Inheritance is a mechanism in which one object acquires all the properties and behaviour of another object.
The idea behind inheritance is that you can create new classes that are built upon existing classes. When you inherit from an existing class, you reuse (or inherit) methods and fields, and you add new methods and fields to adapt your new class to new situations.Inheritance represents the IS-A relationship.
Why use Inheritance?
1)For Method Overriding.
2)For Code Reusability.
class Subclass-name extends Superclass-name
{
//methods and fields
}
The keyword extends indicates that you are making a new class that derives from an existing class.
In the terminology of Java, a class that is inherited is called a superclass. The new class is called a subclass.EXAMPLE:
As displayed in the above figure, Programmer is the subclass and Employee is the superclass. Relationship between two classes is Programmer IS-A Employee.It means that Programmer is a type of Employee.
class Employee{
int salary=40000;
}
class Programmer extends Employee{
int bonus=10000;
Public Static void main(String args[]){
Programmer p=new Programmer();
System.out.println("Programmer salary is:"+p.salary);
System.out.println("Bonus of Programmer is:"+p.bonus);
}
}
Output:Programmer salary is:40000
Bonus of programmer is:10000
To reduce the complexity and simplify the language,multiple inheritance is not supported in java.For Example:
class A{
void msg(){System.out.println("Hello");}
}
class B{
void msg(){System.out.println("Welcome");}
}
class C extends A,B{//suppose if it were
Public Static void main(String args[]){
C obj=new C();
obj.msg();//Now which msg() method would be invoked?
}
}
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