CODEWITHSUNDEEP
javaarraysarraylist
Phatter
Phatter

Reputation: 23

How to combine more set of ArrayList to 1 set ArrayList

I've an Arraylist variable 

ArrayList<ArrayList<String>> nodes = new ArrayList<ArrayList<String>>();
And
ArrayList<String> split;

Then i used nodes.add(split);

And I've a result of ArrayList like this

[[hasAttribute, hasPart, has_RP-09, has_RP-10], [hasAttribute, hasPart, has_RP-03, has_RP-06]]

How to combine that to be a result like this

[hasAttribute, hasPart, has_RP-09, has_RP-10, has_RP-03, has_RP-06]

Thank you guys for the answer.

Upvotes: 0

Views: 76

Answers (2)

Jacky
Jacky

Reputation: 8935

Java 8 can help you a lot. 

Set<String> combined = nodes.stream().flatMap(n -> n.stream()).collect(Collectors.toSet());

Upvotes: 0

M A
M A

Reputation: 72844

You can loop over the individual list and add all of its elements to a Set:

ArrayList<ArrayList<String>> nodes = new ArrayList<ArrayList<String>>();
...
Set<String> set = new HashSet<String>();
for (ArrayList<String> list : nodes) {
    set.addAll(list);       
}

If you want to preserve the order, use a LinkedHashSet instead of the HashSet.

Upvotes: 2

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