Final classes and methods in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a final class named Vehicle.

PHP

<?php
final class [1] {
    // class body
}
?>

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

AClass

Bfinal

CCar

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the keyword 'final' as the class name.

Using lowercase 'class' as the class name.

Forgetting to write the class name.

The keyword final is used before the class name to declare a final class. Here, the class name should be Vehicle.

2fill in blank

medium

Complete the code to declare a final method named startEngine inside a class.

PHP

<?php
class Car {
    public [1] function startEngine() {
        echo "Engine started.";
    }
}
?>

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

Astatic

Bfinal

Cabstract

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'static' instead of 'final'.

Using 'abstract' which is for methods without body.

Using 'private' which controls visibility, not overriding.

The keyword final before a method means it cannot be overridden in child classes.

3fill in blank

hard

Fix the error by completing the code to prevent overriding the method display in the subclass.

PHP

<?php
class Base {
    public final function display() {
        echo "Base display.";
    }
}

class Derived extends Base {
    public function [1]() {
        echo "Derived display.";
    }
}
?>

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

Ashow

Bdisplay

CdisplayBase

Dprint

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to override the final method with the same name.

Using a method name that already exists as final in the parent.

The method display is final in the base class and cannot be overridden. The subclass must use a different method name like show.

4fill in blank

hard

Fill both blanks to declare a final class and a final method inside it.

PHP

<?php
[1] class Calculator {
    public [2] function add($a, $b) {
        return $a + $b;
    }
}
?>

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

Afinal

Bstatic

Dabstract

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'static' or 'abstract' instead of 'final'.

Forgetting to put 'final' before the method.

The class is declared final to prevent inheritance, and the method is declared final to prevent overriding.

5fill in blank

hard

Fill all three blanks to declare a final class, a final method, and call the method.

PHP

<?php
[1] class Printer {
    public [2] function printText($text) {
        echo $text;
    }
}

$printer = new Printer();
$printer->[3]("Hello World!");
?>

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

Afinal

CprintText

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'static' instead of 'final'.

Calling a method name that does not exist.

The class and method are declared final. The method printText is called on the object.