How to use rest API with retrofit in Android Kotlin

Implementing Retrofit in Android Kotlin is an easy process that can be performed in just a few steps. With only 4-5 steps, you can successfully integrate Retrofit into your Android Kotlin project. Please note that I will integrate the retrofit into Kotlin without utilizing Coroutines and LiveData. This approach is beginner-friendly and should make it easier for you to understand the implementation. You just need to follow these steps:-

1. Before you dive into Android programming, it is necessary to have a functional RESTful API ready. Just for instance, you can use as a test API. So be ready for the next steps.

2. Add retrofit dependencies to your app/build.gradle file

3. Now create a data class for your API response which is in JSON format. To give you an idea, I am using response to generate data class. Exceuting mentioned rest api give you response just this.

Now, I will copy the above response and paste into this url, which will then generate a data class for me. Now copy the generated data class. Create a package named models and inside this create a class UserData.kt just like below.

4. Let’s create an interface class named ApiClientInterface.kt to enable Retrofit to work with different REST API endpoints.

Note that for the simplicity, I’ve just use one endpoint here. You may create as many as you want.

5. Now , we need to to create an RetrofitClient.kt class.

6. We have done everything required to run retrofit. Now it’s time to use Retrofit class in our MainActivity.kt.

For simplicity, I’ve just create an method named response() and called inside onCreate(). You can perform the same thing on a button click.

Also, Do not forgot to add internet permission to your Androidmanifest.xml

In case you encounter any difficulties during the implementation process, please refer to the contents of the project zip file for assistance.