Android映射api v2。无法实例化活动

Question

错误： java.lang.RuntimeException：无法在loader dalvik.system中实例化活动ComponentInfo {com.example.my_map / com.example.my_map.activities.MainActivity}：java.lang.ClassNotFoundException：com.example.my_map.activities.MainActivity。 PathClassLoader [/data/app/com.example.my_map-1.apk]

主要活动

package com.example.my_map;

import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;

import android.os.Bundle;
import android.widget.FrameLayout;

public class MainActivity extends SherlockFragmentActivity {

    private FrameLayout frameMap;
    private GoogleMap myMap;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        frameMap = (FrameLayout) findViewById(R.id.frame_map);
        SupportMapFragment mapFragment = SupportMapFragment.newInstance();
        getSupportFragmentManager().beginTransaction().add(R.id.frame_map , mapFragment , "MAP").commit();
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        myMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentByTag("MAP")).getMap();

        myMap.setMyLocationEnabled(true);
        myMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
    }
}

清单

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.my_map"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15"/>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"></uses-permission>
    <permission android:name="com.example.my_map.permission.MAPS_RECEIVE" android:protectionLevel="signature"></permission>
    <uses-feature android:glEsVersion="0x00020000" android:required="true">
    </uses-feature>

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="BLABLABLA" />
    </application>

   

</manifest>

XML活动

<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" >

     <framelayout  
        android:id="@+id/frame_map" 
        android:layout_height="match_parent" 
        android:layout_width="match_parent"> 
     </framelayout>

</RelativeLayout>