Recently, there is a function to locate the current city in the project. At the beginning, I chose to use Baidu map api to develop this function. However, according to the code written in the development document provided by Baidu map, the obtained city location is null every time I run. Strangely, I can get the longitude and latitude of the current location again. Therefore, I found many blogs on csdn to find solutions, and found that the obtained city value is still null, Choose Gaode map decisively in the back.

Let's share how I realize this function

Official website of Gaode map developer: http://developer.amap.com/
Development documentation: http://developer.amap.com/api/android-sdk/summary/

1. Go to Gaode developer platform to create applications and create key s

Register a key on the official website of Gaode map developer (Note: a key can only correspond to one project)
SHA1 code acquisition method
packname is the package name of the project

2. Manually add the jar package of Gaode map

stay Gaode map api official website Download the relevant jar package (I have only one location function)

After adding, remember to right-click and select Add As Library to manually add the jar package to the dependent library

3. Create the jniLibs directory under the main directory

Add so Library
Note: only 3D maps need to add so library, and 2D maps do not need this step

4. Androidmanifest in AS Add the corresponding key in the application tag of the XML configuration file

		<!-- Cartographic key -->
        <meta-data
            android:name="com.amap.api.v2.apikey"
            android:value="Yours key">
        </meta-data>

5. Add corresponding permissions (including static permissions and dynamic permissions)

You can open the permission of the application through another blog: How to enable dynamic permissions
(Note: you can add corresponding permissions according to your own items)

6. Get the current location (do not display the map, only display the current location)

public class MainActivity extends AppCompatActivity {

    //Declare AMapLocationClient class object
    AMapLocationClient mLocationClient = null;
    //Declare AMapLocationClientOption object
    public AMapLocationClientOption mLocationOption = null;

    private TextView mTextViewLocation;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextViewLocation = findViewById(R.id.textView_location);

        //Get current location information
        getCurrentLocationLatLng();
    }

    /**
     * Initialize location and set location callback listening
     */
    private void getCurrentLocationLatLng() {
        //Initialize positioning
        mLocationClient = new AMapLocationClient(getApplicationContext());
        //Set location callback listening
        mLocationClient.setLocationListener(mLocationListener);
        //Initialize the AMapLocationClientOption object
        mLocationOption = new AMapLocationClientOption();

        // At the same time, network positioning and GPS positioning are used to give priority to returning the positioning results with the highest accuracy and the corresponding address description information
        mLocationOption.setLocationMode(AMapLocationClientOption.AMapLocationMode.Hight_Accuracy);
        //Set the positioning interval in milliseconds. The default is 2000ms and the minimum is 1000ms. The default minimum time interval of continuous positioning and cutting is 1000ms
        mLocationOption.setInterval(3500);
        //Set positioning parameters for positioning client objects
        mLocationClient.setLocationOption(mLocationOption);
    }


    /**
     * Locate callback listener
     */
    public AMapLocationListener mLocationListener = new AMapLocationListener() {
        @Override
        public void onLocationChanged(AMapLocation amapLocation) {
            if (amapLocation != null) {
                if (amapLocation.getErrorCode() == 0) {
                    //Locate the callback information successfully and set relevant messages
                    //Obtain the source of current positioning results, such as network positioning results. See the positioning type table for details
                    amapLocation.getLocationType();
                    //Get latitude
                    double currentLat = amapLocation.getLatitude();
                    //Get longitude
                    double currentLon = amapLocation.getLongitude();
                    //Get current city location
                    mTextViewLocation.setText(amapLocation.getCity());
                    Log.i("currentLocation", "currentLat : " + currentLat + " currentLon : " + currentLon);
                    //Get accuracy information
                    amapLocation.getAccuracy();
                } else {
                    //The error message is displayed. ErrCode is the error code and errInfo is the error message. See the error code table for details.
                    Log.e("AmapError", "location Error, ErrCode:"
                            + amapLocation.getErrorCode() + ", errInfo:"
                            + amapLocation.getErrorInfo());
                }
            }
        }
    };


    @Override
    protected void onStart() {
        super.onStart();
        if (mLocationClient != null) {
            // Start positioning
            mLocationClient.startLocation();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (mLocationClient != null) {
            //Stop positioning
            mLocationClient.stopLocation();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mLocationClient != null) {
            //Destroy location client
            mLocationClient.onDestroy();
        }
    }

}

After completing the above operations, you can obtain the current location information.

reference resources: Official development document of Gaode map