Parent and child classes in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a child class that inherits from a parent class.

Java

class Child [1] Parent {}

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

Aimplements

Bextends

Cinherits

Duses

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'implements' instead of 'extends' for class inheritance.

Using 'inherits' which is not a Java keyword.

In Java, a child class inherits from a parent class using the extends keyword.

2fill in blank

medium

Complete the code to call the parent class constructor from the child class constructor.

Java

class Child extends Parent {
    Child() {
        [1]();
    }
}

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Asuper

Bthis

Cparent

Dbase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this()' which calls the current class constructor.

Using 'parent()' or 'base()' which are not Java keywords.

The super() call invokes the parent class constructor in Java.

3fill in blank

hard

Fix the error in the child class method overriding the parent method.

Java

class Parent {
    void greet() {
        System.out.println("Hello from Parent");
    }
}

class Child extends Parent {
    @Override
    void [1]() {
        System.out.println("Hello from Child");
    }
}

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

Ahello

Bgreeting

CsayHello

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Changing the method name so it does not override the parent method.

Missing the @Override annotation (not an error but good practice).

The child class must use the exact method name greet to override the parent method.

4fill in blank

hard

Fill both blanks to create a constructor in the child class that calls the parent constructor with a parameter.

Java

class Parent {
    Parent(String name) {
        System.out.println("Parent name: " + name);
    }
}

class Child extends Parent {
    Child(String name) {
        [1]([2]);
    }
}

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

Asuper

Bthis

Cname

D"John"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this' instead of 'super' to call the parent constructor.

Passing a string literal instead of the parameter.

The child constructor calls the parent constructor using super(name); passing the parameter.

5fill in blank

hard

Fill all three blanks to override a method in the child class and call the parent method inside it.

Java

class Parent {
    void display() {
        System.out.println("Parent display");
    }
}

class Child extends Parent {
    @Override
    void [1]() {
        [2].[3]();
        System.out.println("Child display");
    }
}

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

Adisplay

Bsuper

Dthis

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this' instead of 'super' to call the parent method.

Changing the method name so it does not override.

The child overrides display() and calls the parent method with super.display();.