Java Inheritance

In Java, it is possible to inherit attributes and methods from one class to another. We group the "inheritance concept" into two categories:

• subclass (child) - the class that inherits from another class
• superclass (parent) - the class being inherited from

To inherit from a class, use the extends keyword.

In the example below, the Car class (subclass) inherits the attributes and methods from the Vehicle class (superclass):

Example

class Vehicle < protected String brand = "Ford"; // Vehicle attribute public void honk() < // Vehicle method System.out.println("Tuut, tuut!"); >> class Car extends Vehicle < private String modelName = "Mustang"; // Car attribute public static void main(String[] args) < // Create a myCar object Car myCar = new Car(); // Call the honk() method (from the Vehicle class) on the myCar object myCar.honk(); // Display the value of the brand attribute (from the Vehicle class) and the value of the modelName from the Car class System.out.println(myCar.brand + " " + myCar.modelName); >> 

Did you notice the protected modifier in Vehicle?

We set the brand attribute in Vehicle to a protected access modifier. If it was set to private , the Car class would not be able to access it.

Why And When To Use "Inheritance"?

- It is useful for code reusability: reuse attributes and methods of an existing class when you create a new class.

Tip: Also take a look at the next chapter, Polymorphism, which uses inherited methods to perform different tasks.

The final Keyword

If you don't want other classes to inherit from a class, use the final keyword:

If you try to access a final class, Java will generate an error:

final class Vehicle < . >class Car extends Vehicle

The output will be something like this: