How to get index of findFirst() in java 8?

Question

I have the following code:

ArrayList <String> entries = new ArrayList <String>();

entries.add("0");
entries.add("1");
entries.add("2");
entries.add("3");

String firstNotHiddenItem = entries.stream()
                    .filter(e -> e.equals("2"))
                    .findFirst()
                    .get();

I need to know what is the index of that first returned element, since I need to edit it inside of entries ArrayList. As far as I know get() returns the value of the element, not a reference. Should I just use

int indexOf(Object o)

instead?

Answer 1

You can get the index of an element using an IntStream like:

int index = IntStream.range(0, entries.size())
                     .filter(i -> "2".equals(entries.get(i)))
                     .findFirst().orElse(-1);

But you should use the List::indexOf method which is the preferred way, because it's more concise, more expressive and computes the same results.