Question

Design a class with the following requirements:

1- give the class a name from your choice.

2- write some code that creates three instance variables, choose a name and type for each one of them. (must have two private and one public variables)

3- Initialize the variables using two different constructors.

4- Use mutator and accessor methods (set and get) for the private data members.

5- Display the value of each member variable using a method.

6- In the main, create an object to fill the class data and display the class information.

in java language

Answer 1

Hi,

Hope you are doing fine. I have cooded the program in java as per your requirement. The code is clearly explained using comments that have been highlighted in bold. Also, in the main methos I have initialized two objects in order to depict the difference between the parameterized and non parameterized constructors that are used during initialization of an object. You may change the main method as per your requirement.

Program:

//class to store information about a student
public class StudentData {
   //declaring instance variables
   //name is a public string variable that stores name of student
   public String name;
   // marks is a public double variable that stores the marks of a student
   private double marks;
   //department is a private string variable that stores the department of a student
   private String department;
  
   //initializing the variable using a non parameterized constructor
   public StudentData() {
       this.name="none";
       this.marks=0;
       this.department="none";
   }

   //initializing the variable using a parameterized constructor
   public StudentData(String name, double marks, String department) {
       this.name = name;
       this.marks = marks;
       this.department = department;
   }
  
   //getters and setters for private data members
   //getter for marks
   public double getMarks() {
       return marks;
   }
   //setter for marks
   public void setMarks(double marks) {
       this.marks = marks;
   }
   //getter for department
   public String getDepartment() {
       return department;
   }
   //setter for department
   public void setDepartment(String department) {
       this.department = department;
   }
   //method to display the value of each member variable using a method.
   public void display()
   {
       System.out.println("Name: "+name);
       System.out.println("Marks: "+marks);
       System.out.println("Department: "+department);
   }

   public static void main(String[] args) {
       //creating new object s1 using non parameterized constructor of StudentData
       StudentData s1=new StudentData();
       //creating new object s1 using non parameterized constructor of StudentData
       StudentData s2=new StudentData("Harry",90,"Computer Science");
       //printing contents of s1
       System.out.println("S1 before setting values manually: ");
       s1.display();
      //setting values to instance variable of s1 objects.
       //since name is public we need not use a setter to set some value
       s1.name="Ron";
       //using setters for marks and department
       s1.setMarks(40);
       s1.setDepartment("Electronics");
       //printing contents of s1
       System.out.println("\nS1 after setting values manually: ");
       s1.display();
       //printing contents of s1
       System.out.println("\nValues of S2: ");
       s2.display();

   }

}

Executable code snippet:

Output: