CLASS EMPLOYEE JAVA

 A class called Employee, which models an employee with an ID, name and salary, is designed as shown in the following class diagram. The method raiseSalary (percent) increases the salary by the given percentage. Develop the Employee class and suitable main method for demonstration.

PROGRAM:

package jo;

 

public class Employee {

    int id;

    String name;

    double salary;

 

    public Employee(int id, String name, double salary) {

        this.id = id;

        this.name = name;

        this.salary = salary;

    }

 

    public void raiseSalary(double percentage) {

        if (percentage > 0) {

            salary += salary * (percentage / 100.0);

        }

    }

 

    public String toString() {

        return "ID: " + id + "\nName: " + name + "\nSalary: " + salary;

    }

 

    public static void main(String[] args) {

        Employee employee1 = new Employee(1, "John Doe", 50000.0);

        Employee employee2 = new Employee(2, "Jane Smith", 60000.0);

 

        System.out.println("Initial Employee Information:");

        System.out.println(employee1);

        System.out.println(employee2);

 

        // Raise the salary of employee1 and employee2

        employee1.raiseSalary(10);

        employee2.raiseSalary(5);

 

        // ✅ These lines are now inside main()

        System.out.println("\nEmployee Information After Raise:");

        System.out.println(employee1);

        System.out.println(employee2);

    }

}

 

 

 

 

 

OUTPUT:

Viva answers

1) Why do we use this keyword?
In Java, the this keyword is used to refer to the current object of the class.

Uses of this:

1.      To refer to instance variables when local variables have the same name.

2.      To call other constructors in the same class.

3.      To pass the current object as a parameter.

 Example:

public class Student {

    int id;

    String name;

    Student(int id, String name) {

        this.id = id;         // this.id refers to the instance variable

        this.name = name;     // name is the parameter

    }

}

Without this, Java wouldn't know if you're referring to the local variable or the instance variable.

2) What is a Constructor?

Answer:
A constructor is a special method in Java that is automatically called when an object is created.

·         It has the same name as the class.

·         It does not have a return type.

·         It is used to initialize objects.

Example:

public class Employee {

    int id;

    String name;

    // Constructor

    Employee(int id, String name) {

        this.id = id;

        this.name = name;

    }

}

You can also have default constructors (no parameters) or parameterized constructors (with parameters).

3) What is the toString() method?
The toString() method in Java is used to convert an object into a readable string format.

Why use it:

·         It is automatically called when you print an object using System.out.println().

·         You can override it to display your custom output.

Example:

public class Student {

    int id;

    String name;

    Student(int id, String name) {

        this.id = id;

        this.name = name;

    }

    public String toString() {

        return "ID: " + id + ", Name: " + name;

    }

}

When you do:

Student s = new Student(1, "Alice");

System.out.println(s);

It will print:

ID: 1, Name: Alice

Instead of the default like Student@1a2b3c.

 

4) A class called MyPoint, which models a 2D point with x and y coordinates, is designed as follows:

● Two instance variables x (int) and y (int).

● A default (or "no-arg") constructor that construct a point at the default location of (0, 0).

● A overloaded constructor that constructs a point with the given x and y coordinates.

● A method setXY() to set both x and y.

● A method getXY() which returns the x and y in a 2-element int array.

● A toString() method that returns a string description of the instance in the format "(x, y)".

● A method called distance(int x, int y) that returns the distance from this point to another point at the

given (x, y) coordinates

● An overloaded distance(MyPoint another) that returns the distance from this point to the given MyPoint

instance (called another)

● Another overloaded distance() method that returns the distance from this point to the origin (0,0)

Develop the code for the class MyPoint. Also develop a JAVA program (called TestMyPoint) to test all the

methods defined in the class.