How to use findViewById in Fragment?

This example demonstrate about How to use findViewById in Fragment
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"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:orientation = "vertical"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent">
   <LinearLayout
      android:id = "@+id/linearlayout01"
      android:layout_width = "fill_parent"
      android:layout_height = "fill_parent"
      android:background = "#ccc"
      android:layout_weight = "1"
      android:orientation = "vertical">
      <fragment android:name = "com.example.myapplication.FirstFragment"
         android:id = "@+id/frag_1"
         android:layout_width = "fill_parent"
         android:layout_height = "fill_parent" />
   </LinearLayout>
   <LinearLayout
      android:id = "@+id/linearlayout02"
      android:layout_width = "fill_parent"
      android:layout_height = "fill_parent"
      android:layout_weight = "1"
      android:background = "#eee"
      android:orientation = "vertical">
      <fragment android:name = "com.example.myapplication.SecondFragment"
         android:id = "@+id/frag_2"
         android:layout_width = "fill_parent"
         android:layout_height = "fill_parent" />
   </LinearLayout>
</LinearLayout>
In the above code, we have taken two fragments.
Step 3 − Add the following code to src/MainActivity.java
<?xml version = "1.0" encoding = "utf-8"?>
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity {
   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
   }
}
Step 4 − Add the following code to src/ FirstFragment.java
<?xml version = "1.0" encoding = "utf-8"?>
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class FirstFragment extends Fragment {
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment, null);
      TextView but = (TextView) root.findViewById(R.id.text);
      return root;
   }
}
Step 4 − Add the following code to src/ SecondFragment.java
<?xml version = "1.0" encoding = "utf-8"?>
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class SecondFragment extends Fragment {
   TextView textView;
   View view;
   @Nullable
   @Override
   public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
      view = inflater.inflate(R.layout.fragment, container, false);
      return view;
   }
}
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