step for creating files

1) File --> New --> Spring Starter Project
2) Name --> Calculator
3) Select Maven as Type
4) Click Next
5) Add Dependencies: DevTools, Web, Thymeleaf
6) Click Next, Finish
7) Go to src/main/java --> Create a package called com.example.demo.controller
8) Now, right click the newly created package.
9) Create a class -> Calc_Controller
10) Add @Controller annotation
11) Add below content:
@GetMapping("/")
public String show_calculator()
{
return "calc";
}
12) Now, go to src/main/resources --> templates
13) Create a filed named as 'calc.html'

package com.example.demo.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.ui.Model;

@Controller
public class calc_Controller {
    @GetMapping("/")
    public String show_calculator()
    {
        return "calc";
    }
    @PostMapping("/calculate_values")
    public String do_calculations(@RequestParam double num1,@RequestParam double num2,@RequestParam String operations, Model model)
    {
        model.addAttribute("no1", num1);
        model.addAttribute("no2", num2);
        model.addAttribute("ops", operations);
        double result = 0; 
        switch(operations)
        {
        case"+": result = num1 + num2; break;
        case"-": result = num1 - num2; break;
        case"*": result = num1 * num2; break;
        case"/": result = num1 / num2; break;
        }
        model.addAttribute("result",result);
        return "calc";
    }
}

14) Create Mapping for /calculate_values [action of form]

@RequestParam
Annotation which indicates that a method parameter should be bound to a web request parameter.

15) Create below method in Controller:

Calculator
    
    
        
        Number 1: 
          
        Number 2:
          
        
             Add
             Subtract
             Multiply
             Divide
        
          
             
         
              Result  
              
                
                
                
                =
                
              
    




    Enter fullscreen mode
    


    Exit fullscreen mode
    




outputhttp://localhost:8080/calculate_values