Collections Interface

The Collections interface in Java is a member of the Java Collections Framework. It is a type of interface that is used to represent the different types of collections such as lists, sets, and maps. It is a part of the java.util package and contains many utility methods that can be used to perform various operations on collections.

The Collections interface provides a standard way to manipulate collections and has methods for searching, sorting, and modifying collections. It also provides methods for creating read-only collections and synchronized collections.

The Collections interface has several sub-interfaces, each of which is designed for a specific type of collection. The sub-interfaces of Collections are:

List: This sub-interface is used to represent an ordered collection of elements. It can contain duplicate elements and is index-based.

Set: This sub-interface is used to represent a collection of elements that contains no duplicates.

Map: This sub-interface is used to represent a collection of key-value pairs.

SortedSet: This sub-interface is used to represent a set of elements that are sorted in a specific order.

SortedMap: This sub-interface is used to represent a map of key-value pairs that are sorted in a specific order.

The Collections interface also provides several utility methods such as sorting, searching, and reversing collections. Some of the commonly used methods of the Collections interface are:

sort(): This method is used to sort the elements of a list.

reverse(): This method is used to reverse the order of the elements in a list.

binarySearch(): This method is used to search for an element in a list using binary search.

shuffle(): This method is used to randomly shuffle the elements in a list.

max(): This method is used to find the maximum element in a collection. min(): This method is used to find the minimum element in a collection.