使用 Mapsactivity 时遇到错误（新手）

Question

我无法获取我的位置我不知道为什么我在 google 上尝试了所有东西，因为我是 android 的新手请帮我解决这个问题

package com.parkaspot.najeeb.project;
import java.io.IOException;
import java.util.ArrayList;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {
final String TAG = "MAIN";
ArrayList<RecentData> list;
RecentAdapter recentAdapter;
LinearLayoutManager linearLayoutManager;
RecyclerView recyclerView;
Drawer result;
Toolbar toolbar;
Double lat, lng;
Location location;
SharedPreferences sharedPreferences, sharedPreferences1;
String name, password;
SpotsDialog dialog;

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

    dialog = new SpotsDialog(this,"Loading...", R.style.Loading);

    sharedPreferences = getSharedPreferences("login", Context.MODE_PRIVATE);
    sharedPreferences1 = getSharedPreferences("userDetails", Context.MODE_PRIVATE);

    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    boolean networkEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

    if (networkEnabled) {
        Log.d(TAG,"network is enabled"); //shows successfully
        if ((ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) && (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)) {  
            Log.d(TAG,"permission ******************granted"); //This log Tag Never appears in logcat

            return;
        }
        location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        Log.d(TAG, "Location is initialized"); //shows successfully
    }

    if (location != null) {
        lat = location.getLatitude();
        lng = location.getLongitude();
        Log.d(TAG, "getting latlng values"); //**Never shows
    }else{       //******Always returning NULL HERE****
        Toast.makeText(getBaseContext(),"location returning null",Toast.LENGTH_LONG).show();
        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
        startActivity(intent);
    }

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    list = new ArrayList<>();
    recentAdapter = new RecentAdapter(this, list);

    recyclerView = (RecyclerView) findViewById(R.id.parkingRecyclerView);
    linearLayoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(linearLayoutManager);
    recyclerView.setAdapter(recentAdapter);

    setUpDrawer();
    init();
}


private void setUpDrawer() {
/*
    final PrimaryDrawerItem item1 = new PrimaryDrawerItem().withIdentifier(1).withName("Home");
*/

    final ProfileDrawerItem profile1 = new ProfileDrawerItem().withName("Najeeb Pasha").withEmail("Najeeb@gmail.com");

    final PrimaryDrawerItem item1 = new PrimaryDrawerItem().withName("Search By Location");
    final PrimaryDrawerItem profile = new PrimaryDrawerItem().withName("Your Profile");
    final PrimaryDrawerItem logOut = new PrimaryDrawerItem().withName("Log Out");
    final PrimaryDrawerItem gps = new PrimaryDrawerItem().withName("GPS");

    AccountHeader headerResult = new AccountHeaderBuilder()
            .withActivity(this)
            .withOnAccountHeaderListener(new AccountHeader.OnAccountHeaderListener() {
                @Override
                public boolean onProfileChanged(View view, IProfile profile, boolean current) {
                    startActivity(new Intent(getApplicationContext(), ProfileActivity.class));
                    return false;
                }
            })
            .withCompactStyle(true)
            .withHeaderBackground(R.color.drawer1)
            .withCloseDrawerOnProfileListClick(true)
            .withSelectionListEnabled(false)
            .withTranslucentStatusBar(true)
            .addProfiles(profile1)
            .build();

    result = new DrawerBuilder()
            .withActivity(this)
            .withToolbar(toolbar)
            .withSelectedItem(-1)
            .withRootView(R.id.drawer_container)
            .withDisplayBelowStatusBar(false)
            .withActionBarDrawerToggleAnimated(true)
            .withCloseOnClick(true)
            .withAccountHeader(headerResult)
            .addDrawerItems(
                    item1,
                    profile,
                    logOut,
                    gps,

                    new SectionDrawerItem().withName("Others")
            )
            .withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() {
                @Override
                public boolean onItemClick(View view, int position, IDrawerItem drawerItem) {
                    if (drawerItem == item1) {
                        startActivity(new Intent(getApplicationContext(), MapsActivity.class)
                                .putExtra("url", Constants.getPlaceUrl(lat,lng)));
                    } else if (drawerItem == logOut) {
                        logOut();
                    } else if (drawerItem == profile) {
                        startActivity(new Intent(getApplicationContext(), ProfileActivity.class));
                    }else if (drawerItem == gps) {
                        startActivity(new Intent(getApplicationContext(), GpsActivity.class));
                    }
                    return false;
                }


            })
            .build();

}

private void logOut() {
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.clear();
    editor.apply();

    SharedPreferences.Editor editor1 = sharedPreferences1.edit();
    editor1.clear();
    editor1.apply();

    recreate();
    Intent intent = new Intent(MainActivity.this, SignInActivity.class);
    MainActivity.this.startActivity(intent);

}


public void init() {
    new Load().execute();
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    return super.onOptionsItemSelected(item);
}


@Override
public void onBackPressed() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Are you sure you want to exit?")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    finishAffinity();
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });
    AlertDialog alert = builder.create();
    alert.show();
}

private class Load extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        dialog.show();

    }

    protected Void doInBackground(Void... params) {

        OkHttpClient client = new OkHttpClient.Builder()
                .connectTimeout(60, TimeUnit.SECONDS)
                .writeTimeout(60, TimeUnit.SECONDS)
                .readTimeout(60, TimeUnit.SECONDS)
                .build();

        System.out.println(Constants.getPlaceUrl(lat,lng));

        Request request = new Request.Builder()
                /*.url("http://192.168.0.101/parking/place.php?lat=17.308531&lng=78.5364463")*/
                .url(Constants.getPlaceUrl(lat,lng))
                .build();
        try {
            Response response = client.newCall(request).execute();
            String responseData = response.body().string();

            System.out.println(responseData);

            JSONArray jsonArray = new JSONArray(responseData);


            for (int i = 0; i < jsonArray.length(); i++) {

                JSONObject jsonObject = jsonArray.getJSONObject(i);

                RecentData data = new RecentData(
                        jsonObject.getString("name"),
                        jsonObject.getString("address"),
                        jsonObject.getString("lat"),
                        jsonObject.getString("lng"),
                        jsonObject.getString("distance"),
                        jsonObject.getString("filled"),
                        jsonObject.getString("total"),
                        jsonObject.getString("service"));

                list.add(data);
            }

        } catch (JSONException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        return null;
    }

    protected void onPostExecute(Void aVoid) {
        dialog.hide();
        recentAdapter.notifyDataSetChanged();
    }
}

这总是返回 null 请从头开始帮助我，我不知道如何解决它，我对 android 非常陌生，这是我的大学家庭作业项目，即使使用 gps 或网络供应商。 **请帮我解决这个问题，然后我的项目就会完成。

Returning location as Null
Iam a Newbie;
please reply me the whole code with change please.request(Noob) Thank u very much sir

Answer 1

为了获取位置，您需要使用位置管理器上的方法 requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener) 请求位置更新。

创建一个将打印数据的侦听器，例如：

requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 10, new LocationListener(){  
    @Override 
    public void onLocationChanged(Location location){
        Log.d("LOCATION", location.toString());
    }
});

这将要求位置管理器每 1000 毫秒 (1s) 向我提供一次，如果我从上一个位置移动 10m 一个新位置。

使用 Mapsactivity 时遇到错误（新手）

Facing Error working with Mapsactivity (Newbie)

java

maps

android

geolocation

currentlocation