Question

I have a list that I am trying to fill with numbers from a different List. However, when I change the number in the list I copied from, it changes them in the other list. Is there any way to stop this from happening?

Answer 1

You need to copy the values in your list into a new list:

List<Integer> list1 = Arrays.asList(1, 2, 3);
List<Integer> list2 = new ArrayList<String>(list1); // copy the values of list1 into list2

That will copy all of the values in list1 into list2. Then you can make changes to list2 without modifying list1 and vice versa.

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Just to clarify:

That will not do a deep copy. However, this is not an issue of deep/shallow copying. The issue here is that the OP was passing his list into another method and then was surprised to learn that his list had had numbers added/removed.