Undeleting Records In Apex (Salesforce)

UnDeleteContacts.cls

List<Contact> contactsToUnDelete = new List<Contact>();
for(Contact c : [Select Id, Name, IsDeleted from Contact LIMIT 50000 ALL ROWS]){
    if( c.IsDeleted == true ) {
		 System.debug('Undeleting Contact ='+c.Name+' : '+c.IsDeleted);
         contactsToUnDelete.add(c);
    }
}
if( contactsToUnDelete.size() > 0 ){
    System.debug('Undeleting In Total '+contactsToUnDelete.size()+' Contacts');
	undelete contactsToUnDelete;
}