Why abstraction is required in Java - See It in Action

Why Abstraction is Required in Java

📖 Scenario: Imagine you are building a simple program to manage different types of vehicles. Each vehicle has some common actions like starting and stopping, but the details of how these actions happen can be different for each vehicle type.

🎯 Goal: You will create a basic Java program that shows why abstraction is needed by defining a general vehicle structure and specific vehicle types that hide complex details.

📋 What You'll Learn

Create an abstract class called Vehicle with abstract methods start() and stop()

Create two classes Car and Bike that extend Vehicle and provide their own versions of start() and stop()

Create a main method to create objects of Car and Bike and call their start() and stop() methods

Print messages that show the specific starting and stopping actions for each vehicle

💡 Why This Matters

🌍 Real World

Abstraction is used in software to hide complex details and show only what is necessary, like how a driver only needs to know how to start a vehicle without knowing the engine details.

💼 Career

Understanding abstraction is key for writing clean, maintainable code and is a fundamental concept in object-oriented programming used in many software development jobs.

1

Create the abstract class Vehicle

Create an abstract class called Vehicle with two abstract methods: start() and stop().

Java

abstract class Vehicle {
    // Your code here
}

Need a hint?

Use the abstract keyword before the class and methods to define abstraction.

2

Create Car and Bike classes extending Vehicle

Create two classes called Car and Bike that extend Vehicle. Implement the start() and stop() methods in each class with print statements describing how they start and stop.

Java

abstract class Vehicle {
    abstract void start();
    abstract void stop();
}

class Car extends Vehicle {
    // Your code here
}

class Bike extends Vehicle {
    // Your code here
}

Need a hint?

Remember to use extends Vehicle and override both methods with void start() and void stop().

3

Create main method to test vehicles

Create a Main class with a main method. Inside main, create one object of Car and one object of Bike. Call their start() and stop() methods.

Java

abstract class Vehicle {
    abstract void start();
    abstract void stop();
}

class Car extends Vehicle {
    void start() {
        System.out.println("Car is starting with a key ignition.");
    }
    void stop() {
        System.out.println("Car is stopping by pressing the brake pedal.");
    }
}

class Bike extends Vehicle {
    void start() {
        System.out.println("Bike is starting with a kick start.");
    }
    void stop() {
        System.out.println("Bike is stopping by pulling the brake lever.");
    }
}

public class Main {
    public static void main(String[] args) {
        // Your code here
    }
}

Need a hint?

Create objects using new and call the methods on those objects inside main.

4

Print the output showing abstraction benefit

Run the program and print the output of the start() and stop() methods for both Car and Bike.

Java

abstract class Vehicle {
    abstract void start();
    abstract void stop();
}

class Car extends Vehicle {
    void start() {
        System.out.println("Car is starting with a key ignition.");
    }
    void stop() {
        System.out.println("Car is stopping by pressing the brake pedal.");
    }
}

class Bike extends Vehicle {
    void start() {
        System.out.println("Bike is starting with a kick start.");
    }
    void stop() {
        System.out.println("Bike is stopping by pulling the brake lever.");
    }
}

public class Main {
    public static void main(String[] args) {
        Car myCar = new Car();
        Bike myBike = new Bike();
        myCar.start();
        myCar.stop();
        myBike.start();
        myBike.stop();
    }
    // Output should be visible when running
}

Need a hint?

Run the program to see the printed messages from each vehicle's start and stop methods.