Java calulator throws -bad operand types for binary operator '-'-

Question

I get this error; bad operand types for binary operator '-' All other operations work...when I leave out the subtraction via comments like // and /* */; can someone help? This is the code by the way; the exception is on the subtraction line. ``` public class Calculator { /* *use 'javac Calculator.java' to compile; *use 'jar cvf Calculator.jar Calculator.class' for jar; *use 'java Calculator' to run; */ public static void main(String []args) { String NewName Scanner user_input = new Scanner( System.in ); System.out.println("Type your name please."); NewName = user_input.next(); System.out.println(""); System.out.println("Hello " + NewName + "."); System.out.println("I am Hunter's java calculator program."); System.out.println(""); //mathematical input String operator; float cal1, cal2; System.out.println("Type a Number..."); cal1 = user_input.nextFloat(); System.out.println(""); System.out.println("Type another Number..."); cal2 = user_input.nextFloat(); System.out.println(""); Scanner…

Accepted Answer

You need parenthesis:

```
System.out.println("The answer is " + (cal1-cal2) + ".");
```

Otherwise what you have is treated as

```
System.out.println(("The answer is " + cal1) - (cal2 + "."));
```

which is invalid since you can't subtract strings.

Why don't you have an error with the other operators? Well, `*` and `/` have higher precedences, so those are working as expected. `+`, on the other hand, is overloaded to concatenate strings:

```
System.out.println("The answer is " + cal1+cal2 + "."); // concatenates, doesn't add
```

For example, if `call1` is `1` and `call2` is `2`, the result will be:

```
The answer is 12.
```

which isn't what you want. Again, this can be solved with parenthesis.

Java calulator throws -bad operand types for binary operator '-'-

Solution

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