What’s the time complexity of this anagram checker?

What is the time complexity of this method? I read that time complexity of contains() method of String is O(n) and I’m using it inside my loop that goes over the input string is the time complexity O(n²)?

public static boolean isAnagram(String str, String str1) {
    if(str.length() != str1.length()) {
        return false;
    }
    
    for(int i = 0; i < str.length(); i++) {
        String letter = String.valueOf(str.charAt(i));
        
        if(!str1.contains(letter)) {
            return false;
        }
        
        letter = String.valueOf(str1.charAt(i));
        if(!str.contains(letter)) {
            return false;
        }
    }
                
    return true;
}

Answer

Yup O(n^2) since there is n number of iteration for the for loop and each iteration call contains twice