Calculate how many ArrayLists are in an ArrayList in Java

Question

Is there away of finding out how many Lists an ArrayList holds?

ArrayList<ArrayList<Integer>> myList = new ArrayList<ArrayList<Integer>>(); List<Integer> myOtherList = new LinkedList<Integer>();

FThompson · Accepted Answer · 2012-12-02 00:04:49Z

5

As with any list, you can find out how many objects it is holding with List#size().

int size = myList.size(); // amount of sublists that myList holds

answered Dec 2, 2012 at 0:04

FThompson

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2 Comments

binary101 Over a year ago

Oh, of course. I can't believe i didn't think of this. Thank you. :D

FThompson Over a year ago

We all have those days, no worries ;) Just don't forget to mark the answer as accepted when you can.

hd1 · Accepted Answer · 2012-12-02 00:12:30Z

2

@Vulcan's response will get you the size of the list. If you want only the ArrayLists contained within the List, you'll need to check the element type using instanceof and increment the count that way:

int listcount = 0;
for (Object e : list) {
   if (e instanceof ArrayList) listcount++;
}

answered Dec 2, 2012 at 0:12

hd1

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