java completable promise example

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.TimeUnit;

import java.util.function.Supplier;

import java.util.concurrent.*;

class Main {

public static void main(String[] args) throws ExecutionException, InterruptedException {

        CompletableFuture<String> whatsYourNameFuture = CompletableFuture.supplyAsync(()-> {

         

           // public String get() {

              System.out.println("in promise");

                try {

                    TimeUnit.SECONDS.sleep(1);

                } catch (InterruptedException e) {

                    throw new IllegalArgumentException(e);

                }

                return "Rajeev";

           // }

        });

        CompletableFuture<String> promiseExample = CompletableFuture.supplyAsync(()-> {

            //public String get() {

              System.out.println("in promise");

                try {

                    TimeUnit.SECONDS.sleep(1);

                } catch (InterruptedException e) {

                    throw new IllegalArgumentException(e);

                }

                return "Kumar";

           // }

        });

      CompletableFuture<String> result = whatsYourNameFuture.thenCombine(promiseExample, (str1, str2) -> {

        String name=str1 + " " + str2;

        return name;

        });

        System.out.println("Value- " + result.get());

        //System.out.println(welcomeText.get());

    }

}

completable feature example

https://github.com/maoyunfei/CompletableFuture-Examples/tree/master/src/main/java/com/maoyunfei/study

String length differnce in php for utf-8 char.

<?php
$name="Si vous n'arrivez pas à récupérer";
echo strlen($name);
echo mb_strlen($name,'UTF-8');
?>

AWS lambda with Java

https://www.baeldung.com/aws-lambda-dynamodb-java

cricute breaker

https://spring.io/guides/gs/circuit-breaker/

completeable feture java

https://netjs.blogspot.com/2018/11/completablefuture-in-java-with-examples.html

java stream api manupalation for arraylist of integer to comma sepertaed

import java.util.*;

import java.util.stream.Collectors;

class Main {

  public static void main(String[] args) {

   List<String> strings = new LinkedList<>();

     strings.add("Java");strings.add("is");

     strings.add("cool");

     String message = String.join(", ", strings);

     System.out.println(message);

      List<Integer> num = new LinkedList<>();

     num.add(2);

     num.add(5);

     num.add(7);

     String message1 =num.stream().map((gameId)-> gameId.toString()).collect(Collectors.joining(","));

     System.out.println(message1);

     //message returned is: "Java is cool"

  }

}

https://www.baeldung.com/java-string-with-separator-to-list

s3 bucket naming convention

The legacy rules for bucket names in the US East (N. Virginia) Region allowed bucket names to be as long as 255 characters, and bucket names could contain any combination of uppercase letters, lowercase letters, numbers, periods (.), hyphens (-), and underscores (_).

springboot annotation

https://www.javaguides.net/2018/10/spring-boot-annotations.html

How to revert a commit from remote branch

1.Take remote branch commit number 

2.git revert hashid

git revert b2e9537b33f6a9a9d3d001c33e91ca0d441a8f04

3.then git push to your remote branch 

git push origin mybranchname.

source tree git tutorial

https://www.freecodecamp.org/news/how-to-undo-changes-in-git-e1da7930afdb/