Salesforce - Get Present Time and Week Day with Apex Coding

         //2018-05-06 15:33:41, get time only
         String presenttime=String.valueOf(datetime.now()).substringAfter(' ');
         System.assertEquals('15:33:41',presenttime);




public String getWeekDay(){
        String dayOfWeek='';       
        // Cast the Date variable into a DateTime
        DateTime myDateTime = (DateTime) System.today();
        dayOfWeek = myDateTime.format('E');
        // dayOfWeek is Sun, Mon, Tue, Wed, Thu, Fri, Sat.
        return dayOfWeek;
    }