Implementing polymorphism
- 1. M.Rajshree II-MSC(IT) Nadar saraswathi college of arts&science
- 2. Polymorphism is the ability of a message to be displayed in more than one form The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object. Any Java object that can pass more than one a test is considered to be polymorphic
- 3. Create a completely separate class specific to each type of object These object classes would share a lot of members in common, but they would be completely separate from each other for example, that had the generic object members such as the speed property and the travel method
- 4. There is another object oriented Programming concept that is closely related to abstract classes called interface Interfaces allow us to define polymorphism in a declarative way unrelated to implementation In interfaces, you can only define (not implement) methods inside the parent class
- 5. Use the concept of an Interface class that will define (but will not implement) common properties and methods for the more specific classes Create separate classes then implement each specific type of object that you will need And that use the interface class to specify common functionality
- 6. The classes that implement the Interface must implement all members of the Interface An Interface is a class that has only a method body but no implementation Example: public interface shape { void draw(); }
- 7. Shape is an interface with only one method, i.e. draw(). Basically, it is a contract that when you are implementing that interface, you have to implement the draw functionality, or else you are not a complete class So for any class like Triangle or Rectangle, when we implement that Interface, they must implement the draw() method
- 8. We sometimes use an arraylist, we are not as concerned about how the feature set by the list interface have been implemented by arraylist Example : List l = New ArrayList(); l.add() we needed to use an LinkedList instead of an ArrayList, we could easily do that by changing: List l = new LinkedList(); ArrayList used in our program because we used them through the contract published by the Interface
- 9. The methods cannot be implemented inside the interface Variables (properties) cannot be defined inside the interface All the methods defined inside the interface need to be implemented in the child class All the necessary variables need to be defined inside the child class Man interface enforces its implementing classes to implement all the methods in the interface
- 10. Implementation interfaces, there are several rules a class can implement more than one interface at a time A class can extend only one class but it implement many interfaces An interface can extend another interface in a similar way as a class can extend another class
- 11. Thank you