Android MVVM DataModel with Context -

i trying learn & implement mvvm databinding in app. facing difficulties in understanding/deciding few things.

i have 1 header view in app need use in multiple activities, created this

view_header.xml headerviewmodel.java (implements java.util.observer) headerdatamodel.java (extends java.util.observable) 

where headerviewmodel bound view_header.xml. include view_header.xml in activity_xyz.xml & set viewmodel of header view xyzactivity this,

xyzviewbinding.setheadervm(new headerviewmodel(new headerdatamodel(mcontext))); 

now have questions based on this:

1) headerdatamodel needs context work sharedpreference & broadcastreceiver, initialize inside xyzactivity instead of headerviewmodel- correct approach?

2) had rely on broadcast receiver update header view, registered inside constructor of headerdatamode. headerdatamodel observable, whenever receive broadcast, call notifyobservers() observer(headerviewmodel) detects & updates view.- correct approach?

3) register receiver in constructor of headerdatamodel, created ondestroy() method inside data model unregister & call ondestroy xyzactivity’s ondestroy().- correct approach?

1. as headerdatamodel needs context work sharedpreference & broadcastreceiver, initialize inside xyzactivity instead of headerviewmodel- correct approach? - no, wrong. must initialize in headerdatamodel later on if want update headerdatamodel, can it.
2. i had rely on broadcast receiver update header view, registered inside constructor of headerdatamode. headerdatamodel observable, whenever receive broadcast, call notifyobservers() observer(headerviewmodel) detects & updates view.- correct approach? - yes told in first point.
3. as register receiver in constructor of headerdatamodel, created ondestroy() method inside data model unregister & call ondestroy xyzactivity’s ondestroy().- correct approach? - yes. make public ondestroy() method in headerdatamodel class.