如何提示用户输入无效并恢复值？

Question

谁能解释为什么while循环两次问“ NightNight”？ 以及如果用户输入的内容不是“ r”或“ c”，则如何提示用户输入无效

    for(int x = 1; x <= inputInt; x++) {
    char whatNight  = JOptionPane.showInputDialog("Enter c or r for what type of night").charAt(0); 
    boolean pleasework = whatNight == 'c' || whatNight == 'C';
    boolean imbeggingu = whatNight == 'r' || whatNight == 'R';
    boolean doesNotWork = whatNight != 'c' && whatNight != 'C' && whatNight != 'r' && whatNight != 'R';

    //why does the while loop ask twice even if u enter c or r?
    while(pleasework || imbeggingu || doesNotWork) {

        if(doesNotWork) 
            JOptionPane.showMessageDialog(null, "INvalid letter");
             whatNight = JOptionPane.showInputDialog("Enter c or r for what type of night").charAt(0);
        //reprompt not storing in whatNight variable :/

             if(pleasework)  
            JOptionPane.showMessageDialog(null, "You entered c for carnight");

             else if(imbeggingu)  
            JOptionPane.showMessageDialog(null, "You entered r for regular night");
            break;
    }

Answer 1

为了回答您的问题，我建议您首先调试值，例如

System.out.println(pleasework);

您的概念逻辑也很不完善，您应该重新考虑如何处理此问题。 例如，当您输入的不是C或R时，您要求输入一个新的输入，但没有根据它设置任何布尔值。

这应该工作！

for(int x = 1; x <= inputInt; x++) {
    char whatNight  = JOptionPane.showInputDialog("Enter c or r for what type of night").charAt(0); 
    whatNight = checkInput(whatNight);
    boolean nightC = whatNight == 'c' || whatNight == 'C';
    boolean nightR = whatNight == 'r' || whatNight == 'R';

    if(nightC) {
        JOptionPane.showMessageDialog(null, "You entered c for carnight");
    } else if(nightR) {
        JOptionPane.showMessageDialog(null, "You entered r for regular night");
    }
}

---------------------------------------------------------------------

private char checkInput(char input) {
    if(input == 'c' || input == 'C' || input == 'r' || input == 'R') {
        return input;
    }
    char whatNight = JOptionPane.showInputDialog("You entered a wrong letter, enter either c or r for what type of night it was").charAt(0);
    return checkInput(whatNight);
}

如果您不懂，请告诉我，我会解释！