扫描仪无法使用While循环

Question

Maybe my google-fu is just terrible, but I'm having a very hard time figuring out how to do this. I'm trying to get a scanner to read a string, add the inputs, and return a value. I feel like I am just missing something... for example, I'm not sure how to get a variable set to the first double in the scanner.

import java.util.Scanner;


public class adding {
  public static double sum(Scanner input){
    Scanner s=new Scanner (System.in);
    double i = (s.nextDouble());
    double sumAnswer = 0;
    while (s.hasNext()){
      sumAnswer = sumAnswer + i;
      i = s.nextDouble();
    }
    return sumAnswer;
  }

  public static void main(String[] args){
    System.out.println(sum(new Scanner("1.2 2.8 3.9")));
  }
}

Answer 1

You don't really need an i variable.

And, as already mentioned, don't have 2 Scanner 's.

public static double sum(Scanner input){
  double sumAnswer = 0;
  while (input.hasNext()){
    sumAnswer += input.nextDouble();
  }
  return sumAnswer;
}

Answer 2

You shouldn't be resetting the scanner after passing the input.

public class adding {
     public static double sum(Scanner input){
     double i = (input.nextDouble());
     double sumAnswer = 0;
     while (input.hasNext()){
          sumAnswer = sumAnswer + i;
          i = input.nextDouble();
     }
     return sumAnswer;
}

That ought to work better for you, maybe. I could also be mixing something up there...