How to call an activity method from a fragment in Android App?

This example demonstrates how do I call an activity method from a fragment in android.
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"
   android:padding="8dp"
   tools:context=".MainActivity">
   <FrameLayout
      android:id="@+id/frameLayout"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.java
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import android.os.Bundle;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      FragmentManager fragmentManager = getSupportFragmentManager();
      FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
      fragmentTransaction.replace(R.id.frameLayout, new SampleFragment()).commit();
   }
   public void FragmentMethod() {
      Toast.makeText(MainActivity.this, "Method called From Fragment", Toast.LENGTH_LONG).show();
   }
}
Step 4 − Create a new Fragment Activity and add the following codes −
SampleFragment.java −
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class SampleFragment extends Fragment {
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      View view = inflater.inflate(R.layout.fragment_sample, container, false);
      ((MainActivity) getActivity()).FragmentMethod();
      return view;
   }
}
fragment_sample.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=".SampleFragment">
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Calling a simple method from Fragment"
      android:textAlignment="center"
      android:textSize="24sp"
      android:textStyle="bold" />
</RelativeLayout>
Step 5 − 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=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <categoryandroid: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 the 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.