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情况： 我有一个OpenActivity，我想要有当前的位置，要做到这一点我要求所有需要的权限，之后我想打开新的活动并提供这个数据。Android-等待改变经纬度
问题：第一次启动我提供的经度和纬度= 0.00。
问题：我该如何解决这个问题？只有当我的位置设置正确时，我才会呼叫新的活动。
这是我的代码：
public class OpenActivity extends AppCompatActivity {
public static final int PERMISSIONS_REQUEST_LOCATION = 99;
public static final int PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 98;
public Boolean networkPermission=false;
public Boolean locationPermission=false;
public Boolean storagePermission=false;
private TrackGPS gps = null;
double longitude=0.00;
double latitude=0.00;
private Location location=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_open);
checkLocationPermission();
checkStoragePermission();
networkPermission=checkNetworkState();
getLocation();
Intent i = new Intent(OpenActivity.this,MainActivity.class);
i.putExtra("location",location);
startActivity(i);
}
public void getLocation(){
if(locationPermission){
gps = new TrackGPS(OpenActivity.this);
if(gps.canGetLocation() && gps.getLoc()!=null){
location=gps.getLoc();
latitude=location.getLatitude();
longitude=location.getLongitude();
}
else
{
if (!gps.canGetLocation())
{
gps.showSettingsAlert();
}
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case PERMISSIONS_REQUEST_LOCATION:
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
locationPermission=true;
} else {
locationPermission=false;
}
break;
case PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE:
{
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
storagePermission=true;
} else {
storagePermission=false;
}
}
break;
}
}
private void checkStoragePermission() {
if (ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.READ_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.READ_EXTERNAL_STORAGE)) {
new AlertDialog.Builder(this)
.setTitle("Storage Permission Needed")
.setMessage("This app needs the Storage permission, please accept to use Storage functionality")
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
ActivityCompat.requestPermissions(OpenActivity.this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
}
})
.create()
.show();
} else {
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
}
}else{
storagePermission=true;
}
}
private void checkLocationPermission() {
if (ContextCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
android.Manifest.permission.ACCESS_FINE_LOCATION)) {
new AlertDialog.Builder(this)
.setTitle("Location Permission Needed")
.setMessage("This app needs the Location permission, please accept to use location functionality")
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
ActivityCompat.requestPermissions(OpenActivity.this,
new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSIONS_REQUEST_LOCATION);
}
})
.create()
.show();
} else {
ActivityCompat.requestPermissions(this,
new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSIONS_REQUEST_LOCATION);
}
}else{
locationPermission=true;
}
}
protected boolean checkNetworkState(){
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(OpenActivity.this.CONNECTIVITY_SERVICE);
if(connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
return true ;
}
else {
return false;
}
}
}
TrackGPS.java
public class TrackGPS extends Service implements LocationListener {
private final Context mContext;
boolean checkGPS = false;
boolean checkNetwork = false;
boolean canGetLocation = false;
Location loc;
double latitude;
double longitude;
public Location getLoc() {
return loc;
}
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10;
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1;
protected LocationManager locationManager;
public TrackGPS(Context mContext) {
this.mContext = mContext;
getLocation();
}
private Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
checkGPS = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
checkNetwork = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!checkGPS && !checkNetwork) {
Toast.makeText(mContext, "No access", Toast.LENGTH_SHORT).show();
} else {
this.canGetLocation = true;
if (checkNetwork) {
try {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
if (locationManager != null) {
loc = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
if (loc != null) {
latitude = loc.getLatitude();
longitude = loc.getLongitude();
}
}
catch(SecurityException e){
}
}
}
if (checkGPS) {
if (loc == null) {
try {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
if (locationManager != null) {
loc = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (loc != null) {
latitude = loc.getLatitude();
longitude = loc.getLongitude();
}
}
} catch (SecurityException e) {
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return loc;
}
public double getLongitude() {
if (loc != null) {
longitude = loc.getLongitude();
}
return longitude;
}
public double getLatitude() {
if (loc != null) {
latitude = loc.getLatitude();
}
return latitude;
}
public boolean canGetLocation() {
return this.canGetLocation;
}
public void showSettingsAlert() {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
alertDialog.setTitle("GPS non attivo");
alertDialog.setMessage("E' necessario abilitare il GPS, vuoi abilitarlo");
alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
((Activity)mContext).finish();
}
});
alertDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
public void stopUsingGPS() {
if (locationManager != null) {
locationManager.removeUpdates(TrackGPS.this);
}
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onStatusChanged(String s, int i, Bundle bundle) {
}
@Override
public void onProviderEnabled(String s) {
}
@Override
public void onProviderDisabled(String s) {
}
}
在gradle这个：compile 'com.google.android.gms:play-services:9.4.0'
从[摆脱'TrackGPS'类开始]（https://stackoverflow.com/questions/43082062/code-will-only-return-0-0-0-0-gps-coordinate-while-投掷nullpointerexceptio）。然后，在获得许可之前不要调用getLocation（）。然后，不要调用'startActivity（）'直到从LocationListener获得位置（因为'getLastKnownLocation（）'可能返回'null'）。 – CommonsWare
@CommonsWare如何在“获得许可之前不要调用getLocation（）”？如果我使用正常的条件，不工作，如果我使用循环条件，我的程序在循环中崩溃 – Juantums