Yes an abstract class can extends concrete class. Example: Concrete .java public class Concrete { public void add(){ int i = 3; int j = 5; int z = i+j; System.out.println("Sum is:"+z);
An enterprise Bean's home interface defines the methods that allow a client to create, find, and remove EJB objects. All bean classes must implement javax.ejb.EnterpriseBean so it is necessary to implement all the method of interface.