spring boot java project_Calc

#java #springboot #html #payliagam

             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:

<!DOCTYPE html>
<html xmlns:th="http:www.thymeleaf.org">
    <head>
        <title>Calculator</title>
    </head>
    <body>
        <form action="calculate_values" method="post">
        <labal>Number 1: </labal>
        <input type="Number"name="num1"> <br> <br>
        <label>Number 2:</label>
        <input type="number"name="num2"> <br> <br>
        <select name="operations">
            <option value="+"> Add</option>
            <option value="-"> Subtract</option>
            <option value="*"> Multiply</option>
            <option value="/"> Divide</option>
        </select>
         <br> <br>
         <input type="submit" value="Calculate">    
         </form>
              <h2>Result</h2> <br> <br>
              <p>
                <span th:text ="${no1}"></span>
                <span th:text ="${ops}"></span>
                <span th:text ="${no2}"></span>
                <span>=</span>
                <sapn th:text="${result}"></sapn>
              </p>
    </body>
</html>

output

http://localhost:8080/calculate_values

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