OOP principles overview in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class named Car.

Java

public class [1] {
    // class body
}

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ACar

Bcar

CVehicle

DcarClass

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase for class names

Using a different name than intended

The class name should start with a capital letter and match the intended name. Here, Car is correct.

2fill in blank

medium

Complete the code to create an object of class Car.

Java

Car myCar = new [1]();

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AVehicle

Bcar

CCar

DMyCar

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or different names

Using a class name that does not exist

To create an object, use the class name exactly as declared. Here, Car is correct.

3fill in blank

hard

Fix the error in the code to properly override the method start in class Car.

Java

public class Car {
    public void start() {
        System.out.println("Car started");
    }
}

public class SportsCar extends Car {
    @Override
    public void [1]() {
        System.out.println("SportsCar started fast");
    }
}

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AStart

Brun

Cbegin

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase first letter in method name

Using a different method name

Method names are case-sensitive. To override, use the exact method name start.

4fill in blank

hard

Fill both blanks to define a class that inherits from Vehicle and overrides the move method.

Java

public class Car [1] Vehicle {
    @Override
    public void [2]() {
        System.out.println("Car is moving");
    }
}

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Aextends

Bimplements

Cmove

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using implements instead of extends

Using wrong method name

Use extends to inherit from a class and override the move method.

5fill in blank

hard

Fill all three blanks to create a simple interface and a class that implements it.

Java

public interface [1] {
    void [2]();
}

public class Car implements [3] {
    public void start() {
        System.out.println("Car started");
    }
}

Drag options to blanks, or click blank then click option'

AVehicle

Bstart

DEngine

Attempts:

3 left

💡 Hint

Common Mistakes

Using class names instead of interface names

Mismatch between interface and implemented method names

The interface is named Engine, it declares the method start, and the class Car implements Engine.