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Gourav Kadu
Gourav Kadu

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Interface In JAVA & Multiple Inheritance

MULTIPLE INHERITANCE

*Lets Understand what multiple inheritance is *
Multiple inheritance is a feature of some object-oriented computer programming languages in which an object or class can inherit features from more than one parent object or parent class.
Inheritance-sm.jpg

as shown in above figure in multiple inheritance child class can have 2 or more base class to achieve this we need INTERFACE.

INTERFACE

An interface in Java is a blueprint of a class. It has static constants and abstract methods.
i.e. An Interface can only contain abstract methods() and variables, it cannot have body of a method.
It cannot be instantiated just like the abstract class.

  • So where do we declare the body of these methods??

    The body of method is declared inside a class where the method is needed according to the programmer's requirement.

  • How to declare and interface?

    Interface is declared using interface keyword
    Syntax :
    interface interface_name{ abstract methods}

  • Note

    To use declared interface in class we need to use implements keyword

Implementation

First we will create a interface "print" and inside it we will create a abstract method print();

interface printgib{
void print();
}
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Now we got our interface ready to be used by classes so lets create classes abc and gk and implement interface in it.


public class abc implements printgib{
public void print(){                     //1st implementation of print 
System.out.println("I love you 3000"); 
}
public static void main(String[] args){
abc obj = new abc();
gk obj1 = new gk();
obj.print();
obj1.print();
}
}

class gk implements printgib{
public void print(){                   //2nd implementation of print 
System.out.println("I am Gk");
}
}
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as shown in above code we achieved multiple inheritance and implemented interface.

  • Now to run the code save the file and
javac file_name.java
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java abc
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Output:-

image.png

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