How to add element based on index in android CopyOnWriteArrayList?

Before getting into example, we should know what CopyOnWriteArrayListis. It is a thread-safe variant of ArrayListand operations add, set, and so on by making a fresh copy of the underlying array.

This example demonstrate about How to add element based on index in android CopyOnWriteArrayList

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayoutxmlns:android="https://schemas.android.com/apk/res/android"
   xmlns:app="https://schemas.android.com/apk/res-auto"
   xmlns:tools="https://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:gravity="center"
   android:layout_height="match_parent"
   tools:context=".MainActivity"
   android:orientation="vertical">

   <TextView
      android:id="@+id/actionEvent"
      android:textSize="40sp"
      android:layout_marginTop="30dp"
      android:layout_width="wrap_content"
      android:layout_height="match_parent" />
</LinearLayout>

In the above code, we have taken text view to showCopyOnWriteArrayListelements.

Step 3 − Add the following code to src/MainActivity.java

package com.example.myapplication;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CopyOnWriteArrayList;
public class MainActivityextends AppCompatActivity {
   CopyOnWriteArrayListcopyOnWriteArrayList;
   String head;
   @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      copyOnWriteArrayList= new CopyOnWriteArrayList<String>();
      final TextViewactionEvent = findViewById(R.id.actionEvent);
      copyOnWriteArrayList.add("sai");
      copyOnWriteArrayList.add("ram");
      copyOnWriteArrayList.add("krishna");
      copyOnWriteArrayList.add("prasad");
      copyOnWriteArrayList.add("ram");
      actionEvent.setText("" + copyOnWriteArrayList);
      actionEvent.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            copyOnWriteArrayList.add(0,"first element");
            actionEvent.setText("" + copyOnWriteArrayList);
         }
      });
   }
}

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Click on textview, It will give the result as shown below −