Remove all elements except one from JSONArray of JSONObjects

Question

I have a JSONArray (org.json) like this:

[
    { \"a\": \"a\" },
    { \"b\": \"a\" },
    { \"c\": \"a\" },
    { \"d\": \"a\" },
    { \"e\": \"a\" },
    { \"         


        

Answer 1

What we can do is map all JSONObjects to a List if they contain the key a. Then we can create a new JSONArray from that List of objects, which in this case is only 1.

You can technically do this in a single line but it looks a bit worse IMO.

List objects = IntStream.range(0, array.length())
        .filter(index -> array.get(index) instanceof JSONObject)
        .mapToObj(array::getJSONObject)
        .filter(object -> object.has("a"))
        .collect(Collectors.toList());

JSONArray reduced = new JSONArray(objects);