Java – List of Employee Objects – Ameerpet Technologies

List of Objects:

Collections are mainly used to store and process information of Employees, Students, Customers, Products, Books, Accounts etc.
Object is a set of dissimilar elements. For example, Employee has ID, Name and Salary.
We create objects with details and store the object into collection as follows.

Program to create and display List of Employees:

Employee.java: contains Employee class
Main.java: contains code of creating ArrayList with Employees and display.

Employee.java:

Create Employee class with instance variables id, name, salary
Define parameterized constructor to initialize the object.

class Employee
{
            int id;
            String name;
            double salary;
            Employee(int id, String name, double salary) {
                        this.id = id;
                        this.name = name;
                        this.salary = salary;
            }
}

Main.java:

Create 3 Employee objects and add to List
Display details using for-each loop

import java.util.*;
class Main
{
            public static void main(String[] args) {
                        List<Employee> list = new ArrayList<Employee>();

                        Employee e1 = new Employee(101, “Amar”, 35000);
                        Employee e2 = new Employee(102, “Harin”, 45000);
                        Employee e3 = new Employee(103, “Satya”, 40000);
                        list.add(e1);
                        list.add(e2);
                        list.add(e3);
                        System.out.println(“Details are : “);
                        for(Employee e : list)
                        {
                                    System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
                        }
            }
}

You can directly add objects to the list as follows:

import java.util.*;
class Main
{
            public static void main(String[] args) {
                        List<Employee> list = new ArrayList<Employee>();

                        list.add(new Employee(101, “Amar”, 35000));
                        list.add(new Employee(102, “Harin”, 45000));
                        list.add(new Employee(103, “Satya”, 40000));

                        System.out.println(“Details are : “);
                        for(Employee e : list)
                        {
                                    System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
                        }
            }
}

Display using for loop:

System.out.println(“Details are : “);
for(int i=0 ; i<=list.size()-1 ; i++)
{
Employee e = list.get(i);
System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
}

Display Employees List in reverse order:

We must use for() loop to iterate in reverse order.
For-each loop can move only in forward direction.

System.out.println(“Details are : “);
for(int i=list.size()-1 ; i>=0 ; i–)
{
Employee e = list.get(i);
System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
}

Display using Iterator:

System.out.println(“Details are : “);
Iterator<Employee> itr = list.iterator();
while(itr.hasNext())
{
Employee e = itr.next();
System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
}

Display reverse list using ListIterator:

System.out.println(“Details are : “);
ListIterator<Employee> itr = list.listIterator(list.size());
while(itr.hasPrevious())
{
Employee e = itr.previous();
System.out.println(e.id + ” , ” + e.name + ” , ” + e.salary);
}

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