Top Java Collection Interview Questions for 2021 To consolidate your knowledge and concepts in Java, here we've listed the most commonly asked Java interview questions so you can crush that interview! by Collections in Java In Java, Collection is a framework that provides an architecture to store and manipulate groups of objects. The “Collection Framework” has been defined in JDK 1.2 and it holds all the collection classes and interfaces in it. The two main interfaces of the Java Collection classes are the Collection interface (java.util.Collection) and the Map interface (java.util.Map). Java Collections can perform all operations on data such as searching, sorting, insertion, manipulation, and so on. Java Collection Framework provides interfaces such as Set, List, Queue, Deque, and classes such as ArrayList, Vector, LinkedList, HashSet, PriorityQueue, TreeSet, and LinkedHashSet.