Java 我的getLocation方法始终返回null

我正在制作一个应用程序来获取用户位置并将其显示在谷歌地图上，但由于getLocation方法返回空值，应用程序总是崩溃，有人能告诉我问题出在哪里吗

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.getyourlocation">

<!--
     The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
     Google Maps Android API v2, but you must specify either coarse or fine
     location permissions for the 'MyLocation' functionality. 
-->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <!--
         The API key for Google Maps-based APIs is defined as a string resource.
         (See the file "res/values/google_maps_api.xml").
         Note that the API key is linked to the encryption key used to sign the APK.
         You need a different API key for each encryption key, including the release key that is used to
         sign the APK for publishing.
         You can define the keys for the debug and release targets in src/debug/ and src/release/. 
    -->
    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

    <activity
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

}

这是我的MapsActivity.java

package com.example.android.getyourlocation;

import android.location.Location;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsActivity extends FragmentActivity implements 
OnMapReadyCallback {

private GoogleMap mMap;

private Location mLocation;
private GpsManager mGpsManager;

double latitude;
double longitude;

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

    mGpsManager = new GpsManager(getApplicationContext());
    mLocation = mGpsManager.getLocation();


    latitude = mLocation.getLatitude();
    longitude = mLocation.getLongitude();

    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}


/**
 * Manipulates the map once available.
 * This callback is triggered when the map is ready to be used.
 * This is where we can add markers or lines, add listeners or move the camera. In this case,
 * we just add a marker near Sydney, Australia.
 * If Google Play services is not installed on the device, the user will be prompted to install
 * it inside the SupportMapFragment. This method will only be triggered once the user has
 * installed Google Play services and returned to the app.
 */
@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng myLocation = new LatLng(latitude, longitude);
    mMap.addMarker(new MarkerOptions().position(myLocation).title("I Am Here"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(myLocation));
}

---

}

使用新的API，您可以尝试以下操作

build.gradle

implementation 'com.google.android.gms:play-services-location:11.6.0'

GpsManager.java

public class GpsManager extends LocationCallback {

    private FusedLocationProviderClient client;
    private Callback callback;

    public interface Callback {
        void onLocation(Location location);
    }

    public boolean start(Context context, Callback callback) {
        this.callback = callback;
        client = LocationServices.getFusedLocationProviderClient(context);
        if (!checkLocationPermission(context)) return false;
        client.requestLocationUpdates(getLocationRequest(), this, null);
        return true;
    }

    public void stop() {
        client.removeLocationUpdates(this);
    }

    @Override
    public void onLocationResult(LocationResult locationResult) {
        for (Location location : locationResult.getLocations()) {
            callback.onLocation(location);
        }
    }

    private boolean checkLocationPermission(Context context) {
        int permissionCheck = ContextCompat.checkSelfPermission(
                context, android.Manifest.permission.ACCESS_FINE_LOCATION);
        return permissionCheck == PackageManager.PERMISSION_GRANTED;
    }

    private LocationRequest getLocationRequest() {
        return LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(30_000L)
                .setFastestInterval(20_000L);
    }
}

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GpsManager.Callback  {

    private static final int PERMISSION_REQUEST_FINE_LOCATION = 1;
    private GpsManager mGpsManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        mGpsManager = new GpsManager(getApplicationContext(), this);

        // check if user gave permissions, otherwise ask via dialog
        if (!checkPermission()) {
            getLocationPermissions();
            return;
        }

        mGpsManager.start();
        ...
    }

    @Override
    protected void onStop() {
        super.onStop();
        mGpsManager.stop();
    }

    @Override
    public void onLocation(Location location) {
        // do something with your location
    }

    // CHECK PERMISSIONS PART

    private boolean checkPermission() {
        return isGranted(ActivityCompat.checkSelfPermission(this, ACCESS_FINE_LOCATION)) &&
                isGranted(ActivityCompat.checkSelfPermission(this, ACCESS_COARSE_LOCATION));
    }

    @TargetApi(Build.VERSION_CODES.M)
    private void getLocationPermissions() {
        requestPermissions(new String[] {Manifest.permission.ACCESS_FINE_LOCATION},
                PERMISSION_REQUEST_FINE_LOCATION);
    }

    @Override
    public void onRequestPermissionsResult(int code, @Nullable String permissions[], @Nullable int[] results) {
        switch (code) {
            case PERMISSION_REQUEST_FINE_LOCATION:
                if (isPermissionGranted(results)) {
                    getLocationRequest();
                }
        }
    }

    private boolean isPermissionGranted(int[] results) {
        return results != null && results.length > 0 && isGranted(results[0]);
    }

    private boolean isGranted(int permission) {
        return permission == PackageManager.PERMISSION_GRANTED;
    }
}

。。。然后像这样将其附加到您的

活动中

MapsActivity.java

public class GpsManager extends LocationCallback {

    private FusedLocationProviderClient client;
    private Callback callback;

    public interface Callback {
        void onLocation(Location location);
    }

    public boolean start(Context context, Callback callback) {
        this.callback = callback;
        client = LocationServices.getFusedLocationProviderClient(context);
        if (!checkLocationPermission(context)) return false;
        client.requestLocationUpdates(getLocationRequest(), this, null);
        return true;
    }

    public void stop() {
        client.removeLocationUpdates(this);
    }

    @Override
    public void onLocationResult(LocationResult locationResult) {
        for (Location location : locationResult.getLocations()) {
            callback.onLocation(location);
        }
    }

    private boolean checkLocationPermission(Context context) {
        int permissionCheck = ContextCompat.checkSelfPermission(
                context, android.Manifest.permission.ACCESS_FINE_LOCATION);
        return permissionCheck == PackageManager.PERMISSION_GRANTED;
    }

    private LocationRequest getLocationRequest() {
        return LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(30_000L)
                .setFastestInterval(20_000L);
    }
}

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GpsManager.Callback  {

    private static final int PERMISSION_REQUEST_FINE_LOCATION = 1;
    private GpsManager mGpsManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        mGpsManager = new GpsManager(getApplicationContext(), this);

        // check if user gave permissions, otherwise ask via dialog
        if (!checkPermission()) {
            getLocationPermissions();
            return;
        }

        mGpsManager.start();
        ...
    }

    @Override
    protected void onStop() {
        super.onStop();
        mGpsManager.stop();
    }

    @Override
    public void onLocation(Location location) {
        // do something with your location
    }

    // CHECK PERMISSIONS PART

    private boolean checkPermission() {
        return isGranted(ActivityCompat.checkSelfPermission(this, ACCESS_FINE_LOCATION)) &&
                isGranted(ActivityCompat.checkSelfPermission(this, ACCESS_COARSE_LOCATION));
    }

    @TargetApi(Build.VERSION_CODES.M)
    private void getLocationPermissions() {
        requestPermissions(new String[] {Manifest.permission.ACCESS_FINE_LOCATION},
                PERMISSION_REQUEST_FINE_LOCATION);
    }

    @Override
    public void onRequestPermissionsResult(int code, @Nullable String permissions[], @Nullable int[] results) {
        switch (code) {
            case PERMISSION_REQUEST_FINE_LOCATION:
                if (isPermissionGranted(results)) {
                    getLocationRequest();
                }
        }
    }

    private boolean isPermissionGranted(int[] results) {
        return results != null && results.length > 0 && isGranted(results[0]);
    }

    private boolean isGranted(int permission) {
        return permission == PackageManager.PERMISSION_GRANTED;
    }
}

现在，您必须确保在您的应用程序中拥有所有权限

AndroidManifest.xml

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

<uses-feature android:name="android.hardware.location.gps" />
<uses-feature android:name="android.hardware.location.network" />

希望有帮助

尝试更新Google Play服务

添加到gradle，

classpath'com.google.android.gms:play services位置：11.8.0'

maven{url”https://maven.google.com“}

，将其添加到所有项目->存储库中

添加

实现'com.google.android.gms:play services location:11.8.0'

build.gradle（Modeule.app）的内部依赖项

---

另一个androidhive所谓的受害者tutorial@Selvin那是肯定的。很好。