Question

i have an ArrayList with elements for example:

[a,b,c,d,e,f,g,h];

and need to take elements [a,b,c] also it should be an ArrayList and remove them from first List and again i take some elements from first list after i take i remove them.

So what is the best way (considering a time) to do this job ?
I mean i should iterate over elements or should convert to array and than work with it ?

maybe there are some fast way to do this ?

Thanks.

Answer 1

Create a new list using subList() to get a view into the first, then use clear() on the subList. Example:

subList = originalList.subList(0, 3);
newList = new ArrayList(subList);
subList.clear();

This is much more efficient than iterating over the original list removing one element at a time since removing an element from an ArrayList involves shifting all the elements. Using a subList does the shift just once.