Hvordan får jeg en arraylist til at fungere?

public ArrayList<String> wordsStartingWith(String prefix)
This method returns a list of all words from the dictionary that start
with the given prefix.

public ArrayList<String> wordsContaining(String text)
This method returns a list of all words from the dictionary that include
the given substring.

Make sure that your wordsStartingWith and wordsContaining methods are
case-insensitive. That means, for instance, that looking up words
starting with “gilb” should find “Gilbert”.