java.lang.Integer cannot be cast to java.lang.Long

Both Integer and Long are subclasses of Number, so I suspect you can use:

long ipInt = ((Number) obj.get("ipInt")).longValue();

That should work whether the value returned by obj.get("ipInt") is an Integer reference or a Long reference. It has the downside that it will also silently continue if ipInt has been specified as a floating point number (e.g. "ipInt": 1.5) in the JSON, where you might want to throw an exception instead.

You could use instanceof instead to check for Long and Integer specifically, but it would be pretty ugly.

We don't know what obj.get() returns so it's hard to say precisely, but when I use such methods that return Number subclasses, I find it safer to cast it to Number and call the appropriate xxxValue(), rather than letting the auto-unboxing throw the ClassCastException:

long ipInt = ((Number)obj.get("ipInt")).longValue();

That way, you're doing explicit unboxing to a long, and are able to cope with data that could include a ., which would return a Float or Double instead.