June 2019

Saturday, June 22, 2019

Basic spring boot setup and running simple hello world page in Intellij Community Edition Spring boot MVC

1) Install Spring Assistant Plugin for intellij.
2) Create Web project with Spring Web Starter.
3) add dependency in pom file:
<dependency>

   <groupId>org.apache.tomcat.embed</groupId>
   <artifactId>tomcat-embed-jasper</artifactId>
   <scope>compile</scope>
</dependency>
<dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>jstl</artifactId>
</dependency>

4) add following in application.properties file in src/main/resources

       spring.mvc.view.prefix: /WEB-INF/jsp/

       spring.mvc.view.suffix: .jsp

5) Create controller class named SpringJava4sController.java

       import org.springframework.stereotype.Controller;

       import org.springframework.ui.Model;
       import org.springframework.web.bind.annotation.*;
       import org.springframework.web.servlet.ModelAndView;

       @RestController       public class SpringJava4sController {

      @RequestMapping(value="/test", method=RequestMethod.GET)
       public ModelAndView showLoginPage(Model model) {
       model.addAttribute("message", "Welcome to Java4s Spring Boot Tutorials");

       return new ModelAndView("welcomePage");
       }
     }

6) Make sure we have class with main as

     import org.springframework.boot.SpringApplication;

     import org.springframework.boot.autoconfigure.SpringBootApplication;

     @SpringBootApplication     public class DemoApplication {

     public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
    }

7) create webapp/WEB-INF/jsp folder within src/main

8) place jsp file welcomePage inside jsp as:

    <html  xmlns:th="http://www.thymeleaf.org">

     <body>

   
    ${message}

   
    </body>
   </html>

9) go to browsrer and see localhost:8080/test

Monday, June 17, 2019

Java program to calculate subset in o(n) time complexity using ArratList

Brutforce:

for(int i = 0; i < len; i++) {
//This loop adds the next character every iteration for the subset to form and add it to the array
for(int j = i; j < len; j++) {
arr[temp] = str.substring(i, j+1);
temp++;
}
}

Subset can be implemented with the concept of decision tree:

How we can implement decision tree in code is:

CODE in JAVA:

	import java.sql.SQLOutput;
	import java.util.ArrayList;

	public class subset {
	static ArrayList<ArrayList<Character>> calculateSubset(String test){
	char[] charArray = test.toCharArray();
	ArrayList<ArrayList<Character>> alist = new ArrayList<ArrayList<Character>>();
	ArrayList<Character> empty = new ArrayList<>();
	alist.add(empty);
	for(char a:charArray){
	ArrayList<ArrayList<Character>> alistTemp = new ArrayList<ArrayList<Character>>();

	for(ArrayList<Character> loop :alist){
	ArrayList<Character> temp1 = new ArrayList<>();
	for(Character ch:loop){
	temp1.add(ch);
	}
	temp1.add(a);
	alistTemp.add(temp1);
	alistTemp.add(loop);

	}
	alist = alistTemp;


	}
	return alist;
	}
	public static void main(String []args){
	String test = "abcde";
	ArrayList<ArrayList<Character>> result = calculateSubset(test);
	System.out.println(result.size());
	System.out.println(result);
	}
	}

view raw subset_Java.java hosted with ❤ by GitHub

Sunday, June 16, 2019

Java Program to calculate Unrank of permutation

Calculate the unrank of of permutaion:

	import java.util.Collection;
	import java.util.Collections;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.stream.Collectors;

	public class unrank {

	public static int factorial(int number){
	if (number == 1 \|\| number==0)
	return 1;
	return number * factorial(number-1);
	}

	public static String calculateUnrank(String test, int unranknum) {
	List<Character> answer = new LinkedList<>();
	List<Character> lst = new LinkedList<Character>();
	for (char a : test.toCharArray()) {
	lst.add(a);
	}
	Collections.sort(lst);
	while (lst.size() != 0) {
	int totalPermutation = factorial(lst.size());
	int eachblock = totalPermutation / lst.size();
	int dividend = unranknum / eachblock;
	unranknum = unranknum % eachblock;
	char value = lst.get(dividend);
	answer.add(Character.valueOf(value));
	lst.remove(Character.valueOf(value));

	}

	return answer.stream().map(String::valueOf).collect(Collectors.joining());
	}
	public static void main (String args[]){
	String test = "SPAIN";
	int unranknum = 115;
	String result = calculateUnrank(test,unranknum);
	System.out.println(result);
	}
	}

view raw Unrank_Permutation.java hosted with ❤ by GitHub

Java program to calculate rank of permutation.

1) Rank program in java

	import java.util.Arrays;
	import java.util.LinkedList;
	import java.util.List;

	public class rank {

	public static int factorial(int number){
	if (number == 1 \|\| number==0)
	return 1;
	return number * factorial(number-1);
	}

	public static int getRank(String test){
	char[] chararray = test.toCharArray();
	Arrays.sort(chararray);
	List<Character> lst = new LinkedList<>();
	for (char c :chararray){
	lst.add(c);
	}

	int sum = 0;
	int length = chararray.length;
	for(char c: test.toCharArray()){
	int index = lst.indexOf(c);
	sum = sum + (index)* factorial(length-1);
	length=length-1;
	lst.remove(Character.valueOf(c));
	}
	return sum;

	}

	public static void main(String args[]){

	String test = "BCA";
	int rank = getRank(test);
	System.out.println(rank);

	}

	}

view raw Rank_of_Permutatio.java hosted with ❤ by GitHub

Thursday, June 13, 2019

Java Program to check federal holidays in US using ZonedDateTime API java8

This is the program n=in java where it checks whether the given zoneddatetime is holidays or not.

It uses java8 ZonedDateTime to determine the zoned date and time.

Code to check whether a given date falls on weekend or holidays

	public static boolean isHolidays(ZonedDateTime zdt){
	Month month = zdt.getMonth();
	int date = zdt.getDayOfMonth();
	DayOfWeek day = zdt.getDayOfWeek();
	// check if New Year's Day
	if(month.equals(Month.JANUARY) && date == 1){
	return true;
	}
	if(month.equals(Month.JANUARY) &&
	date == 31 &&
	day.equals(DayOfWeek.FRIDAY) ){
	return true;
	}
	if(month.equals(Month.JANUARY)
	&& date == 2 &&
	day.equals(DayOfWeek.MONDAY) ){
	return true;
	}

	// check MLK Day (3rd Monday of January)
	if (month.equals(Month.JANUARY)
	&& zdt.get(ChronoField.ALIGNED_WEEK_OF_MONTH) == 3
	&& day.equals(DayOfWeek.MONDAY)) {
	return true;
	}

	//// check Memorial Day (last Monday of May)
	if(month.equals(Month.MAY)
	&& day.equals(DayOfWeek.MONDAY)
	&& date > (31-7)) {
	return true;
	}

	// check if 4th of July
	if(month.equals(Month.JULY)
	&& date == 4){
	return true;
	}
	if(month.equals(Month.JULY)
	&& date == 3
	&& day.equals(DayOfWeek.FRIDAY) ) {
	return true;
	}
	if(month.equals(Month.JULY)
	&& date == 5
	&& day.equals(DayOfWeek.MONDAY) ){
	return true;
	}

	// check Labor Day (1st Monday of September)
	if (month.equals(Month.SEPTEMBER)
	&& zdt.get(ChronoField.ALIGNED_WEEK_OF_MONTH) == 1
	&& day.equals(DayOfWeek.MONDAY)) {
	return true;
	}

	// check if Christmas
	if(month.equals(Month.DECEMBER)
	&& date == 25){
	return true;
	}
	if(month.equals(Month.DECEMBER)
	&& date == 24
	&& day.equals(DayOfWeek.FRIDAY) ){
	return true;
	}
	if(month.equals(Month.DECEMBER)
	&& date == 26
	&& day.equals(DayOfWeek.FRIDAY) ){
	return true;
	}

	// check Thanksgiving (4th Thursday of November)
	if (month.equals(Month.NOVEMBER)
	&& zdt.get(ChronoField.ALIGNED_WEEK_OF_MONTH) == 4
	&& day.equals(DayOfWeek.THURSDAY)) {
	return true;
	}

	//check Thanksgiving following friday
	if (month.equals(Month.NOVEMBER)
	&& zdt.get(ChronoField.ALIGNED_WEEK_OF_MONTH) == 4
	&& day.equals(DayOfWeek.FRIDAY)) {
	return true;
	}
	//edge case when following day is 29 won't fall in align week 4
	if (month.equals(Month.NOVEMBER)
	&& zdt.get(ChronoField.ALIGNED_WEEK_OF_MONTH) == 5
	&& date == 29
	&& day.equals(DayOfWeek.FRIDAY)) {
	return true;
	}

	return false;
	}

view raw check_holiday.java hosted with ❤ by GitHub

CODING EVERYTHING

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