Forem: Abhishek Avati

Java Terminologies

Abhishek Avati — Wed, 03 May 2023 06:49:43 +0000

Basic Terminologies

Class : The class is a blueprint of the instance of a class. It is defined as a logical template that share some properties and methods
Object : It is an instance of class, entity that has behavior and state.
Method : The behavior of an object is the method
Instance Variable : Every object has its own unique set of instance variables.

Syntax :

Single line Comment :

// this is a single line comment

Multi line comment:

/* this is 
a multi-line
comment
*/

Documentation Comment

/** Documentation */

Source file name
the name of a source file should exactly match the public class name with the extension of .java
ex: Simple.java

Java is case-sensitive language

Class Names:

the first letter of the class should be in uppercase
If several words are used to form name of class, each inner word's first letter should be in uppercase.

Method Names : all the method names should start with a lowercase letter

Keywords : are the words in a language that are used for some internal process or represents some predefined actions

ex: abstract, boolean, break etc

Introduction To Java

Abhishek Avati — Wed, 03 May 2023 06:15:42 +0000

What is JAVA ?
-> so java is an object-oriented programming language, It is high level and secure programming language.
It was developed by SUN MICROSYSTEMS in year 1995, JAMES GOSLING is known to be father of JAVA.

Types of JAVA APPLICATIONS

Standalone Java Applications: known as desktop app or window-based app. Traditional software that we have to install on every machine. Ex: Media player, antivirus. AWT and SWING are used for creating them
Web Java Application : app that run on server side and creates a dynamic web pages. Servlet, JSP, Spring, Hibernate etc technologies are used for creating web app in java
Enterprise Application : An app that is distributed in nature, such as banking app etc is called and enterprise app. It has high level security, load balancing and clustering.
Mobile Application : Apps that are created for mobile devices. Currently android and Java ME are used for building them.

Simple.java

class Simple{
    public static void main(String args[]){
        System.out.println("Hello Java");
    }
}

Featurs of Java

Simple: Its syntax is simple, clean and easy to understand.
Object Oriented : Everything in Java is an object.
Platform Independent : Java is write once, run anywhere language.
Secured
Robust: Strong memory management, automatic garbage collection.
Architectural-neutral
Portable
High Performance
Distributed
Multi threaded

Git & Github

Abhishek Avati — Wed, 18 May 2022 11:52:17 +0000

Imagine you have a project or application and you want to collaborate with other people.
Saving your development process in different checkpoints and you wish to go back to particular checkpoint.
So git and github help us to contribute on a project with other people, we can save history of every new feature added to project

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

What is Github ? : Github is an online platform which allow us to host our project repository.

Why we use Git and Github ?

sharing our code with the world
maintaining history of the project.
who made the changes, when the changes occurred.

How we use Git
download GIT from here,

we will use git from command line interface.

all the history of our code/project is being stored under the folder called as .git

how to initialise the git repository in our project.
enter command $git init which will initialise the git repository in current project.
It will be hidden, so it wont be visible to us.

$git status : This commands tells which files are not tracked to git repository commit or what is the current status of overall repository.

I have created a file which is not staged or commited to repository
so the status will be as followed

$git add . This command will transfer all the un-tracked files to the staging area and '.' represent all files should be added to staging area.
If we want to add a specific file to staging area then we write it as
$git add filename

$git commit -m "your message here" The git commit command captures a snapshot of the project's currently staged changes. Committed snapshots can be thought of as “safe” versions of a project—Git will never change them unless you explicitly ask it to.

$git log : this command gives the history or information of all the commits which were made previously.

$git stash : This command locally stores all the most recent changes in a workspace and resets the state of the workspace to the prior commit state

$git stash pop : The popping option removes the changes from stash and applies them to your working file.

$git stash clear : clear all stashes from repo

$git remote add origin url_of_remote_repository : This command add a url of a remote repository to your local repo

$git push origin main : whenever we want to update the local changes to remote repo we have to use git push command

git branch it is basically a pointer to snapshot of changes/ features we are adding that we have to get them merged with the main branch

Note : whenever you are working on a new feature always make sure that you create a branch and then work on that feature.

$git branch branchName : command to create the branch

$git checkout branchName : switch to the branch

git push origin branchName : push the changes over the branch

what is fork ? Creation of exact copy of a git repo
whenever we create a fork of repo there are two url one for original repo and other for forked repo so the original repo url is called as upstream url, this upstream url is helpful to fetch changes from the original repo into the copied repo
command for it is as follows.
$git fetch upstream / $git pull upstream main

pull request : A pull request is an event in Git where a contributor asks a maintainer of a Git repository to review code they want to merge into a project.
It opens a platform where a contributor discuss their ideas and maintainer verifies the code and rejects the pull request if there are some bugs in it.

steps to contribute any open source project

fork the project.
clone your forked project.
check the origin of forked project.
add upstream of the forked project.
pull the upstream project changes.
create a branch.
make changes to local repo.
commit those changes.
push your changes to fork.
make a pull request to actual project.

THE END!!
Thanks for reading!!
Hope you liked it, feel free to comment over the blog or any changes are welcomed!!
Abhishek Avati.

Web 3.0 Day: 2

Abhishek Avati — Sat, 12 Mar 2022 05:47:10 +0000

Today let us learn about basic understanding of ehthereum, what is ethereum, why we use it

What is ethereum ?

Ethereum is a decentralized,open-source blockchain with smart contract functionality, moreover ethereum is a decentralized computer network that executes programs called as smart contract.
Using these smart contracts developers are able to create or develop digital assets it includes creating digital artworks and collectables,video game assets like weapon skins,interesting it also includes digital representation of real world entities like tickets to real world concert,events or movie or even one create their own cryptocurrency, or token, that can be purchased with Ether.
Now Combining these smart contracts with user interfaces developers are able to create variety of decentralised applications, basically dapps includes games,marketplaces and so on.

what are technological benefits of Dapps ?

These technical benefits are very closely related to the backbone of ethereum architecture as whole

There is zero downtime : since it has peer to peer network there is no single point of failure.
Privacy : Developers or any user doesn't really reveal their real world identities in order to build these dapps or to use them

ETHER

Ether is a cryptocurrency of the ethereum network , it is basically a decentralised token.
Ether is mainly used for two purpose :

It is traded as digital currency in exchange of other cryptocurrencies
Ether is like a fuel for running commands on ethereum platforms and is used by developers to build and run application on the platform

Web 3.0 Day 1

Abhishek Avati — Tue, 01 Mar 2022 06:07:21 +0000

Introduction To Blockchain
what is Blockchain
Basically there are n no of blocks and all of them are connected with each other

Actual Definition : A blockchain is a distributed immutable ledger (ledger : a place where transaction information is recorded and the information is immutable and cannot be changed once it is recorded)

Each block of a blockchain contains some data , hash of that block and hash of it's previous block. Data stored in block depends on blockchain.
The first block of any blockchain is called a Genesis block.

why blockchain is distributed ? Blockchain is actually distributed all over the network every node/computer of network has the copy of that blockchain

how the distribution of immutable ledgers takes place
Now consider host 'A' as a miner ( A person who mines a particular block and creates a particular block )
Now A mines a block and added that block to the existing blockchain, once he has completed then he transfer the information of block chain to all the nodes/hosts which are connected to same network after verifying and validating the newly added block all other hosts also include that newly added block to their blockchain.

For instance, Wikipedia is a type of blockchain. The data on Wikipedia is not written by a single person. The information is added and written by various users across different locations and the information added on the Wikipedia page is verified by all the writers of that particular page and then it is validated and added to the page.

1. blockchain cannot be corrupted
Each block in the blockchain is linked to the previous block by storing the cryptographic hash function of the parent block. Hence if there is data tamper in any block, there will be a change in the hash in all the subsequent blocks. This way, any user will easily identify tampering at any point of the ledger without having to check each and every block. If anyone wants to tamper with the blockchain data then one would have to make changes in all the other blocks as well without being noticed. This way, blockchain cannot be corrupted.

2. blockchain is decentralized
Blockchain is designed in a way that it is distributed and synchronized across networks. This way it is not centrally governed or operated by any single organization. It can be run by a group of users privately connected through LAN or run across with thousands of users over the internet. Every user is informed about the creation of new blocks in the ledger.

3. Blockchain works on consensus
To execute any transaction or add information to the blockchain, it is necessary to have validation from all other nodes and after the agreement of all, the new block is added or the transaction is completed. There may be millions of nodes and they might not trust each other, but they trust the algorithms of the system. It works like a voting system. With the ‘consensus’ system, there are no chances of frauds and it helps keep the data most accurate