Question

当我尝试在手机中打开我的应用程序时，它总是说“不幸的是应用程序已停止”有人可以帮我解决这个问题。这是我的代码

我在这里得到错误setUpMapIfNeeded（）;

@Override
protected void onResume() {
    super.onResume();
    setUpMapIfNeeded();
}

如果（mMap == null）{

，我在这里得到错误

     private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            setUpMap();
        }
    }
}

    private void setUpMap() { 
    mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet")); 

     mMap.setMyLocationEnabled(true); 

     LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);   
    Criteria criteria = new Criteria(); 
    String provider = locationManager.getBestProvider(criteria, true);   
    Location myLocation = locationManager.getLastKnownLocation(provider);  
    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);   
     double latitude = myLocation.getLatitude();   
     double longitude = myLocation.getLongitude(); 
     LatLng latLng = new LatLng(latitude, longitude); 
     mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng)); 
    mMap.animateCamera(CameraUpdateFactory.zoomTo(14)); 
    mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located")); 
}

logcat的

 08-20 18:04:40.626  10733-10733/com.example.rontaku.mapsdemo E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.rontaku.mapsdemo, PID: 10733
java.lang.RuntimeException: Unable to resume activity {com.example.rontaku.mapsdemo/com.example.rontaku.mapsdemo.MapsActivity}: java.lang.NullPointerException
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3076)
        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3105)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
        at android.app.ActivityThread.access$900(ActivityThread.java:175)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:146)
        at android.app.ActivityThread.main(ActivityThread.java:5602)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.example.rontaku.mapsdemo.MapsActivity.setUpMapIfNeeded(MapsActivity.java:55)
        at com.example.rontaku.mapsdemo.MapsActivity.onResume(MapsActivity.java:47)
        at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1198)
        at android.app.Activity.performResume(Activity.java:5530)
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3066)

Answer 1

我认为您应该将这些权限添加到您的应用清单文件中。

<uses-permission android:name="android.permission.INTERNET"
      android:name="android.permission.WRITE_EXTERNAL_STORAGE"
      android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"
      android:name="android.permission.ACCESS_COARSE_LOCATION"
      android:name="android.permission.ACCESS_FINE_LOCATION"
      android:name="your_package_name.MAPS_RECEIVE" />

修改

private void setUpMap() { mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet")); mMap.setMyLocationEnabled(true); LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); Criteria criteria = new Criteria(); String provider = locationManager.getBestProvider(criteria, true); Location myLocation = locationManager.getLastKnownLocation(provider); mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); if (myLocation != null) { double latitude = myLocation.getLatitude(); double longitude = myLocation.getLongitude(); LatLng latLng = new LatLng(latitude, longitude); mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng)); mMap.animateCamera(CameraUpdateFactory.zoomTo(14)); mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located")); }

Answer 2

如果您刚刚安装或重新安装了应用程序，getLastKnownLocation（）将返回null，请使用以下代码获取位置

public Location getLocation() {
try {
    locationManager = (LocationManager) mContext
            .getSystemService(LOCATION_SERVICE);

    // getting GPS status
    isGPSEnabled = locationManager
            .isProviderEnabled(LocationManager.GPS_PROVIDER);

    // getting network status
    isNetworkEnabled = locationManager
            .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

    if (!isGPSEnabled && !isNetworkEnabled) {
        // no network provider is enabled
    } else {
        this.canGetLocation = true;
        if (isNetworkEnabled) {
            locationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER,
                    MIN_TIME_BW_UPDATES,
                    MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
            Log.d("Network", "Network Enabled");
            if (locationManager != null) {
                location = locationManager
                        .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                if (location != null) {
                    latitude = location.getLatitude();
                    longitude = location.getLongitude();
                }
            }
        }
        // if GPS Enabled get lat/long using GPS Services
        if (isGPSEnabled) {
            if (location == null) {
                locationManager.requestLocationUpdates(
                        LocationManager.GPS_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("GPS", "GPS Enabled");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
        }
    }

} catch (Exception e) {
    e.printStackTrace();
}

return location;
}

希望这有效

Answer 3

您正在尝试读取最后一个已知位置，假设有一个，但如果没有最后已知位置，该方法可以为空，只需更改为：

private void setUpMap() { 
    mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet")); 
    mMap.setMyLocationEnabled(true); 
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);   
    Criteria criteria = new Criteria(); 
    String provider = locationManager.getBestProvider(criteria, true);   
    Location myLocation = locationManager.getLastKnownLocation(provider);  

    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);   
    if (null != myLocation){
        double latitude = myLocation.getLatitude();   
        double longitude = myLocation.getLongitude(); 
        LatLng latLng = new LatLng(latitude, longitude); 
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng)); 
        mMap.animateCamera(CameraUpdateFactory.zoomTo(14)); 
        mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located"));
    }  
}

谷歌地图当前位置崩溃

3 个答案: