Removing duplicates from arraylist using set

Question

Have 2 sets with duplicates set1 ={1,2,3,4,5} set2 = {1,3,6,7} and the result should be set3 ={2,4,5,6,7} Please let me reiterate that I want to use Set interface and the result set should be ordered natural.

So what have you tried so far? Have you looked at the Set interface? — Jon Skeet
– Jon Skeet, Commented Jun 9, 2015 at 9:10
this has been asked before. We want to help people out, but please check google before posting a question :) — John M
– John M, Commented Jun 9, 2015 at 9:13
I don't see how "looked at this was an interview question" answers my question at all... — Jon Skeet
– Jon Skeet, Commented Jun 9, 2015 at 9:19

almightyGOSU · Accepted Answer · 2015-06-09 09:29:35Z

2

Find the intersection
Find the union
Subtract the intersection from the union

Code:

 public static void main(String[] args) {

    Set<Integer> set1 = new HashSet<Integer>(Arrays.asList(1, 2, 3, 4, 5));
    Set<Integer> set2 = new HashSet<Integer>(Arrays.asList(1, 3, 6, 7));

    Set<Integer> intersection = new HashSet<Integer>(set1);
    intersection.retainAll(set2);

    // set1 is now the union of set1 and set2
    set1.addAll(set2);

    // set1 is now (union - intersection)
    // All elements in set1 or set2, but not in both set1 & set2
    set1.removeAll(intersection);

    for(Integer n : set1) {
        System.out.println(n);
    }
}

Output:

answered Jun 9, 2015 at 9:29

almightyGOSU

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Comments

k.shamsu · Accepted Answer · 2015-06-09 09:17:06Z

1

You may try this -

Set set1, set2;
Set newSet = new HashSet(set1);
newSet.addAll(set2);

answered Jun 9, 2015 at 9:17

k.shamsu

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2 Comments

user_falafel Over a year ago

Will the result set be ordered?

almightyGOSU Over a year ago

Is that correct? Shouldn't you get the union, get the intersection, and remove the intersection from the union?

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