A Regular Expression (or Regex) is a pattern (or filter) that describes a set of strings that matches the pattern.

Regular expressions are used to search strings for a specific pattern or to validate the user-input value like to validate the email address entered by the user.

Colosseum, Rome, Italy

Why we use Regular Expression?

To perform a certain action on a given string based on the characters present in it. Action can be validating the string or it can be changing certain parts of it.

Types of Regular expression:

A character class allows you to match any symbol from a certain character set. …


Docker-compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application’s services. Then, with a single command, you create and start all the services from your configuration.

Why Docker-compose?

Let say we want to containerize an application having Node backend, React-js frontend, and MongoDB database. If we go by the simple approach then we need to first create the images of all the applications individually then run those images using the docker run command. It requires multiple long docker commands. …


Java 9 Features

Creates a immutable list (read-only), cannot modify the list once it is created.

List.of(1,2,3);
  • Cannot add null value, it will throw NullPointerException.
  • Cannot add more values to the list, it will throw UnsupportedOperationException.
  • Can add values only at the time of initialization.
Set.of(1,2,3);
  • Cannot add duplicate values like Set.of(1,1,2), it will throw IllegalArgumentException.
  • Cannot add null value, it will throw NullPointerException.
  • Cannot add more values to the set, it will throw UnsupportedOperationException.
  • Can add values only at the time of initialization.

we can create immutable map in 2 ways:

Map.of(K1,V1,K2,V2);      // K refers to key and V refers to value


Collectors is a final class that extends the Object class. It provides reduction operations, such as accumulating elements into collections, summarizing elements according to various criteria, etc. Java Collectors class provides various methods to deal with elements.

1. Creating list: toList()

It is used to accumulate elements into a list. It will create a new list (It will not change the current list).

List<Integer> integers = Arrays.asList(1,2,3,4,5,6,6);integers.stream().map(x -> x*x).collect(Collectors.toList());// output: [1,4,9,16,25,36,36]

2. Creating set: toSet()

It is used to accumulate elements into a set, It will remove all the duplicate entries.

List<Integer> integers = Arrays.asList(1,2,3,4,5,6,6);integers.stream().map(x -> x*x).collect(Collectors.toSet());// output: [1,4,9,16,25,36]

3. Creating specific collection: toCollection()

We can accumulate data in…


Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.

If you are working on any software project, then there are good chances that you already heard of GIT before. In this article we will deep dive into some useful but not so common git commands which can make out life easier.

Stashing in GIT

It is used to store all the local changes (staged and unstaged changes) for future use and reverts them from your working copy. It takes you back to the working directory HEAD (last…


In this blog, we will learn about how we can containerize a react application. Here we will see the generic steps which we can follow with any react application. Just for the sake of completion, we will start from scratch, we will first create a react application and then we will containerize it.

If you just started working on docker, I will highly recommend you to check my other blog first which is moreover related to the basic of docker commands

https://medium.com/swlh/important-docker-commands-you-should-know-60735f821068

Creating react application

npx create-react-app my-app
cd my-app
npm install

The first command will create our project, the second command is…


Docker provides the ability to package and run an application in a loosely isolated environment called a container. The isolation and security allow you to run many containers simultaneously on a given host.

What are a docker image and docker container?

As per the official website, a Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries, and settings.

And docker container is an instance of the docker image, docker container is a docker image brought to life.

Breakdown of docker commands syntax:

Every docker command can be broken down into 3 parts :

1. Keyword 'docker'
2. Main…


As ECMAScript11 came, let’s quickly revise all the major features of ES6 to ES10.

ECMAScript6 -ECMAScript 2015

Its the protocol on which Javascript works. So we can say its javascript version.

The let statement allows us to declare a variable with block scope and we cannot redeclare the same object in the same scope

var x = 10;
{
let x = 2;
let x = 4; // ERROR (cant redeclare)
x = 5; // works fine
// In this block x is equal to 5
}
// here x is 10

The const statement is the same as let, the only difference…


In the last blog, we looked at what is Quarkus. How it works internally. and ways to create a quarkus project. If you have not read that blog yet I will highly recommend you do that first.

Understanding the power of Quarkus

In this blog, we will see how we can integrate PostgreSQL with Quarkus and will create a CRUD application.

So let's start with the dependencies

Dependencies

        <dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-hibernate-orm-panache</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-jdbc-postgresql</artifactId>
</dependency>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-hibernate-validator</artifactId>
</dependency>

These are the 3 dependencies we require for our database connection and validation.

Configuration

We need to provide the database name, driver…


Quarkus is a full-stack, light-weight, superfast java framework for the JVM and the native application.

But why so hype about Quarkus? Why should we learn Quarkus? when we already have Spring boot like framework. which is an open-source framework. It gives a simple way to build, configure, and build web applications.

So let’s start out talking with the comparison between Quarkus and Spring boot.

Quarkus vs Spring boot

1. Start-up time :

If we compare the startup time between the Quarkus native, Quarkus JIT, and traditional native application(Spring boot). We can clearly see the difference.

Rohan Aggarwal

Full stack developer

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