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

## Problem 1: Numbers greater than 50

Given an array of numbers, find all the numbers that are greater than 50.

## Solution

There is a `tailSet(E e)` method in the **TreeSet** class that returns a set of all the elements that are greater than the provided element. We will add all the elements from the array to a **TreeSet**. Then we will find all the elements greater than 50 using the `tailSet()` method.

# Problem 1: Numbers greater than 50

Given an array of numbers, find all the numbers that are greater than 50.

# Solution

There is a `tailSet(E e)` method in the **TreeSet** class that returns a set of all the elements that are greater than the provided element. We will add all the elements from the array to a **TreeSet**. Then we will find all the elements greater than 50 using the `tailSet()` method.

Let's look at the solution of TreeSet exercises.

Introduction

ArrayList

LinkedList

CopyOnWriteArrayList

HashSet

TreeSet

HashMap

TreeMap

LinkedHashMap

Additional Map Implmentations

Arrays

Collections class

TreeSet Exercise Solution

Problem 1: Numbers greater than 50

Solution