ANDROID：在其他类中获取纬度和经度，但值变为0.0答案

【问题标题】：ANDROID: getting latitude&longitude in other class, but the value become 0.0ANDROID：在其他类中获取纬度和经度，但值变为0.0
【发布时间】：2014-08-05 05:29:21
【问题描述】：

我有两个类.. First.java 和 Second.java，

在 First class.. 纬度、经度和地址在 TextView 中正确显示。但是在第二类中，经纬度变为 0.0 ，地址变为空。

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。爪哇

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(); }

【问题讨论】：

您正在初始化一个新实例 data_dr_location = new AddLocation();并获取位置、纬度和经度，因此它显然是 0。您实际上需要使用意图将数据从 class1 传递到 class2。我假设这两个类都是活动类。
@RajenRaiyarela：谢谢.. 是的，两个课程都是活动课程。但是当我删除 data_dr_location = new AddLocation(); ，第二节课崩溃了。还有什么问题吗？
@NishanthiGrashia 我没有找到标记。对不起..我是新来的。
@vhiefa ...正如我所写，您需要将数据从一个活动传递到另一个活动。此外，如果您删除初始化代码，那么显然当前实例为空且未初始化，因此会给出 NPE 并且会崩溃，因为我看到您没有使用任何 try catch。请检查此链接hmkcode.com/android-passing-java-object-another-activity 了解如何将类对象从一个活动传递到另一个活动。同样正如其他人提到的，您需要添加 setter 方法来设置变量的值。
@RajenRaiyarela 感谢您的链接。我跟着它，它就像一个魅力。 :D

标签： java android geolocation latitude-longitude

【解决方案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（比如你得到纬度/经度/地址的任何地方），添加这些行。

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

【讨论】：

@vhiefa：请通过接受它作为答案来确认答案。单击答案旁边的灰色刻度线以接受作为答案。
@vhiefa：在这个答案旁边，你会发现一个灰色的勾号。您必须检查它并将其设为绿色以接受答案。接受答案您将获得 +2 分

【解决方案2】：

你只获得了价值。意味着你已经写了 getter mehtod。您尚未使用 setter 方法设置值。请尝试并检查。

public void setLatitude(double latitude){
this.latitude = latitude;
 }

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


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

【讨论】：