How to close all activities at once in android?

This example demonstrates how do I close all activities at once in android app.
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"?>
<RelativeLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_above="@id/button"
      android:text="Activity_One"
      android:gravity="center"
      android:layout_marginBottom="20sp" />
   <Button
      android:id="@+id/button"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="Click here to start Second Activity!"
      android:layout_centerInParent="true" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.java
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
   Button button;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      button = (Button)findViewById(R.id.button);
      button.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this, SecondActivity.class);
            startActivity(intent);
         }
      });
   }
}
Step 4 − Create a new Activity(SecondActivity) and add the following code to res/layout/activity_second.xml.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".SecondActivity">
   <Button
      android:id="@+id/terminateButton"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="Terminate all the activities"
      android:layout_centerInParent="true"/>
</RelativeLayout>
Step 5 − Add the following code to src/SecondActivity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.os.Process;
public class SecondActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_second);
      Button button = (Button)findViewById(R.id.terminateButton);
      button.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            finish();
         }
      });
   }
   protected void onDestroy(){
      Process.killProcess(Process.myPid());
      super.onDestroy();
   }
}
Step 6 − Add the following code to androidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".SecondActivity"></activity>
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
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 here to download the project code.