Carlos Lombardii Carlos Lombardii - 9 months ago 31
Java Question

How to resolve "Syntax error on token "else"" in Java?

I am new around here but let's get straight to the question:
When I was writing the following code for a class project calculator I came across a "token error". This is the full error message:

Exception in thread "main" java.lang.Error: Unresolved compilation problem:
Syntax error on token "else", delete this token

at calculatorApplet.main(calculatorApplet.java:42)


I wrote this code:

import java.util.Scanner;
import javax.swing.JOptionPane;
public class calculatorApplet
{
Scanner sc = new Scanner(System.in);
public static void main(String[] args)
{
JOptionPane.showMessageDialog(null, "Welcome to the Calculator!");
String option = JOptionPane.showInputDialog(null, "Which calculator mode do you want?");
if (option.equals("Addition"))
{
Double add1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your addition problem."));
Double add2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your addition problem."));
Double preAdd = add1+add2;
Double Add = preAdd;
JOptionPane.showMessageDialog(null, "The sum is " + Add + ".");
}
else
{
JOptionPane.showMessageDialog(null, "Huh?");
}
if (option.equals("Subtraction"))
{
Double sub1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your subtraction problem."));
Double sub2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your subtraction problem."));
Double preSub = sub1-sub2;
Double Sub = preSub;
JOptionPane.showMessageDialog(null, "The difference is " + Sub + ".");
}
else
{
JOptionPane.showMessageDialog(null, "Huh?");
}
if (option.equals("Multiplication"));
{
Double mult1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your multiplication problem."));
Double mult2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your multiplication problem."));
Double preMult = mult1*mult2;
Double Mult = preMult;
JOptionPane.showMessageDialog(null, "The product is " + Mult + ".");
}
else //Here is the error.
{
JOptionPane.showMessageDialog(null, "Huh?");
} //Here ends the error.
if (option.equals("Division"))
{
Double div1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your division problem."));
Double div2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your division problem."));
Double preDiv = div1/div2;
Double Div = preDiv;
JOptionPane.showMessageDialog(null, "The quotient is " + Div + ".");
}
else
{
JOptionPane.showMessageDialog(null, "Huh?");
}
//End of if statements.
}

}


That's the code and I commented the area where the token error is. Maybe the solution is right in my face. I want my code to be a calculator so if you guys can fix my code to not conflict with the math operations. Thanks and I appreciate any help.

Answer Source

The problem is the semicolon after the if.

The grammar is if ( condition ) expression-or-block { else expression-or-block }

Since ; is an empty expression, this works for an if clause and nothing happens in the then clause - in your case syntactically there is no else clause, since your if statement statements ends with the semicolon and is followed by a simple block. Then the tokenizer detects a dangling else token and complains.