如何使用Java Stream从列表中获取任何数据的特定索引？

Question

Here is a code to check if particular string is matched or not from List

if (Stream.of(getPlayingSongList()).filter(o -> o.getId().equals(songList.get(position).getId())).findFirst().isPresent()) {
           ToastMethod.show(getActivity(), "Song is already in queue", true);
        } 

I want to know, which index from getPlayingSongList() is matching.

I am using com.annimon:stream library in android.

Answer 1

What about using IntStream.range ?

Since I don't have you whole code, I'm just putting a dummy example :

String[] myArray = { "a", "b", "c", "d" };
OptionalInt c = IntStream.range(0, myArray.length).filter(n -> "c".equals(myArray[n])).findFirst();

if (c.isPresent()) {
   System.out.println(c.getAsInt());
}

>>>> 2

Answer 2

using Akah's suggestion, for android, below code works well.

Optional<Integer> c = Stream.range(0, getPlayingSongList().size()).filter(n -> songList.get(position).getId().equals(getPlayingSongList().get(n).getId())).findFirst();

            if (c.isPresent()) {
                Log.i("get index", c.get()+" ok");
            }

Thanks a lot.