Retrofit is an awesome type-safe HTTP client for Android and Java built by awesome folks at Square. Retrofit makes it easy to consume JSON or XML data which is parsed into Plain Old Java Objects (POJOs).

If you just want to get the sample project, then you can find it here.

https://medium.com/@prakash_pun/retrofit-a-simple-android-tutorial-48437e4e5a23

In Android, Retrofit is a REST Client for Java and Android by Square inc under Apache 2.0 license. Its a simple network library that used for network transactions. By using this library we can seamlessly capture JSON response from web service/web API. It’s easy and fast library to retrieve and upload the data(JSON or any other structured data) via a REST based web service.

https://abhiandroid.com/programming/retrofit