Abstract methods in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Java

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

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AmakeSound

Babstract

Cvoid

Dsound

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'void' as the method name instead of the return type.

Writing 'abstract' again inside the method declaration.

Using a variable name instead of a method name.

The method name must be provided after the abstract keyword and return type. Here, makeSound is the method name.

2fill in blank

medium

Complete the code to make the class abstract.

Java

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

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Aabstract Dog

BDog

Cabstract

DAbstractDog

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the 'abstract' keyword before the class name.

Trying to declare the class as 'AbstractDog' without the keyword.

Placing 'abstract' after the class name.

To declare an abstract class, the keyword abstract must come before the class name.

3fill in blank

hard

Fix the error in the abstract method declaration.

Java

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

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Astatic

Bpublic

Cabstract

Dfinal

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving a method body for an abstract method.

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

Not using the 'abstract' keyword.

An abstract method must be declared with the abstract keyword and cannot have a body (no braces {}).

4fill in blank

hard

Fill both blanks to correctly declare an abstract method in an abstract class.

Java

abstract class Shape {
    [1] [2] area();
}

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Aabstract

Bdouble

Cvoid

Dpublic

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'void' as the return type for an abstract method that should return a value.

Forgetting the 'abstract' keyword.

Using access modifiers incorrectly.

The method must be declared as abstract and have a return type. Here, double is the return type for the method area.

5fill in blank

hard

Fill all three blanks to correctly declare an abstract method with public access and int return type.

Java

abstract class Calculator {
    [1] [2] [3]();
}

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Aabstract

Bint

Ccalculate

Dpublic

Attempts:

3 left

💡 Hint

Common Mistakes

Placing 'abstract' after the method name.

Omitting the access modifier.

Using 'void' instead of 'int' as return type.

The method must be declared with the access modifier public, the keyword abstract, and a method name, here calculate, with return type int.