How to start angular development

This blog post aim to start the development environment with Angular as quickly as possible.

Prerequisites

1. Install npm and node latest versions
   In my computer, node version : v8.10.0, npm version : 3.5.2
2. Install angular cli. Use below command  to install angular cli.
   npm install -g @angular/cli
   My Angular CLI version : 6.1.2. Type ng -v to see angular CLI version.
3. Install visual code editor. This editor is great tool with lot of helper plugins to start with angular development.

Now time to create new angular project!

1. Type below command to create a new project called test-app

ng new test-app

This will create basic project scaffolding to start with. Now go to test-app folder and start a development server from there

cd test-app

ng serve --open

This will open browser window automatically at http://localhost:4200/ url.

Now time to hack the generated project code and create an awesome project!

Type code . to open the code in visual code editor.

Boost the speed of calculating Large Primes with Golang

Following points are used

1. Check whether the last digit of the integer can be divided by 2 or not
2. Check whether the sum of all digits of the integer can be divided by 3 or not
3. Check whether the last digit of the integer can be divided by 5 or not
4. If all the above checks fails Check whether there is an integer from 7 to square root of number which is divide the number

	package main
	import (
	"fmt"
	"math"
	"strconv"
	)
	func main() {
	fmt.Printf("275489 is a prime : %t", isPrime(275489))
	}
	func isPrime(num int) bool {
	if num == 2 || num == 3 || num == 5 {
	return true
	}
	if !canBeDivideBy2(num) && !canBeDivideBy3(num) && !canBeDivideBy5(num) {
	isPrime := true
	//If the number can not be divided by 2, 3 or 5 divide from 7 to squre root of the number to check the existence of a factor
	for i := 7; i <= int(math.Sqrt(float64(num))); i++ {
	if num%i == 0 {
	isPrime = false
	break
	}
	}
	return isPrime
	}
	return false
	}
	// If the last digit can be divided by 2 whole number can be divided by 2
	func canBeDivideBy2(num int) bool {
	numAsStr := strconv.Itoa(num)
	lastNum, _ := strconv.Atoi(string(numAsStr[len(numAsStr)-1]))
	return lastNum%2 == 0
	}
	// If the digit sum can be divided by 3 whole number can be divided by 3
	func canBeDivideBy3(num int) bool {
	numAsStr := strconv.Itoa(num)
	sum := 0
	for i := 0; i < len(numAsStr); i++ {
	iThNum, _ := strconv.Atoi(string(numAsStr[i]))
	sum += iThNum
	}
	return sum%3 == 0
	}
	//If the last digit can be divided by 5 whole number can be divided by 5
	func canBeDivideBy5(num int) bool {
	numAsStr := strconv.Itoa(num)
	lastNum, _ := strconv.Atoi(string(numAsStr[len(numAsStr)-1]))
	return lastNum%5 == 0
	}

view raw is_prime.go hosted with ❤ by GitHub

package main import ( "fmt" "math" "strconv" ) func main() { fmt.Printf("275489 is a prime : %t", isPrime(275489)) } func isPrime(num int) bool { if !canBeDivideBy2(num) && !canBeDivideBy3(num) && !canBeDivideBy5(num) { isPrime := true //If the number can not be divided by 2, 3 or 5 divide from 7 to squre root of the number to check the existence of a factor for i := 7; i <= int(math.Sqrt(float64(num))); i++ { if num%i == 0 { isPrime = false break } } return isPrime } return false } // If the last digit can be divided by 2 whole number can be divided by 2 func canBeDivideBy2(num int) bool { numAsStr := strconv.Itoa(num) lastNum, _ := strconv.Atoi(string(numAsStr[len(numAsStr)-1])) return lastNum%2 == 0 } // If the digit sum can be divided by 3 whole number can be divided by 3 func canBeDivideBy3(num int) bool { numAsStr := strconv.Itoa(num) sum := 0 for i := 0; i < len(numAsStr); i++ { iThNum, _ := strconv.Atoi(string(numAsStr[i])) sum += iThNum } return sum%3 == 0 } //If the last digit can be divided by 5 whole number can be divided by 5 func canBeDivideBy5(num int) bool { numAsStr := strconv.Itoa(num) lastNum, _ := strconv.Atoi(string(numAsStr[len(numAsStr)-1])) return lastNum%5 == 0 }

Check last JRE access time

JRE will create and update a file in a directory called oracle_jre_usage located  in

• Windows : %ProgramData%\Oracle\Java\.oracle_jre-usage\ 
• All other operating systems: ${user.home}/.oracle_jre_usage/

ex: I have used ubuntu 18.04. So when I start intellij idea it will create a file like  below

lakshman@lakshman-Latitude-3580:~/.oracle_jre_usage$ vim 9e360713136aba0a.timestamp

File content is as follows

/usr/lib/jvm/java-8-oracle/jre
1530512372457
~       

As you can see the last access time can be found in timestamp format.

From JDK 8u171 and later updates and JDK 10 and later, usage tracking can be disabled by using jdk.disableLastUsageTracking property.

ex: java -Djdk.disableLastUsageTracking=true -jar lastUsageTracking-executable.jar