Underscore in int

In Java SE 7 and later, any number of underscore characters (_) can appear anywhere between digits in a numerical literal. This feature enables you, for example, to separate groups of digits in numeric literals, which can improve the readability of your code.

For instance, if your code contains numbers with many digits, you can use an underscore character to separate digits in groups of three, similar to how you would use a punctuation mark like a comma, or a space, as a separator.

e.g.

int i= 100_000_000;

Some comments can be executed in java

Executable comments:

https://www.geeksforgeeks.org/executable-comments-java/

java interview puzzles

http://javadecodedquestions.blogspot.com/2013/01/java-interviews-frequently-asked-puzzles.html

Java Rest web service using jersey

I was facing problems while running the restful api

Adding below import solved the problem
Tomcat version - 8.5
Java - 8


import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Code :

package test;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@Path("/hello")
public class Hello {

@GET
@Produces(MediaType.TEXT_XML)
public String sayHelloXML() {
String resource = "<? xml version='1.0' ?>" + "<hello> Hi Pragya </hello>";

return resource;
}

@GET
@Produces(MediaType.APPLICATION_JSON)
public String sayHelloJSON() {
String resource = null;

return resource;
}


@GET
@Produces(MediaType.TEXT_HTML)
public String sayHello(@QueryParam("name") String name) {
String resource = "<h1> this is HTML method </h1>" + "Hi "+name;

return resource;
}


}

web.xml file:

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

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns="http://xmlns.jcp.org/xml/ns/javaee"

xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"

id="WebApp_ID" version="3.1">

<display-name>JavaRestAPI</display-name>

<servlet>

<servlet-name>JAVA API</servlet-name>

<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>

<init-param>

<param-name>jersey.config.server.provider.packages</param-name>

<param-value>test</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>JAVA API</servlet-name>

<url-pattern>/rest/*</url-pattern>

</servlet-mapping>

</web-app>


URL:

http://localhost:8000/JavaRestAPI/rest/hello?name=pragya

I am using port 8000 coz 8080 had some other thing running

References: https://www.youtube.com/watch?v=5jQSat1cKMo

Big O notation

http://bigocheatsheet.com/

Bubble Sort again !!

References : https://www.youtube.com/watch?v=F13_wsHDIG4

package com.mylearnings;

public class BubbleSort {

public static void main(String[] args) {
int input[] = {5,7,6,8,65,87,12,3,343,44,767,78};
BubbleSort sort = new BubbleSort();
int[] out = sort.bubbleSort(input);
for(int i = 0; i < out.length; i++) {
System.out.println(out[i]);
}
}


public int[] bubbleSort(int inp[]) {
int len = inp.length;
for(int i = 0; i < len; i++) {
// start from 1 else we will get ArrayIndexOutOfBoundsException
for(int j=1; j< len-i; j++) {
if(inp[j-1] > inp[j]) {
int temp = inp[j-1];
inp[j-1] = inp[j];
inp[j] = temp;
}
}
}
return inp;
}
}

Jump Search

package com.mylearnings;

public class JumpSearch {

public static void main(String[] args) {
// TODO Auto-generated method stub

int sortedInput[] = {5,6,12,15,18,25,45,65,70,75,78,80,82,83,85,88,90,98,100,105,107};
JumpSearch se =  new JumpSearch();
System.out.println(se.jumpSearch(sortedInput, 0, 4, 4, 85));
}

public int jumpSearch(int[] input , int start , int end, int jump , int search) {
//int mid = (end - start) /2;
if(end <= input.length) {
if((input[start] >= search) || (search < input[end])) {
for(int i =start ; i <= end ; i++) {
if(search == input[i]) {
return i;
}
}
}else {
return jumpSearch(input , end , end + jump, jump,  search);
}
}
return -1;
}

}

The most optimum value of jump would be sqrt(size of array)

References : 

http://theoryofprogramming.com/2016/11/10/jump-search-algorithm/

Binary Search

package com.mylearnings;

public class BinarySearch {

public static void main(String[] args) {
int input[] = {5,7,6,8,65,87,12,3,343,44,767,78};
int sortedInput[] = {5,6,12,15,18,25,45,65,70,75,78,80,82,83,85,88,90,98,100,105,107};
BinarySearch search  = new BinarySearch();
int index = search.binarySearch(sortedInput, 0, sortedInput.length, 65);
System.out.println(index);
}

public int binarySearch(int[] input, int startIndex, int endIndex, int search) {
if(startIndex <= endIndex) {

int mid= startIndex + (endIndex - startIndex)/2;
int midVal = input[mid];
if(midVal == search) {
//System.out.println("Value found at index : "+mid);
return mid;
}else if(search < midVal) {
return binarySearch(input, startIndex , mid-1, search);
}else {
return binarySearch(input, mid+1, endIndex, search);
}
}

return -1;
}

}