RecyclerView Tutorial

Introduction

RecyclerView is a flexible and efficient component for displaying large sets of data in a list or grid in Android applications. It is a more advanced and powerful version of ListView and GridView.

Setup

To use RecyclerView, you need to add the RecyclerView dependency to your project's build.gradle file.

dependencies {
    implementation 'androidx.recyclerview:recyclerview:1.2.1'
}

Layout XML

Create a layout file that contains a RecyclerView widget.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

Adapter and ViewHolder

Create an adapter and view holder to manage the data and bind it to the RecyclerView.

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    private List<String> mData;
    private LayoutInflater mInflater;

    // data is passed into the constructor
    public MyAdapter(Context context, List<String> data) {
        this.mInflater = LayoutInflater.from(context);
        this.mData = data;
    }

    // inflates the row layout from xml when needed
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.recyclerview_row, parent, false);
        return new ViewHolder(view);
    }

    // binds the data to the TextView in each row
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        String animal = mData.get(position);
        holder.myTextView.setText(animal);
    }

    // total number of rows
    @Override
    public int getItemCount() {
        return mData.size();
    }

    // stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView myTextView;

        ViewHolder(View itemView) {
            super(itemView);
            myTextView = itemView.findViewById(R.id.tvAnimalName);
        }
    }
}

Row Layout XML

Create a layout file for the items in the RecyclerView.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="16dp">

    <TextView
        android:id="@+id/tvAnimalName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp" />
</LinearLayout>

Initialize RecyclerView

Initialize the RecyclerView in your Activity or Fragment.

public class MainActivity extends AppCompatActivity {
    MyAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // data to populate the RecyclerView with
        ArrayList<String> animalNames = new ArrayList<>();
        animalNames.add("Horse");
        animalNames.add("Cow");
        animalNames.add("Camel");
        animalNames.add("Sheep");
        animalNames.add("Goat");

        // set up the RecyclerView
        RecyclerView recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new MyAdapter(this, animalNames);
        recyclerView.setAdapter(adapter);
    }
}

Conclusion

RecyclerView is a powerful tool for displaying large datasets efficiently. By following the steps above, you can set up a RecyclerView in your Android application to display and manage data in a flexible and efficient manner.