RETROFIT: - • It’s a very popular Android and Java library which makes sending and retrieving data pretty easy from a web service. • Provides abstraction layer over HTTP code and automatically generates all the complicated low-level networking code for us. • GSON convertor converts post JSON objects into post Java objects.

Implementation: - • Put dependencies(Retrofit & GSON Convertor) in build.gradle(app). • Create a model class for that specific route from which we’ve to retrieve data. • Declare the required variables in above model class and if the JSON key and the variable name differ then we use GSON Annotation(@SerializedName(“JSON key”)) • Generate Getter method of the declared variables. • Create Recycler View to display the retrieved data. • Create a Java Interface that represents the API of the web service in our app. • Create a method in the above interface which will return a Call object(which will convert JSON array into Java List) and name it (for eg. getPosts()) • Annotate the above created method using @GET(“API route”) • Code in MainActivity.java to get data in our app: - Declare a TextView then, link it with the XML element. • Create a Retrofit object and call Builder class which uses Builder API to allow defining the URL end point for the HTTP operations and finally build a new Retrofit object. • Define .baseURL .addConvertorFactory in the above object and then call build(). • Create JSON placeholder API • Use call.enqueue(Callback Method) to execute call on the background thread as we can’t run 2 network operations on the same thread(in this case main thread) • If the response is successful then we get all the entries using for loop. • Give Internet Permission as well.