Learn about collections in Java such as LinkedLists, HashSet, HashMap and more.

Java for Programmers

Collections is one of the most important topics for Java Programming. Without the proper knowledge of every collection type in Java, it becomes difficult for you to decide which option to pick in a particular scenario.

This course will give you a great understanding of all collection types available in the Collections Framework like lists, linked lists, sets, and hashmaps.

After completing this course, you will know how data can be modified within a collection, how to sort a collection, and how it can be made thread-safe. You will also cover the internal working of each Java collection so you can work with them more efficiently.

Java Collections

## Solution to HashSet exercise 

We know that when we insert an element into a **HashSet** it returns `false` if the element is already present. To solve this problem we will insert each element into the HashSet. If for a particular element false is returned, then it means the element is a duplicate.

# Solution to HashSet exercise 

We know that when we insert an element into a **HashSet** it returns `false` if the element is already present. To solve this problem we will insert each element into the HashSet. If for a particular element false is returned, then it means the element is a duplicate.

Let's look at a solution for the HashSet problem.

Introduction

ArrayList

LinkedList

CopyOnWriteArrayList

HashSet

TreeSet

HashMap

TreeMap

LinkedHashMap

Additional Map Implmentations

Arrays

Collections class

HashSet: Exercise Solution

Solution to HashSet exercise