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javastack-overflow

Why do i get a StackOverflowError

I made a function that computes the sum of digits of an integer. Trying to make the code shorter, I put in comment the if statement to see if it would still work so I can remove it but I get a StackOverflowError, why? This is my code:

public static int sumDigits(int n) {


    //if(n%10==n){ return n;}

      return n%10+sumDigits(n/10);

    }

public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println(sumDigits(12611));

}
Solution

  • It never returns, but just recurses deeper and deeper.

    You do have a return statement, but before returning it needs to compute the value of the expression n%10+sumDigits(n/10) which involves infinite recursion.

    NB: Each time you call the function from itself, the function's context (local variables) are added on top of the stack. The stack has a limited size. Eventually you reach that size and StackOverflowError is the error that's thrown in that condition.