Web3j is a Java library that provides a simplified interface for communicating with Ethereum clients from JVM languages like Java, lowering the barriers to working with Ethereum. It handles tasks like JSON-RPC implementation, contract ABIs, and numeric types, generating Java wrappers for smart contracts. The roadmap includes core JSON-RPC over HTTP, account management and transaction signing, asynchronous/synchronous requests, and additional features like offline transaction signing and IPC/WebSocket interfaces.

1. web3j
Web3 Java Ðapp API
@conors10

2. What
• Minimal integration layer to communicate with
Ethereum clients from JVM languages
• Think Nethereum, but in Java

3. Why?
• Simple interface for communication
• Lowers barriers to entry for working with Ethereum - don’t worry about:
• JSON-RPC implementation
• Contract application binary interface encoders/decoders
• 256 bit numeric types
• …
• ethereumj is a full client
• unnecessary dependencies for just Ethereum client communication

4. Example

5. Smart Contract Wrappers
• Auto-generation of Java smart contract function
wrappers from Solidity ABI files

6. Solidity Code

7. Generated Java Code

8. Call Smart Contract from
Java

9. Roadmap
Release v0.3.0
• Core JSON-RPC over HTTP
• Geth/Parity methods for managing accounts and signing transactions
• Async/sync client requests
• Smart contract wrappers in Java
Coming soon
• Offline transaction singing, inc. RLP encoding
• IPC interface support
• WebSocket interface support

10. Find out more
• Code - https://github.com/web3j/web3j
• Chat - https://gitter.im/web3j