You need to track the Position(s) of each Device on your Server.
Each device must send updates when the position changes.
You need to query your Server about the (maybe updated) Position of Device X.
You can communicate with your server using okhttputils2.
Installation instructions: - Register your app in Google developer console: https://console.developers.google.com You need to enable Google Maps Android API. Then click on Credentials -> Create Credentials -> API Key -> Android Key. You should get a key that looks like...
You need to Create a new Marker for Each Device you want to Track.
Hold a reference to all Markers in a Map using the DeviceID as Key and the Marker as Value).
If you later query your server about a position, get the marker from the Map and updates its Location.