In this article "Enhancement of Java Collection classes" we will learn about the origin of classes in different versions of jdk. Also, If any new class introduced, what was the purpose of introducing that? What was the weakness of previous version of the class? Why the new class introduced? What all new features introduced in Collection classes? and so on. We are going to discuss about these kinds of questions in this article accordingly. In fact, we will learn about Enhancement of java collection classes step by step & also version by version simultaneously. Particularly, we will focus on Java collection classes features in JDK 1.0, 1.2, 1.4, 1.5, 1.6 and 1.8 respectively. What is Collection in Java? As we might already