Interview question: the difference between collection and collections in Java

1. java. util. collection is Set Interface. It provides common interface methods for basic operations on collection objects. The collection interface has many specific implementations in the Java class library. The collection interface provides a unified operation mode to maximize various specific sets. Collection
Shortlist
│ Invalid parameter list
│ ├ Arraylist
│ Vector
│ Elastic Stack
Sorted set 2. java. util. collections is a packaging class. It contains various Set Operations The static polymorphism method is used for searching, sorting, and thread security operations on various sets.Such Cannot be instantiated, Like ToolsTo serve the Java Collection framework.

Import java. util. arraylist;
Import java. util. collections;
Import java. util. List;

public class testcollections {
Public static void main (string ARGs []) {
// note that List implements the collection interface
List list = new arraylist ();
double array [] = {112,111, 23,456,231 };
for (INT I = 0; I list. add (New Double (array [I]);
}< br> collections. sort (list);
for (INT I = 0; I system. out. println (list. get (I);
}< br> // result: 23.0 111.0 112.0 231.0 456.0
}< BR >}< br>