Homework

Scenario

Its your first day of class when Mr. Mortenson asks you to identify all the students and list some characteristics about them. Create a class to use as a template to create student objects and create 3 imaginary students.

Instructions

  1. Create a class
    • Instance variables:
    • String name
    • int grade
    • int pets
    • int siblings
    • MAKE YOUR OWN
  2. In main:
    • Create three student objects.
// Main.java
public class Main {
    public static void main(String[] args) {
        // Create three student objects
        Student s1 = new Student("Person 1", 10, 1, 0, "Robotics");
        Student s2 = new Student("Person 2", 11, 2, 3, "Cyber");
        Student s3 = new Student("Person 3", 9, 0, 1, "Piano");

        // Print them out
        System.out.println(s1);
        System.out.println(s2);
        System.out.println(s3);
    }
}

/**
 * Template (class) for creating Student objects.
 */
class Student {
    // Instance variables
    private String name;       // student's full name
    private int grade;         // grade level (e.g., 9, 10, 11, 12)
    private int pets;          // how many pets they have
    private int siblings;      // how many siblings they have
    private String favoriteHobby; // <-- MAKE YOUR OWN (custom field)

    // Constructor
    public Student(String name, int grade, int pets, int siblings, String favoriteHobby) {
        this.name = name;
        this.grade = grade;
        this.pets = pets;
        this.siblings = siblings;
        this.favoriteHobby = favoriteHobby;
    }

    // Getters (optional, but handy)
    public String getName() { return name; }
    public int getGrade() { return grade; }
    public int getPets() { return pets; }
    public int getSiblings() { return siblings; }
    public String getFavoriteHobby() { return favoriteHobby; }

    // toString to print a friendly description
    @Override
    public String toString() {
        return String.format(
            "Student{name='%s', grade=%d, pets=%d, siblings=%d, favoriteHobby='%s'}",
            name, grade, pets, siblings, favoriteHobby
        );
    }
}

New Scenario

You find out that one of the students that you created an object for goes by a nickname. Using your knowledge of reference variables, create another object that references back to the same student.

Instructions

  1. Use your previous code

  2. In main:

    • Create a reference variable with a different name that points to the same student.
    • Output the instance attributes of this student
// Main.java
public class Main {
    public static void main(String[] args) {
        // Original three students
        Student s1 = new Student("Avery Kim", 10, 1, 0, "Robotics");
        Student s2 = new Student("Luca Ramirez", 11, 2, 3, "Basketball");
        Student s3 = new Student("Maya Patel", 9, 0, 1, "Piano");

        // Create a second reference to the SAME object as s1
        Student Ace = s1; // Avery goes by the nickname "Ace"

        // Output the instance attributes via the nickname reference
        System.out.println("Nickname reference ->");
        System.out.println("Name: " + Ace.getName());
        System.out.println("Grade: " + Ace.getGrade());
        System.out.println("Pets: " + Ace.getPets());
        System.out.println("Siblings: " + Ace.getSiblings());
        System.out.println("Favorite Hobby: " + Ace.getFavoriteHobby());

        // (Optional) Show it's truly the same object:
        // changing through one reference is visible via the other.
        // For example, if we had a setter for hobby we could change it here.
        // Since we don't, we can still show they share the same identity:
        System.out.println("\nAre s1 and Ace the same object? " + (s1 == Ace)); // true

        // Print both references (they'll show the same data)
        System.out.println("\ns1:  " + s1);
        System.out.println("Ace: " + Ace);
    }
}

/**
 * Template (class) for creating Student objects.
 */
class Student {
    // Instance variables
    private String name;       // student's full name
    private int grade;         // grade level (e.g., 9, 10, 11, 12)
    private int pets;          // how many pets they have
    private int siblings;      // how many siblings they have
    private String favoriteHobby; // custom field

    // Constructor
    public Student(String name, int grade, int pets, int siblings, String favoriteHobby) {
        this.name = name;
        this.grade = grade;
        this.pets = pets;
        this.siblings = siblings;
        this.favoriteHobby = favoriteHobby;
    }

    // Getters
    public String getName() { return name; }
    public int getGrade() { return grade; }
    public int getPets() { return pets; }
    public int getSiblings() { return siblings; }
    public String getFavoriteHobby() { return favoriteHobby; }

    // toString for easy printing
    @Override
    public String toString() {
        return String.format(
            "Student{name='%s', grade=%d, pets=%d, siblings=%d, favoriteHobby='%s'}",
            name, grade, pets, siblings, favoriteHobby
        );
    }
}