Making a webbase calculator $($used spring mvc with maven$)$

This is WebcalculatorController.java

package com.example.Webcalculator;

import org.springframework.stereotype.Controller;

import org.springframework.ui$.$Model;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.RequestParam;

@Controller

public class WebcalculatorController $\{$

@GetMapping$("/")$

public String showCalculator$()\{$

return "calculator"; $//$ This will return the calculator.html view

$\}$

@PostMapping$("/$calculate$")$

public String calculate$($@RequestParam$("$inputA$")$ double inputA,

@RequestParam$("$inputB$")$ double inputB,

@RequestParam$("$operation$")$ String operation,

Model model$)\{$

double result;

switch $($operation$)\{$

case "add":

result $=$ inputA $+$ inputB;

break;

case "subtract":

result $=$ inputA $-$ inputB;

break;

$//$ Add more cases for other operations $($multiply$,$ divide, etc.$)$

default:

throw new IllegalArgumentException$("$Invalid operation: $"+$ operation$)$;

$\}$

model.addAttribute$("$result$",$ result$)$;

return "result"; $//$ This will return the result.html view

$\}$

$\}$

this is Calculator.html