web3j is a lightweight, reactive, type-safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network. It allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.
Create, deploy, transact with and call smart contracts from native Java code
Create and manage Ethereum wallet files.
Transfer Ether, manage wallets, generate wrappers from the command line
Simple, fully asynchronous API supporting Futures or RxJava’s Observables