There is a subtlety in creating new Android fragments in Android Studio that Android Studio does a horrible job of negotiating.

If you try to create a new Blank fragment (File > New > Fragment > Fragment (Blank)) without initially proving some context regarding in what package the fragment should be generated, you may/will get a “Fragment name is not a valid class name” error. The simplest solution is to select the package in the left had project navigator pane and then create the fragment.

Android Studio might generate code that makes your new fragment derive from android.support.v4.app.Fragment rather than android.app.Fragment. That's not what we want.

In the preceding chapter, you were instructed to remove the project's dependency on com.android.support:appcompat-v7:<whatever> and/or com.android.support:appcompat-v4:<whatever> to work around an Android Studio bug. However, the DrawerLayout that we will use in a bit requires the v4 compat libs.

A dependence on com.android.support:appcompat-v7:<whatever> will automatically bring in v4.

Here's what I ended up with:

TopFragment.java

package com.hfad.bitsandpizzas;
 
 
import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
 
/**
 * A simple {@link Fragment} subclass.
 */
public class TopFragment extends Fragment {
 
 
    public TopFragment() {
        // Required empty public constructor
    }
 
 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_top, container, false);
    }
 
}

Notice the required empty public constructor not included in the book's code.

And here's the layout:

fragment_top.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">
 
 
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/title_top" />
 
</RelativeLayout>

Android studio might set tools:context to some value other than .MainActivity. Be sure to make the change.

The exposition here gets a little squirrelly and the “updated MainActivity.java” isn't all quite there, so here's what MainActivity.java should look like at the end of p. 415:

MainActivity.java