How to access a distributed ledger technology blockchain from a Java application using web3j. The Ethereum blockchain is a decentralized platform that is the backbone of a secure, decentralized internet and is driven by the eponymous cryptocurrency Ether. Conor Svensson authored web3j, a lightweight Java library for building Java applications on the Ethereum blockchain.
In a first article, which appeared in the Java Magazine, Conor Svensson gives the background of the Ethereum blockchain technology and explains how to create a blockchain that is connected to a Java application. Web3j, a wrapper of client remote procedure calls using JSON, manages the transaction interactions with Ethereum clients.
In a second article, he details how to use web3j to query the Ethereum blockchain via its reactive-functional API. He explains how to use RxJava’s Observables to add reactive functionality to the blockchain.
An Ethereum client like Geth or Parity is the first step to getting you started. Clients will synchronize the Ethereum blockchain with one another and provide a gateway to interact with the blockchain. Ethereum takes care of Ether cryptocurrency payment transactions via the network. With just a few lines of code, you can hook up to the Ethereum blockchain and be notified of new blocks being added to the blockchain and start pulling information out of the blockchain in real time.
For code and step by step examples, read the full article here