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

If you're seeking a functional style solution, you can wrap the Iterator into a Stream and then do whatever you want.

One of the functional solutions:

JSONArray newJsonArray =
        StreamSupport.stream(jsonArray.spliterator(), false)
                     .filter(JSONObject.class::isInstance)
                     .map(JSONObject.class::cast)
                     .filter(j -> j.has("a"))
                     .collect(collectingAndThen(toList(), JSONArray::new));

Note: The solution above does not modify the original JSONArray. Following the principles of functional programming one should prefer collecting into a new object rather than modifying the existing one.