Well the best way would be to code the same app but for different platforms like dropbox or evernote have done. This would mean that the app would work perfectly on both platforms, however it does mean having to make both apps and keep on top of both of them. Plus running two apps means you're doubling the chance of something going wrong.
Another way is to create the android app and then run it both on your phone and your laptop by running an android emulator, but if I recall correctly the emulator is still pretty buggy so I'm not too sure if you would be able to run things through a cloud server without things getting complicated.
Also when you say "having a cloud based server host the app" do you mean the actual app would be hosted there or do you mean that your personal files related to the app would be stored there? If the actual app were to be stored there I'd consider just making a website that could be run on the phone to do the job of the app to make the entire process easier.
