The difference between collection and collections in Java

Today, look at the Java pen Test, found that there is such a problem, compare collection and collections differences. Keep a record of the differences here.

1, Java.util.Collection is a collection interface . It provides a common interface method for basic manipulation of collection objects. The collection interface has many specific implementations in the Java class Library. The meaning of the collection interface is to provide a maximum unified operation for a variety of specific collections.

Collection
├list
│├linkedlist
│├arraylist
│└vector
│└stack
└set

2, Java.util.Collections is a packaging class. It contains a variety of static polymorphic methods related to set operations. This class cannot be instantiated , just like a tool class that serves the Java collection framework.

Java code 650) this.width=650; "class=" star "src=" Http://pengcqu.iteye.com/images/icon_star.png "alt=" Favorite Code "style=" border:0px; "/>

2. import java.util.ArrayList;

4. import java.util.Collections;

6. import java.util.List;

10. Public class testcollections {

14. Public Static void Main (String args[]) {

16. //Note that the list is implemented with the collection interface

18. List List = new ArrayList ();

20. double array[] = { 111, 456, 231 };

22. for (int i = 0; i < array.length; i++) {

24. List.add (new Double (Array[i]));

26. }

28. Collections.sort (list);

30. for (int i = 0; i < array.length; i++) {

32. System.out.println (List.get (i));

34. }

36. //Result: 23.0 111.0 112.0 231.0 456.0

38. }

40. }

The difference between collection and collections in Java