ArrayList, Linked List, Vector

Array List:
Java ArrayList class can contain duplicate elements.
Java ArrayList class maintains insertion order.
Java ArrayList class is non synchronized.
Java ArrayList allows random access because array works at the index basis.
In Java ArrayList class, manipulation is slow because a lot of shifting needs to be occurred if any element is removed from the array list.

Linked List:;

Java LinkedList class can contain duplicate elements.

Java LinkedList class maintains insertion order.

Java LinkedList class is non synchronized.

In Java LinkedList class, manipulation is fast because no shifting needs to be occurred.

Java LinkedList class can be used as list, stack or queue.

java LinkedList class in collection framework

1) Since Array is an index based data-structure searching or getting element from Array with index is pretty fast. Array provides O(1) performance for get(index) method but remove is costly in ArrayList as you need to rearrange all elements. On the Other hand LinkedList doesn't provide Random or index based access and you need to iterate over linked list to retrieve any element which is of order O(n).

2) Insertions  are easy and fast in LinkedList as compared to ArrayList because there is no risk of resizing array

and copying content to new array if array gets full which makes adding into ArrayList of O(n) in worst case, while adding is O(1) operation in LinkedList in Java. ArrayList also needs to update its index if you insert something anywhere except at the end of array.

3) Removal is like insertions better in LinkedList than ArrayList.

Vector implements a dynamic array. It is similar to ArrayList, but with spme differences:

• Vector is synchronized.
• Vector proves to be very useful if you don't know the size of the array in advance or you just need one that can change sizes over the lifetime of a program.