The main difference between Collection and Collections is that Collection is the root interface of Java Collections Framework while Collections is a utility class which is a member of the Java Collections Framework.
Collection and Collections are widely used in Java programming. Both Collection and Collections are available in java.util package. Collection is the topmost interface while Collection is a class in the Java Collection framework. Overall, Collection allows storing multiple objects as one Collection object. On the other hand, Collections allow performing operations on that object.
Key Areas Covered
1. What is Collection
– Definition, Functionality
2. What is Collections
– Definition, Functionality
3. What is the Difference Between Collection and Collections
– Comparison of Key Differences
Collection, Collections, Java
What is Collection
Collection is the root interface of the Java Collection framework. It has many sub-interfaces such as List, Set, etc. Map interface also belongs to the collection framework, but it does not inherit from Collection interface. Collection extends from an Interface called Iterator and obtains all functionalities of that interface.
All the methods of Collection interface are public and abstract. Some common methods are as follows.
boolean add() – Allows inserting a specific element to the collection
boolean addAll(Collection c) – Allows adding all the elements to the collection
clear() – Removes all the elements from the collection
boolean isEmpty() – Helps to find whether the collection is empty or not
int size() – Helps to find the number of elements in the collection
boolean contains(Object o) – Checks whether the collection contains a specified object
boolean remove(Object o) – Removes a specified instance from the collection
What is Collections
“Collections” is a utility class of the Java Collection framework. It has static methods that allow performing operations on the objects of the type Collection. Some common methods in the Collection class are as follows.
Collections.max() – Helps to find the maximum value present in the collection
Collection.min() – Helps to find the maximum value present in the collection
Collection.sort() – Allows sorting the elements of the collection
Collection.copy() – Helps to copy elements of one collection into some other collection
Collection.reverse() – Allows reversing the order of the elements in the collection
Collections.binarySerach() – Helps to search an element using the binary search algorithm
Difference Between Collection and Collections
Collection is the parent interface of all other child interfaces and classes of the Java Collection framework while Collections is a utility class of Java Collection framework that consists of static utility functions. Thus, this is the main difference between Collection and Collections.
Moreover, another difference between Collection and Collections is that Collection consists of sub-interfaces such as List, Set, and Queue while Collections consist of static utility methods such as sort, reverse, etc.
Furthermore, Collection helps to store a set of objects into a single Collection object while Collections helps to perform an operation on the object of Collection. Hence, this is also a difference between Collection and Collections.
There is a distinct difference between Collection and Collections although most people use these two terms interchangeably. The main difference between Collection and Collections is that Collection is the root interface of Java Collections Framework while Collections is a utility class which is a member of the Java Collections Framework. In brief, Collection is an interface whereas Collections is a class.
1. “Interface Java.util.Collection.” Courses.cs.washington.edu, Available here.
1. “Java collection interfaces” By Original version created by b:User:Ervinn, SVG version created by myself – Own work (CC BY-SA 2.5) via Commons Wikimedia
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