There appear to be at least two versions of the Samsung J7. The two models are often labeled by model year (2015, 2016), but there's a lot of inconsistency (and confusion) with that identification. I've seen phone retailers, phone reviewers, and phone cover vendors identify the same phone as both "2015" and "2016", which renders that distinction virtually useless.
However, the phone models can be distinguished by their physical features. One model has THREE openings on the upper back side: LED light, camera lens, and speaker (from left to right). The other model has just TWO openings on the back side: LED light and camera lens.
So, when shopping for a phone case, don't rely on the model year designation. Be sure to look carefully at the photos of the back side of the phone and phone case, and make sure those match the phone that you have.
FYI: My J7 was purchased at Best Buy in June 2016, and It was identified on the Best Buy site as a "2016". The phone has three openings on the back. I purchased a phone case on eBay, from a vendor who identified his case (designed for three openings) as fitting the "2015" model. However, the vendor's photo matched my phone exactly (and his photo of the "2016" case did NOT match my phone). And when the cover arrived, it did in fact fit my phone.