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How to implement Nested Recycler View with retrofit

#android #api #androidrecyclerview #retrofit

Implementing a Nested RecyclerView with Retrofit can be a challenging task, but with the right guidance, it can become a fun and rewarding experience. In this article, we will explore how to achieve this in a step-by-step manner.

Before we dive into the implementation, let's quickly understand what a Nested RecyclerView is. It is a RecyclerView that contains another RecyclerView as one of its child views. This allows us to create complex and hierarchical layouts where each child RecyclerView can display a list of items.

First, let's start by setting up our project. Make sure you have the latest version of Retrofit added to your dependencies in the build.gradle file:

implementation 'com.squareup.retrofit2:retrofit:2.9.0'

Next, we need to create the necessary models for our data. Let's assume we are building an app for a bookstore. We will have two models: Bookstore and Book. The Bookstore model will contain a list of books:

public class Bookstore { private String name; private List books; // getters and setters } public class Book { private String title; private String author; // getters and setters }

Now, let's move on to the implementation of the Nested RecyclerView. We will need two RecyclerView adapters: one for the outer RecyclerView (BookstoreAdapter) and another for the inner RecyclerView (BookAdapter).

In the BookAdapter, we will inflate the layout for each individual book item:

public class BookAdapter extends RecyclerView.Adapter { private List books; // other methods public class ViewHolder extends RecyclerView.ViewHolder { private TextView titleTextView; private TextView authorTextView; public ViewHolder(View itemView) { super(itemView); titleTextView = itemView.findViewById(R.id.titleTextView); authorTextView = itemView.findViewById(R.id.authorTextView); } } }

In the BookstoreAdapter, we will inflate the layout for each individual bookstore item and also set up the inner RecyclerView:

public class BookstoreAdapter extends RecyclerView.Adapter { private List bookstores; // other methods public class ViewHolder extends RecyclerView.ViewHolder { private TextView nameTextView; private RecyclerView bookRecyclerView; private BookAdapter bookAdapter; public ViewHolder(View itemView) { super(itemView); nameTextView = itemView.findViewById(R.id.nameTextView); bookRecyclerView = itemView.findViewById(R.id.bookRecyclerView); bookAdapter = new BookAdapter(); bookRecyclerView.setLayoutManager(new LinearLayoutManager(itemView.getContext())); bookRecyclerView.setAdapter(bookAdapter); } } }

Finally, we need to make API calls using Retrofit to fetch the data for our Nested RecyclerView:

public interface BookstoreService { @GET("bookstores") Call\> getBookstores(); } public class BookstoreApi { private static final String BASE\_URL = "https://example.com/api/"; private Retrofit retrofit; public BookstoreApi() { retrofit = new Retrofit.Builder() .baseUrl(BASE\_URL) .addConverterFactory(GsonConverterFactory.create()) .build(); } public BookstoreService getService() { return retrofit.create(BookstoreService.class); } }

With this setup, you can now make API calls and populate the Nested RecyclerView with data from your server. Happy coding!

References:

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