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bdk-android

README.md

bdk-android

This project builds an .aar package for the Android platform that provide Kotlin language bindings for the bdk library. The Kotlin language bindings are created by the bdk-ffi project which is included in the root of this repository.

How to Use

To use the Kotlin language bindings for bdk in your Android project add the following to your gradle dependencies:

repositories {
    mavenCentral()
}

dependencies { 
    implementation("org.bitcoindevkit:bdk-android:<version>")
}

Snapshot releases

To use a snapshot release, specify the snapshot repository url in the repositories block and use the snapshot version in the dependencies block:

repositories {
    maven("https://s01.oss.sonatype.org/content/repositories/snapshots/")
}

dependencies { 
    implementation("org.bitcoindevkit:bdk-android:<version-SNAPSHOT>")
}

Example Projects

How to build

Note that Kotlin version 1.9.23 or later is required to build the library.

  1. Clone this repository.
git clone https://github.com/bitcoindevkit/bdk-ffi
  1. Follow the "General" bdk-ffi ["Getting Started (Developer)"] instructions.
  2. Install Rust (note that we are currently building using Rust 1.77.1):
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
rustup default 1.77.1
  1. Install required targets
rustup target add x86_64-linux-android aarch64-linux-android armv7-linux-androideabi
  1. Install Android SDK and Build-Tools for API level 30+
  2. Setup ANDROID_SDK_ROOT and ANDROID_NDK_ROOT path variables which are required by the build tool. Note that currently, NDK version 25.2.9519653 or above is required. For example:
# macOS
export ANDROID_SDK_ROOT=~/Library/Android/sdk
export ANDROID_NDK_ROOT=$ANDROID_SDK_ROOT/ndk/25.2.9519653

# linux
export ANDROID_SDK_ROOT=/usr/local/lib/android/sdk
export ANDROID_NDK_ROOT=$ANDROID_SDK_ROOT/ndk/25.2.9519653
  1. Build kotlin bindings
# build Android library
cd bdk-android
./gradlew buildAndroidLib
  1. Start android emulator and run tests
./gradlew connectedAndroidTest

How to publish to your local Maven repo

cd bdk-android
./gradlew publishToMavenLocal -P localBuild

Note that the commands assume you don't need the local libraries to be signed. If you do wish to sign them, simply set your ~/.gradle/gradle.properties signing key values like so:

signing.gnupg.keyName=<YOUR_GNUPG_ID>
signing.gnupg.passphrase=<YOUR_GNUPG_PASSPHRASE>

and use the publishToMavenLocal task without the localBuild flag:

./gradlew publishToMavenLocal

Known issues

JNA dependency

Depending on the JVM version you use, you might not have the JNA dependency on your classpath. The exception thrown will be

class file for com.sun.jna.Pointer not found

The solution is to add JNA as a dependency like so:

dependencies {
    // ...
    implementation("net.java.dev.jna:jna:5.12.1")
}

x86 emulators

For some older versions of macOS, Android Studio will recommend users install the x86 version of the emulator by default. This will not work with the bdk-android library, as we do not support 32-bit architectures. Make sure you install an x86_64 emulator to work with bdk-android.