Java Program to count number of employees working in a company (Completed With Garbage Collection)

    // Java Program to count number of employees working in a company (Completed With Garbage Collection)

    class Employee {

        private String name;

        private int age;

        private int ID;

        private static int nextId = 1;

       

       

        public Employee (String name, int age) {

            this.name = name;

            this.age = age;

            this.ID = nextId++;

        }

       

        public void show()

        {

            System.out.println( "\nID=" + ID +  "\nName=" + name + "\nAge=" + age);

        }

       

        public void showNextId()

        {

            System.out.println("Next employee id will be=" + nextId);

        }

       

        protected void finalize()

        {

            --nextId;

            // In this case,

            // gc will call finalize()

            // for 2 times for 2 objects.

        }

    }

    class HelloWorld {

        public static void main(String[] args) {

            Employee E = new Employee("Ayush", 28);

            Employee F = new Employee("Abhinav", 24);

            E.show();

            F.show();

           

            //Sub block

            {

                Employee X = new Employee("GFG4", 23);

                Employee Y = new Employee("GFG5", 21);

                X.show();

                Y.show();

               

                X = Y = F = null;

                System.gc();

                System.runFinalization();

            }

           

            E.showNextId();

        }

    }

   

This Java program defines two classes: Employee and HelloWorld. It demonstrates the use of garbage collection in Java to manage object destruction and resource reclamation.

Here's a breakdown of the code:

1. Employee Class:

• Employee is a class representing employees in a company.
• It has private instance variables name, age, and ID, representing the employee's name, age, and a unique identifier.
• nextId is a static variable that keeps track of the next available ID for a new employee.
• The constructor initializes the name and age of the employee and assigns a unique ID to the ID variable using the nextId static variable.
• The show method prints the details of the employee (ID, name, and age).
• The showNextId method prints the next available employee ID.
• The finalize method is called by the garbage collector before an object is reclaimed. In this case, it decrements the nextId variable.

1. 2. HelloWorld Class:

   • • HelloWorld is the main class with the main method.
   • • Inside the main method:
     • • Two Employee objects, E and F, are created with specific names and ages. Their details are then displayed using the show method.
     • • A sub-block is created, where two additional Employee objects, X and Y, are created and displayed.
     • • The references X, Y, and F are set to null, indicating that there are no more references to those objects.
     • • The System.gc() method is called, suggesting to the JVM that it's an appropriate time to run the garbage collector.
     • • System.runFinalization() is called to ensure that the finalize method is executed for objects pending finalization.
     • • The showNextId method of the original Employee object E is called to display the next available employee ID.

Note: The use of System.gc() and System.runFinalization() is generally discouraged, and it's usually up to the JVM to decide when to run the garbage collector. Explicitly invoking these methods is not a recommended practice in most cases. The finalize method is also not guaranteed to be called promptly by the garbage collector, and it's generally advised to use other resource management techniques.