Opportunity trigger

This code update close date  

trigger changeStage on Opportunity (after update) {
    list<Opportunity> listOfOpportunity = [select Id,stageName,CloseDate  from Opportunity where ID IN : trigger.new];
    list<Opportunity>   tempListOfOpportunity=  new list<Opportunity>();
        for(Opportunity oppNew :listOfOpportunity)
        {
           if(oppNew.StageName!=trigger.oldMap.get(oppNew.id).stageName)
           {
              if(oppNew.stageName.equalsIgnoreCase('Closed Won') || oppNew.stageName.equalsIgnoreCase('Closed Lost'))
               {
                oppNew.CloseDate = Date.today();
                tempListOfOpportunity.add(oppNew);
                } 
           }
        }
        update tempListOfOpportunity; 
}

Thanks.