#salesforce #Winter24 release came with Collator class, that is meant to provide locale sensitive sorting. This video gives a hands-on demo of the class, along with areas where its meant to be used, and where not to use it.

TestCollator.cls

@istest
public class TestCollator {
    /*
	   	In German, characters like "ä", "ö", and "ü" 
		have specific sorting rules. 
     */
    static final String[] germanWords = new String[] {'Apfel', 'Unter', 'Auto', 'Öl', 'äpfel'};
        
    /*
 		In French, characters like "é", "è", "ê", and "ë" 
		have specific sorting rules that differ from their base character "e". 
     */ 
	static final String[] frenchWords = new String[] {'école', 'élève', 'eclair', 'écrit', 'effort'};

        
	static User runAsUser = new User(Alias = 'standt', Email='standarduser@testorg.com',
                          EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US', 
                          TimeZoneSidKey='America/Los_Angeles',
                          ProfileId = [SELECT Id FROM Profile WHERE Name='Standard User'].Id,
                          UserName='standarduser' + DateTime.now().getTime() + '@testorg.com');

    
    @IsTest
    static void frenchUserLocaleSort() {
        
        string userLocale = 'fr_FR';
        
        runAsUser.LocaleSidKey=userLocale;
        System.runAs(runAsUser) {            
             
            frenchWords.sort();
            System.debug (' French Sorting - Without Collator - ' + frenchWords);
            
            // Sort based on user Locale
            Collator myCollator = Collator.getInstance();
            frenchWords.sort(myCollator);
            System.debug (' French Sorting - With Collator - ' + frenchWords);
            
        }
    }
    
    @IsTest
    static void germanUserLocaleSort() {
        
        string userLocale = 'en_DE';
        
        runAsUser.LocaleSidKey=userLocale;
        System.runAs(runAsUser) {            

            germanWords.sort();
            System.debug (' German Sorting - Without Collator - ' + germanWords);
            
            // Sort based on user Locale
            Collator myCollator = Collator.getInstance();
            germanWords.sort(myCollator);
            System.debug (' German Sorting - With Collator - ' + germanWords);
            
        }
    }
    
     
}