Implementing interfaces in Java - Mini Project: Build & Apply

Implementing interfaces

📖 Scenario: You are creating a simple program to manage different types of vehicles. Each vehicle can start and stop. You will use an interface to define these actions and then create classes that implement this interface.

🎯 Goal: Build a Java program that defines an interface called Vehicle with methods start() and stop(). Then create two classes, Car and Bike, that implement the Vehicle interface. Finally, create objects of these classes and call their methods.

📋 What You'll Learn

Create an interface named Vehicle with two methods: start() and stop().

Create a class Car that implements the Vehicle interface.

Create a class Bike that implements the Vehicle interface.

In each class, provide simple print statements inside start() and stop() methods to show which vehicle is starting or stopping.

Create objects of Car and Bike and call their start() and stop() methods.

💡 Why This Matters

🌍 Real World

Interfaces are used in real-world Java programs to define common behaviors that different classes can share, like vehicles starting and stopping.

💼 Career

Understanding interfaces is essential for Java developers because they enable flexible and maintainable code design, especially in large projects and frameworks.

1

Create the Vehicle interface

Create an interface called Vehicle with two methods: void start() and void stop().

Java

// Your code here
// Define interface Vehicle with methods start() and stop()

Need a hint?

An interface in Java uses the keyword interface. Methods inside interfaces do not have a body.

2

Create the Car class implementing Vehicle

Create a class called Car that implements the Vehicle interface. Implement the start() method to print "Car is starting" and the stop() method to print "Car is stopping".

Java

public interface Vehicle {
    void start();
    void stop();
}

// Your code here
// Define class Car implementing Vehicle with start() and stop() methods

Need a hint?

Use implements Vehicle after the class name. Implement both methods with public void and add print statements inside.

3

Create the Bike class implementing Vehicle

Create a class called Bike that implements the Vehicle interface. Implement the start() method to print "Bike is starting" and the stop() method to print "Bike is stopping".

Java

public interface Vehicle {
    void start();
    void stop();
}

public class Car implements Vehicle {
    public void start() {
        System.out.println("Car is starting");
    }
    public void stop() {
        System.out.println("Car is stopping");
    }
}

// Your code here
// Define class Bike implementing Vehicle with start() and stop() methods

Need a hint?

Similar to the Car class, implement the Vehicle interface and add print statements for Bike.

4

Create objects and call methods

In a Main class with a main method, create an object of Car named myCar and an object of Bike named myBike. Call start() and stop() on both objects.

Java

public interface Vehicle {
    void start();
    void stop();
}

public class Car implements Vehicle {
    public void start() {
        System.out.println("Car is starting");
    }
    public void stop() {
        System.out.println("Car is stopping");
    }
}

public class Bike implements Vehicle {
    public void start() {
        System.out.println("Bike is starting");
    }
    public void stop() {
        System.out.println("Bike is stopping");
    }
}

// Your code here
// Create Main class with main method, create myCar and myBike objects, call start() and stop() on both

Need a hint?

Remember to create a Main class with a public static void main(String[] args) method. Create objects and call methods in order.