Java quiz 01: Passing parameters to constructors

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Hi guys, I would emphasize that understanding constructors helps you by initializing instance variables. In the following code, I try to make that concept clear. I use a trick to make it difficult to guess the result if you don’t understand the constructor block.

Java quiz 1: Passing parameters to constructors

Level: Normal

What is the output of the following program?

public class Student
{
  String name = "Emily";
  int age = 20;

  Student(String name, int age)
  {
    this.name = name;
    this.age = 22;
  }
  public static void main(String[] args)
  {
    Student st = new Student("Oliver", 21);
    System.out.print(st.name + ", " + st.age);
  }
}
Author: Sar Maroof

Select the correct answer.


Answer explanation

  1. By creating the object st using the constructor of the Student class, we need to pass two parameters to the constructor.
  2. Inside the constructor we assign the name parameter to the class variable name by using the statement this.name = name;. Therefore the name is Oliver.
  3. In the constructor the age parameter is not assigned to the variable age. No matter which age you pass to the constructor, the value 22 is assigned to the age. See the statement this.age = 22;.

The right answer is a. Oliver, 22

If you found this difficult, you might consider reading my book Java quizmaster for beginners. It is easier and organized to learn Java in 17 days and it guides you to master Java code by solving 105 quizzes and 117 assignments. This book explains each chapter properly before starting with exercises and assignments. It is available on Amazon. See inside the book here!

Please, leave your questions, feedback and suggestions in the comments below!
SarMaroof.com offers a practical method to learn and improve your Java skills. It avoids unnecessary long boring theoretical explanations, but it uses many exercises and quizzes.




Sar Maroof is graduated from HBO Amsterdam “higher professional education” when he already had a bachelor of science degree in Physics.
He is a SUN certified JSP as well as EJB. He has experience with Java since 2001 and worked for several big as well as small companies and later as a freelancer.
He is the author of Java quizmaster and Build a Java application in 7 days.

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