Telegram Channel BitcoinJ   Bitcoin Project – 4 Members

https://bitcoinj.github.io/

https://github.com/bitcoinj/bitcoinj

What is bitcoinj?

  
Some projects using bitcoinj

bitcoinj is a library for working with the Bitcoin protocol. It can maintain a wallet, send/receive transactions without needing a local copy of Bitcoin Core and has many other advanced features. It’s implemented in Java but can be used from any JVM compatible language: examples in Python and JavaScript are included.

It comes with full documentation and many large, well known Bitcoin apps and services are built on it.

Features

• Highly optimised lightweight simplified payment verification (SPV) mode. In this mode, only a small part of the block chain is downloaded, making bitcoinj suitable for usage on constrained devices like smartphones or cheap virtual private servers.
• Experimental full verification mode, which does the same verification work as Bitcoin Core. In this mode, the unspent transaction output set (UTXO set) is calculated and, thanks to a PostgreSQL store, can be indexed into a database allowing for fast lookup of balance by address.
• A wallet class with encryption, fee calculation, multi-signing, deterministic key derivation, pluggable coin selection/coin control, extensions support and event listeners that let you stay up to date with changes in your balance.
• Support for micropayment channels that let you set up a multi-signature contract between client and server, and then negotiate on the channel, allowing fast micropayments that avoid miner fees.
• Provides both async and thread-per-connection for network IO, allowing you to choose between scalability and blocking-only features like SOCKS proxying.
• Easily implement apps that use Bitcoin’s contracts features.
• A simple GUI wallet app that you can use as the basis for your own apps. Watch or read a tutorial on how to customise it and build a native installer that does not require Java.
• Command line tools for working with wallet and chain files, the payment protocol, the network and more.
• Strong Bitcoin standards support.
• A friendly and helpful community!

Documentation

Read the API documentation: 0.15.7 API documentation

There are also some more in depth articles covering various topics. For best understanding, read them in order.

Basics

• Limitations and missing features
• Understanding the bitcoinj security model
• Working with bitcoinj – basic patterns and things you should know
• How the different components of your app fit together
• How to test your software

Core APIs in depth

• Working with transactions
• Working with the wallet, which covers:
  • Setting one up
  • Receiving and sending money
  • Crafting custom transactions and contracts
  • Balances, coin selection and how to customise
  • Wallet maintenance
  • Encryption and passwords
  • Watching/following wallets
  • Multisig/married wallets and pluggable transaction signing
  • Connecting the wallet to an external unspent outputs store e.g. for web wallets
• Working with monetary amounts
• How to use the network API

bitcoinj TV

• Video tutorial: how to make a simple GUI wallet using the wallet template app
• Video tutorial: how to build and bundle a document timestamping contracts app in under 30 minutes

Advanced features

• API contexts
• How to use the experimental fully verifying mode
• Working with contracts
• Working with the BIP70 payment protocol
• Working with micropayment channels
• Information on block chain synchronisation optimisations
• Using bitcoinj from other languages like C++, JavaScript, Ruby, Python, etc
• Coding conventions in the library itself

You can read the release notes for each release starting from 0.3.

Community

• View bitcoinj on Github – make sure to star us!
• Ask questions and discuss improvements on the mailing list
• Search and report issues on the Issues Data Base (to ask for help please use the mailing list, not the Issues DB)
• Join our IRC channel, #bitcoinj on freenode.