How to compare a String or parts of string with strings in an arraylist(java noob)

Question

I need write a method called "occurences" that takes a string and a list of words as parameter that returns how many times a certain String in that list occurs. It needs to ignore upper and lowercase and also that parts of the string may also count as occurence, for example:

i wanna check the string "Dogregister" in my list of [cat, dog, ister], the program is supposed to return 2, because "dog" and "ister" is both in the string "Dogregister".

So i have started with making the arraylist with the words and now i wanna implement the method that can return how many occurences there are in the list. i am not sure how to implement the list as a parameter in my method? do i write ArrayList words = new ArrayList<>(); ,

also i havent figured out how to count occurence of parts of a string yet, im trying to find a string method that can help me achieve what i want.

Answer 1

You can use Regex.

List<String> words = new ArrayList<>();
words.add("katt");
words.add("hund");
words.add("ister");

String word = "Hundregister";
int count = 0;

for (int i = 0; i < words. Size(); i++) {
    String current = words.get(i);
    boolean occurrence = occurrence(current, word.toLowerCase(Locale.ROOT));
    
    if (occurrence) {
       count++;
    }
}

System.out.println(count);

private static boolean occurrence(String searchedWord, String word) {
        Pattern pattern = Pattern.compile(searchedWord);
        Matcher matcher = pattern.matcher(word);
        return matcher.find();
}