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JAVA Caulculator in Workspaces?

Hello TreeHouse forums,

Is it possible to create a Calculator ( JAVA ) in TreeHouse workspaces? I've tired simple one but without a success ( can't define anything except addition and even that's broke )

Input works fine, once i declare function + instead of addition it does this :

5 + 3 = 53 instead of 8

Also any other function like division are returning error

//import features
import java.io.Console;
public class Calculator {

    public static void main(String[] args) {
      Console console = System.console();
        // Type code below
        // Welcome message
      System.out.printf("You've just enabled the best calculator in the world!\n");
        //Input 1
     String firstInput = console.readLine("Enter first number:  \n");
      //Function Input
      String function = console.readLine("Please enter function:  \n");
      //Input 2
      String secondInput = console.readLine("Please enter second digit:  \n");
      String result;
      //Functions List
      if (function.equals("+")) {
         result = firstInput + secondInput;
         System.out.printf("Result is :  %s\n", result);



Thank you in advance for suggestions ;)

2 Answers

Seth Kroger
Seth Kroger
56,403 Points

Because the inputs are all strings, you're concatenating 2 to strings together (String + String), not adding two numbers together (double + double, or int + int). You need to convert the inputs to numbers with either of the static methods Integer.parseInt(String) or Double.parseDouble(String).

String firstInput = console.readLine("Enter first number:  \n");
double firstNumber = Double.parseDouble(String);

Thanks for advice, it really works it's almost 100% correct ( 10+5 = 15,050 for example ) And what about other functions?

I've defined subtraction same as addition :

 if (function.equals("-")) {
     result = firstNumber - secondInput;
     System.out.printf("Result is :  %s\n", result);


but it gives me the error: (also for any other function such as division )

Calculator.java:28: error: bad operand types for binary operator '-'
result = firstNumber - secondInput;
first type: double
second type: String
1 error

Seth Kroger
Seth Kroger
56,403 Points

You need to convert the second input into a number as well. Another thing you need to be aware of is when printing a number you need to use %d for a whole number or %f for a decimal number in place of %s.