Java ArrayList<double> 没有按预期工作

Question

I'm trying to write a program that will take numbers input through a user and store the numbers into an ArrayList. Currently I have:

public static void main(String[] args) {
    System.out.println(numberstorage());
}
public static ArrayList<Double> numberstorage() {
    Scanner s = new Scanner(System.in);
    ArrayList<Double> numbers = new ArrayList<Double>();
    System.out.println("Enter a number between 0 - 100");
    do {
        numbers.add(s.nextDouble());
    } while (s.nextDouble() != 0);
    s.close();
    return numbers;
}

When I input 1, 2, 3, for some reason my output is 1.0, 3.0. Is there a reason it's skipping one line of input?

Answer 1

You call s.nextDouble() twice per loop -- once to add it to numbers , and once to check the while condition.

Instead, you only want to call it once, and use the same value each time. Store it in a variable.