gistfile1.txt

If this is expected to be a non trivial application I would probably use the strategy pattern.

    public class CommandLineCalculator{

        public static void main(String[] args){
          CommandLineCalculator commandLineCalculator = new CommandLineCalculator();
          
          int total = 0;
          int lastValue = 0;

          for(String arg : args){
              if(commandLineCalculator.isSymbol(arg)){
                  total = 
              }
          }

        }

        private Map<String, CalculationStrategy> strategies;

        public CommandLineCalculator(){
           strategies = new HashMap<String, CalculationStrategy>();
           strategies.add("+", new AddStrategy());
        }

        public boolean isSymbol(String possibleSymbol){
           return strategies.get(possibleSymbol) != null;
        }

        public static interface CalculationStrategy{
             public int calculate(int num1, int num2);
        }

        public static class AddStrategy implements CalculationStrategy{
           @Override
           public int calculate(int num1, int num2){
               return num1 + num2;
           }
        }

    }