Question

I have a fragment with the following layout: my_fragment.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent">

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/appName"
        android:id="@+id/textView" android:layout_gravity="center"
        android:layout_margin="5dp"/>

<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/button1"
        android:id="@+id/button1"
        android:layout_gravity="center"/>

and corresponding MyFragment.java

package com.example.appdemo;

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.Button;
import android.widget.Toast;

public class MyFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.top_bar, container, false);

    Button button1 = (Button)view.findViewById(R.id.button1);
    button1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Toast.makeText(getActivity(), "Button Pressed", Toast.LENGTH_SHORT).show();
        }
    });

    return view;
    }
}

and this is hosted inside MainActivity.java

package com.example.appdemo;

import android.support.v4.app.FragmentActivity;
import android.os.Bundle;

public class MainActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}
}

with the following layout activity_main.xml

<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" >

<fragment
    android:id="@+id/fragment"
    android:name="com.example.appdemo.MyFragment"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

</RelativeLayout>

Now, my question is why does this only work when I extend FragmentActivity? I’d like to extend Activity. How do I accomplish that?

Answer 1

Why does this only work inside a host class that extends FragmentActivity?

Because you are inheriting from android.support.v4.app.Fragment instead of android.app.Fragment.