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

## Removing an element from an ArrayList
Elements can be removed from an **ArrayList** in the following ways.

### Removing an element at a particular index

We can use the `remove(int index)` method to remove an element at a particular index. The index should be less than the size of **ArrayList**, otherwise, `IndexOutOfBoundsException` is thrown.

### Removing a particular element from the ArrayList
We can also specify the element that we want to remove using the `remove(Object o)` method, and the first occurrence of that element will be removed.



### Removing all the elements within a range
Let's suppose we need to remove all the elements from index 5 to 9. This can be done using the `removeRange(int fromIndex, int toIndex)` method. This method will remove, from this list, all of the elements whose index is between *fromIndex*, inclusive, and *toIndex*, exclusive. Please note that this method is not defined in the List class. So, it can be used only when the reference type is also **ArrayList** and not List.


# Removing an element from an ArrayList
Elements can be removed from an **ArrayList** in the following ways.

## Removing an element at a particular index

We can use the `remove(int index)` method to remove an element at a particular index. The index should be less than the size of **ArrayList**, otherwise, `IndexOutOfBoundsException` is thrown.

## Removing a particular element from the ArrayList
We can also specify the element that we want to remove using the `remove(Object o)` method, and the first occurrence of that element will be removed.



## Removing all the elements within a range
Let's suppose we need to remove all the elements from index 5 to 9. This can be done using the `removeRange(int fromIndex, int toIndex)` method. This method will remove, from this list, all of the elements whose index is between *fromIndex*, inclusive, and *toIndex*, exclusive. Please note that this method is not defined in the List class. So, it can be used only when the reference type is also **ArrayList** and not List.


Let's discuss some operations that can be done in an ArrayList.

Introduction

ArrayList

LinkedList

CopyOnWriteArrayList

HashSet

TreeSet

HashMap

TreeMap

LinkedHashMap

Additional Map Implmentations

Arrays

Collections class

ArrayList: Few More Operations

Removing an element from an ArrayList

Removing an element at a particular index

Removing a particular element from the ArrayList

Removing all the elements within a range