继续进行循环，直到用户输入正确的输入类型为止？

Question

I am supposed to write a program that asks the user for 5 non-negative integers and then displays the sum of these integers. Also if the user enters a non-integer value, I have to keep asking until the user has inputted 5 acceptable values.

How do I do this using non-nested for statements?? Thanks!!!

Answer 1

This should work for you. It continues to scan until the user has typed an integer.

    Scanner scan = new Scanner(System.in);
    int sum = 0;

    for(int i = 0; i < 5; i++)
    {

    System.out.println("Enter integer value: ");
    while (!scan.hasNextInt())
    {
        System.out.println("That's not a number, try again: ");
        scan.next();
    }
    sum += scan.nextInt();
    }
    System.out.println(sum);

Answer 2

Use a while() loop.

int sentinel = 0;
Scanner s = new Scanner(System.in);
int sum = 0;

while (sentinel < 5 && s.hasNextInt()){
  int num = s.nextInt();
  if(num>=0){
    sum += num;
    sentinel++;
  }else
    System.out.println("That wasn't a non-negative int :(");
}

And then just print out the sum.