12 lore ~/project1/code $ cat Calculator.java
//will just check if there is 2, 3 ... .digit number since I like to be able to input 2 + 2 in the same line.
/*
Simple calculator in java, using simple I/O, and structures.
Just did it for fun, and becouse someone in a forum need it.
I'll include more things when I feel like it....although its preatty simple.
Needs Savitchin class, which makes it even simple, but preatty useable.
*/
import java.util.*;

public class Calculator
{
    double firstNumber;
    double secondNumber;
    double result;

    public boolean intCheck(char anyChar)
    {



        return anyChar == '0' || anyChar == '1' || anyChar == '2' || anyChar == '3' || anyChar == '4' || anyChar == '5' || anyChar == '6' || anyChar == '7' || anyChar == '8' || anyChar ==  '9';
            //will just check if there is 2, 3 ... .digit number since I like to be able to input 2 + 2 in the same line.

    }


    public double add (double firstNumber, double secondNumber)
    {
        result = firstNumber + secondNumber;
        return result;
    }

    public double substract (double firstNumber, double secondNumber)
    {
        result = firstNumber - secondNumber;
        return result;
    }

    public double multiply (double firstNumber, double secondNumber)
    {
        result = firstNumber * secondNumber;
        return result;
    }

    public double divide (double firstNumber, double secondNumber)
    {
        if (secondNumber == 0)
        {
            System.out.print ("Error can't divide by 0");
            return 0;

        }
        else
        {
            result = firstNumber/secondNumber;
            return result;
        }
    }

    public double power (double firstNumber, double secondNumber)
    {
        result = 1;
        //while a Number which = 0, is lower than the second number, it should multiply firstNumber * firstNumber, is more fun this way, although you can use mathpow......which is lame, still thinking about negatives and irrationals
        for (int counter = 0 ; counter < secondNumber ; counter ++ ) {

            result = result * firstNumber;
        }
        return result;
    }

    public void start ()
    {
        System.out.println ("This is a calculator, please use control + z to exit");
        System.out.println ("Usage 2 + 2, 2 ^ 2, 2 - 2, 2 / 2, 2 * 2 (spaces are important!)");
        String operator;
        boolean infinite=true;
        while (infinite = true) {

            //      int  position1 = 0, position2 = 4;
            //String userInput;
            StringTokenizer  userInput = new StringTokenizer ( SavitchIn.readLine () );
            if (userInput.hasMoreTokens())
            {
                firstNumber=Double.parseDouble(userInput.nextToken());
            }
            else
            {
                return;
            }
            if (userInput.hasMoreTokens())
            {
        operator  = (String)(userInput.nextToken());

            }
            else
            {
                return;
            }
            if (userInput.hasMoreTokens())
            {

                secondNumber  = Double.parseDouble(userInput.nextToken());

            }
            else
            {
                return;
            }


            //   firstNumber = (double) userInput.charAt(position1);

            //secondNumber = (double) userInput.charAt(position2);

            if (operator.equals("+") ){
               add(firstNumber, secondNumber);
               System.out.println ("= " + result);
            }

            else if (operator.equals("-") ){
                substract(firstNumber, secondNumber);
                System.out.println ("= " + result);
            }
            else if (operator.equals ("*")){
                multiply(firstNumber, secondNumber);
                System.out.println ("= " + result);
            }
            else if (operator.equals ("/") ){
               divide(firstNumber, secondNumber);
                System.out.println ("= " + result);
            }
            else if (operator.equals ("^") ){
                power(firstNumber, secondNumber);
                System.out.println ("= " + result);
            }


        }
    }



    public static void main (String [] args)
    {
      Calculator calc = new Calculator();
      calc.start();
    }

}