web3j - Connect Java and Android apps to the Ethereum blockchain

web3j is a lightweight, reactive, type safe Java and Android library for integrating with clients (nodes) on the Ethereum network. This allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.

• 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
• Reactive-functional API for working with filters
• Command line tools