Super keyword in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the parent class constructor.

Java

class Parent {
    Parent() {
        System.out.println("Parent constructor called");
    }
}

class Child extends Parent {
    Child() {
        [1]();
        System.out.println("Child constructor called");
    }
}

public class Main {
    public static void main(String[] args) {
        new Child();
    }
}

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

Asuper

Bthis

Cparent

Dbase

Attempts:

3 left

💡 Hint

Common Mistakes

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

Trying to call 'parent()' which is not a valid keyword.

The keyword 'super' is used to call the parent class constructor in Java.

2fill in blank

medium

Complete the code to access the parent class method from the child class.

Java

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

class Child extends Parent {
    void show() {
        [1].show();
        System.out.println("Child show method");
    }
}

public class Main {
    public static void main(String[] args) {
        Child c = new Child();
        c.show();
    }
}

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

Athis

Bparent

Csuper

Dbase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this.show()' which calls the child method recursively.

Using 'parent.show()' which is not valid in Java.

The 'super' keyword is used to call the parent class method from the child class.

3fill in blank

hard

Fix the error in the constructor call to the parent class.

Java

class Parent {
    Parent(int x) {
        System.out.println("Parent constructor with value: " + x);
    }
}

class Child extends Parent {
    Child() {
        [1](10);
        System.out.println("Child constructor");
    }
}

public class Main {
    public static void main(String[] args) {
        new Child();
    }
}

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

Abase

Bthis

Cparent

Dsuper

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this(10);' which calls the same class constructor and causes recursion.

Using 'parent(10);' which is not a valid keyword.

Use 'super(10);' to call the parent constructor with an argument.

4fill in blank

hard

Fill the blank to override a method and call the parent method inside it.

Java

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

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

public class Main {
    public static void main(String[] args) {
        Child c = new Child();
        c.display();
    }
}

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

Asuper

Bthis

Cparent

Dbase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this.display();' which causes recursive call.

Using 'parent.display();' which is invalid.

The 'super' keyword is used to call the parent class method from the overridden method in the child class.

5fill in blank

hard

Fill both blanks to use super keyword for constructor and method calls.

Java

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

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

public class Main {
    public static void main(String[] args) {
        Child c = new Child();
        c.greet();
    }
}

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

Athis

Bsuper

Cparent

Dbase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'this()' in constructor to call itself causing recursion.

Using 'parent' or 'base' which are invalid keywords.

Use 'super()' to call the parent constructor and 'super.greet()' to call the parent method.