Question

我正在尝试使用GoogleApiClient查找设备的最后已知位置，因此我使用了精细级别访问，但因为位置来自null而获得以下异常。

    E/AndroidRuntime: FATAL EXCEPTION: main
        Process: com.example.kuldeep.location2, PID: 1421
            java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference
                at com.example.kuldeep.location2.MainActivity.onConnected(MainActivity.java:51)

                private GoogleApiClient mGoogleApiClient;

                @Override
                protected void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.activity_main);

                    mGoogleApiClient = new GoogleApiClient.Builder(this)
                        .addConnectionCallbacks(this)
                        .addOnConnectionFailedListener(this)
                        .addApi(LocationServices.API)
                        .build();
                }

                @Override
                protected void onStart() {
                    mGoogleApiClient.connect();
                    super.onStart();
                }

                @Override
                protected void onStop() {
                    mGoogleApiClient.disconnect();
                    super.onStop();
                }

                @Override
                public void onConnected(Bundle bundle) {

                    try {
                        Location mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
                            mGoogleApiClient);
                        Toast.makeText(this, mLastLocation.getLatitude() + ", " + mLastLocation.getLongitude(), Toast.LENGTH_SHORT);
                    } catch (SecurityException e){
                        e.printStackTrace();
                    }
                }

我的清单文件如下：

        <?xml version="1.0" encoding="utf-8"?>
        <manifest xmlns:android="http://schemas.android.com/apk/res/android"
            package="com.example.kuldeep.location2">

            <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
        </manifest>

Answer 1

首先，getLastLocation（）可以为null，因此您可以小心地直接访问mLastLocation而不进行“null”检查。第二，我建议你添加你的清单：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

然后调用LocationRequest。

if(locRequest== null)
{
    locRequest= new LocationRequest();
    locRequest.setInterval( interval );
    locRequest.setFastestInterval( fastestInterval );
    locRequest.setPriority( priority );

    LocationServices.FusedLocationApi.requestLocationUpdates(yourGoogleApiClient, locRequest, this);
}

Answer 2

使用 GoogleApiClient 找到类似以下的CurrentLocation：

private GoogleApiClient googleApiClient;
private Location mLastLocation;

                @Override
                protected void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.activity_main);

                    isCheckLocationServiceisOn(context);

                    if(googleApiClient == null) {
                    googleApiClient = new GoogleApiClient.Builder(this)
                   .addConnectionCallbacks(this)
                   .addOnConnectionFailedListener(this)
                   .addApi(LocationServices.API)
                   .build();
        }

                @Override
                protected void onStart() {
                    mGoogleApiClient.connect();
                    super.onStart();
                }

                @Override
                protected void onStop() {
                    mGoogleApiClient.disconnect();
                    super.onStop();
                }


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

              @Override
              public void onConnected(Bundle arg0) {

             if(googleApiClient.isConnected()) {
              mLastLocation = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);

            if (mLastLocation != null) {
                System.out.println("latiTude....."+ String.valueOf(mLastLocation.getLatitude()));
                System.out.println("longiTude....."+ String.valueOf(mLastLocation.getLongitude()));
            }   
        }
    }

    @Override
    public void onConnectionFailed(ConnectionResult arg0) {
        System.out.println("onConnectionFailed...."+ arg0.toString());
    }


    @Override
    public void onConnectionSuspended(int arg0) {
        System.out.println("onConnectionSuspended...."+ arg0);
    }

在清单中添加权限：

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

在这里，

为支持的覆盖方法实现 ConnectionCallbacks ， OnConnectionFailedListener 接口，它们必须 com.google.android.gms.common.api.GoogleApiClient < / em> 包。

必须记住：

如果没有，则必须在设备中启用Wi-Fi和GSM和GPS，然后在 onConnected（）
中生成这类错误
我给你代码检查＆amp;开放式服务也是：

public static void isCheckLocationServiceisOn (final Context context) { LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE); boolean gps_enabled = false; boolean network_enabled = false; try { gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER); } catch(Exception ex) {} try { network_enabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER); } catch(Exception ex) {} if(!gps_enabled && !network_enabled) { // notify user AlertDialog.Builder dialog = new AlertDialog.Builder(context); dialog.setMessage("Location Services Disabled. \n Please enable location services."); dialog.setPositiveButton("Enable", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface paramDialogInterface, int paramInt) { Intent myIntent = new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS); context.startActivity(myIntent); //get gps } }); dialog.setNegativeButton("Cancle", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface paramDialogInterface, int paramInt) { } }); dialog.show(); } }

android location apis：FusedLocationApi.getLastLocation给出null

2 个答案: