How to create recycler view in android javaAndroid Development
September 22, 20203 minutesuserPankaj Valani
How to create recycler view in android java
What is a recycler view?

  • RecyclerView is used to show the data in the form of a scrollable list. It is a ViewGroup to display a large set of data. For each item in a large dataset, it displays a View. So RecyclerView is very useful no use the scrollable list.

Why use RecyclerView in Android?

  • One reason is so we can create a List through the LinearLayout and the orientation can be vertical. For example, in the Facebook application, all parameters will be the same as share, comment, like, etc. Now if we will take LinearLayout, all the views will create separate views in the memory.
Add dependencies :



dependencies {  

    implementation "androidx.recyclerview:recyclerview:1.1.0"
} 

Notes:

  • Androidx in recycler view dependencies:  implementation "androidx.recyclerview:recyclerview:1.1.0"
  • Your android studio, not androidx:  implementation 'com.android.support:recyclerview-v7:28.0.0'

Now we will add the RecyclerView layout in our activity_main.xml file

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
xmlns:app="http://schemas.android.com/apk/res-auto"  
xmlns:tools="http://schemas.android.com/tools"  
android:layout_width="match_parent"  
android:layout_height="match_parent"  
tools:context=".MainActivity">  
  
<androidx.recyclerview.widget.RecyclerView  
    android:id="@+id/recyclerView"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent" />  
  
</RelativeLayout>

We create a layout file named row_layout.xml.

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
xmlns:app="http://schemas.android.com/apk/res-auto"  
xmlns:tools="http://schemas.android.com/tools"  
android:layout_width="match_parent"  
android:layout_height="match_parent"  
tools:context=".MainActivity">  
  
<androidx.recyclerview.widget.RecyclerView  
    android:id="@+id/recyclerView"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent" />  
  
</RelativeLayout>

We create a layout file named row_layout.xml

<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="horizontal">  
  
    <ImageView  
        android:id="@+id/image"  
        android:layout_width="300px"  
        android:layout_height="300px"  
        android:layout_marginLeft="10dp"  
        android:layout_marginTop="10dp"  
        android:src="@color/colorPrimaryDark" />  
  
    <TextView  
        android:id="@+id/description"  
        android:layout_width="250dp"  
        android:layout_height="55dp"  
        android:layout_toRightOf="@id/image"  
        android:layout_marginLeft="15dp"  
        android:layout_marginTop="35dp"  
        android:text="abcd"  
        android:textColor="#000"  
        android:textSize="30sp" />  
  
</RelativeLayout>

Create a Model Class :

public class Data {  
  
    public String name;  
  
    public String getName() {  
        return name;  
    }  
  
    public void setName(String name) {  
        this.name = name;  
    }  
  
    public int getImageId() {  
        return imageId;  
    }  
  
    public void setImageId(int imageId) {  
        this.imageId = imageId;  
    }  
  
    public int imageId;  
  
    Data(String name, int imageId) {  
        this.name = name;  
        this.imageId = imageId;  
    }  
} 

Create RecyclerVIew_Adapter.java

public class RecyclerView_Adapter extends RecyclerView.Adapter<View_Holder> {  
  
    List<Data> list = Collections.emptyList();  
    Context context;  
  
    public RecyclerView_Adapter(List<Data> data, Application application) {  
        this.list = data;  
        this.context = application;  
    }  
  
    @NonNull  
    @Override  
    public View_Holder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {  
        //Inflate the layout, initialize the View Holder  
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout, parent, false);  
        View_Holder holder = new View_Holder(v);  
        return holder;  
    }  
  
    @Override  
    public void onBindViewHolder(@NonNull View_Holder holder, int position) {  
  
        //Use the provided View Holder on the onCreateViewHolder method to populate the current row on the RecyclerView  
        holder.name.setText(list.get(position).name);  
        holder.imageView.setImageResource(list.get(position).imageId);  
  
    }  
  
    @Override  
    public int getItemCount() {  
        return list.size();  
    }  
} 

  • onCreateViewHolder()- It inflates the row layout and initializes the view holder. It handles findViewById) (methods, find views once, and recycle them so that repetitive calls are avoided.
  • onBindViewHolder()- It uses the onCreateViewHolder() View Holder to fill in the current RecyclerView row with data.
  • getItemCount()- This method returns the collection size which contains the items that we wish to show.
The code file of the ViewHolder Java class is listed below.

import android.view.View;  
import android.widget.ImageView;  
import android.widget.TextView;  
import androidx.recyclerview.widget.RecyclerView;  
  
public class View_Holder extends RecyclerView.ViewHolder {  
  
    TextView name;  
    ImageView imageView;  
  
    View_Holder(View itemView) {  
        super(itemView);  
        name = (TextView) itemView.findViewById(R.id.name);  
        imageView = (ImageView) itemView.findViewById(R.id.image);  
    }  
} 

MainActivity.java class file:

 public class MainActivity extends AppCompatActivity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
  
        List<Data> data = fill_with_data();  
  
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);  
        RecyclerView_Adapter adapter = new RecyclerView_Adapter(data, getApplication());  
        recyclerView.setAdapter(adapter);  
        recyclerView.setLayoutManager(new LinearLayoutManager(this));  
  
    }  
  
    public List<Data> fill_with_data() {  
  
        List<Data> data = new ArrayList<>();  
        data.add(new Data("Android", R.drawable.c));  
        data.add(new Data("Kotlin", R.drawable.cc));  
		data.add(new Data("Kotlin", R.drawable.ccc));  
        return data; 
    }  
}