Incompatible Types String and Char

Question

I\'m not sure why I\'m getting this error. I think the code in general is okay although I\'m sure there is a shorter way then using all the else ifs. The problem is it says

Answer 1

char is not String. Declare R2D2 as char

char R2D2 = '';

To check vowel make a method like below and reuse this method at for loop and count the vowel occurrence:

static boolean isVowel(char ch) {
    ch = Character.toLowerCase(ch);
    if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
        return true;
    }
    return false;
 }