Java program showing concept of Inheritance

What is Inheritance?
Inheritance is a feature of Object oriented language like JAVA where child class acquires properties and methods of it's parent class.

Program

package inheritance;

public class SuperDemo
{
public void showname()
{
System.out.println("This is my SuperClass");
}
}

public class DemoClass extends SuperDemo
{
public void display()
{
System.out.println("This is subclass");
}
public static void main(String[] args)
{
DemoClass demo=new DemoClass();
demo.showname();
demo.display();
}
}

Output

This is my SuperClass
This is subclass

Explanation

Above is simple program showing the inheritance in Java.

The program declares a class named SuperDemo and one method in it.

the second class DemoClass extends the SuperDemo class and declares another method in it.

In the Main method , object of subclass i.e DemoClass is created and called the method of SuperDemo class and then the method of DemoClass.

---

Using super

super keyword is used to access the members of superclass directly from subclass where the members of superclass and sub class having the same name.

It is also used to call superclass constructor from subclass.

Program

package inheritance;
public class Expensive
{
int tv_price=20000;
public void showExpense()
{
System.out.println("The price of tv is " + tv_price);
}
}

public class NonExpensive extends Expensive
{
int cooler=5000;
public void showExpense()
{
System.out.println("The price of cooler is " + cooler);
}
public void getExpense()
{
NonExpensive nonex=new NonExpensive();
//call subclass method
nonex.showExpense();
//call superclass method
super.showExpense();
//get the value of tv in superclass
int k=super.tv_price;
System.out.println(k);
}
public static void main(String[] args)
{
NonExpensive ex=new NonExpensive();
ex.getExpense();
}
}

Output

The price of cooler is 5000
The price of tv is 20000
20000

Explanation

Above program declares a superclass named Expensive and a variable 'tv' and assign a value to it. A method is implemented to show the price of tv

A subclass named Nonexpensive extends superclass and declared a method.

In the method of subclass the super keyword is used to access the method and member of a superclass.