Johny Kumar

Thursday 9 November 2023

How to implement Quick Sort Alogrithm in Java

The quick sort partitions an array and then calls itself recursively twice to sort the resulting two subarray. This algorithm is quite efficient for large sized data sets as its average and worst case complexity are of O(nlogn) where n are no. of items

package in.jk.sort;

public class QuickSortApplication {

public int[] numbers = { 5, 1, 8, 3, 6, 7, 9, 4, 2, 10 };

public int partition(int left, int right) {

int pivot = numbers[right];

int leftPointer = left - 1;

for (int i = left; i <= right - 1; i++) {

if (numbers[i] < pivot) {

leftPointer++;

swap(leftPointer, i);

}

int leftPointerIncriment = leftPointer + 1;

swap(leftPointerIncriment, right);

return leftPointerIncriment;

}

public void quickSort(int left, int right) {

if (left < right) {

int parttion = this.partition(left, right);

quickSort(left, parttion - 1);

quickSort(parttion + 1, right);

}

public void swap(int left, int right) {

int temp = numbers[left];

numbers[left] = numbers[right];

numbers[right] = temp;

}

public static void main(String[] args) {

QuickSortApplication quickSortApplication = null;

quickSortApplication =QuickSortApplication ();

int left = 0;

int right = quickSortApplication .numbers.length - 1;

quickSortApplication .quickSort(left, right);

System.out.println("Sorted Array :: ");

for (int element : quickSortApplication .numbers) {

System.out.print(element + " ");

}

Output :

Sorted Array ::
1 2 3 4 5 6 7 8 9 10

Friday 24 February 2023

Monday 28 June 2021

How to create Spring MVC Application with Springboot

Springboot MVC Application :

In Springboot MVC application employee form accept the employee details forward to

employee details page where display employee details with two static resource image file .

Following files are required for creating Spring boot MVC application .

Directory Structure of Springboot MVC Application

EmployeeController.java

package in.jk.Springboot.controller;

import org.springframework.stereotype.Controller;

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

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

import org.springframework.web.servlet.ModelAndView;

import in.jk.Springboot.request.EmployeeRequest;

@Controller

public class EmployeeController {

@RequestMapping("/employee")

public ModelAndView employee() {

System.out.println("Employee Controller ");

ModelAndView modelAndView = new ModelAndView("employee","command",new EmployeeRequest());

return modelAndView;

}

@RequestMapping("/employeeDetails")

public ModelAndView employeeDetails(@ModelAttribute("employeeRequest")EmployeeRequest employeeRequest ) {

ModelAndView modelAndView = new ModelAndView("employeeDetails","command",employeeRequest);

return modelAndView;

}

EmployeeRequest.java

public class EmployeeRequest {

private String name;

private String company;

private String address;

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getCompany() {

return company;

}

public void setCompany(String company) {

this.company = company;

}

public String getAddress() {

return address;

}

public void setAddress(String address) {

this.address = address;

}

@Override

public String toString() {

return "EmployeeRequest [name=" + name + ", company=" + company + ", address=" + address + "]";

}

SpringbootMVCConfiguration.java

package in.jk.Springboot.configuration;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.servlet.config.annotation.EnableWebMvc;

import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistration;

import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;

import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration

@EnableWebMvc

public class SpringbootMVCConfiguration implements WebMvcConfigurer {

public void addResourceHandlers(ResourceHandlerRegistry registry) {

ResourceHandlerRegistration resourceRegistration = registry

.addResourceHandler("resources/**");

resourceRegistration.addResourceLocations("/resources/**");

registry.addResourceHandler("/css/**").addResourceLocations("/css/**");

registry.addResourceHandler("/images/**").addResourceLocations("/images/");

registry.addResourceHandler("/js/**").addResourceLocations("/js/**");

}

SpringbootApplication .java

package in.jk.Springboot;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.servlet.config.annotation.EnableWebMvc;

import org.springframework.web.servlet.view.InternalResourceViewResolver;

@SpringBootApplication

@EnableWebMvc

@Configuration

public class SpringbootApplication {

public static void main(String[] args) {

SpringApplication.run(SpringbootApplication.class, args);

System.out.println("Springboot Application Started :: ");

}

@Bean

public InternalResourceViewResolver viewResolver() {

InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();

viewResolver.setPrefix("/WEB-INF/views/");

viewResolver.setSuffix(".jsp");

return viewResolver;

}

employee.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Johny</title>

</head>

<body>

<h2>Enter Employee Details</h2>

<form:form method="POST" action="employeeDetails">

<table>

<tr>

<td><form:label path="name">Enter Name</form:label></td>

</tr>

<tr>

<td><form:label path="company">Company</form:label></td>

</tr>

<tr>

<td><form:label path="address">Address</form:label></td>

</tr>

<tr>

</tr>

</table>

</form:form>

</div>

</body>

</html>

employeedetails.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Employee Details</title>

</head>

<body>

</div>

Employee Name : ${employeeRequest.name} <br></br>

Employee company : ${employeeRequest.company}<br></br>

Employee Address : ${employeeRequest.address}

</body>

</html>

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

</parent>

<artifactId>Springboot</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>Springboot</name>

<description>Demo project for Spring Boot</description>

<java.version>1.8</java.version>

</properties>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

<version>2.2.2.RELEASE</version>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-tomcat</artifactId>

<version>2.0.0.RELEASE</version>

<scope>compile</scope>

</dependency>

<groupId>org.apache.tomcat.embed</groupId>

<artifactId>tomcat-embed-jasper</artifactId>

<scope>provided</scope>

</dependency>

</dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

</dependency>

</dependencies>

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

</plugin>

</plugins>

</build>

</project>

Employee Form

Employee Details

Thursday 20 May 2021

How to Change Desktop background in Java using Java Native Access (JNA) Library

Java Native Access JNA

Java Native Access (JNA) is a community-developed library that provides Java programs easy access to native shared libraries without using the Java Native .

Dowl oad Java Native Access(JNA) 3.5.2 Library here ....

HaileePhotoDesktopSetter.java

package us.javaj.johny.hailee.desktop;

import com.sun.jna.Native;

import com.sun.jna.platform.win32.Advapi32Util;

import com.sun.jna.platform.win32.WinReg;

import com.sun.jna.win32.StdCallLibrary;

public class HaileePhotoDesktopSetter {

public static void main(String[] args) {

HaileePhotoDesktopSetter.changeDesktopWallpaper();

}

private interface MyUser32 extends StdCallLibrary {

MyUser32 INSTANCE = (MyUser32) Native.loadLibrary("user32", MyUser32.class);

boolean SystemParametersInfoA(int uiAction, int uiParam, String fnm, int fWinIni);

}

public static void changeDesktopWallpaper() {

// -----------------------------------

String johny = "Johny Invoke the Desktop Background Setter with Love in Hailee Stienfeld ::";

System.out.println();

System.out.println("------------------------------Hailee Johny --------------------------------------");

System.out.println();

System.out.println(johny);

System.out.println();

String filePath = "E:\\Hailee-Johny\\Hailee_Stienfeld_Johny_S\\Desktop\\Hailee.jpg";

HaileePhotoDesktopSetter.setWallpaper(filePath);

System.out.println("Desktop Images Set Succussfully ");

System.out.println("Image File Path :: "+filePath);

}

public static void setWallpaper(String filePath) {

Advapi32Util.registrySetStringValue(WinReg.HKEY_CURRENT_USER,

"Control Panel\\Desktop", "FitWallpaper",filePath);

// WallpaperStyle = 10 (Fill), 6 (Fit), 2 (Stretch), 0 (Tile), 0 (Center)

// For windows XP, change to 0

int SPI_SETDESKWALLPAPER = 0x14;

int SPIF_UPDATEINIFILE = 0x01;

int SPIF_SENDWININICHANGE = 0x02;

// User32.System

boolean result = MyUser32.INSTANCE.SystemParametersInfoA(SPI_SETDESKWALLPAPER, 0,

filePath,SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE);

}

Desktop Wallpaper before running above code

Desktop Wallpaper before running after code

Output in java console

-------------------------------- Hailee Johny --------------------------------------

Johny Invoke the Desktop Background Setter with Love in Hailee Stienfeld ::

Desktop Images Set Succussfully

Image File Path :: E:\Hailee-Johny\Hailee_Stienfeld_Johny_S\Desktop\Hailee.jpg

Saturday 7 November 2020

How to call Kotlin code in Java Application: Java and Kotlin Interoperability

Java is fully compatible with Kotlin . So to call java code in kotlin first write following java and

kotlin code two separate file .

KotlinApplication.kt

fun main(args:Array<String>){

println("Kotlin Application Started ..... ")

}

fun navigateToKotlinApplication(){

println("Welcome in Kotlin Application ..... ")

}

JavaApplication.java

public class JavaApplication {

public static void main(String []args){

System.out.println("Java Application Started ...... ");

System.out.println("---------------------------------- ");

System.out.println("Navigating to Kotlin Application ......");

System.out.println("--------------------------------- ");

KotlinApplicationKt.navigateToKotlinApplication();

}

Commands to compile and run above two code

1 . First Compile KotlinApplication.kt file

kotlinc KotlinApplication.kt

Note :- After Compiling of KotlinApplication.kt kotlinc compiler conventionally generate KotlinApplicationKt.class by default kotlinc compiler append Kt in suffix of kotlin file name.

2 . Running KotlinApplicationKt.class file

kotlin KotlinApplicationKt

3 . Compiling Java code JavaApplication.java

javac JavaApplication.java

4 . Running Java Application

java JavaApplication

Output in Console.....

How to call Java code in Kotlin Application: Java and Kotlin Interoperability

Java is fully compatible with Kotlin . So to call java code in kotlin first write following java and kotlin code two separate file .

KotlinApplication.kt

fun main(args:Array<String>){

println("Kotlin Application Started ....... ");

var javaApplication = JavaApplication();

println("-------------------------------------------");

println("Navigating to Java Application ....... ");

println("-------------------------------------------");

javaApplication.naivgateToJavaApplication();

}

JavaApplication.java

public class JavaApplication{

public JavaApplication(){}

public static void main(String []args){

System.out.println("Java Application Started ..... ");

}

public void naivgateToJavaApplication(){

System.out.println("Welcome in Java Application .......");

}

To Compile and run above two file there is two method .

First Method to Compile and run java code in kotlin application

Compile using kotlinc and Running using Kotlin

1 . Complie java file

javac JavaApplication.java

2 .Running java file

java JavaApplication

3.Compling kotlin file by setting class path of JavaApplication.class file

kotlinc -cp . KotlinApplication.kt

Note :-

After Compiling of KotlinApplication.kt kotlinc compiler conventionally generate

KotlinApplicationKt.class

by default kotlinc compiler append Kt in suffix of kotlin file name.

4. Now at last Runing KotlinApplicationKt.class by seting class path of JavaApplication.class file

kotlin -cp . KotlinApplicationKt

Output in Console ......

Second Method to Compile and run java code in kotlin application

Complie and package into java jar using kotlinc and Runing java jar using Java

Running with Java Jar using Java

1 .Compile java file

javac JavaApplication.java

2 .Running java file

java JavaApplication

3.Compling kotlin file by setting class path of JavaApplication.class file

kotlinc -cp . KotlinApplication.kt -include-runtime -d kotlinapplication.jar

4. Updating kotlinapplication.jar with JavaApplication.class file

jar -uf KotlinApplication.jar JavaApplication.class

5. Running KotlinApplication.jar file

java -jar KotlinApplication.jar

Output in Console .....

First program to print Hello World message in Kotlin

Write following code in any text editor save the file .

Kotlin.kt

import java.time.LocalDateTime;

fun main (args : Array<String>){

val currentTime = LocalDateTime.now();

println("Hello Kotlin World ....")

println("Welcome in Kotlin World ...currtent Time is :: $currentTime")

}

Command to compile code and package in jar

kotlinc Kotlin.kt -include-runtime -d Kotlin.jar

Command to run Kotlin.jar file

java -jar Kotlin.jar

Output Console .....

Hello Kotlin World ....

Welcome in Kotlin World ...currtent Time is :: 2020-10-21 T 12:31:21.879