Pre-release notes

These versions are not yet released. For official releases, see the release notes.

Version 0.17 alpha 1

See the preliminary API documentation.

Requirements for developers and consumers:

• JDK 11+ is required for building the project. In particular, we support LTS releases JDK 11 and JDK 17.
• The Gradle requirement moderately updated: 4.4+ for everything except: bitcoinj-wallettemplate: 4.10+, bitcoinj-integration-test: 4.6+. If you want to use the new testOnJdk8 task, Gradle 6.7+ is required.
• The Java API requirement for bitcoinj-core remains unchanged at Java 8. For any other module it has been raised to Java 11.
• The Android API requirement for bitcoinj-core has been raised to API level 26 (Android 8.0).
• Unchanged is the possibility to use up to Java 8 language features (except bitcoinj-wallettemplate: Java 11).

Breaking changes:

• A considerable number of previously deprecated methods and classes have been removed. If you want to ease the migration to bitcoinj 0.17, please migrate usages of deprecated API before updating your bitcoinj dependency.
• We moved many classes to two new packages:
  • org.bitcoinj.base: provides fundamental types with minimal dependencies. This will become its own module in bitcoinj 0.18.
  • org.bitcoinj.crypto: we’ve removed direct usage of BouncyCastle in our crypo API. If you’ve been using BC KeyParameters to encrypt wallets, please use our very similar AesKey wrapper.

  In general, an “optimize imports” should be enough to resolve the new packages. Many method signatures have changed though. We tried to provide deprecation stubs for the old signatures to ease the migration.

• We’re extracting many aspects of NetworkParameters to a new Network interface and its implementing BitcoinNetwork enum. Many APIs that used NetworkParameters now use Network. Again, we’re providing deprecation stubs.
• We’re not using the term “prod” (or “prodnet”) any more. It’s now BitcoinNetwork.MAINNET.
• We moved many internal helpers/utils to .internal packages. These are not public API, please don’t use them from your app. If there is a helper which you think would be useful for everyone, please drop us a note and we’ll consider adding it to the public API.
• We removed the (semi-automatic) upgrade path from basic to deterministic keychains/wallets. It was useful back in the time, but nowadays it’s becoming difficult to maintain code for unexpected behaviour. For more information see this issue.
• We finally removed all Serializable and Cloneable!
• PrefixedChecksummedBytes has been renamed to EncodedPrivateKey.
• Constructors in the Message hierarchy previously taking a byte[] message payload are now consuming from ByteBuffer. There are no deprecation stubs provided for this change. Payloads are now never retained.
• If you’ve been using PeerDataEventListener to observe the blockchain download, use BlockchainDownloadEventListener now.

Feature removals:

• HttpDiscovery, implementing the protocol to discover seeds via HTTP, is no more. We suggest to use DnsDiscovery or use a hardcoded “seed node” (see new feature below).
• Removed support for querying Bitcoin XT nodes for UTXOs. GetUTXOsMessage and UTXOsMessage were removed.
• All database-backed block stores have been removed.
• The C++/JNI wallet interface has been deprecated and will be removed in a future release. For more information see this issue.
• Likewise, the native interface to libsecp256k1 has been deprecated. For more information see this issue.
• Setting tags on objects (TaggableObject) has been deprecated and will go away in a future release.
• On Android, LinuxSecureRandom isn’t automatically installed anymore. The class is still around for manual installation if you’re supporting Android 4.x affected by the RNG vulnerability.

New noteworthy features:

• PeerGroup can now add addresses discovered via addr and addrv2 messages to the pool of nodes to connect to. This means one or more hardcoded nodes can act as a seed for others. This means you can run realistically run a PeerGroup without any PeerDiscovery at all.
• Support for Signet.
• Transaction.addSignedInput() now also support segwit.
• Wallet has two new static constructors to load from file: loadFromFile(), loadFromFileStream()
• KeyChainGroupStructure now also supports a BIP-43/BIP-44/BIP-84 structure.
• We now have an AddressParser, which replaces the previous static Address.fromString() constructors.
• ECKey can now sign and verify messages with segwit addresses (BIP-137). There is a new MessageVerifyUtils to aid with signing and verifying messages.

General improvements:

• We’re going all-in on Java 8 language features! Lambdas, method references, you name it! Generally speaking, we’re on a quest to adopt functional programming style.
• In the API and internally, all integer timestamps have been replaced with java.time.Instant.
• Likewise, integer-based intervals now use java.time.Duration.
• Transaction lock time values are wrapped in a new class LockTime.
• Accessors that could previously return null are being migrated to java.util.Optional.
• In value-based/immutable classes we’re in the process of stripping the prefix “get” from the accessor names.
• All usages of Guava ListenableFuture have been migrated to CompletableFuture. To ease the migration, we use ListenableCompletableFuture which implements both.
• We’re on a mission to replace Guava with JDK 7+ equivalents. Our new org.bitcoinj.base package is not depending on Guava at all!
• WalletTool is slowly evolving into a standalone tool:
  • It now lives in its own bitcoinj-wallettool submodule.
  • Its build generates man, html5 and adoc manpages from the picocli annotations.
• We updated the DNS seeds.
• We refreshed the bundled checkpoints.
• We’re now using SLF4J 2.0 with its fluent logging API.
• Our integration tests have moved to a new submodule bitcoinj-integration-test. It makes early use of JUnit 5 and requires Gradle 4.6+ because of that.
• Our CI has improved a lot:
  • On GitHub Actions, we’re testing a large matrix of supported and future operating systems, JDKs and versions of Gradle. We’re also testing for accidental usage of API only available past JDK 8. A new testOnJdk8 task has been added for this (requires Gradle 6.7+).
  • On Gitlab CI, the focus is on testing compatibility with an “all free software” toolchain (Debian) and reproducible builds.
• We now have a Matrix space! Join us there if you’ve got questions or suggestions.