我在设备中运行当前的android项目时遇到了一些麻烦。该项目没有构建错误（使用ecplise），但是当我运行时会发生此错误：
12-22 11:31:18.064: E/AndroidRuntime(10283): FATAL EXCEPTION: main
12-22 11:31:18.064: E/AndroidRuntime(10283): java.lang.RuntimeException: Unable to start activity ComponentInfo{br.trocatela.com/br.trocatela.com.GoogleMapsActivity}: java.lang.NullPointerException
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2295)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread.access$700(ActivityThread.java:159)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.os.Handler.dispatchMessage(Handler.java:99)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.os.Looper.loop(Looper.java:176)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread.main(ActivityThread.java:5419)
12-22 11:31:18.064: E/AndroidRuntime(10283): at java.lang.reflect.Method.invokeNative(Native Method)
12-22 11:31:18.064: E/AndroidRuntime(10283): at java.lang.reflect.Method.invoke(Method.java:525)
12-22 11:31:18.064: E/AndroidRuntime(10283): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
12-22 11:31:18.064: E/AndroidRuntime(10283): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
12-22 11:31:18.064: E/AndroidRuntime(10283): at dalvik.system.NativeStart.main(Native Method)
12-22 11:31:18.064: E/AndroidRuntime(10283): Caused by: java.lang.NullPointerException
12-22 11:31:18.064: E/AndroidRuntime(10283): at br.trocatela.com.GoogleMapsActivity.onCreate(GoogleMapsActivity.java:68)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.Activity.performCreate(Activity.java:5372)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
12-22 11:31:18.064: E/AndroidRuntime(10283): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2257)
12-22 11:31:18.064: E/AndroidRuntime(10283): ... 11 more
我的课是：
package br.trocatela.com;
import java.util.List;
import android.content.Context;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;
public class GoogleMapsActivity extends MapActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
Intent intent = getIntent();
String lat1 = intent.getStringExtra("lat");
String longt = intent.getStringExtra("longt");
LocationManager LM = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
String bestProvider = LM.getBestProvider(new Criteria(),true);
//System.out.println("*************"+LM.getBestProvider(new Criteria(),true));
Location l = LM.getLastKnownLocation(bestProvider);
//Toast.makeText(this, "lat"+lat1, Toast.LENGTH_SHORT).show();
//Toast.makeText(this, "longt"+longt, Toast.LENGTH_SHORT).show();
// Displaying Zooming controls
MapView mapView = (MapView) findViewById(R.id.map_view);
mapView.setBuiltInZoomControls(true);
/**
* Changing Map Type
* */
mapView.setSatellite(true); // Satellite View
// mapView.setStreetView(true); // Street View
// mapView.setTraffic(true); // Traffic view
/**
* showing location by Latitude and Longitude
* */
MapController mc = mapView.getController();
double lat = Double.parseDouble(lat1);
double lon = Double.parseDouble(longt);
double lat2=l.getLatitude();
double long2=l.getLongitude();
Toast.makeText(this, "Encontra se a "+ lat2+ "º de latitude", Toast.LENGTH_SHORT).show();
Toast.makeText(this, "Encontra se a "+ long2+ "º de longitude", Toast.LENGTH_SHORT).show();
GeoUtils g = new GeoUtils();
GeoCoordinate g1 = new GeoCoordinate(lat, lon);
GeoCoordinate g2 = new GeoCoordinate(lat2, long2);
double dist= g.geoDistanceInKm(g1, g2);
Toast.makeText(this, "Voce Encontra se a "+ dist+ "km do local pretendido", Toast.LENGTH_SHORT).show();
GeoPoint geoPoint = new GeoPoint((int)(lat * 1E6), (int)(lon * 1E6));
mc.animateTo(geoPoint);
mc.setZoom(15);
mapView.invalidate();
/**
* Placing Marker
* */
List<Overlay> mapOverlays = mapView.getOverlays();
Drawable drawable = this.getResources().getDrawable(R.drawable.mark_red);
AddItemizedOverlay itemizedOverlay =
new AddItemizedOverlay(drawable, this);
OverlayItem overlayitem = new OverlayItem(geoPoint, "Hello", "Sample Overlay item");
itemizedOverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedOverlay);
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
}
map.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=
"http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<com.google.android.maps.MapView
android:id="@+id/map_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:enabled="true"
android:clickable="true"
android:apiKey="0CZ0aW7qB1Q__jlO6qkhl3IfFJTwGvwYUv7VDTQ"
/>
</LinearLayout>
类MainActivity放在我项目中的正确目录中（与其他项目一样，运行没有问题）。
任何人都可以看到我在这里缺少的东西吗？
答案 0 :(得分：1)
检查LM.getLastKnownLocation(bestProvider)是否未返回null;