Question: In my application, I am starting the Google Navigation with the help of following set of code.

```
String uri = "http://maps.google.com/maps?saddr="+ gpsLatitude
            + "," + gpsLongitude
            + "&daddr="
            + updateAcceptedOfferDetailsData.getDestinationLat()+","+updateAcceptedOfferDetailsData.getDestinationLon();
            Intent intent = new Intent(android.content.Intent.ACTION_VIEW,
                    Uri.parse(uri));
            intent.setClassName("com.google.android.apps.maps",
            "com.google.android.maps.MapsActivity");
            startActivity(intent);

```

I am passing the Source Lat/Lng and Destination Lat/Lng of the respective addresses.

**Problem:-** Here my problem is when the Navigation Screen opens there is no option to **"Start"** rather there is another option **"Preview"**, This problem do not happens at all the places it works fine for some places but not for all. May I know what the whole mess is??

Thanks

Answer: 
I had a new (Samsung) phone and the problem was that the Location permission was not enabled yet for Maps.

The fix for this issue is to set the starting location to "My Location" and it will prompt you to grant the Location permission, and the issue will be resolved.

The root cause of the problem is that turn-by-turn only works if Maps thinks the device is already at the starting location. Since Location permission is off, it will only show a route preview.
I have done some research on this and it appears that there is no way around it. The preview button will appear wherever navigation is not available for the requested route, the only reliable source I could find (Google was not massively helpful on this) to prove this is [here](https://support.google.com/gmm/answer/2839865?hl=en&ref_topic=3137719) which states (under navigation):

> 
> To launch turn-by-turn navigation, touch the Start navigation button represented by a chevron in the bottom right of the screen. When Navigation is not available, the icon will appear as a preview arrow , and you can view the directions step by step.
> 
> 
> 

The only suggestion that I have would be to somehow check whether or not navigation is in fact available for the given route prior to passing to the maps application, and if not then display a prompt to the user, but I do not know the android API's well enough to be of any help here. 

[A list of supported countries and territories is available here.](https://support.google.com/gmm/answer/172221?hl=en-GB) 

Hope this helps.