Counting vowels in a java string?

Question:

How to count vowels in a string?
How to count upper case vowels in a string?
How to count lower case vowels in a string?

Code:

public class CountVowels {
  public static void main(String[] args) {
 
    String str = "abcdefg HIJKLMNOP qrstuvwxyz";
 
    int upper = 0;
    int lower = 0;
    int non = 0;
 
    String vowels = "aeiouAEIOU";
    char[] array = str.toCharArray();
 
    for(char c: array) {
      if(vowels.indexOf(c) != -1){
        if(Character.isLowerCase(c)){
          lower = lower + 1;
        } else if(Character.isUpperCase(c)){
          upper = upper + 1;
        }
      } else {
         non = non + 1;
      }
    }
    System.out.println("String: " + str);
    System.out.println("Upper case vowels: " + upper);
    System.out.println("Lower case vowels: " + lower);
    System.out.println("Non vowels: " + non);
  }
}

Output:

$ java CountVowels
String: abcdefg HIJKLMNOP qrstuvwxyz
Upper case vowels: 2
Lower case vowels: 3
Non vowels: 23