Fluid UI is an amazing online tool for wireframing that has support also for Android. You can easily build rapid prototypes with it. It even allows you to link the pages together and simulate the UI interactions.
While building you can easily jump into a simulation
It supports multiple display sizes so you can see how your layout looks on a tablet.
Try it yourself here: https://www.fluidui.com/editor
[Edit] And as if the web app wasn't enough they also have a mobile app you can put to your Android device and click through the prototypes there!
Download the APK from here http://www.fluidui.com/android/
Login to the Fluid UI and you'll see a QR code that will open the mockup on your phone (my example would look better if I hadn't added the Android controls to it).