Minus operation in java 8 for subtracting Lists

Question

Suppose I have two lists:

List<Integer> list1 =  Arrays.asList(1, 2, 3);
List<Integer> list2 =  Arrays.asList(1, 2, 4, 5);

Now I want to perform (list1 - list2). The expected ouptut is {3}. How to do this using java 8 streams?

Solution 1

If you must use Streams :

List<Integer> diff = list1.stream()
                          .filter(i -> !list2.contains(i))
                          .collect (Collectors.toList());

Solution 2

Try this:

List<Integer> difference = new ArrayList<>(list1);
difference.removeAll(list2);
System.out.println("Remove: " + difference); //3

Solution 3

Using Apache commons:

CollectionUtils.subtract(list1, list2);

Pros: Very readable. Cons: No type safety