Difference Between Collection And Collections In Java

This question seems confusing because both “Collection” and “Collections” look similar. Both are part of java collection framework, but both serve different purpose. Collection is a top level interface of java collection framework where as Collections is an utility class. In this article, we will discuss the differences between Collection and Collections in java.

Collection Interface :

Collection is a root level interface of the Java Collection Framework. Most of the classes in Java Collection Framework inherit from this interface. List, Set and Queue are main sub interfaces of this interface. JDK doesn’t provide any direct implementations of this interface. But, JDK provides direct implementations of it’s sub interfaces. ArrayList,Vector, HashSet, LinkedHashSet, PriorityQueue are some indirect implementations of Collection interface. Map interface, which is also a part of java collection framework, doesn’t inherit from Collection interface. Collection interface is a member of java.util package.

Collections Class:

Collections is an utility class in java.util package. It consists of only static methods which are used to operate on objects of type Collection. For example, it has the method to find the maximum element in a collection, it has the method to sort the collection, it has the method to search for a particular element in a collection. Below is the list of some important methods of Collections class.

Collections.max()	This method returns maximum element in the specified collection.
Collections.min()	This method returns minimum element in the given collection.
Collections.sort()	This method sorts the specified collection.
Collections.shuffle()	This method randomly shuffles the elements in the specified collection.
Collections.synchronizedCollection()	This method returns synchronized collection backed by the specified collection.
Collections.binarySearch()	This method searches the specified collection for the specified object using binary search algorithm.
Collections.disjoint()	This method returns true if two specified collections have no elements in common.
Collections.copy()	This method copies all elements from one collection to another collection.
Collections.reverse()	This method reverses the order of elements in the specified collection.