Combine Lists Of Letters

import java.util.ArrayList;
import java.util.Scanner;

public class combineListsOfLetters {

    public static void main(String[] args)
    {
        Scanner input= new Scanner(System.in);

        String list1 = lists.nextLine();
        ArrayList<Character> listOfCharacters1 = Convert(list1);
        String list2 = lists.nextLine();
        ArrayList<Character> listOfCharacters2 = Convert(list2);
        ArrayList<Character> combinedList = new ArrayList<Character>(listOfCharacters1);

        for (Character newLetter : listOfCharacters2) {
            if (!listOfCharacters1.contains(newLetter)) {
                combinedList.add(newLetter);
            }
        }
        for (Character letter : combinedList ) {
            System.out.print("" + letter + " ");
        }

    }
    public static ArrayList<Character> Convert (String input){
        ArrayList<Character> listOfCharacters = new ArrayList<Character>();
        for (char letter : input.replaceAll("\\s+","").toCharArray()) {
            listOfCharacters.add(letter);
        }
        return listOfCharacters;
    }
}