Can you please guide me what's wrong in the code?

Question

The line in MainActivity.java in which WorkoutDetailFragment is casted shows error that it cannot be done. Please tell me why it isn't working. I copied the code from a book.

MainActivity

package gangster.workout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 WorkoutDetailFragment frag = (WorkoutDetailFragment) getFragmentManager().findFragmentById(R.id.detail_frag);
 frag.setWorkout(1);
}
}

Workout.Java

package gangster.workout;
public class Workout {
private String name;
private String description;
public static final Workout[] workouts = {
 new Workout("The Limb Loosener" , " Pta nhi kya ksgdrna hai isme") ,
 new Workout("The Timb Loosener" , " Pta nhi kya asdfasasfasasdkrna hai isme") ,
 new Workout("The Pimb Loosener" , " Pta nhi kyaasf krna hai isme") ,
 new Workout("The Zimb Loosener" , " Pta nhi kyasfasa krna hai isme") ,
};
private Workout(String name , String description){
 this.name = name;
 this.description = description;
}
public String getDescription(){
 return description;
}
public String getName(){
 return name;
}
public String toString(){
 return this.name;
}
}

WorkoutDetailFragment.java

package gangster.workout;
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 WorkoutDetailFragment extends Fragment {
private long workoutId;
public void setWorkout(long id) {
 this.workoutId = id;
}
@Override
public void onStart() {
 super.onStart();
 View view = getView();
 if (view != null) {
 TextView title = (TextView) view.findViewById(R.id.textTitle);
 Workout workout = Workout.workouts[(int) workoutId];
 title.setText(workout.getName());
 TextView description = (TextView) view.findViewById(R.id.textDescription);
 description.setText(workout.getDescription());
 }
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
 Bundle savedInstanceState) {
 // Inflate the layout for this fragment
 return inflater.inflate(R.layout.fragment_workout_detail, container, false);
}
}

Answer 1

use getSupportFragmentManager() instead of getFragmentManager()

• Vikrant Arora: Dude, it works. Thank you. What was wrong in using that one though?
• Abdalla Elarabi: your code indicates that you're using android.support.v7.app.AppCompatActivity and android.support.v4.app.Fragment and both are from the android support library. which requires getting the correct FragmentManager by calling getSupportFragmentManager(). Please accept the answer since it solves your problem :)
• Vikrant Arora: I'm a beginner. Can you please explain a bit more un-sophisticatedly? :P I can accept the answer after 4 minutes.
• Abdalla Elarabi: The Android team offers a Support Library which provides backward-compatible versions of new features. for example Fragments were introduced in API v11, but using the support library you can use it in API v4 and up. you can read this part in the link I provided, you'll get the idea.