Introduction

In this introductory tutorial, students will learn how to use Web3j and Java to check the Ethereum balance for a provided address. Before taking this course, it is recommended that you familiarize yourself with the basics of Java programming and have experience building a Java project using Ant or Maven.

The following stages are covered in this course:

1. Using Infura.io to set up an Ethereum endpoint: You will connect to the Ethereum network via Infura.io, a well-known service that does not require running a whole Ethereum node.
2. Configuring the Web3j SDK: You will learn how to add the Web3j library to your Java project and import the required classes to communicate with Ethereum.
3. Finding balance: You will learn how to find the balance of a given Ethereum address. First, you must establish a Web3j instance and connect it to the Ethereum network.
4. Scaling and More: You will investigate methods for managing big amounts and translating the Wei balance to various currencies.

By the time this course ends, you will know how to use Web3j to retrieve Ethereum balances and incorporate this feature into your Java applications.

Understanding Infura.io

Infura.io makes it easier for developers to connect with the Ethereum network and access the blockchain without requiring them to manage their own nodes. It provides a dependable and expandable gateway that handles the difficulties involved in running Ethereum nodes.

Through Infura.io, students can access the Ethereum Mainnet and many test networks, such as Rinkeby, Kovan, and Ropsten.

One of Infura.io’s primary advantages is that developers can use its API endpoints to connect with Ethereum nodes. Removing the requirement for developers to set up and manage their own node infrastructure lowers operational overhead and streamlines the integration process.

Infura.io ensures scalability and stability by handling the infrastructure requirements of Ethereum nodes, leaving developers to concentrate on creating their applications. It is an Ethereum ecosystem standard for network connectivity, and it is compatible with many other blockchain projects, decentralized applications, and wallets.

A developer-friendly API offered by Infura.io encapsulates the complexity of node interaction and offers features like:

1. Making transactions
2. Accessing account balances
3. Submitting queries to smart contracts
4. Monitoring events

It also allows developers to get real-time updates and notifications from the Ethereum network over WebSocket connections, enabling instantaneous data streaming.

Understanding Web3j

With the popular Java package Web3j, programmers may utilize Java to create decentralized apps (dApps) and communicate with the Ethereum blockchain. It provides utilities, APIs, and tools that make integrating Java apps with the Ethereum network easier. Web3j serves as an Ethereum client library that lets programmers:

1. Establish connections with Ethereum nodes
2. Send and receive transactions
3. Set up smart contracts
4. Access blockchain information

It offers a user-friendly interface by abstracting the complexities of Ethereum's JSON-RPC API.

Web3j's easy integration with the Ethereum network allows developers to seamlessly work with smart contracts, accounts, and blockchain data. It enables developers to write Java wrappers for simpler interaction and allows the compilation, deployment, and interaction with Solidity-written smart contracts. By offering tools for creating, approving, and monitoring transactions as well as for calculating gas prices and storing transaction receipts, Web3j streamlines the transaction management process.

Additionally, it enables developers to listen for events generated by smart contracts, enabling real-time notifications and interaction with other systems. Web3j smoothly integrates with Ethereum infrastructures, such as Infura.io, to offer access to the Ethereum network without the need for a local node. It supports several Ethereum standards, including ERC-20, ERC-721, and ERC-1155, which makes it easier for tokens and decentralized finance (DeFi) systems to communicate with one another.

Setting up Web3j SDK

Create an account on Infura.io to set up an Ethereum endpoint using Infura.io. Get the project ID and endpoint URL by starting a new project.

After that, include the Web3j library in your Java project to configure the Web3j SDK. To handle dependencies, you may either use a build automation tool like Maven or Gradle or download the JAR file and add it to the classpath of your project. Add the required Web3j classes to your Java class import:

1. import org.web3j.protocol.Web3j;
2. import org.web3j.protocol.core.DefaultBlockParameterName;
3. import org.web3j.protocol.http.HttpService;
4. import org.web3j.protocol.core.methods.response.EthGetBalance;
5. import org.web3j.utils.Convert;

Getting Balance

Talents can use these procedures to find the Ethereum balance associated with a certain address:

1. Using the Infura.io endpoint URL, create an instance of the Web3j object and establish a connection to the Ethereum network:

Web3j web3 = Web3j.build(new HttpService("https://mainnet.infura.io/v3/YOUR_PROJECT_ID"));

1. Provide the Ethereum address for which you want to retrieve the balance:

String address = "0xYourEthereumAddress";

1. Use the web3.ethGetBalance method to obtain the balance of the specified address:

EthGetBalance balanceResponse = web3.ethGetBalance(address, DefaultBlockParameterName.LATEST).send();

1. Check the success of the response and retrieve the balance value in Wei:

if (balanceResponse.hasError()) {

   System.out.println("Error occurred: " + balanceResponse.getError().getMessage());

} else {

   BigInteger balanceWei = balanceResponse.getBalance();

   System.out.println("Balance in Wei: " + balanceWei);

}

1. Convert the balance from Wei to Ether using the Convert.fromWei method:

String balanceEther = Convert.fromWei(balanceWei.toString(), Convert.Unit.ETHER).toPlainString();

System.out.println ("Balance in Ether: " + balanceEther);

What is Wei?

Named after cryptographer Wei Dai, Wei is the smallest unit of ether (ETH), the native cryptocurrency of the Ethereum network. It performs the same role as Satoshi does for Bitcoin as the primary unit of value in the Ethereum ecosystem. Wei, an integer that denotes whole numbers, serves as the foundational unit for expressing and measuring Bitcoin values. Wei and other Ether denominations are converted using a decimal system in which every higher unit is a multiple of 1,000.

1. One Ether (ETH) is equivalent to 1,000,000,000,000,000,000 Wei (10^18 Wei)
2. One Gwei to 1,000,000,000 Wei (10^9 Wei)
3. One Mwei (or Szabo) to 1,000,000 Wei (10^6 Wei)
4. One Kwei (or Ada) to 1,000 Wei (10^3 Wei)
5. For readability and convenience, Ethereum balances are commonly translated to higher currencies like Ether, Gwei, or Szabo, even though they are often represented in Wei.

Scaling

The resulting balance is expressed in Wei, the smallest Ether unit. If necessary, you may convert it to different currencies like Ether, Gwei, or Szabo. Use java.math package BigInteger class to handle big numbers. Use try-catch blocks to make sure you handle errors correctly when utilizing Web3j APIs. With Web3j and Java, you have now successfully obtained the Ethereum balance. To create more complex Ethereum apps, you can alter and expand this code.