Recursion 1:First Index of Number

public class Solution {
    public static int firstIndex(int input[], int x) {
        //method overloading
        return firstIndex(input,x,0);		

    }
    private static int firstIndex(int input[],int x,int startIndex){
        if(startIndex==input.length)
            return -1;
        if(input[startIndex]==x)
            return startIndex;
        return firstIndex(input,x,startIndex+1);
        }
}