What is the main difference between Collection and Collections in Java?

Question

a little javadoc now and then hasn't hurt anyone.. – Bozho Nov 25 '09 at 11:34 — Bozho, Nov 25 '09 at 11:34

score 80 · Accepted Answer · edited Oct 09 '17 at 03:39

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Collection is a base interface for most collection classes, whereas Collections is a utility class. I recommend you read the documentation.

edited Oct 09 '17 at 03:39

intrepid_em

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answered Nov 25 '09 at 11:20

Mirek Pluta

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Which would be: http://java.sun.com/javase/6/docs/api/java/util/Collections.html http://java.sun.com/javase/6/docs/api/java/util/Collection.html – omerkudat Nov 25 '09 at 11:43
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Or, for Java 8: https://docs.oracle.com/javase/8/docs/api/java/util/Collections.html https://docs.oracle.com/javase/8/docs/api/java/util/Collection.html – Ollie Jun 08 '18 at 03:00

uckelman · Answer 2 · 2009-11-25T11:27:35.393

Are you asking about the Collections class versus the classes which implement the Collection interface?

If so, the Collections class is a utility class having static methods for doing operations on objects of classes which implement the Collection interface. For example, Collections has methods for finding the max element in a Collection.

The Collection interface defines methods common to structures which hold other objects. List and Set are subinterfaces of Collection, and ArrayList and HashSet are examples of concrete collections.

score 17 · Answer 3 · edited Nov 06 '15 at 02:15

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collection : A collection(with small 'c') represents a group of objects/elements.

Collection : The root interface of Java Collections Framework.

Collections : A utility class that is a member of the Java Collections Framework.

edited Nov 06 '15 at 02:15

John

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answered Nov 25 '09 at 11:29

jai

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*one of* the root interfaces. – Kevin Bourrillion Nov 25 '09 at 16:11
First line in the Collection documentation: "The root interface in the collection hierarchy" – dahui Nov 07 '16 at 13:09

score 13 · Answer 4 · answered Nov 25 '09 at 11:27

Collection, as its javadoc says is "The root interface in the collection hierarchy." This means that every single class implementing Collection in any form is part of the Java Collections Framework.

The Collections Framework is Java's native implementation of data structure classes (with implementation specific properties) which represent a group of objects which are somehow related to each other and thus can be called a collection.

Collections is merely an utility method class for doing certain operations, for example adding thread safety to your ArrayList instance by doing this:

List<MyObj> list = Collections.synchronizedList(new Arraylist<MyObj>());

The main difference in my opinion is that Collection is base interface which you may use in your code as a type for object (although I wouldn't directly recommend that) while Collections just provides useful operations for handling the collections.

Of course, now `Iterable` is the root interface of the collection hierarchy. — Tom Hawtin - tackline, Nov 25 '09 at 12:12
I'd say that Iterable is the root interface of the iterable hierarchy. :) — Kevin Bourrillion, Nov 25 '09 at 16:12
Iterator is a generalized view to a collection, how'd that sound? :) — Esko, Nov 26 '09 at 08:35

score 12 · Answer 5 · edited Nov 15 '15 at 14:39

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Collection is an interface containing List, Set and Queue.

Collections is a class containing useful methods like Collections.sort() and Collections.synchronizedlist(), etc.

edited Nov 15 '15 at 14:39

Jonathan Lam

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answered Nov 15 '15 at 14:11

Ankitha sridhar

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score 3 · Answer 6 · answered Jun 25 '14 at 06:48

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Collection is an root interface of Java collection framework. Collections is a utility class which contains static methods. example Collections.sort()

answered Jun 25 '14 at 06:48

Abhilash

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score 2 · Answer 7 · answered Jun 12 '13 at 07:39

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Collection is an Interface which can used to Represent a Group of Individual object as a single Entity.

Collections is an utility class to Define several Utility Methods for Collection object.

answered Jun 12 '13 at 07:39

srikanth

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score 2 · Answer 8 · answered Sep 21 '15 at 15:24

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Collection is a interface which is used to represent group of individual object as a single entity.

Collections is an utility class present in java.util. package to define several utility method (like sorting,searching ) for collection object.

answered Sep 21 '15 at 15:24

Sitanshu Shukla

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score 2 · Answer 9 · answered Feb 14 '12 at 04:14

Collection, as its javadoc says is "The root interface in the collection hierarchy." This means that every single class implementing Collection in any form is part of the Java Collections Framework.

The Collections Framework is Java's native implementation of data structure classes (with implementation specific properties) which represent a group of objects which are somehow related to each other and thus can be called a collection.

Collections is merely an utility method class for doing certain operations, for example adding thread safety to your ArrayList instance by doing this:

List list = Collections.synchronizedList(new Arraylist());

The main difference in my opinion is that Collection is base interface which you may use in your code as a type for object (although I wouldn't directly recommend that) while Collections just provides useful operations for handling the collections.

score 1 · Answer 10 · answered Aug 31 '12 at 12:00

Collection is a base interface for most collection classes (it is the root interface of java collection framework) Collections is a utility class

Collections class is a utility class having static methods It implements Polymorphic algorithms which operate on collections.

score 1 · Answer 11 · edited Dec 10 '12 at 08:13

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The Collections class is a utility class having static methods for doing operations on objects of classes which implement the Collection interface. For example, Collections has methods for finding the max element in a Collection.

edited Dec 10 '12 at 08:13

Echilon

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answered Dec 10 '12 at 07:56

kevendra

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score 1 · Answer 12 · answered Sep 23 '13 at 16:07

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Collection is an interface from which other class forms like List, Set are derived. Collections (with "S") is a utility class having static methods to simplify work on collection. Ex : Collections.sort()

answered Sep 23 '13 at 16:07

user2450176

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score 1 · Answer 13 · answered Jul 24 '15 at 05:46

As per Java Doc Collection is:

The root interface in the collection hierarchy. A collection represents a group of objects, known as its elements. Some collections allow duplicate elements and others do not. Some are ordered and others unordered. The JDK does not provide any direct implementations of this interface: it provides implementations of more specific subinterfaces like Set and List. This interface is typically used to pass collections around and manipulate them where maximum generality is desired.

Where as Collections is:

This class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, "wrappers", which return a new collection backed by a specified collection, and a few other odds and ends.

score 0 · Answer 14 · answered Sep 06 '12 at 11:20

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Collections is a class which has some static methods and that method returns the collection. Collection is an interface,rather than root interface in collection hierarchy.

answered Sep 06 '12 at 11:20

titas roy

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Hi titas. The same answer was answered by @Luno and accepted three years ago. No need to repeat it. – MByD Sep 22 '12 at 01:41

score 0 · Answer 15 · answered Jun 09 '15 at 05:03

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Yes, Collections is a utilty class providing many static methods for operations like sorting... whereas Collection in a top level interface.

answered Jun 09 '15 at 05:03

Shailendra Singh

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score 0 · Answer 16 · answered Jul 24 '15 at 05:31

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Collection is a interface and Collections is class in Java.util package

answered Jul 24 '15 at 05:31

Ramnath

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score 0 · Answer 17 · answered Sep 30 '15 at 10:24

Collections is a utility class, meaning that it defines a set of methods that perform common, often re-used functions, such as sorting a list, rotating a list, finding the minimum value etc. And these common methods are defined under static scope.

Collection is an interface that is implemented by AbstractCollection which in turn is implemented by AbstractList, AbstractSet etc.

Also, Collections class has thirty-two convenience implementations of its collection interfaces, providing unmodifiable collections, synchronized collections. Nearly all of these implementations are exported via static factory methods in one noninstantiable class (java.util.Collections).

Reference: Effective Java

score -2 · Answer 18 · answered Feb 23 '12 at 10:36

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collection is an interface and it is a root interface for all classes and interfaces like set,list and map.........and all the interfaces can implement collection interface.

Collections is a class that can also implements collection interface.......

answered Feb 23 '12 at 10:36

raju

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downvote for `Collections is a class that can also implements collection interface....... ` Mind that `Collections` is a utility class – Suganthan Madhavan Pillai Aug 23 '15 at 15:49

What is the main difference between Collection and Collections in Java?

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