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.javabynataraj;

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("Murali");
  mylist.add("Shakir");
  mylist.add("Aravind");
  mylist.add("Jayaprakash");
  mylist.add("Vivek");
  mylist.add("Sivaraj");
  
  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

[Murali, Shakir, Aravind, Jayaprakash, Vivek, Sivaraj]

Collections class having a method to reverse the list is

Collections.sort(mylist);
 Collections.reverse(mylist);
 System.out.println(mylist);

The Output wil be:

[Vivek, Sivaraj, Shakir, Murali, Jayaprakash, Aravind]

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());
     }

for this iteration the elements will be displayed in console as:

Murali
Shakir
Aravind
Jayaprakash
Vivek
Sivaraj

Output: