Using The Google Maps Geolocation API

It looks like the problem is here is that the HttpPost object defaults to sending its parameters as x-www-form-urlencoded, but you need to send it as application/json. This thread explains what happens if you do this: How to use parameters with HttpPost

There are a couple of ways that should fix it. One is to set the Content-type header on the HttpPost object:

request.setHeader("Content-type", "application/json");

The other, which I think is better, is to use the setContentType method of StringEntity documented here

entity.setContentType("application/json");

Either of these single lines used before you send the request should fix the problem.

Is your JSON request object complete? I mean it looks like the keys you are using are part of a single "tower" description, but that this is just part of the larger request body, which should be formatted like:

{  "homeMobileCountryCode": 310,  "homeMobileNetworkCode": 410,  "radioType": "gsm",  "carrier": "Vodafone",  "cellTowers": [   // See the Cell Tower Objects section below.  ],  "wifiAccessPoints": [    // See the WiFi Access Point Objects section below.  ]}

Where the tower objects are formatted like:

{'cellTowers': [  {    'cellId': 42,    'locationAreaCode': 415,    'mobileCountryCode': 310,    'mobileNetworkCode': 410,    'age': 0,    'signalStrength': -60,    'timingAdvance': 15  }]}

I guess I'm missing how your json object gets turned into the complete one?

https://developers.google.com/maps/documentation/business/geolocation/