Question

我尝试过执行do while循环并得到一个无限循环，而不是在catch部分重复错误消息。在用户输入数值之前，如何使此代码循环播放？

  try {
    System.out.print("How many people are in your group? ");
    int group = sc.nextInt(); 
    System.out.println("Okey, " + group + " people");
 }  
 catch (InputMismatchException e) {
    System.out.println("Error, please enter a numerical value");
 }

Answer 1

只需将while(true)循环添加到您的代码中即可：

 public static int getInt(Scanner sc) {
    while(true) {
        try {
            System.out.print("How many people are in your group? ");
            int group = sc.nextInt(); 
            System.out.println("Okey, " + group + " people");
            return group;
        } catch (InputMismatchException e) {
            System.out.println("Error, please enter a numerical value");
        }
    }
 }

Answer 2

由于do实例（while）的内部缓冲区使您保持错误，所以您的代码（用Scanner ... sc语句包围）将陷入无限循环。）在发生InputMismatchException时输入。您可以使用Scanner.next方法（无论其值是什么，都读取String）和Integer.parseInt进行转换来重写逻辑：

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    Integer group = null;
    do {
        try {
            System.out.print("How many people are in your group? ");
            String input = sc.next();
            group = Integer.parseInt(input);
            System.out.println("Okey, " + group + " people");
        } catch (NumberFormatException e) {
            System.out.println("Error, please enter a numerical value");
        }
    } while(group == null);
}

在Java中进行while循环时，如何使此代码循环直到用户输入数值？

2 个答案: