Making a webbase calculator using spring mvc with maven

On my controller java file, public class Webcalculator, public string showCalcualtor and public string calcualte is grey out and says it got no usage right now and this is why my html won't calculate the results out so I need a fix for this

on the images are WebcalculatorApplication.java, pom.xml and calcualtor.html in order

this is the WebCalculatorController.java

package com.Junhyeok.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 $\{$

$//$ This method handles GET requests to the root URL $("/")$ and displays the calculator form.

@GetMapping$("/")$

public String showCalculator$()\{$

$//$ Return the name of the HTML file $($view$)$ that contains the calculator form

return "calculator"; $//$

$\}$

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

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

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

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

Model model$)\{$

double result;

$//$ Perform different calculations based on the provided operation

switch $($operation$)\{$

case "add":

result $=$ inputA $+$ inputB;

break;

case "subtract":

result $=$ inputA $-$ inputB;

break;

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

default:

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

$\}$

$//$ Add attributes to the model to be displayed in the calculator view

model.addAttribute$("$result$",$ result$)$; $//$ Result of the calculation

model.addAttribute$("$inputA$",$ inputA$)$; $//$ First input value

model.addAttribute$("$inputB$",$ inputB$)$; $//$ Second input value

model.addAttribute$("$operation$",$ operation$)$; $//$ Operation performed

$//$ Return the name of the HTML file $($view$)$ that contains the calculator form

return "calculator";

$\}$

$\}$