Not unless Car is abstract
'
I am explaining more elaborate.
My super class Vehicle extends Thread. Hence any subclass extends from Vehicle may implement run method. Super class Vehcicle is abstract. Hence whichever sub class is going to extend from Vehcile Super class should implement expense method.
I want to implement expense method only in sub class 'Bus', not in the sub class 'Car'. Why should i implement sub Class Car as Abstract ?