How to Create String Array List that removes Strings that are already contained in list

Question

I am trying to add "Luis" 3 times to array list and then remove "Luis" so there is only one "Luis". Seems to be a problem with the if.

import java.util.ArrayList;

public class Menu {
    private ArrayList<String> meals;

    public Menu() {
        this.meals = new ArrayList<String>();
    }

    // Implement the methods here
    public void addMeals() {

        this.meals.add("Luis");
        this.meals.add("Luis");
        this.meals.add("Luis");
        for (String container : this.meals) {
            for (int counter = 0; counter < this.meals.size(); counter++) {
                ***if (counter > 1 && this.meals.contains(container)) {
                    this.meals.remove(this.meals.indexOf(container));
                }***
            }
        }
        System.out.println(this.meals);
    }

}

Not homework, just preparing for a class that I will take soon :P — Lsanc274, Oct 22 '15 at 21:33
Won't this throw a `ConcurrentModificationException`? You are removing an element from the list while iterating over it. — OneCricketeer, Oct 22 '15 at 21:36
@cricket_007 Yes. That is what I am getting. How could I solve this? — Lsanc274, Oct 22 '15 at 21:38
Well, for starters, you could update your question to specify that is the part that is not working. — OneCricketeer, Oct 22 '15 at 21:39
Here is how you would do it without an error. https://repl.it/BTPA/1 — OneCricketeer, Oct 22 '15 at 22:02
Exactly what I was looking for. I understand why we need import java.util.ArrayList; but do we really need import java.util.Iterator; ? — Lsanc274, Oct 22 '15 at 22:27

score 0 · Answer 1 · answered Oct 22 '15 at 21:32

0

An ArrayList can contain duplicates. There are other Java collection classes which can only contain unique elements, such as Set.

I'd suggest you look at the documentation for Set and its implementations, this would likely solve your issue.

answered Oct 22 '15 at 21:32

acanby

2,936
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You are forgetting this is probably assignment, and in assignments the code has to follow crazy rules, just because. Even if there is better way to eliminate the pre-condition altogether before it occurs due to poor design, it has to happen, so you can try to "eliminate" it.. – The Law Oct 22 '15 at 21:36

How to Create String Array List that removes Strings that are already contained in list

1 Answers1