Android Unable to instantiate activity: Didn't find class on path

Question

I've imported project into eclipse and when I try to run it, then this exception is thrown:

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.polygraf/com.polygraf.activity.Dashboard}: java.lang.ClassNotFoundException: Didn't find class "com.polygraf.activity.Dashboard" on path: /data/app/com.polygraf-1.apk

I've tried to clean the project, then check if all class names and manifest are ok, but still can't find why this happens. Can you help me a little please?

Dashbard class:

public class Dashboard extends FragmentActivity {

private static final String WELCOME_TYPE = "WELCOME_TYPE";
private static final String HELP_TYPE = "HELP_TYPE";

public static final String ADRESS_CONTENT = "ADRESS_CONTENT";
public static final String DOC_NAME = "DOC_NAME";

private Transcript mContent;
private ISettableContent mListOfDocument;

private String mAddress;

private String mDocName;

public Dashboard() {
}

/** Called with the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.dashboard);

    boolean content = false;
    // View gc = (NoSaveStateFrameLayout)
    // findViewById(R.id.content_fragment);
    //

    Fragment frContent = getSupportFragmentManager().findFragmentById(R.id.content_fragment);
    mContent = ((IGetContent) frContent).getContent();
    TranscriptSetting cc = Polygraf.getInstance().getContentSetting();

    Fragment frDocumentsList = getSupportFragmentManager().findFragmentById(R.id.documents);
    mListOfDocument = (ISettableContent) frDocumentsList;
    cc.registerContent(mListOfDocument);

    if (getIntent().hasExtra(ADRESS_CONTENT)) {
        mAddress = getIntent().getStringExtra(ADRESS_CONTENT);
        mDocName = getIntent().getStringExtra(DOC_NAME);
        mContent.setAddress(mAddress, mDocName);
        content = true;
    } else if (getIntent().hasExtra(WELCOME_TYPE)) {
        content = true;
        prepareVisibilityBtnTranscript();
    } else if (getIntent().hasExtra(HELP_TYPE)) {
        content = true;
        mContent.showHelp();

    }

    if (content) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.hide(frDocumentsList);
        ft.commit();

        // because on diferent layouts for small and large device
        // some views missing, so the test is inportant
        View contentLayout = findViewById(R.id.contentLayout);
        if (contentLayout != null) {
            contentLayout.setVisibility(View.VISIBLE);
        }
        prepareVisibilityBtnWelcome();
        // cp.setContent(mContent);
    }

    cc.registerContent(mContent);
    // cp.setListener(cc);

}
    .
    .
    .
}

And manifest file:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

<uses-sdk
    android:minSdkVersion="7"
    android:targetSdkVersion="17" />

<application
    android:name=".Polygraf"
    android:allowBackup="true"
    android:hardwareAccelerated="true"
    android:icon="@drawable/icon"
    android:label="@string/skeleton_app"
    android:theme="@android:style/Theme.Black.NoTitleBar" >
    <activity
        android:name="com.polygraf.activity.Dashboard"
        android:configChanges="orientation|keyboard" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <!-- This places this activity into the main app list. -->
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name="com.polygraf.activity.SettingActivity"
        android:label="@string/skeleton_app" />
    <activity
        android:name="com.polygraf.activity.ContentActivity"
        android:label="@string/skeleton_app" >
    </activity>
    <activity
        android:name="com.polygraf.activity.PlayVideo"
        android:configChanges="orientation|keyboard"
        android:label="@string/skeleton_app" />
</application>

Answer 1

I suppose you're using Eclipse. Your activity is there alright, but Eclipse didn't include the support package in the APK ... If you look above your error in stacktrace you will notice the root of your problem: "Unable to find FragmentActivity". Or you can unpack the apk, undex it and you will see the compatibility package classes were not included.

To fix this, right-click your project, properties, build path and go to export tab. There make sure "Android private libraries" are checked. A clean and rebuild should put you on track ...