How to get all elements of ArrayList exactly once in java?

Question

If i have an ArrayList that contains "Cat" "Cat" "Dog" "Bee" "Dog" "Cat".

How can i then produce an array that contains each element exactly once in java?

I want to end up having the following array:

"Cat" "Dog" "Bee"

Use a Set instead of an ArrayList. It's called "the right tool for the job." — duffymo, Mar 09 '13 at 15:17

score 2 · Accepted Answer · answered Mar 09 '13 at 15:17

2

You can use a Set for this:-

Set<String> uniqueElements = new HashSet<String>(myList);

This Set will now have all the Elements of your ArrayList but without duplicates.

answered Mar 09 '13 at 15:17

RainMaker

Thx for all the replies. I used the above example - works good :) – Diemauerdk Mar 09 '13 at 15:31

score 2 · Answer 2 · answered Mar 09 '13 at 15:17

2

You should add the elements to a Set which by definition requires the elements to be unique.

answered Mar 09 '13 at 15:17

Jason Braucht

score 1 · Answer 3 · answered Mar 09 '13 at 15:18

1

Set contains unique elements:

Set<String> set = new HashSet<String>(list);

Then convert it to array:

String[] array = set.toArray(new String[set.size()]);

answered Mar 09 '13 at 15:18

Balázs Németh

3 Answers3