[Solved] How Java ArrayList works internally [closed]

Question

If you pass an ArrayList to a function it passes a pointer back to the original list. That means any updates in the method will be updating your original ArrayList because they are the same thing.

ArrayList<String> list2 = new ArrayList<String>(list);

That makes a copy of list and saves it into list2. list and list2 are completely separate ArrayList‘s.

Accepted Answer

If you pass an ArrayList to a function it passes a pointer back to the original list. That means any updates in the method will be updating your original ArrayList because they are the same thing.

ArrayList<String> list2 = new ArrayList<String>(list);

That makes a copy of list and saves it into list2. list and list2 are completely separate ArrayList‘s.