使应用程序等到定位服务已打开？

Question

I have an application that depends on location services being enabled.

Thus, when the user starts the application- a dialog box appears and it checks if the location service is enabled or not. However, I want the application to pause until the user goes to the settings page (Which he is redirected to on clicking "okay" in the dialog box) and enables location services. Once he does, he should be able to return back to the MainActivity and the code should continue where he left off.

If I don't let the app pause, the code just continues and tries to execute code that requires the location services to be on, and the app crashes.

I currently have this, so how can I modify it so that it waits?

if(!location_enabled) {
    // notify user
    AlertDialog.Builder dialog = new AlertDialog.Builder(this);
    dialog.setMessage("Location services are currently not " +
            "enabled. You must enable this in order to continue. Would you like to do this now?");

    dialog.setPositiveButton("Take me to location services", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface paramDialogInterface, int paramInt) {
            startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
            // WAIT UNTIL LOCATION SERVICES ENABLED
        }
    });

    dialog.setNegativeButton(context.getString(R.string.Cancel), new DialogInterface.OnClickListener() {

        @Override
        public void onClick(DialogInterface paramDialogInterface, int paramInt) {
            //EXIT APPLICATION

        }
    });
    dialog.show();
}

if(location_enabled) {
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED ) {
        //DO FANCY STUFF WITH LOCATION
    }
}

Answer 1

You can easily use startActivityForResult in your case.

When you're starting the settings to enable your location, you may start the intent like this.

// Declare a global variable first
private final int ACTION_LOCATION_SETTING = 100;

// Now change the onClickListener like this
dialog.setPositiveButton("Take me to location services", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface paramDialogInterface, int paramInt) {
        Intent locationSettingIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
        startActivityForResult(locationSettingIntent, ACTION_LOCATION_SETTING);
    }
});

Now when you return from the location setting, you'll get a callback here.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
        case ACTION_LOCATION_SETTING:
            if (resultCode == Activity.RESULT_OK) {
                if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED ) {
                    //DO FANCY STUFF WITH LOCATION
                }
            }
            break;
        default:
            super.onActivityResult(requestCode, resultCode, data);
    }
}

Simple!