Using recursion to find a character in a string

Question

I am trying to find the first occurrence of a letter in a string. For example, p in apple should return 1. Here is what I have:

// Returns the index of the of the character ch
public static int indexOf(char ch, String str) {

    if (str == null || str.equals("")) {
        return -1;
    } else if(ch == str.charAt(0)) {
        return 1+ indexOf(ch, str.substring(1));
    }

    return indexOf(ch, str.substring(1));
}

It just doesn't seem to be returning the correct value.

Answer 1

I'll give you some hints:

1. When you've found the letter, you don't need to recurse further. Additionally, think about what you should be returning in this case.
2. When do you recurse, also think about what the function should return.
3. Is there anything special you need to do if the recursive call returns -1?