By default, items in ArrayList are displayed in the order in which they are inserted into the list, but sometimes you need to browse these items in ascending or descending order. This code implements the Collections.sort() which sorts a Arraylist in ascending and descending order.

Sort ArrayList in ascending order

import java.util.ArrayList; 
import java.util.Collections; 

public class Tri {

 public static void main(String[] args) {
 ArrayList unsorted = new ArrayList(); 
 nonsort.add("01"); 
 nonsort.add("0A"); 
 unsorted.add("0B"); 
 unsorted.add("ETX"); 
 unsorted.add("00"); 
 unsorted.add("0C"); 
 nonsort.add("NUL"); 
 unsorted.add("05"); 
 unsorted.add("19"); 
 unsorted.add("0001011"); 
 
 System.out.println("Before sorting"); 
 for(int i=0; i < unsorted.size(); i++)
 System.out.println(unsorted.get(i)); 
 
 System.out.println("\nAfter sorting"); 
 Collections.sort(unsorted); 
 for(int i=0; i < unsorted.size(); i++)
 System.out.println(unsorted.get(i)); 
 }
}

Output:

Before tri
01 
0A 
0B 
ETX 
00 
0C 
NUL 
05 
19 
0001011 
< br />After sorting
00 
0001011 
01 
05 
0A 
0B 
0C 
19 
ETX 
NUL 

Sort ArrayList in descending order

The Collections class has another method Collections.sort(List< T>, Comparator< T>) which allows you to sort an ArrayList in ascending and descending order. This function uses an object comparator that compares two objects each time with the function o1.compareTo(o2).

import java.util.ArrayList; 
import java.util.Collections; 
import java.util.Comparator; 

public class Tri {

 public static void main(String[] args) {
 ArrayList unsorted = new ArrayList(); 
 unsorted.add("11000000"); 
 unsorted.add("10101000"); 
 unsorted.add("00000001"); 
 unsorted.add("00001111"); 
 nontrié.add("00001100"); 
 unsorted.add("00001111"); 
 unsorted.add("11111111"); 
 nonsort.add("11111100"); 
 unsorted.add("00000000"); 
 unsorted.add("00000011"); 
 unsorted.add("00001110"); 
 
 System.out.println("Before sorting"); 
 for(int i=0; i < unsorted.size(); i++)
 System.out.println(unsorted.get(i)+" "); 
 
 System.out.println("\nAfter sorting"); 

 Collections.sort(nonsort, new Comparator() {
 @Override
 public int compare(String s1, String s2)
 {
 /*s2 compared to s1 so that the order is descending
 return s2.compareTo(s1); 
 }
 }); 
 for(int i=0; i < unsorted.size(); i++)
 System.out.println(unsorted.get(i)+" "); 
 }
}

Output:

Before Sort
11000000 
10101000 
00000001 
00001111 
00001100 
00001111 
11111111 
11111100 
00000000 
00000011 
00001110 

After sort
11111111 
11111100 
11000000 
10101000 
00001111 
00001111 
00001110 
00001100 
00000011 
00000001 
00000000 

References:
American Standard Code for Information Interchange
Documentation Collections.sort
stackOverFlow:How to sort an ArrayList in java