Inheritance in JavaInheritance in Java is a mechanism in which one object acquires all the properties and behaviors of a parent object. It is an important part of OOPs (Object Oriented programming system). The idea behind inheritance in Java is that you can create new classes that are built upon existing classes. When you inherit from an existing class, you can reuse methods and fields of the parent class. Moreover, you can add new methods and fields in your current class also. Inheritance represents the IS-A relationship which is also known as a parent-child relationship. Why use inheritance in java
Terms used in Inheritance
The syntax of Java InheritanceThe extends keyword indicates that you are making a new class that derives from an existing class. The meaning of "extends" is to increase the functionality. In the terminology of Java, a class which is inherited is called a parent or superclass, and the new class is called child or subclass. Java Inheritance ExampleAs displayed in the above figure, Programmer is the subclass and Employee is the superclass. The relationship between the two classes is Programmer IS-A Employee. It means that Programmer is a type of Employee. Test it NowProgrammer salary is:40000.0 Bonus of programmer is:10000 In the above example, Programmer object can access the field of own class as well as of Employee class i.e. code reusability. Types of inheritance in javaOn the basis of class, there can be three types of inheritance in java: single, multilevel and hierarchical. In java programming, multiple and hybrid inheritance is supported through interface only. We will learn about interfaces later. Note: Multiple inheritance is not supported in Java through class.When one class inherits multiple classes, it is known as multiple inheritance. For Example: Single Inheritance ExampleWhen a class inherits another class, it is known as a single inheritance. In the example given below, Dog class inherits the Animal class, so there is the single inheritance. File: TestInheritance.java Output: barking... eating... Multilevel Inheritance ExampleWhen there is a chain of inheritance, it is known as multilevel inheritance. As you can see in the example given below, BabyDog class inherits the Dog class which again inherits the Animal class, so there is a multilevel inheritance. File: TestInheritance2.java Output: weeping... barking... eating... Hierarchical Inheritance ExampleWhen two or more classes inherits a single class, it is known as hierarchical inheritance. In the example given below, Dog and Cat classes inherits the Animal class, so there is hierarchical inheritance. File: TestInheritance3.java Output: meowing... eating... Q) Why multiple inheritance is not supported in java?To reduce the complexity and simplify the language, multiple inheritance is not supported in java. Consider a scenario where A, B, and C are three classes. The C class inherits A and B classes. If A and B classes have the same method and you call it from child class object, there will be ambiguity to call the method of A or B class. Since compile-time errors are better than runtime errors, Java renders compile-time error if you inherit 2 classes. So whether you have same method or different, there will be compile time error. Test it NowCompile Time Error Next TopicAggregation in java (HAS-A) |
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