Forem: V I N O T H

Registration Form Application in Spring boot java

V I N O T H — Thu, 17 Apr 2025 12:27:40 +0000

*Registration From Application *

1.controller

package com.example.demo;

import java.util.List;

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 Regn_controller {

    @GetMapping("/")
    public String display(Model model)
    {
    model.addAttribute("genders", List.of("Male","Female","Other"));
    model.addAttribute("countries", List.of("Japan","U.S","Londan"));
    model.addAttribute("hobbies", List.of("Football","Cricket","GYM"));
        return "register"; 
    }

    @PostMapping("registered")
    public String getDetails(@RequestParam String username,
            @RequestParam String gene,
            Model model)
    {
        model.addAttribute("name", username);
        model.addAttribute("gend", gene);
        return "success"; 
    }
}

2.Register.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <head>
        <title> Registration Form</title>

    </head>
    <body>
        <form action="registered" method="post">
        <label> Name: </label> 
        <input type="text" name="username" placeholder="Enter Your Name" required>
        <br><br>
        <label> Gender: </label>
        <input type="radio" name="gene"
         th:each="gender:${genders}" th:value="${gender}" th:text="${gender}">
        <br><br>
        <label> Country: </label>
        <select name="nation">
<option th:each="country:${countries}" th:value="${country}" 
th:text="${country}">

            </option>
        </select>
        <br><br>
        <label> Hobby: </label>

        <input type="checkbox" name="hob" 
        th:each="hobby:${hobbies}" th:value="${hobby}" 
        th:text="${hobby}">
        <br><br>
        <input type="submit" value="Enter Details">
        </form>
    </body>


</html>

3.Success.html

Registered Successfully
<p th:text="${name}">

</p>
<p th:text="${gend}">

</p>

OUTPUT

background color change using spring boot mini project

V I N O T H — Tue, 15 Apr 2025 17:35:10 +0000

package com.example.demo.controller;


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

@Controller
public class Color_controller {

    @GetMapping("/")
    public String change_color(@RequestParam(defaultValue = "blue") String colors, Model model)
    {
        model.addAttribute("selectedColor", colors);
        return "color"; 
    }

}

<!DOCTYPE html>
<html xmlns:th="http://www.thymelear.org">
    <head>
        <title> Color Picker </title>
    </head>
<body th:style="'background-color:' + ${selectedColor}">
        <form action="/" method="get">
            <input type="color" th:value='${selectedColor}' name="colors">
            <input type="submit" value="Change Color">
        </form>

    </body>
</html>

OUTPUT

spring boot java project_Calc

V I N O T H — Thu, 10 Apr 2025 17:48:14 +0000

             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

Spring Boot,Annotation

V I N O T H — Thu, 03 Apr 2025 16:53:22 +0000

1.what is Spring Boot?
Spring Boot is a framework built on top of Spring Framework that simplifies the development of Java-based web applications and microservices. It eliminates the need for complex configurations and allows developers to quickly build and deploy applications with minimal setup.

2.key points of Spring
Spring Boot – Key Points 🚀
✅ Built on Spring Framework – Simplifies Java web and microservices development.
✅ Auto-configuration – Reduces manual setup, configures beans automatically.
✅ Embedded Servers – Comes with Tomcat, Jetty, or Undertow, no need for external servers.
✅ Spring Boot Starters – Pre-configured dependencies for faster development.
✅ Microservices Support – Ideal for cloud-based applications.
✅ Spring Boot Actuator – Provides monitoring, metrics, and health checks.
✅ Production-Ready – Has logging, exception handling, and security features.
✅ Spring Initializr – Generates a project setup quickly (start.spring.io).
✅ Simplified Deployment – Can be packaged as a JAR and run independently.

Example program

package com.example.demo;

import org.springframework.stereotype.Component;

@Component 
public class Engine {

//  String fuel1, fuel2;
//  public Engine(String fuel1, String fuel2) 
//  {
//      this.fuel1 = fuel1;
//      this.fuel2 = fuel2;
//  }

    public void Start() {
        System.out.println("Engine Started");
    }
}

package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class Car {

@Autowired
Engine engine;

public static void main(String[] args) {

    // Car maruti = new Car();
    // maruti.drive();
}

public void drive() {
    // TODO Auto-generated method stub
    // Engine engine = new Engine("Petrol");
    engine.Start();

}

}

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext cac= 
        SpringApplication.run(DemoApplication.class, args);
        Car Bezn = cac.getBean(Car.class);
        Bezn.drive();
    }

}

Output

. ____ _ __ _ _
/\ / ' __ _ ()_ __ __ _ \ \ \ \
( ( )_ | '_ | '| | ' \/ ` | \ \ \ \
\/ _)| |)| | | | | || (| | ) ) ) )
' |__| .|| ||| |_, | / / / /
=========||==============|_/=////

:: Spring Boot :: (v3.4.4)

2025-04-03T18:18:10.927+05:30 INFO 10662 --- [demo] [ restartedMain] com.example.demo.DemoApplication : Starting DemoApplication using Java 21.0.6 with PID 10662 (/home/neelakandan/Documents/workspace-spring-tool-suite-4-4.29.1.RELEASE/demo/target/classes started by neelakandan in /home/neelakandan/Documents/workspace-spring-tool-suite-4-4.29.1.RELEASE/demo)
2025-04-03T18:18:10.930+05:30 INFO 10662 --- [demo] [ restartedMain] com.example.demo.DemoApplication : No active profile set, falling back to 1 default profile: "default"
2025-04-03T18:18:10.973+05:30 INFO 10662 --- [demo] [ restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2025-04-03T18:18:10.973+05:30 INFO 10662 --- [demo] [ restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2025-04-03T18:18:11.812+05:30 INFO 10662 --- [demo] [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port 8080 (http)
2025-04-03T18:18:11.824+05:30 INFO 10662 --- [demo] [ restartedMain] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2025-04-03T18:18:11.824+05:30 INFO 10662 --- [demo] [ restartedMain] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.39]
2025-04-03T18:18:11.850+05:30 INFO 10662 --- [demo] [ restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2025-04-03T18:18:11.851+05:30 INFO 10662 --- [demo] [ restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 876 ms
2025-04-03T18:18:12.163+05:30 INFO 10662 --- [demo] [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2025-04-03T18:18:12.183+05:30 INFO 10662 --- [demo] [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port 8080 (http) with context path '/'
2025-04-03T18:18:12.192+05:30 INFO 10662 --- [demo] [ restartedMain] com.example.demo.DemoApplication : Started DemoApplication in 1.585 seconds (process running for 1.88)
Engine Started

HashSet removing duplication in java

V I N O T H — Wed, 02 Apr 2025 16:45:19 +0000

package framework;

import java.util.HashSet;
import java.util.LinkedHashSet;

public class String_arry_list {
public static void main(String[] args) {
    String name="neelakanadan";
    LinkedHashSet al=   new LinkedHashSet();    
    for(int i=0;i<name.length();i++)
    {
        boolean add=al.add(name.charAt(i));
        if(add==false) 
        {
            System.out.println(name.charAt(i));
        }
    }System.out.println(al);
}
}

output

e
a
n
a
a
n
[n, e, l, a, k, d]

HashMap in java

V I N O T H — Mon, 31 Mar 2025 14:34:44 +0000

Java HashMap Example

import java.util.*;
public class HashMapExample1{
public static void main(String args[]){
HashMap map=new HashMap();//Creating HashMap.
map.put(1,"Mango"); //Put elements in Map.
map.put(2,"Apple");
map.put(3,"Banana");
map.put(4,"Grapes");

2.Idli, Dosai,Pongal with prices

package framework;

import java.util.HashMap; 

public class map {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        HashMap hm = new HashMap();
        hm.put("Idli",20);//entry
        hm.put("Dosai", 30);//entry
        hm.put("Pongal", 50);//entry
        //key--->set
        //Values-->Collection
        System.out.println(hm);
    }

}

output

{Dosai=30, Idli=20, Pongal=50}

Idli,Dosai,Pongal without prices

package framework;

import java.util.HashMap;
import java.util.Set; 

public class map {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        HashMap hm = new HashMap();
        hm.put("Idli",20);//entry
        hm.put("Dosai", 30);//entry
        hm.put("pongal", 50);//entry
        //key--->set
        //Values-->Collection
//      System.out.println(hm);
        Set s = hm.keySet(); 
        System.out.println(s);
    }

}

output

[Dosai, Idli, Pongal]

treeset in java

V I N O T H — Mon, 31 Mar 2025 13:36:23 +0000

package framework;

import java.util.TreeSet;

public class treeset {
    public static void main(String[] args) {

        String name = "amalareegan";
                TreeSet hs = new TreeSet();
                hs.add(50);
                hs.add(10);
                hs.add(20);
                hs.add(30);
                System.out.println(hs);
        }
    }

output

[10, 20, 30, 50]

While loop task

V I N O T H — Tue, 04 Feb 2025 16:19:37 +0000

Key words in While loop:

In a while loop, the key Java keywords and concepts used are:

while – This keyword is used to start a while loop. It repeatedly executes a block of code as long as the given condition is true.
Loop Condition – The condition inside the parentheses (no1 < 10) determines if the loop should continue or stop.
Loop Body – The block of code inside {} runs repeatedly while the condition is true.
Loop Control Variable – A variable (no1 in your case) that changes inside the loop to eventually break the loop.
Increment/Decrement Statement – no1++ increases the loop variable to prevent an infinite loop.
Break Condition (Implicit) – The loop stops when the condition (no1 < 10) becomes false.
System.out.println – Used inside the loop to print output during each iteration.

Task 1:

package loopingDemo;

public class First_Looping {

    public static void main(String[] args) {
//       TODO Auto-generated method stub
        int total=0;
        int no1=0;
        int no2=3;
        while(no1<10) {
            no1=no1+1;      
            total=no1*no2;
            System.out.println(no1+"*"+no2+"="+total); 
        }
    }

Output

1*3=3
2*3=6
3*3=9
4*3=12
5*3=15
6*3=18
7*3=21
8*3=24
9*3=27
10*3=30

Task 2:

package loopingDemo;

public class First_Looping {

    public static void main(String[] args) {
int count=1;
        while(count<=5) {

            System.out.println("12345");
            count++;
        }       
}
}

Output

Control flow statement:

V I N O T H — Wed, 29 Jan 2025 07:52:22 +0000

while task.1

A while loop in Java executes a block of code repeatedly as long as the given condition remains true.

package Mistak;

public class Ifcount {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            int count=1;
            while(count<=5) {
                System.out.println(1);
                count=count+1;
            }
            }
                                    //ANS = 1 1 1 1 1
}

TASK 2

package Mistak;

public class Countwhile {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int count=5;
        while(count>=1) {
            System.out.println(count); 
            count=count-1;
        }
        // ANS = 5 4 3 2 1

    }

}

TASK 3.

package Mistak;

public class While {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int count=1;
        while(count<=10) {
            System.out.println(count);
            count=count+2;
        }
    }               //ANS = 1 3 5 7 9

}

TASK 4.

package Mistak;

public class Countwhile {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int count=5;
        while(count>=1) {
            System.out.println(count); 
            count=count-1;
        }
        // ANS = 5 4 3 2 1

    }

}

Key Points:

The loop executes as long as the condition is true.
If the condition is false at the start, the loop won't execute even once.
Ensure the loop condition eventually becomes false to avoid an infinite loop.

  Here are some key points about the while loop in Java:

Entry-Controlled Loop: The condition is checked before executing the loop body.
Executes 0 or More Times: If the condition is false initially, the loop won't run at all.
Condition Must Change: Ensure the condition eventually becomes false to avoid an infinite loop.
Used for Indeterminate Iterations: Best suited when the number of iterations is unknown beforehand.
Can be Interrupted: Use break to exit the loop prematurely and continue to skip an iteration.
May Cause Infinite Loops: If the condition never turns false, the loop will run forever.
Better for Waiting Scenarios: Often used when waiting for a condition to become true dynamically.

Day 11 Encupsulation

V I N O T H — Wed, 18 Dec 2024 14:02:10 +0000

Input 1:

class Friend1
{
String name;
long mobileNo;
int atmPin;

public Friend1(String name, long mobileNo, int atmPin)
{
this.name = name;
this.mobileNo = mobileNo;
this.atmPin = atmPin;
}

public static void main(String[] args)
{
Friend1 f1 = new Friend1("Kavin", 1234, 1111);
f1.withdraw();
}
private void withdraw()
{
System.out.println(atmPin);
}
public void tour()
{
System.out.println("Going for a ride");
}

public void publish_results()
{
System.out.println("Pass with good marks ");
}

}

Input 2:

class Friend2
{

public static void main(String[] args)
{
Friend1 ff = new Friend1("Arul", 3434, 2323);
ff.tour();
ff.withdraw();
}

}

Output:

Day10 Task

V I N O T H — Tue, 17 Dec 2024 15:22:20 +0000

Create a class Called PlayGround
Create non-static variables as below. int score, balls, catches; String player_name;
Create main method.
Inside main method, create two instances as below. PlayGround player1 = new PlayGround("dhoni", 100, 3); PlayGround player2 = new PlayGround("jadeja", 56, 2, 30);
Create appropriate constructors for handling above objects.
Using player1 object, call batting() method. Print - score, player_name.
Using player2 object, call allrounder() method. Print - score, player_name, balls, catches

Input:

class Playground
{
int score,balls,catches;
String player_name;

public Playground(String player_name,int score,int catches)
{
this.score = score;
this.player_name = player_name;
this.catches = catches;
}
public Playground(String player_name,int score,int catches,int balls)
{
this.score = score;
this.player_name = player_name;
this.balls = balls;
this.catches = catches;
}
public static void main(String[] args)
{
Playground player1 = new Playground("dhoni",100,3);
Playground player2 = new Playground("jadeja",56,2,30);

player1.batting();
player2.allround();
}
public void batting()
{
System.out.println(player_name+" "+score+" "+catches);
}
public void allround()
{
System.out.println(player_name+" "+score+" "+balls+" "+catches);
}
}

Output:

DAY 9 Task

V I N O T H — Mon, 16 Dec 2024 12:10:09 +0000

Create a class 'Employee'
Have main method in it.
Inside main method, create an object.
Using this object, call method called 'develop'.
using this object, call method called 'work(10)'
Define appropriate methods develop() and work(int no)
From work method, return no * 10
Store the returned value as 'output' in main method.
Print the 'output'.

Program:

Output: