java - ANDROID:在其他类中获取经纬度，但值变为0.0

Question

我有两个类..First.java 和 Second.java，

在第一类中.. 纬度、经度和地址在 TextView 中正确显示。但在第二类中，纬度和经度变为 0.0 ，地址变为 null。

谁能帮我解释一下为什么？

这是 First.java 的代码

public class First extends Activity {
private Context context=null;
AppLocationService appLocationService;


String address;
double latitude;
double longitude;


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

    context=this;
    appLocationService = new AppLocationService(First.this);

    btngetLocation=(Button)findViewById(R.id.button_getLocation);

    btngetLocation.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {

            // getting GPS status
            boolean isGPSEnabled = appLocationService
                    .getStatus(LocationManager.GPS_PROVIDER);
            // getting network status
            boolean isNetworkEnabled = appLocationService
                    .getStatus(LocationManager.NETWORK_PROVIDER);

            if( isGPSEnabled==false && isNetworkEnabled==false){
                showSettingsAlert("Location Service");                  
            }
            else {
                Toast.makeText(
                        getApplicationContext(),
                        "Attempt to get location...Please Wait.. ",
                        Toast.LENGTH_LONG).show();
                if( isNetworkEnabled ==true ){
                Location nwLocation = appLocationService
                            .getLocation(LocationManager.NETWORK_PROVIDER);
                    if (nwLocation == null){
                        Toast.makeText(
                                getApplicationContext(),
                                "Network bermasalah.. Pastikan Anda terkoneksi Internet, dan coba get Location lagi",
                                Toast.LENGTH_LONG).show();
                    }
                    else {
                     latitude = nwLocation.getLatitude();
                     longitude = nwLocation.getLongitude();

                    Toast.makeText(
                            getApplicationContext(),
                            "Mobile Location (NW): \nLatitude: " + latitude
                                    + "\nLongitude: " + longitude,
                            Toast.LENGTH_LONG).show();
                    }
                }
                else {
                    Location gpsLocation = appLocationService
                            .getLocation(LocationManager.GPS_PROVIDER);
                    if (gpsLocation == null){
                        Toast.makeText(
                                getApplicationContext(),
                                "GPS bermasalah.. Silahkan di ruangan terbuka atau aktifkan network provider Anda, dan coba get Location lagi",
                                Toast.LENGTH_LONG).show();
                    }
                    else {
                    latitude = gpsLocation.getLatitude();
                    longitude = gpsLocation.getLongitude();
                    Toast.makeText(
                            getApplicationContext(),
                            "Mobile Location (GPS): \nLatitude: " + latitude
                                    + "\nLongitude: " + longitude,
                            Toast.LENGTH_LONG).show();
                        }
                }
            }               

        }
    });

}


public class AppLocationService extends Service implements LocationListener{
    protected LocationManager locationManager;
    Location location;


    private static final long MIN_DISTANCE_FOR_UPDATE = 10; //10 meter
    private static final long MIN_TIME_FOR_UPDATE = 1000 * 60 * 3; //3 menit

    public AppLocationService(Context context) {
        locationManager = (LocationManager) context
                .getSystemService(LOCATION_SERVICE);
    }

    public boolean getStatus(String provider){
        return locationManager.isProviderEnabled(provider); / 
    }

    public Location getLocation(String provider) {
                  MIN_TIME_FOR_UPDATE, MIN_DISTANCE_FOR_UPDATE, this);
            if (locationManager != null) {
                location = locationManager.getLastKnownLocation(provider);
                locationManager.removeUpdates(this);
                return location;
            }

        return null;
    }

    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub
    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub
    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }
}

public  String getAddress(Context ctx, double latitude, double longitude) {
   // StringBuilder result = new StringBuilder();
    String alamat=null;
    try {
        Geocoder geocoder = new Geocoder(ctx, Locale.getDefault());
        List<Address> addresses = geocoder.getFromLocation(latitude, longitude, 1);
        if (addresses.size() > 0) {
            Address address = addresses.get(0);
            String jalan = (address.getAddressLine(0));
            String locality=address.getLocality();
            String country=address.getCountryName();
            String country_code=address.getCountryCode();
            String zipcode=address.getPostalCode();

            alamat = jalan +", "+ locality +", "+ country+", " + country_code+", " + zipcode;

        }
    } catch (IOException e) {
        Log.e("tag", e.getMessage());
    }

    return alamat; 
}



public double getLatitude(){
    return latitude;
}

public double getLongitude(){
    return longitude;
}


public String getAlamat(){
    return address;
}

这是第二个。 java

public class Second extends Activity{

AddLocation data_dr_location;

 Double latitude;
 Double longitude;
 String address;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.add_description);

    data_dr_location = new AddLocation(); 

    address= data_dr_location.getAlamat();
    latitude = data_dr_location.getLatitude();
    longitude = data_dr_location.getLongitude(); }

Answer 1

在你的第一个java中，只有getter方法，没有setter方法!

private double latitude;
private double longitude;
private String address;

public double getLatitude(){
    return latitude;
}

public double getLongitude(){
    return longitude;
}


public String getAlamat(){
    return address;
}

/*  THE BELOW SETTER METHODS ARE MISSING IN YOUR CODE.*/
public void setLatitude(double latitude){
    this.latitude = latitude;
}

public void setLongitude(double longitude){
    this.longitude=longitude;
}


public setAlamat(String address){
    this.address=address;
}

在适当的位置(例如您获得纬度/经度/地址的任何位置)，添加这些行。

 latitude = nwLocation.getLatitude();
     setLatitude (latitude);
 longitude = nwLocation.getLongitude();
     setLongitude (longitude);