Calc.java

import java.util.Scanner;

public class Calc {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    boolean keepRunning = true;
    Tokenizer tokenizer = new Tokenizer();

    while (keepRunning) {
      System.out.println("Enter 'exit' to quit, Or Enter a Problem:");
      String inputNumber = scanner.nextLine();

      if (inputNumber.equalsIgnoreCase("exit")) {
        keepRunning = false;
        System.out.println("Goodbye.");
      } else {
          String[] tokens = tokenizer.tokenize(inputNumber);
          System.out.println("Tokens:");
          for (String t : tokens) {
            System.out.println(t);
        }

      }

    }
    scanner.close();
  }

}