Why does this function always return either 0 or 1

Question

I'm trying to learn something about recursion so I'm tryin' to do some exercises but now I'm kind of stucked because I can't figure out why does this function always return me 1 or 0 Im trying to count number of appearences of 11 in int array.

public class Uloha06 {
public static int count = 0;
public static int array11(int[] nums, int index){
    if(index<nums.length){
        if(nums[index]==11)
            count+=1;
        index++;
        array11(nums,index);
        if(index<nums.length)
            return index;
    } 
    return count;
}
public static void main(String[] args) {

    int array11[]={11,1,2,36,11};
    System.out.println(array11(array11, 0));
    }
}

Answer 1

It returns 0 for an empty array, and 1 for a non-empty array. The result you see came from index, not from count as you are expecting.

I would write it without a field involved.

public int m(int[] nums, int index, int count) {
    return index < nums.length ?
            m(nums, index + 1, nums[index] == 11 ? ++count : count) :
            count;
}

or (suggested by @Pshemo in the comments)

public int m(int[] nums, int index) {
    return index < nums.length ?
            (nums[index] == 11 ? 1 : 0) + m(nums, ++index) :
            0;
}