My code works fine here, but to my mind, the exception should be thrown. My function is continuously invoking itself. Eventually, it is being called on the last element in the array and adds that number. Then, I make a copy of the array from the next position to the end. But since I do not have that next element, so I cannot make a copy of the array starting from the subsequent one (I am already at the very last position), why is it working?

System.out.println(sumOfArrayRecursively(new int[]{5, 9, 45, 6, 2, 7, 34, 8, 6, 90, 5, 243}));

public static int sumOfArrayRecursively(int [] arr){
    if(arr.length == 0) return 0;
    else{
        return arr[0]   sumOfArrayRecursively(Arrays.copyOfRange(arr, 1, arr.length));
    }
}

CodePudding user response：

This is just how recursion works: once your function gets called the last time, the array length is 0 and returns without trying to access an element out of bounds.

Here is an article describing something similar to your problem