No other collection type in Java has a isNotEmpty method that I know of. I'd rather just have the isEmpty check then in your example, it would look like:

JSONObject example = new JSONObject();
    example.length() == 0; // was 
    example.isEmpty(); // become 

    example.length() != 0; // was 
    example.isNotEmpty(); // become 

    List<JSONObject> list = ...;
    list.stream().filter(JSONObject::isEmpty).filter(item -> !item.isEmpty()).count();

@johnjaylward
Yep, java collections does not have it, but JSONObject != java collection, isn't it? :)
Some libs provide such method, e.g. CollectionUtils to make it easier to read.

Arguably, but Scala collections/strings/option have nonEmpty method as part of standard API as well.
Comparing both approaches with lambda, I would prefer method reference way.
list.stream().filter(JSONObject::isNotEmpty).count();

May be we need more opinions.

No objection to adding isEmpty(), but please do it the right way:

• Add the method to JSONArray as well, unless you have some reason why it should not be included.
• Update the code in the lib where JSONObject and JSONArray empty condition is checked. I think there are about 4 occurrences.
• Update those unit tests that check for JSONObject and JSONArray empty condition. There should be about 16 occurrences.
• If you do the previous 2 steps it won't be necessary to add explicit unit tests.

I don't think there is a valid use case for isNotEmpty().

• Added isEmpty() to JSONArray
• Removed isNotEmpty() method
• Refactored some usages of length() method for JSONArray, JSONObject and String

Will update tests later.

Starting 3 day comment window

@stleary If we want to ensure Android compatability, then the other classes should not be updated, only JSONArray and JSONObject.

i.e. if using the CDL class in android, you'll get a no method exception for isEmpty.

My bad, thanks @johnjaylward. @strkkk please revert the changes to CDL, JSONML, and XML. I will need to update the Wiki regarding Android compatibility.

Ok, I will change it.
by the way, why changes in this classes will break Android compatibility?

@stleary
Tests are updated, changes for mentioned classes are partially reverted.