java - 使用 "requesLocationUpdates()"时出现一些错误

Question

我有一个应用程序，可以向用户显示当前坐标并每 5 米更新一次。但我在调用“requestLocationUpdates”的行中遇到问题，该行位于此行中:

 Location location1 = locationManager.requestLocationUpdates(GpsProvider, 0, MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, mylocationListener);

.

如果我将 Context 作为最后一个参数，我将收到一个错误，告诉我(请注意“GpsTracker”是我的主要 Activity ):

"Cannot resolve method 'requestLocationUpdates(java.lang.String, int, long, com.project.gpstrackerr.GpsTracker)'"

如果我放置位置监听器，我会收到一个错误，其中显示:

Incompatible types.
Required:android.location.Location
Found:void

这是我的 GpsTracker Activity 的完整代码(这是我的主要 Activity)

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.text.SimpleDateFormat;
import java.util.Date;

public class GpsTracker extends Activity
{
    public static final long MINIMUM_DISTANCE_CHANGE_FOR_UPDATES = 1;
    private static final long MINIMUM_TIME_BETWEEN_UPDATES = 20;
    boolean isGPSEnabled = false, isNetworkEnabled = false;
    boolean isGPSEnabled2 = false, isNetworkEnabled2 = false;

    DatabaseTable cn;
    DatabaseManager db = new DatabaseManager(this);
    HttpClass JSONSaver = new HttpClass();
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    Date date = new Date();
    Context context = GpsTracker.this;
    LocationManager locationManager, locationManagerCHECK;
    TextView ET_Coordinates, ET_NU;
    ListView listView;

    //for Coordinates details in Location Listener
    double latitude;
    double longitude;
    String Date;
    //for Getting Coordinates details
    String strLat, strLong, strDate;

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

        //Show Last Known Location
        ShowLastKnownLocation();

        String NetworkProvider = LocationManager.NETWORK_PROVIDER;
        String GpsProvider = LocationManager.GPS_PROVIDER;
        locationManager = (LocationManager) context.getSystemService(LOCATION_SERVICE);
        isGPSEnabled2 = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
        isNetworkEnabled2 = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

    }
    public LocationListener mylocationListener = new LocationListener()
    {
        @Override
        public void onLocationChanged(Location location)
        {

            Date date = new Date();
            Date = dateFormat.format(date);
            latitude = location.getLatitude();
            longitude = location.getLongitude();
        }
        @Override
        public void onStatusChanged(String provider, int status, Bundle extras)
        {
            Toast.makeText(GpsTracker.this, "Provide Status Changed" + "\n"
                            + "Provider: " + provider + "\n"
                            + "Status: " + status + "\n"
                            + "Extras: " + extras + ".",
                    Toast.LENGTH_LONG).show();
        }
        @Override
        public void onProviderEnabled(String provider)
        {
            Toast.makeText(GpsTracker.this,
                    "Provider Turned ON!", Toast.LENGTH_SHORT).show();
        }
        @Override
        public void onProviderDisabled(String provider)
        {
            Toast.makeText(GpsTracker.this,
                    "Provider is OFF!", Toast.LENGTH_SHORT).show();
        }
    };

    protected void showUpdatedLocation(boolean checkGPSEnabled, boolean checkNetworkEnabled, String NetworkProvider, String GpsProvider, LocationManager locationManager)
    {
        if (checkGPSEnabled)
        {
           //I have problem in this Line
            Location location1 = locationManager.requestLocationUpdates(GpsProvider, 0, MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, mylocationListener);

            if (location1 != null)
            {
                Date = dateFormat.format(date);
                latitude = location1.getLatitude();
                longitude = location1.getLongitude();

                db.addContact(new DatabaseTable(Date, latitude, longitude));
                JSONSaver.writeJSON(Date, latitude, longitude);
                showOnTextView(Date, latitude, longitude);
            }
        }
        else if (isNetworkEnabled2)
        {
            Location location1 = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

            if (location1 != null)
            {
                //I have problem in this Line
            Location location1 = locationManager.requestLocationUpdates(NetworkProvider, 0, MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, mylocationListener);

                Date = dateFormat.format(date);
                latitude = location1.getLatitude();
                longitude = location1.getLongitude();

                db.addContact(new DatabaseTable(Date, latitude, longitude));
                JSONSaver.writeJSON(Date, latitude, longitude);
                showOnTextView(Date, latitude, longitude);
            }
        }
    }
}

我想知道我的问题在哪里，我该如何解决它，以及它们中的哪一个(Context 或 LocationListener)更适合用来完成我的工作。

这是我第一次在 Stackoverflow 上提问，所以如果解释有一些缺失或者我不是很清楚或者有其他问题，请随时在评论中询问更多信息，我会尽力尽可能清晰。除此之外，我对编程还很陌生，所以如果你在我的代码中发现一些愚蠢的东西，请不要感到惊讶:D。感谢您的进一步帮助!

Answer 1

错误:不兼容的类型:void 无法转换为 Location。这是运行上面代码时应该得到的实际错误。

您正在等待虚空返回的地方。 requestLocationUpdates 使用 LocationManager 类的 LocationListener 对象来接收有关地理位置的定期更新。

//Implement LocationListener to your class and implement callback methods 
//use the below code at onCreate
//[Changes starts here]
// Get the location manager
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// Define the criteria how to select the locatioin provider -> use default
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);

// Initialize the location fields
if (location != null) {
    System.out.println("Provider " + provider + " has been selected.");
    onLocationChanged(location);
}
//[Changes ends here]

//onLocationChanged method you'll get the updated locatioin
@Override
public void onLocationChanged(Location location) {
    int lat = (int) (location.getLatitude());
    int lng = (int) (location.getLongitude());
}

/* Request updates at startup */
@Override
protected void onResume() {
    super.onResume();
    locationManager.requestLocationUpdates(provider, 400, 1, this);
}

/* Remove the locationlistener updates when Activity is paused */
@Override
protected void onPause() {
    super.onPause();
    locationManager.removeUpdates(this);
}

来源:http://www.vogella.com/tutorials/AndroidLocationAPI/article.html