Inheritance : Tutorials For Selenium WebDriver
What
Is Inheritance In Java?
Inheritance is one
of the feature of Object-Oriented Programming (OOPs). Inheritance
allows a class to use the properties and methods of another class. In
other words, the derived class inherits the states and behaviors from
the base class. The derived class is also called subclass and the
base class is also known as super-class. The derived class can add
its own additional variables and methods. These additional variable
and methods differentiates the derived class from the base class.
Inheritance(parent-child)
Is very useful concept of java object oriented programming language
by which we can reuse the code of parent class. Inheritance Is
providing us a mechanism by which we can inherit the properties of
parent class In to child class. Example : Audi class Is child class
of Car class then Audi class can access/use all the non private
properties (methods, variables..etc) of Car class. Using Inheritance,
we can reuse the code of parent class In to child class so that size
of code will decrease. Maintenance of code will be also very easy.
Inheritance is a
compile-time mechanism. A super-class can have any number of
subclasses. But a subclass can have only one superclass. This is
because Java does not support multiple inheritance.
VIEW
EXAMPLE OF USING INHERITANCE IN SELENIUM WEBDRIVER
extends
keyword Is used to Inherit child class from parent class. Let me show
you very simple example of Inheritance In java. In this example, Car
class Is parent class of Audi class so all the non private properties
of Car class are Inherited and able to use In Audi class.
Parent Class
public class Car
{//Car Class Is Parent Class Of Audi Class
private
String type="Vehicle";
public static int
wheels = 4;
public String color
= "blue";
String fuel =
"Petrol";
public String
getfuel(){
return fuel;
}
protected void
Seats(){
int seat = 4;
System.out.println("Car Seats = "+seat);
}
}
Child Class or
Sub Class
public class Audi
extends Car{//Audi Is child Class Of Car Class.
public int
speed=150;
public static void
main(String[] args) {
Audi A = new
Audi();
A.printdetails();
//Can access
instance variable of parent class using object reference of child
class Inside static methods.
System.out.println("Color Of Audi = "+A.color);
//Can access non
static method of parent class using object reference of child class
Inside static methods.
System.out.println("Fuel Of Audi = "+A.getfuel());
}
public void
printdetails(){
//Can access class
variables of parent class directly Inside child class non static
methods.
System.out.println("Wheels Of Audi = "+wheels);
System.out.println("Speed Of Audi = "+speed);
//Can access non
static methods of parent class directly Inside child class non static
methods.
Seats();
//Can not access private variable of parent class In child class.
//System.out.println("Wheels Of Audi = "+type);
}
}
Output of above
example will looks like bellow.
Wheels Of Audi = 4
Speed Of Audi = 150
Car Seats = 4
Color Of Audi = blue
Fuel Of Audi =
Petrol
Overriding
In sub class, When
you create a method with same signature, return types and arguments
of parent class's method then that sub class's method Is known as
overridden method and It Is called as overriding In java. Overriding
Is useful to change to the behavior of parent class methods. Let me
show you simple example of method overriding In java.
Note : Method
overriding is different than method overloading. VIEW POST on method
overloading.
Consider same above
given example. Generally all cars have 4 seats so we have created
Seats() method with 4 seat variable. But supposing ford car has 6
seats and I wants to print 6 seats for Ford car. In this case we can
use method overriding In Ford class as bellow. For this example,
Consider Car class of above example as parent class of Ford class.
Here method Seats() Is overridden In sub class.
public class Ford
extends Car{//Ford Is child Class Of Car Class.
public static void
main(String[] args) {
Car C = new
Ford();//Created Ford Class object with Car Class reference.
C.Seats();
}
//Parent class
method Seats Is overridden In child class.
protected void
Seats(){
int seat = 6;
System.out.println("Audi Seats = "+seat);
}
}
Output of above
example will looks like bellow.
Audi Seats = 6
