Question

我尝试将两个循环合并到一个do循环中，但每次输入无效值时，它都不会提示我错误消息并要求再次输入值。相反，它只是转到下一个提示语句。

do {
    try {
        dependents = Integer.parseInt(JOptionPane.showInputDialog("number of dependents:"));
    }
    catch (NumberFormatException e) {
        dependents = MIN_DEPENDENTS - 1;
    }
    if (dependents < MIN_DEPENDENTS || dependents > MAX_DEPENDENTS) {
        JOptionPane.showMessageDialog(null, "Number of dependents must be between 0 and 9.");
    }
} while (dependents < MIN_DEPENDENTS || dependents > MAX_DEPENDENTS);

do {
    try {
        income = Double.parseDouble(JOptionPane.showInputDialog("amount of income:"));
    }
    catch (NumberFormatException e) {
        income = MIN_INCOME - 1;
    }
    if (income < MIN_INCOME || income > MAX_INCOME) {
        JOptionPane.showMessageDialog(null, "income must be between $0 and $999,999.");
    }
} while (income < MIN_INCOME || income > MAX_INCOME);

Answer 1

不，但您可以创建某种GetInput函数并传入min，max，promptText和errorText。这样可以避免重复代码。

dependents = getInput(MIN_DEPENDENTS, MAX_DEPENDENTS,"number of dependents:","Number of dependents must be between 0 and 9.")
income = getInput(MIN_INCOME,MAX_INCOME,"amount of income:","income must be between $0 and $999,999.")

private double getInput(double min, double max, String promptText, String errorText) {
   double result = 0.0;
   do {
         try {
            result = Double.parseDouble(JOptionPane.showInputDialog(promptText));
         }
         catch (NumberFormatException e) {
            result = min - 1;
         }

         if (result < min || result > max) {
            JOptionPane.showMessageDialog(null, errorText);
         }
   } while (result < min || result > max);

   return result;
}

Answer 2

Dan，你需要在你的catch区块下面加上显示错误信息并再次提示输入。

catch (NumberFormatException e) {        
                dependents = MIN_DEPENDENTS - 1; 
    JOptionPane.showMessageDialog(null, "Number of dependents must be between 0 and 9.");

    dependents = Integer.parseInt(JOptionPane.showInputDialog("number of dependents:"));
}

Answer 3

另一个选项可以是数组中的主要输入列表，然后在while循环中使用它

Object[][] input = {
            {"number of dependents", MIN_DEPENDENTS, MAX_DEPENDENTS},
            {"amount of income", MIN_INCOME, MAX_INCOME},
    };

    int index = 0;
    int value, min, max;
    do {

        Object[] inputDetails = input[index];

        String label = inputDetails[0].toString();
        min = Integer.valueOf(inputDetails[1].toString());
        max = Integer.valueOf(inputDetails[2].toString());


        try {
            value = Integer.parseInt(JOptionPane.showInputDialog(label));
        } catch (NumberFormatException e) {
            value = min - 1;
        }
        if (value < min || value > max) {
            JOptionPane.showMessageDialog(null, String.format("%s must be between %s and %s", label, min, max));
        } else {
            index++;
        }

    } while ((value < min || value > max) || index < input.length);

是否可以合并这两个do循环

3 个答案: