How to present abstract class which has relationship with interface class in class diagram

I have to do diagram with minimum of one abstract class and interface.I though to be a good idea to implement the interface class here. My table is customer which is the abstract class.The interface …

Java override non abstract method as abstract in extended class

So I have a non-abstract method onStop inside the base class. Is it acceptable to make it abstract in the extented MyTask? The aim is to force the onStop to be implemented by classes that extend the …