Scala Concepts

                                                             

Smallest substring that contains all the characters of a given string

Array Rotation

http://www.geeksforgeeks.org/array-rotation/

Object Reflection Java

http://stackoverflow.com/questions/37628/what-is-reflection-and-why-is-it-useful

Nosql

https://www.youtube.com/watch?v=qI_g07C_Q5I

Spring Framework

Spring Security

http://www.studytrails.com/frameworks/spring/spring-security-custom-login-page.jsp