How to parse in Java?

Tutorial with code examples about tools to generate a parser in Java
15 August 2017   430

There are three ways to parse a language or a document from Java:

  • with an existing library supporting specific language: for example a library to parse XML
  • creating your own parser
  • a tool or library to generate a parser

Use An Existing Library

You can use an existing library if you need to parse well known and supported language, like XML or HTML. A high quality library also include API for building and modifing documents in the language. This is what you can get from a basic parser. The main problem is that ther are not so much  quality libraries and the they support only the most popular languages. 

Building Your Own Custom Parser By Hand

You can choose this option if you have specific needs. If the language you need to parse cannot be parsed with traditional parser generators, or you have specific requirements that you cannot satisfy using a typical parser generator. Or maybe you need the best possible performance or a deep connection between components.

A Tool Or Library To Generate A Parser

The third option is a best one for all other situations. It is the most flexible option and has the shorter development time. Learn more what tool or library to chose to generate a parser from this tutorial.

What is Web3j?

Small review of lightweight Java and Android library for integration with Ethereum clients
15 December 2017   827

What is webj3?

web3j is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network:

web3j architecture
Web3j Architecture

This allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.

According to the developers, these are the features:

  • Complete implementation of Ethereum's JSON-RPC client API over HTTP and IPC
  • Ethereum wallet support
  • Auto-generation of Java smart contract wrappers to create, deploy, transact with and call smart contracts from native Java code (Solidity and Truffle definition formats supported)
  • Reactive-functional API for working with filters
  • Ethereum Name Service (ENS) support
  • Support for Parity's Personal, and Geth's Personal client APIs
  • Support for Infura, so you don't have to run an Ethereum client yourself
  • Comprehensive integration tests demonstrating a number of the above scenarios
  • Command line tools
  • Android compatible
  • Support for JP Morgan's Quorum via web3j-quorum

It has five runtime dependencies:

  • RxJava for its reactive-functional API
  • OKHttp for HTTP connections
  • Jackson Core for fast JSON serialisation/deserialisation
  • Bouncy Castle (Spongy Castle on Android) for crypto
  • Jnr-unixsocket for *nix IPC (not available on Android)

It also uses JavaPoet for generating smart contract wrappers.

Lear more at GitHub.