# Java Collections - LinkedList (In progress)

# Linked List
## 1. introduction
*`LinkedList`* is a doubly linked list which implements the *`List`* and *`Queue`* Iterfaces. It is a part of Java's *`Collections`* framework.

## 2. Features
- It maintains the insertion order
- It can have duplicate and *`null`* values
- It is not synchronized, means it is not thread-safe
- It's *`Iterators`* and *`ListIterators`* are fail-fast, which means after the iterator's creation, if the list is modified a *`ConcurrentModificationException`* is thrown

Although LinkedList is not synchronized, we can get a synchronized version of it by calling the *`Collections.synchronizedList`* method.
```java
List list = Collections.synchronizedList(new LinkedList(...));
```

## 3. Comparison to ArrayList
Both ArrayList and LinkedList implements the List interface, However, they differ completely in the way how they store and retrieve the elements.
### 3.1 Structure
An ArrayList is an index based data-structure backed by an Array. It provides random access to its elements with performance equal to O(1).