android类没找到异常

Question

我正在制作一个googlemap应用程序，其中我在设备中显示地图，它工作正常，但现在我想显示两个城市之间的距离，它给我的类没有找到例外。我正在使用片段活动进行应用，我想画两个城市之间的路径。但是我得到了例外

     public class MainActivity extends FragmentActivity  implements RoutingListener{
    private GoogleMap _googleMap=null;
      protected LatLng start;
        protected LatLng end;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            try
            {
                //loading map
                initilizeMap();
                _googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

                _googleMap.setMyLocationEnabled(true);       

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
   private void initilizeMap() {
            if(_googleMap==null)
            {
                _googleMap = ((SupportMapFragment)  getSupportFragmentManager().findFragmentById(
                        R.id.map)).getMap(); 
            CameraUpdate center=CameraUpdateFactory.newLatLng(new LatLng(18.013610,-77.498803));
                CameraUpdate zoom=  CameraUpdateFactory.zoomTo(15);
                  _googleMap.moveCamera(center);
                _googleMap.animateCamera(zoom);

                start = new LatLng(18.015365, -77.499382);
                end = new LatLng(18.012590, -77.500659);

                Routing routing = new Routing(Routing.TravelMode.WALKING);
                routing.registerListener(this);
                routing.execute(start, end);
             if (_googleMap == null) {
                    Toast.makeText(getApplicationContext(),
                            "Sorry!  map cannot be created", Toast.LENGTH_SHORT)
                            .show();
                }
            }

        }

       @Override
        public void onRoutingFailure() {
            // TODO Auto-generated method stub

        }
    @Override
        public void onRoutingStart() {
        }
      @Override
        public void onRoutingSuccess(PolylineOptions mPolyOptions) {
              PolylineOptions polyoptions = new PolylineOptions();
              polyoptions.color(Color.BLUE);
              polyoptions.width(10);
              polyoptions.addAll(mPolyOptions.getPoints());
              _googleMap.addPolyline(polyoptions);

              // Start marker
              MarkerOptions options = new MarkerOptions();
              options.position(start);
              options.icon(BitmapDescriptorFactory.fromResource(R.drawable.start_blue));
              _googleMap.addMarker(options);

              // End marker
              options = new MarkerOptions();
              options.position(end);
              options.icon(BitmapDescriptorFactory.fromResource(R.drawable.end_green));  
              _googleMap.addMarker(options);
            }
    }




  here is maniefestfile

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

    <permission
        android:name="com.example.demo.permission.MAPS_RECEIVE"
        android:protectionLevel="signature" />

    <uses-permission android:name="info.androidhive.googlemapsv2.permission.MAPS_RECEIVE" />

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <!-- Required to show current location -->
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <!-- Required OpenGL ES 2.0. for Maps V2 -->
    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <!-- Requires OpenGL ES version 2 -->
    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

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

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!-- Goolge API Key -->
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="AIzaSyAw2l6gw-SmJZZ9LlsFA49OR3L7CT7vFSM" />
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
    </application>

</manifest>