Make a class named ‘Courses’. While creating an object of the class, if nothing is passed to it, then the message "I am not enrolled in any course yet" should be displayed. If some course name(s) is/are passed to it, then in place of "I am not enrolled in any course yet" the name(s) of the courses should be displayed.

Here's an implementation of the Courses class that meets the requirements mentioned in the prompt:

Source Code..

public class Courses {

    private String[] courseNames;

 

    public Courses() {

        System.out.println("I am not enrolled in any course yet");

    }

 

    public Courses(String... courseNames) {

        if (courseNames.length > 0) {

            this.courseNames = courseNames;

            System.out.println("My enrolled courses are: " + String.join(", ", courseNames));

        } else {

            System.out.println("I am not enrolled in any course yet");

        }

    }

}

 

The Courses class has a private instance variable courseNames, which is an array of strings. We have defined two constructors:

 

A no-arg constructor, which simply displays the message "I am not enrolled in any course yet".

A parameterized constructor that takes variable arguments courseNames of type String. If courseNames is not empty, the instance variable courseNames is set to the input value and the message "My enrolled courses are: " followed by the names of the courses separated by commas is displayed. Otherwise, the message "I am not enrolled in any course yet" is displayed.

To use this class, we can create objects of Courses and call methods on them as shown below:

 

// create a Courses object without any course name

Courses courses1 = new Courses();

 

// create a Courses object with course names

Courses courses2 = new Courses("Mathematics", "Science", "English");

 

In the above code, we create two objects courses1 and courses2 of Courses class using different constructors. 

The output of the code would be:

For 1^st object.

I am not enrolled in any course yet

 

For 2^nd object.

My enrolled courses are: Mathematics, Science, English