Android - Extract Data From JSON Array using Retrofit Library with Kotlin

In the android application, the response from the server is in the form of JSON. We can get to see either a JSON Array or a JSON Object in the response. JSON Array is the list of data which is having similar JSON objects. In the previous article, we have taken a look at How to parse data from JSON Object in android applications using Kotlin. In this article, we will take a look at How to Extract Data from JSON Array in Android using the Retrofit library in Kotlin. 

Note: If you are looking to extract data from JSON Array in an android application using the Retrofit library in Java. Check out the following article: How to Extract Data from JSON Array in Android using the Retrofit library with Java

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.

Step 2: Add the below dependency in your build.gradle file

Below is the dependency for Volley which we will be using to get the data from API. For adding this dependency navigate to the app > Gradle Scripts > build.gradle(app) and add the below dependency in the dependencies section. We have used the Picasso dependency for image loading from the URL.    

// below dependency for using retrofit.
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.5.0'

// below dependency for using picasso image loading library
implementation 'com.squareup.picasso:picasso:2.71828'

After adding this dependency sync your project and now move towards the AndroidManifest.xml part.  

Step 3: Adding permissions to the internet in the AndroidManifest.xml file

Navigate to the app > AndroidManifest.xml and add the below code to it. 

Step 4: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.

Step 5: Creating a modal class for storing our data

Navigate to the app > java > your app’s package name > Right-click on it > New > Kotlin class and name it as CourseRVModal and add the below code to it. Comments are added inside the code to understand the code in more detail.

Step 6: Creating a layout file for each item of our RecyclerView

Navigate to the app > res > layout > Right-click on it > New > layout resource file and give the file name as course_rv_item and add the below code to it. 

Step 7: Creating an Adapter class for setting data to our RecyclerView item

For creating a new Adapter class navigate to the app > java > your app’s package name > Right-click on it > New > Kotlin class and name it as CourseRVAdapter and add the below code to it. 

Step 8: Creating an interface class for writing our API calls

Navigate to the app > java > your app’s package name > Right-click on it > New > Kotlin class select it as Interface and name the file as RetrofitAPI and add the below code to it. Comments are added inside the code to understand the code in more detail.

Step 9: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Now run your application to see the output of it. 

Output: