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 TreeMap

The following methods can be used to fetch elements from a **TreeMap**.

### Fetching the value for a particular key
We can fetch the value for a particular key using the `get(Object o)` method. This method will return the value of the key if the key is present. If the key is not present, it will return null.

### Fetching the smallest key
As we are aware that a **TreeMap** stores elements in sorted order, we can fetch the smallest key using the `firstKey()` method. If the **TreeMap** is empty, then `NoSuchElementException` is thrown. If we want to get the smallest entry, then the `firstEntry()` method can be used.

### Fetching the largest key
We can fetch the largest key using the `lastKey()` method. If the TreeMap is empty, then `NoSuchElementException` is thrown. If we want to get the largest entry, then the `lastEntry()` method can be used.






# Fetching an element from a TreeMap

The following methods can be used to fetch elements from a **TreeMap**.

## Fetching the value for a particular key
We can fetch the value for a particular key using the `get(Object o)` method. This method will return the value of the key if the key is present. If the key is not present, it will return null.

## Fetching the smallest key
As we are aware that a **TreeMap** stores elements in sorted order, we can fetch the smallest key using the `firstKey()` method. If the **TreeMap** is empty, then `NoSuchElementException` is thrown. If we want to get the smallest entry, then the `firstEntry()` method can be used.

## Fetching the largest key
We can fetch the largest key using the `lastKey()` method. If the TreeMap is empty, then `NoSuchElementException` is thrown. If we want to get the largest entry, then the `lastEntry()` method can be used.






Let's see how we can fetch and remove elements from a TreeMap.

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

TreeMap: Fetching and Removal

Fetching an element from a TreeMap

Fetching the value for a particular key

Fetching the smallest key

Fetching the largest key