RecyclerView is a ViewGroup added to the android studio as a successor of the GridView and ListView. It is an improvement on both of them and can be found in the latest v-7 support packages. It has been created to make possible the construction of any lists with XML layouts as an item that can be customized vastly while improving the efficiency of ListViews and GridViews. In this article, we are going to see how to select a single RadioButton while working on a RecyclerView.
What we are going to build in this article?
Here is a sample video of what we are going to build in this application. Note that we will be using Java language to make this project.
Step by Step Implementation
Step 1: Create a New Project
- Open a new project.
- We will be working on Empty Activity with language as Java. Leave all other options unchanged.
- Name the application at your convenience.
- There will be two default files named activity_main.xml and MainActivity.java.
If you don’t know how to create a new project in Android Studio then you can refer to How to Create/Start a New Project in Android Studio?
Step 2. Adding required dependency
Navigate to Gradle Scripts > gradle.scripts(module) and add the following dependency to it
implementation 'com.google.android.material:material:1.3.0'
Step 3. Working on XML files
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.
XML
<?xml version="1.0" encoding="utf-8"?><RelativeLayout android:layout_width="match_parent" android:layout_height="match_parent" android:padding="16dp" tools:context=".MainActivity"> <androidx.recyclerview.widget.RecyclerView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/recycler_view" tools:listitem="@layout/item_main"/> </RelativeLayout> |
Navigate to app > res > layout > right-click > new > layout resource file and name it as item_main.xml. Use the following code in item_main.xml file-
XML
<?xml version="1.0" encoding="utf-8"?><RadioButton android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/radio_button" android:padding="12dp" android:textSize="18sp" android:textColor="@android:color/darker_gray"></RadioButton> |
Step 4. Working on Java files
Navigate to the MainActivity.java file and use the following code in it. Comments are added to the code to have a better understanding.
Java
package com.example.singleradiobuttonrv; import android.os.Bundle;import android.service.autofill.LuhnChecksumValidator;import android.widget.Toast;import androidx.appcompat.app.AppCompatActivity;import androidx.recyclerview.widget.LinearLayoutManager;import androidx.recyclerview.widget.RecyclerView;import java.util.ArrayList; public class MainActivity extends AppCompatActivity { // Initialize variable RecyclerView recyclerView; ItemClickListener itemClickListener; MainAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Assign variable recyclerView = findViewById(R.id.recycler_view); // initialize array list ArrayList<String> arrayList = new ArrayList<>(); // Use for loop for (int i = 0; i < 20; i++) { // add values in array list arrayList.add("RB " + i); } // Initialize listener itemClickListener = new ItemClickListener() { @Override public void onClick(String s) { // Notify adapter recyclerView.post(new Runnable() { @Override public void run() { adapter.notifyDataSetChanged(); } }); // Display toast Toast .makeText(getApplicationContext(), "Selected : " + s, Toast.LENGTH_SHORT) .show(); } }; // Set layout manager recyclerView.setLayoutManager(new LinearLayoutManager(this)); // Initialize adapter adapter = new MainAdapter(arrayList, itemClickListener); // set adapter recyclerView.setAdapter(adapter); }} |
Navigate to app > right-click > new > java class and name it as MainAdapter.java. Use the following code in it. Comments are added to the code to have a better understanding.
Java
package com.example.singleradiobuttonrv; import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.CompoundButton;import android.widget.RadioButton;import androidx.annotation.NonNull;import androidx.recyclerview.widget.AdapterListUpdateCallback;import androidx.recyclerview.widget.RecyclerView;import java.io.*;import java.util.ArrayList; public class MainAdapter extends RecyclerView.Adapter<MainAdapter.ViewHolder> { // Initialize variable ArrayList<String> arrayList; ItemClickListener itemClickListener; int selectedPosition = -1; // Create constructor public MainAdapter(ArrayList<String> arrayList, ItemClickListener itemClickListener) { this.arrayList = arrayList; this.itemClickListener = itemClickListener; } @NonNull @Override public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { // Initialize view View view = LayoutInflater.from(parent.getContext()) .inflate(R.layout.item_main, parent, false); // Pass holder view return new ViewHolder(view); } @Override public void onBindViewHolder(@NonNull ViewHolder holder, int position) { // Set text on radio button holder.radioButton.setText(arrayList.get(position)); // Checked selected radio button holder.radioButton.setChecked(position == selectedPosition); // set listener on radio button holder.radioButton.setOnCheckedChangeListener( new CompoundButton.OnCheckedChangeListener() { @Override public void onCheckedChanged( CompoundButton compoundButton, boolean b) { // check condition if (b) { // When checked // update selected position selectedPosition = holder.getAdapterPosition(); // Call listener itemClickListener.onClick( holder.radioButton.getText() .toString()); } } }); } @Override public long getItemId(int position) { // pass position return position; } @Override public int getItemViewType(int position) { // pass position return position; } @Override public int getItemCount() { // pass total list size return arrayList.size(); } public class ViewHolder extends RecyclerView.ViewHolder { // Initialize variable RadioButton radioButton; public ViewHolder(@NonNull View itemView) { super(itemView); // Assign variable radioButton = itemView.findViewById(R.id.radio_button); } }} class GFG { public static void main(String[] args) { System.out.println("GFG!"); }} |
Create a new interface and name it as ItemClickListener. Use the following code in the ItemClickListener.java file-
Java
package com.example.singleradiobuttonrv; public interface ItemClickListener { // Create method void onClick(String s);} |
Here is the final output of our application.
Output:
