Why abstraction is required in Java - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an abstract class in Java.

Java

public [1] class Vehicle {
    abstract void start();
}

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Astatic

Bfinal

Cabstract

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'final' instead of 'abstract' to declare an abstract class.

Trying to instantiate an abstract class.

The keyword abstract is used to declare an abstract class in Java.

2fill in blank

medium

Complete the code to declare an abstract method inside an abstract class.

Java

public abstract class Animal {
    public [1] void sound();
}

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Aabstract

Bstatic

Cfinal

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Adding a method body to an abstract method.

Using 'static' or 'final' keywords with abstract methods.

The keyword abstract is used to declare a method without a body inside an abstract class.

3fill in blank

hard

Fix the error in the code by completing the class declaration to use abstraction properly.

Java

public [1] class DisplayClass {
    abstract void display();
}

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Astatic

Bfinal

Cprivate

Dabstract

Attempts:

3 left

💡 Hint

Common Mistakes

Declaring a class with abstract methods as a normal class.

Using 'final' or 'static' keywords incorrectly with abstract classes.

The class must be declared abstract if it contains abstract methods.

4fill in blank

hard

Fill both blanks to complete the code that shows why abstraction is required by hiding details.

Java

abstract class [1] {
    abstract void [2]();
}

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

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AVehicle

Brun

Cstart

DEngine

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names that do not match subclass implementations.

Naming the abstract class incorrectly.

The abstract class is named Vehicle and the abstract method is start to hide implementation details.

5fill in blank

hard

Fill all three blanks to complete the code demonstrating abstraction by hiding complex details.

Java

abstract class [1] {
    abstract void [2]();
}

class [3] extends Device {
    void operate() {
        System.out.println("Device operating");
    }
}

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ADevice

Boperate

CSmartphone

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between method names in abstract class and subclass.

Incorrect subclass name that does not extend the abstract class.

The abstract class is Device, the abstract method is operate, and the subclass is Smartphone demonstrating abstraction.