Set of tutorials regarding Java collections and related coding,concepts and exploring many internal ideas in all current Java versions like 5 , 1.6 and java 7.
This article contains a great deal of summery both common and uncommon details about collection framework.
Generics and Super type object in Collections
Generics was a boon to a wondering developer, it gives us compile time checks to ensure we are actually inserting a predeclared type into the collection, also no casting is required.
Frequency or occurances of collection
With the Java 1.5 , we have a new method available on Collections class, which helps us find the occurrences or number times of an element/collection occurs in a given collection.