add isEmpty and isNotEmpty methods

[strkkk]

What problem does this code solve?
It is clearer to check if object is empty or not by calling method rather then comparing length.
Also, it can be used as method reference, see code snippet below.

    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(JSONObject::isNotEmpty).count(); 

Risks
Low

Changes to the API?
Yes

Will this require a new release?
No

Should the documentation be updated?
Methods are added with javadocs

Does it break the unit tests?
No. This methods are new.

Was any code refactored in this commit?
No Internal uses of length() == 0 and similar code were converted to isEmpty()

Review status
APPROVED
(isNotEmpty() is not included, JSONArray.isEmpty() was added)
Starting 3 day comment window

[johnjaylward]

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();

[strkkk]

@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.

[stleary]

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().

[strkkk]

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

Will update tests later.

[stleary]

Starting 3 day comment window

[johnjaylward]

@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.

[stleary]

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

[strkkk]

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

[strkkk]

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