Constructor chaining in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the default constructor from the parameterized constructor using constructor chaining.

Java

public class Car {
    private String model;

    public Car() {
        this.model = "Unknown";
    }

    public Car(String model) {
        [1]();
        this.model = model;
    }
}

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

ACar

Bnew Car

Cthis

Dsuper

Attempts:

3 left

💡 Hint

Common Mistakes

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

Trying to create a new object with 'new Car()' inside the constructor.

Calling the constructor by its name like a method.

In Java, to call another constructor in the same class, use 'this()'.

2fill in blank

medium

Complete the code to chain constructors so that the three-parameter constructor calls the two-parameter constructor.

Java

public class Box {
    private int length, width, height;

    public Box(int length, int width) {
        this.length = length;
        this.width = width;
        this.height = 0;
    }

    public Box(int length, int width, int height) {
        [1](length, width);
        this.height = height;
    }
}

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

Athis

Bsuper

CBox

Dnew Box

Attempts:

3 left

💡 Hint

Common Mistakes

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

Trying to call the constructor like a method without 'this'.

Using 'new' keyword inside the constructor.

Use 'this(length, width);' to call the two-parameter constructor from the three-parameter constructor.

3fill in blank

hard

Fix the error in the constructor chaining code by completing the blank.

Java

public class Person {
    private String name;
    private int age;

    public Person() {
        this("Unknown", 0);
    }

    public Person(String name, int age) {
        [1] = name;
        this.age = age;
    }
}

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

Athis.name

Bname

Csuper.name

DPerson.name

Attempts:

3 left

💡 Hint

Common Mistakes

Using the parameter name instead of the instance variable.

Trying to use 'super' to access instance variables.

Using the class name to access instance variables.

Use 'this.name' to refer to the instance variable 'name' inside the constructor.

4fill in blank

hard

Fill both blanks to complete constructor chaining where the three-parameter constructor calls the two-parameter constructor and initializes the third field.

Java

public class Rectangle {
    private int length, width, area;

    public Rectangle(int length, int width) {
        this.length = length;
        this.width = width;
        this.area = length * width;
    }

    public Rectangle(int length, int width, int area) {
        [1](length, width);
        this.[2] = area;
    }
}

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

Athis

Bsuper

Carea

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using wrong variable names in the second blank.

Not calling the constructor properly.

Use 'this(length, width);' to call the two-parameter constructor and 'this.area = area;' to set the area.

5fill in blank

hard

Fill all three blanks to complete constructor chaining and initialize all fields correctly.

Java

public class Employee {
    private String name;
    private int id;
    private double salary;

    public Employee(String name) {
        this.name = name;
        this.id = 0;
        this.salary = 0.0;
    }

    public Employee(String name, int id) {
        [1](name);
        this.id = id;
        this.salary = 0.0;
    }

    public Employee(String name, int id, double salary) {
        [2](name, id);
        this.[3] = salary;
    }
}

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

Athis

Csalary

Dsuper

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'super' instead of 'this' for constructor chaining.

Not using 'this' to refer to the salary variable.

Calling constructors incorrectly.

Use 'this(name);' to call the single-parameter constructor, 'this(name, id);' to call the two-parameter constructor, and 'this.salary = salary;' to set the salary.