Module 5: Collections and Generics

Objective

The objective of this module is to get hands-on experience with the following topics:

1. Introduction to Collection Framework
2. Working with Set
3. Working with List
4. Working with Map
5. Working with Generics

Lab 5.3

Objectives

1. Understand and implement Map in Java.

Problem Statement

Create a Map of Employees with empId as the key and Employee object as the value, and iterate through the Map.

Tasks

1. Create the following property under the EmployeeRepository class:

   Map<Integer, Employee> employeeMap;

2. Inside the no-argument constructor, perform the following steps:

   • Initialize employeeMap to HashMap.
   • Add all Employee objects, Developer objects, and Designer objects to employeeMap, mapping their empId as the key and the object as the value.
   • Add one duplicate Employee/Developer/Designer object to employeeMap.

3. Create the following method in EmployeeRepository that returns the Map<Integer, Employee>:

   public Map<Integer, Employee> getEmployeeMap()

4. In the CollectionTest class, get the Employee map by calling getEmployeeMap() method.

5. Print the total number of employees.

6. Run the CollectionTest class and observe that it will print "No of Employees: 6" since we have added one duplicate key.

   • Note: Map doesn't allow duplicate keys but will allow duplicate values.

7. Iterate through employeeMap and display each Employee profile by calling displayProfile(Employee) on the PayrollImpl object.