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Example for Single Level Inheritance
OutputHi : PavanI am from darkedeneurope.comHi: savanI am from ABC
MultiLevel Inheritance : In MultiLevel Inheritance, the parent class method will be inherited by child class and again subclass will inherit the child class method.
Output
Class A is 80Class B is 50 Class C 20
INTERFACES:
An interface is a description of the actions that an object can do.Interface is written in the same way as the class the declaration with interface keyword.Rules of Interfaces:
All methods declared in an interface must be public; this is the nature of an interface.All methods in the interface must be implemented within a class; failure to do so will result in a fatal error.The class implementing the interface must use the exact same method signatures as are defined in the interfaceInterfaces can be extended like classes using the extends operator.Example for the interface class
Output:Describing Mango tree
2) Interface can be extended with another interface using extends keyword
Output:division of 10/2 is 5multiplication of 2*3 is 6
Note on Interfaces:-
We cannot create objects to interface, but the class implementing the interface can have objectsWe cannot define a variable in an interface.If we extend interface all the methods of the interface must be implemented in the child class.
Abstract Classes:
An abstract class is a class that contains at least one abstract method. The abstract method is function declaration without anybody and it has the only name of the method and its parameters.There can be any number of methods in the class and we have to declare the class as abstract only when there is an abstract methodExample for Abstract class
Output for the above code is:Maruthi Suzuki720000Hyundai300000
Notes on Abstract classes:
Objects cannot be created for the abstract classes.If a class has only one method as abstract, then that class must be an abstract class.The child class which extends an abstract class must define all the methods of the abstract class.If the abstract method is defined as protected in the parent class, the function implementation must be defined as either protected or public, but not private.The signatures of the methods must match, optional parameter given in the child class will not be accepted and error will be shown.Abstract classes that declare all their methods as abstract are not interfaces with different names. One can implement multiple interfaces, but not extend multiple classes (or abstract classes).Xem thêm: Sự Thật Về Ung Thư Về Tim Ít Bao Giờ Được Nghe Thấy? Ung Thư Tim Là Gì
Now Let us see the difference between abstract class and interface.
| Abstract class | Interface |
It can have constants, members, method stubs (methods without a body), methods | It can only have constants and methods stubs. |
Methods and members can have public or protected visibility
| Methods of interface should only be public not any other visibility |
The concept of multiple inheritances not supported.
| An interface can extend or a class can implement multiple other interfaces. |
Child class must implement all the abstract method of parent class when extend keyword is used.
| No need of implementing methods from parent interface when interface is extending another interface |
In the end, now we are able to create a class, define objects for the class and create methods. We also learned about different topics of object-oriented like inheritance, interface, abstraction. The basic concepts of OOP is explained in this blog.
