Where can I find sample code for communicating with SharePoint from android device using rest apis?
To use the REST capabilities that are built into SharePoint 2013, you can construct a RESTful HTTP request using the Open Data Protocol (OData) standard that corresponds to the desired client object model API. The client.svc web service handles the HTTP request and serves the appropriate response, in either Atom or JavaScript Object Notation (JSON) format. The client application must then parse that response. Figure 1 shows a high-level view of the SharePoint REST architecture.
If you are using office 365, SharePoint online, it should be possible to access and use the apis from your app.
I have written an article Office 365 Authentication using Visual Studio MVC application which accesses the api from an MVC application. You should be able to use similar approach for android app as well.
