Dotted line is actually not dotted when app is running on real Android device

This is most likely related to hardware acceleration: Dashed lines are not supported in GL mode.

Its documented here:
https://code.google.com/p/android/issues/detail?id=29944

Turn off your HW-acceleration in your AndroidManifest.xml like this:

android:hardwareAccelerated="false"

or:

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null) 

For more information how to use first solution:
http://developer.android.com/guide/topics/graphics/hardware-accel.html