Table of Contents:

Introduction

What is Retrofit?

An Example:

1. Dependencies
2. Permissions
3. JSON data
4. Model
5. Retrofit Instance
6. Define the Endpoints
7. Recyclerview Adapter
8. Initializing the Recyclerview

Final Thoughts

Introduction

In this blog I'm gonna show you how to work with the retrofit in android.

What is Retrofit?

Retrofit is a type-safe HTTP client for Android and Java developed by Square.

Using Retrofit we can easily translate the REST APIs to Java Interfaces. Retrofit can be used as the best alternative to Volley. Retrofit Uses OkHttp for making HTTP requests. Retrofit easily translates JSON or XML response to POJO’s (Plain Old Java Objects).

Dependencies

Open build.gradle (Module:app) and add Retrofit, GSON, RecyclerView and CardView dependencies.


Make sure you have the latest dependencies. You can check them here

Permissions

Add the internet permission in your AndroidManifest.xml

JSON data

Now we will use sample JSON data from https://jsonplaceholder.typicode.com/posts

which looks like this

Model

Make a model class Posts.java and put the following code inside it.



Posts class has fields that represent the post title and body of a post. These fields are annotated with the @SerializedName annotation. The parameter (value) of this annotation is the name to be used when serializing and deserializing objects. For example, the Java field title is represented as a name in JSON.

Later we've set getter and setter for all the variables.

Retrofit Instance

To issue network requests to a REST API with Retrofit, we need to create an instance using the RetrofitClientInstance class and configure it with a base URL. Create a class RetrofitClientInstance.java, here with the URL of our API we will make a call.

Define the Endpoints

Here we will provide the details about the parameters and request method.

Recyclerview Adapter

Now we will create the Adapter class for our recyclerview. Create a class RecyclerviewAdapter.java and paste the following code in it.

Initializing the Recyclerview

Finally, we will initialize the Endpoints interface and the Recyclerview in the MainActivity.




That's All! Happy Coding!


The complete code is available here.

Final Thoughts

One of the most important aspects of retrofit is the hassle-free setup provided by retrofit to integrate different converters used for data serialization. You can add GSON converters, XML converters or even custom converters.

Need some extra help?.
Check out the REST API course using Retrofit2 and MVVM architecture: here.

Authors

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Aayush Upadhyay

www.instagram.com/aayush.5/

Google Associate Android Developer