Unable to resolve FragmentActivity running on Android 2.3.3 with compatibility package v4

Question

I'm building a simple hello world app to learn about the Android Compatibility Package. I'm able to get the app to run on the 3.2 emulator but when I run it on a 2.3.3 emulator I get

10-12 11:36:14.474: WARN/dalvikvm(469): Unable to resolve superclass of Lcom/example/MyActivity; (11) 
10-12 11:36:14.564: WARN/dalvikvm(469): Link of class 'Lcom/example/MyActivity;' failed 
10-12 11:36:14.564: DEBUG/AndroidRuntime(469): Shutting down VM 
10-12 11:36:14.584: WARN/dalvikvm(469): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
10-12 11:36:14.624: ERROR/AndroidRuntime(469): FATAL EXCEPTION: main java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example/com.example.MyActivity}: java.lang.ClassNotFoundException: com.example.MyActivity in loader dalvik.system.PathClassLoader[/data/app/com.example-1.apk]

So obviously it can't find FragmentActivity (which is the super of com.example.MyActivity). I just don't know why.

Some things to note:

1) I'm following the tutorials at http://mobile.tutsplus.com/tutorials/android/android-compatibility-working-with-fragments/ which isn't very thorough.

2) I'm pretty sure I'm building the compatibility package into the APK correctly with maven. I installed the jar in my local maven repository and am depending on it with compile. I think that if I weren't building it in correctly it wouldn't be running on the 3.2 emulator.

3) I've tried building with IntelliJ and the maven-compiler-plugin. Same result.

Any help would be greatly appreciated. Thanks.

EDIT... Here's the Manifest

<uses-sdk android:minSdkVersion="4" android:targetSdkVersion="11" />
<uses-permission android:name="android.permission.INTERNET" />

<application android:label="@string/app_name" android:icon="@drawable/icon">
    <activity android:name=".MyActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".TutViewerActivity"
              android:label="@string/app_name" >
    </activity>
</application>
<uses-sdk android:minSdkVersion="7" />

and the MyActivity definition

public class MyActivity extends FragmentActivity implements TutListFragment.OnTutSelectedListener

Answer 1

I had the same issue, and the problem was the compatibility package was not getting included properly. The exception is ambiguous, as it says it can't find the MyActivity, but the full stack trace will show the FragmentActivity that it can't link. Check the scope, and make sure correct version is in your repository, and it is indeed being included at build time.

If you're still having this issue, try including your pom.xml here.

Answer 2

Add the following to MyActivity's imports:

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

Even if you're not using those classes.

Answer 3

I had the same problem, the compatibility package was not built into the apk properly. To achieve that, you can use the following steps:

From developer.android.com:

To add one of the libraries to your Android project:

In your Android project, create a directory named libs at the root of your project (next to src/, res/, etc.)
Locate the JAR file for the library you want to use and copy it into the libs/ directory.

For example, the library that supports API level 4 and up is located at <sdk>/extras/android/support/v4/android-support-v4.jar.
Add the JAR to your project build path.

In Eclipse, right-click the JAR file in the Package Explorer, select Build Path > Add to Build Path.