how can I solve this error? (not my program but same problem) plss need help

Question

import java.util.Scanner;
import javax.swing.JOptionPane;

public class Java_Calculator {
public static void main(String[] args) {
String firstnumber, secondnumber, operation;
double num1;
double num2;
double sum;
double sub;
double div;
double mul;
double mod;
firstnumber = JOptionPane.showInputDialog ("Enter the first Operand: ");
secondnumber = JOptionPane.showInputDialog ("Enter the second Operand: ");
operation = JOptionPane.showInputDialog ("Enter the Operator: ");
num1 = Double.parseDouble (firstnumber);
num2 = Double.parseDouble (secondnumber);
sum= num1 + num2;
sub= num1 - num2;
div= num1 / num2;
mul= num1 * num2;
mod= num1 % num2;
if (operation == '+'){ JOptionPane.showMessageDialog (null, sum);} if (operation == '-'){ JOptionPane.showMessageDialog (null, sub); } if (operation == '/'){ JOptionPane.showMessageDialog (null, div); } if (operation == '*'){ JOptionPane.showMessageDialog (null, mul); } if (operation == '%'){ JOptionPane.showMessageDialog (null, mod); } } }

Answer 1

variable 'operation' in your code is string type. so instead of if(operation=='+') use if(operation.equals("+")) at all similar places. I think that should do it