How to sort an ArrayList

Sorting any ArrayList is pretty simple. Using Collections.sort( ) method we can sort the ArrayList. Collections class having all the static methods, we can use those methods directly along with the class name. These methods return the object as type Collection.

The important methods to synchronize the List, Set and Map as

synchronizedList(List<T> list)
synchronizedSet(Set<T> s)
synchronizedMap(Map<K,V> m) 

A simple program to sort an ArrayList







package blog.learnwebframeworks;



import java.util.ArrayList;

import java.util.Collections;

import java.util.List;



public class SortArraList {

 public static void main(String[] args) {

   

         List<String> mylist = new ArrayList<String>();

   

  mylist.add("Mani");

  mylist.add("Bala");

  mylist.add("Kishore");

  mylist.add("Vijay");

  mylist.add("Vishnu");

  mylist.add("Manik");

   

  System.out.println("***Before sorting the arrylist***");

  //iterate the list using for-each loop

  for(String names: mylist){

   System.out.println(names);

  }

  //Sort the ArrayList using sort() from Collections class

  Collections.sort(mylist);

  System.out.println("***After sorting the arraylist***");

  //iterate the list using for-each loop

  for(String names: mylist){

   System.out.println(names);

  }

 }



}




Here we are using Collections.sort(mylist) method to sort our list. Here the list is iterating using for-each
 loop. By this we can get the elements one by one in a new line instead 
to displaying as an ArrayList. To display entire arraylist just we can 
use 



System.out.println(mylist);

it will displays the entire arrylist elements as 

[Mani, Bala, Kishore, Vijay, Vishnu, Manik]

Collections class having a method to reverse the list is 




Collections.sort(mylist);

 Collections.reverse(mylist);

 System.out.println(mylist);






if you want to iterate the arraylist without using Iterator loop you can as below given




Iterator<string> it = mylist.iterator();




 while(it.hasNext()){


       System.out.println(it.next());

     }