In this chapter, we have scratched the surface of working with the Ethereum blockchain using your beloved language, Java. Indeed, it was a gentle introduction to web3j by building an Oracle-based application, opening the door to build complex Ethereum applications in Java. From now on, all you need is to dive deep into the web3j documentation. You will find a number of smart contract examples in their main project repository (https://github.com/web3j/web3j/tree/master/codegen/src/test/resources/solidity).
To enrich your knowledge, you can also explore EthereumJ, which is a Java implementation of the Ethereum protocol, or Ethereum Harmony. To step outside of the Java world, you can explore Web3py (https://github.com/ethereum/web3.py), which is a complete Python implementation of web3js.
In the next chapter, our Ethereum journey will continue as we examine how to use Ethereum...