In an interface the default access modifier is 'public'. So if you don't specify an access modifier for a method in an interface, the method is automatically 'public' (and not only package visible, as in a class).
See, Try to understand from OOPS perspective. why we should define like that?? An interface with in an interface and in a class? what are the advantages we will get?? try to write small programmes regarding this? I cam teel you the Answere here but you should learn by yourself. that is the motto in this forum.
HI Seema Sharma for your both questions anwser is YES. if we come to modifiers: if the enclosing one is interface, we can have only public or abstract(like any other interface method). If we inter into inner interface all rules of normal interface will apply. if the enclosing one is class, we can have all four(private, protected,public and default) modifiers. If we inter into inner interface all rules of normal interface will apply. like this we can have class in interface also.