Desoola Anil Kumar, Java Faculty: There are 5 types of Inheritance. 1.Single inheritance, 2.Multiple inheritance, 3.Multilevel Inheritance, 4. Hirarichal inheritance and 5. Hybrid inheritance. Java supports multi level inheritance and hirarichal inheritance.
There are two forms of inheritance in the Java language. The standard form of inheritance is by extension; a class declares that it extends another class, or an interface extends another interface. In this case, the sub-class or sub-interface inherits all the fields and methods of its parent.
The second special form of inheritance is where classes declare that they implement an interface, which has more limited consequences. When a class implements an interface, it inherits any fields from the parent as final constants, but must provide its own implementation of the interface methods.
Types of Inheritance supported by Java
They can be specified as Single Inheritance & Multi level Inheritance.
The example discussed in the previous page is Single Inheritance where the features of one class are inherited by another class.
Multi level inheritance is when there are classes extending one another in a chain format. Ex:
Class A extends Class B, Class B extends Class C and so on...
There is one another form of inheritance called Multiple Inheritance. This is not supported by Java.
The authors of the Java language took a design decision to compromise multiple inheritance with interfaces, the specifics of this decision may be covered in other sources. Practically, multiple inheritance is difficult because of the ambiguities it can create when a class inherits from two superclasses with the same method signature: which version should be called?
But there is a workaround for this problem. Java allows us to achieve partial multiple inheritance using interfaces. A class can implement any number of interfaces and provide implementations for them and achieve partial multiple inheritance.
in simple words java supports simple, hierarchial, multi level and hybrid inheritance but at the same time java also supports multiple inheritance with the help of interfaces.
Java supports 2 types of inheritance directly:
Single & multilevel
Java does not support multiple inheritance directly. We can implement multiple inheritance by using interfaces but direct multiple inheritance is not supported by Java
In the abstract, Java uses the Single-Inheritance model of Object-Oriented Language design. That is, Java allows a Class to directly inherit from only a SINGLE Class.
Java also supports the concept of Interfaces, which allow the inheritance of method prototypes (i.e. definition of a method name and its parameters), but not the implementation of those methods.
Multiple inheritance:
source: instanceofjavaforus.blogspot.in/2014/12/why-java-does-not-supports-multiple.html
Java's interface mechanism can be used to implement multiple inheritance, with one important difference from c++ way of doing MI: the inherited interfaces must be abstract. This obviates the need to choose between different implementations, as with interfaces there are no implementations.
There are three acceptable answers:- "Never," "Rarely," and "When the problem domain cannot be accurately modeled any other way." Consider an Asset class, Building class, Vehicle class, and CompanyCar class. All company cars are vehicles. Some company cars are assets because the organizations own them. Others might be leased. Not all assets are vehicles. Money accounts are assets. real estate holdings are assets. Some real estate holdings are buildings. Not all buildings are assets.
the two most common reasons to use inheritance are
• To promote code reuse (You don't want your colleague sitting right next to you to write the same validation code in his class while he can obviously use the better code you have written :-) )
A Class can re-use or in java terms inherit features/code of another class by just extending it.
Ex:
public class Child extends Parent {
…
}
In the above example by virtue of the extends keyword, all the public code inside the parent class is available for use inside the child class.
A common design approach is to create a fairly generic version of a class with the intention of creating more specialized subclasses that inherit from it. For example:
class Car {
public void goForADrive() {
System.out.println("driving a car");
}
// more code
}
class Ferrari extends Car {
public void takeFerrariForADrive() {
System.out.println("driving a Ferrari");
}
// more code
}
public class TestCars {
public static void main (String[] args) {
Ferrari car = new Ferrari();
car.goForADrive();
car.takeFerrariForADrive();
}
}
Outputs:
driving a car
driving a Ferrari
Notice that the Ferrari class inherits the generic goForADrive() method from the less-specialized class Car, and also adds its own method, takeFerrariForADrive(). Code reuse through inheritance means that methods with generic functionality that could apply to a wide range of different kinds of cars -don't have to be reimplemented. That means all specialized subclasses of Car are guaranteed to have the capabilities of the more generic superclass. You don't want to have to rewrite the goForADrive() code in each of your specialized car classes of a racing game.
1. Single Inheritance
A Scenario where one class is inheriting/extending the behavior of just one super class.
Ex: public class Ferrari extends Car {…}
2. Multilevel Inheritance
A Scenario where one class is inheriting/extending the bahavior of another class which in turn is inheriting behavior from yet another class.
Ex: public class Automobile {…}
Public class Car extends Automobile {…}
Public class Ferrari extends Car {…}
This multilevel inheritance actually has no limitations on the number of levels it can go. So as far as java goes, it is limitless. But for maintenance and ease of use sakes it is better to keep the inheritance levels to a single digit number.
3. Multiple Inheritance
Actually, java does not support multiple inheritance. You can achieve partial multiple inheritance using interfaces but java is not like C or C++ where you can do direct multiple inheritance. However, you can achieve partial multiple inheritance with the help of interfaces.
Ex: public class FerrariF12011 extends Ferrari implements Car, Automobile {…}
And this is under the assumption that Car and Automobile are interfaces.
Here if you see, though you don't inherit concrete code from the Car or the Automobile interface, you do inherit skeleton methods that determine the way your class eventually behaves and hence this can be considered partial Multiple Inheritance.
Inheritance in Java is a system wherein one article gets all the properties and practices of a parent object. It is a significant piece of OOPs (Object Oriented programming framework).
The thought behind legacy in Java is that you can make new classes that are based after existing classes. At the point when you acquire from a current class, you can reuse techniques and fields of the parent class. In addition, you can include new strategies and fields in your present class moreover.
Inheritance speaks to the IS-A relationship which is otherwise called a parent-youngster relationship.
Why use legacy in java
For Method Overriding (so runtime polymorphism can be accomplished).
For Code Reusability.
Terms utilized in Inheritance
Class: A class is a gathering of articles which have regular properties. It is a layout or diagram from which articles are made.
Sub Class/Child Class: Subclass is a class which acquires the different class. It is additionally called a determined class, broadened class, or kid class.
Super Class/Parent Class: Superclass is the class from where a subclass acquires the highlights. It is likewise called a base class or a parent class.
Reusability: As the name indicates, reusability is a system which encourages you to reuse the fields and techniques for the current class when you make another class. You can utilize similar fields and strategies previously characterized in the past class.
Learn more at Java Programming from Javatpoint
the two most common reasons to use inheritance are
Java does not support multiple inheritance.......
Java does not support multiple inheritance. It is done with the help of interfaces in java. a class can implement n number of interfaces, thus showing multiple inheritance. but a class cannot extend multiple classes in java.
in order to acheive a inheritance and data encapsulation property global variables are not declared in java.
Java does not support direct multiple inheritance. You can implement partial multiple inheritance using interfaces. ex: public class ExMultInherit implements interface1, interface2, interface 3 { ... .... ...... }
C++ allows multiple inheritance while Java does not. In my opinion, multiple inheritance is not useful because it can get very confusing very quick. For polymorphism, C++ does early binding by default, while Java does late binding by default. Late binding is more useful than early binding.
Java does not support multiple inheritance.......
Java does not support multiple inheritance
Java does not support direct multiple Inheritance. Harder to implement, not every language support it: C++ does, Java does not.
Java does not support multiple inheritance. It is done with the help of interfaces in java. a class can implement n number of interfaces, thus showing multiple inheritance. but a class cannot extend multiple classes in java.
in order to acheive a inheritance and data encapsulation property global variables are not declared in java.
Java does not support direct multiple inheritance. You can implement partial multiple inheritance using interfaces. ex: public class ExMultInherit implements interface1, interface2, interface 3 { ... .... ...... }
C++ allows multiple inheritance while Java does not. In my opinion, multiple inheritance is not useful because it can get very confusing very quick. For polymorphism, C++ does early binding by default, while Java does late binding by default. Late binding is more useful than early binding.
Yes. Java is an Object Oriented Programming Language and it supports the OOPS concepts like Inheritance, Polymorphism etc
Yes. Java does not support full fledged/proper multiple inheritance. But, whatever partial inheritance that Java supports can be implemented using interfaces Actually, java does not support multiple inheritance. You can achieve partial multiple inheritance using interfaces but java is not like C or C++ where you can do direct multiple inheritance. However, you can achieve partial multiple inheritance with the help of interfaces. Ex: public class FerrariF12011 extends Ferrari implements Car, Automobile {…} And this is under the assumption that Car and Automobile are interfaces. Here if you see, though you don't inherit concrete code from the Car or the Automobile interface, you do inherit skeleton methods that determine the way your class eventually behaves and hence this can be considered partial Multiple Inheritance.
Actually, java does not support multiple inheritance. You can achieve partial multiple inheritance using interfaces but java is not like C or C++ where you can do direct multiple inheritance. However, you can achieve partial multiple inheritance with the help of interfaces. Ex: public class FerrariF12011 extends Ferrari implements Car, Automobile {…} And this is under the assumption that Car and Automobile are interfaces. Here if you see, though you don't inherit concrete code from the Car or the Automobile interface, you do inherit skeleton methods that determine the way your class eventually behaves and hence this can be considered partial Multiple Inheritance.
Java does not support multiple inheritance; a subclass cannot have more than one parent. Java compensates for this with interfaces. A class can implement multiple interfaces, but can only extend one class.
No. Java was designed with programmer friendliness and ease of maintenance of code in mind. Pointers makes code pretty complicated and providing direct access to the memory can have devastating effects in the hand of a mailcious or an inexperienced programmer. Also, direct multiple inheritance is not supported by java. You can achieve partial multiple inheritance with the help of Interfaces.