Gain insights into Java Collections Framework. Delve into lists, sets, and hashmaps. Learn about data modification, sorting, thread-safety, and internal workings for efficient usage.

Collection 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.

Collections in Java

## Fetching an element from a HashMap

There are two ways to get an element from a HashMap.

### Using the `get()` method
The `get(Object key)` method takes a key as a parameter and returns the value corresponding to that key. If the key is not present, it returns `null`.

### Using the `getOrDefault()` method
The `getOrDefault(Object key, V defaultValue)` method is useful if are not sure whether a key is present in the Map or not. If the key is present then this method returns the value corresponding to the key and if the key is not present then the default value is returned.

# Fetching an element from a HashMap

There are two ways to get an element from a HashMap.

## Using the `get()` method
The `get(Object key)` method takes a key as a parameter and returns the value corresponding to that key. If the key is not present, it returns `null`.

## Using the `getOrDefault()` method
The `getOrDefault(Object key, V defaultValue)` method is useful if are not sure whether a key is present in the Map or not. If the key is present then this method returns the value corresponding to the key and if the key is not present then the default value is returned.

Let's discuss the update and deletion operations in HashMap.

Let's Begin

Lists in Java

LinkedList in Java

CopyOnWriteArrayList in Java

Sets in Java

TreeSet in Java

HashMap In Java

TreeMap in Java

LinkedHashMap in Java

Additional Map Implementations

Arrays Class

Collections Class

HashMap: Updation and Removal

Fetching an element from a HashMap

Using the `get()` method

Using the `getOrDefault()` method