web3j by

Where Java meets the blockchain

Connect JVM applications to Ethereum blockchains with web3j - a lightweight, reactive, type safe library for Java, Android, Kotlin and Scala

Create, deploy, transact with and call smart contracts from native Java code

Create and manage Ethereum wallet files

Seamless integration with build tools via Gradle and Maven plugins

Simple, fully asynchronous API supporting Futures or RxJava's Observables

web3j features in the January/February 2017 issue of Java Magazine

Join the discussion on Gitter