An interface in Java defines a set of methods but does not implement them. A class implements an interface to provide the implementation of the methods. Interfaces avoid issues with static class hierarchies by disconnecting method definitions from inheritance. They also support multiple inheritance by allowing a class to implement many interfaces. Interfaces are designed to support dynamic method resolution at runtime rather than requiring method signatures to match at compile time.

1. Abir Hasnat
161-15-6789
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2. Interfaces
 An interface in Java, is essentially an pure abstract class - all methods are abstract.
 Interface can specify what a class must do, but not how it
does it.
 An interface defines a set of methods but does not implement them.
 One Class can implement many interfaces
 One interface can be implemented by many classes

3. Why is an interface?
 This makes a static and non-extensible classing environment –
 because the mechanism gets pushed up higher and higher in the class hierarchy.
 Interfaces avoid this problem by disconnecting the definition of a method from
inheritance hierarchy.
 Support multiple inheritance –
 many interface can being combined in one class

4. Why is an interface?(cont)
 Normally, in order for a method to be called from one class to another, both classes need to
be present at compile time so the Java compiler can check to ensure that the method
signatures are compatible.
 In a system like this, functionality gets pushed up higher and higher in the class hierarchy so
that the mechanisms will be available to more and more subclasses.
 Interfaces are designed to avoid this problem.
 Interfaces are designed to support dynamic method resolution at run time.

5. Multiple Inheritance

6. Multiple Inheritance