unique_in_order

Main.java

package com.company;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Main {

    public static void main(String[] args) {
        String order1 = "AAAABBBCCDAABBB";
        String order2 = "ABBCcAD";
        Integer[] order3 = {1, 2, 2, 3, 3};

        System.out.println(unique_in_order(order1));
        System.out.println(unique_in_order(order2));
        System.out.println(unique_in_order(Arrays.asList(order3)));
    }

    static List<Character> unique_in_order(String order) {
        List<Character> list = new ArrayList<>();
        for (char c : order.toCharArray()) {
            list.add(c);
        }
        return unique_in_order(list);
    }


    static <T> List<T> unique_in_order(List<T> list) {
        ArrayList<T> newList = new ArrayList<>();

        T e = null;
        for (T t : list) {
            if (t != e) {
                e = t;
                newList.add(e);
            }
        }

        return newList;
    }
}