActionListener {

    JButton roll = new JButton("Roll the Dice");
    JButton bet1 = new JButton("5$");
    JButton bet2 = new JButton("10$");
    JButton bet3 = new JButton("25$");
    JButton bet4 = new JButton("50$");
    JButton bet5 = new JButton("100$");

    JTextField betTextField = new JTextField(5);
    String betTextFieldAmount = betTextField.getText();
    int bet = Integer.parseInt(betTextFieldAmount);

    int money = 100;

    JLabel currentBet = new JLabel();
    JLabel currentMoney = new JLabel("Your money: " + money + "$");

    int myDice = new Random().nextInt(12) + 1;
    int AIDice = new Random().nextInt(12) + 1;

    public static void RollTheDice() {
        int myDice = new Random().nextInt(12) + 1;
        int AIDice = new Random().nextInt(12) + 1;
    }

    public RollTheDice() {
        setLayout(new FlowLayout());

        add(currentMoney);

        add(bet1);
        bet1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (money < 5) {
                    JOptionPane.showMessageDialog(null, "Not enough money!");
                } else {
                    money -= 5;
                    bet +=5;
                }
                currentMoney.setText(money + "$");
            }           
        });

        add(bet2);
        bet2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (money < 10) {
                    JOptionPane.showMessageDialog(null, "Not enough money!");
                } else {
                    money -= 10;
                    bet +=10;
                }
                currentMoney.setText(money + "$");
            }           
        });

        add(bet3);
        bet3.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (money < 25) {
                    JOptionPane.showMessageDialog(null, "Not enough money!");
                } else {
                    money -= 25;
                    bet +=25;
                }
                currentMoney.setText(money + "$");
            }           
        });

        add(bet4);
        bet4.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (money < 50) {
                    JOptionPane.showMessageDialog(null, "Not enough money!");
                } else {
                    money -= 50;
                    bet +=50;
                }
                currentMoney.setText(money + "$");
            }           
        });

        add(bet5);
        bet5.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (money < 100) {
                    JOptionPane.showMessageDialog(null, "Not enough money!");
                } else {
                    money -= 100;
                    bet +=100;
                }
                currentMoney.setText(money + "$");
            }           
        });

        add(betTextField);
        betTextField.setEditable(false);
        add(roll);
        roll.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (myDice > AIDice) {
                    money += bet;
                    JOptionPane.showMessageDialog(null, "You won " + bet + "$");
                } else {
                    JOptionPane.showMessageDialog(null, "You lost " + bet + "$");
                }
                currentMoney.setText(money + "$");
                RollTheDice();
            }           
        });
    }

    @Override
    public void actionPerformed(ActionEvent arg0) {
        // TODO Auto-generated method stub

    }
}

Answer 1

这是由于 betTextFieldAmount 的值不是有效整数引起的，因此当您尝试使用 Integer.parseInt(betTextFieldAmount); 转换它时会抛出异常.

您应该使用 try...catch 语句包围 parseInt 调用，并在发生这种情况时向用户显示适当的错误消息。

更好的是，首先尝试通过限制可以在字段中输入哪些字符来防止用户输入非数字值，并添加空检查以捕获字段中未输入值的情况。