Collection and collections

Collection
Collection is the interface of Set List queue and Deque
Queue: Advanced First Out queue
Deque: Two-way linked list


Note: There is no relationship between collection and map
Collection is a set of objects, and Map is a key value pair.


Collections is a class, a container's tool class, just as arrays is an array of tool classes


Reverse
Reverse the data in the list to flip

Package collection;
   
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
   
public class Testcollection {public
    static void Main (string[] args) {
        //initialization collection numbers
        list<integer> Numbers = new arraylist<> ();
         
        for (int i = 0; i < i++) {
            numbers.add (i);
        }
         
        SYSTEM.OUT.PRINTLN ("Data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
        Collections.reverse (numbers);
         
        SYSTEM.OUT.PRINTLN ("Flip Data in a collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
    }

Confuse
Shuffle confuse the order of the data in the list

Package collection;
   
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
   
public class Testcollection {public
    static void Main (string[] args) {
        //initialization collection numbers
        list<integer> Numbers = new arraylist<> ();
         
        for (int i = 0; i < i++) {
            numbers.add (i);
        }
         
        SYSTEM.OUT.PRINTLN ("Data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
        Collections.shuffle (numbers);
         
        SYSTEM.OUT.PRINTLN ("Confusing data in a collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
    }

Sort sorts to sort the data in a list

Package collection;
   
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
   
public class Testcollection {public
    static void Main (string[] args) {
        //initialization collection numbers
        list<integer> Numbers = new arraylist<> ();
         
        for (int i = 0; i < i++) {
            numbers.add (i);
        }
         
        SYSTEM.OUT.PRINTLN ("Data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
 
        Collections.shuffle (numbers);
        SYSTEM.OUT.PRINTLN ("Confusing data in a collection:");
        SYSTEM.OUT.PRINTLN (numbers);
 
        Collections.sort (numbers);
        SYSTEM.OUT.PRINTLN ("Data in a sorted collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
    }

Exchange
Swap for two data locations

Package collection;
   
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
   
public class Testcollection {public
    static void Main (string[] args) {
        //initialization collection numbers
        list<integer> Numbers = new arraylist<> ();
         
        for (int i = 0; i < i++) {
            numbers.add (i);
        }
         
        SYSTEM.OUT.PRINTLN ("Data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
 
        Collections.swap (numbers,0,5);
        SYSTEM.OUT.PRINTLN ("Exchange 0 and 5 subscript data, data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
    }

Rolling
Rotate the data in the list to the right by scrolling the length of the specified unit (looping right)

Package collection;
   
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
   
public class Testcollection {public
    static void Main (string[] args) {
        //initialization collection numbers
        list<integer> Numbers = new arraylist<> ();
         
        for (int i = 0; i < i++) {
            numbers.add (i);
        }
         
        SYSTEM.OUT.PRINTLN ("Data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
 
        Collections.rotate (numbers,2);
        SYSTEM.OUT.PRINTLN ("Roll the set to the right 2 units, after the marked data, the data in the collection:");
        SYSTEM.OUT.PRINTLN (numbers);
         
    }

Thread Safety
Synchronizedlist the non-thread-safe list into a thread-safe list

Package collection;
 
Import java.util.ArrayList;
Import java.util.Collections;
Import java.util.List;
 
public class Testcollection {public
    static void Main (string[] args) {
        list<integer> numbers = new ArrayList <> ();
 
        SYSTEM.OUT.PRINTLN ("Convert non-thread-safe list to Thread-safe list");
        List<integer> synchronizednumbers = (list<integer>) collections.synchronizedlist (numbers);
 
    }