Kotlin Util Library

This repository contains a set of Kotlin-only (no Android dependency) libraries for various purposes, designed specifically for Kotlin Multiplatform projects.

Documentation

Dokka documentation for all modules can be found here.

---

Modules

Module	Description	Version
:data	Extension methods for ByteArray, Byte, Short, and UUID operations.
:id	A simple interface for objects with unique identifiers.
:log	A flexible, lightweight logging facade for KMP libraries and apps.
:log-timber	Timber sink addon for forwarding :log events on Android.

---

Data

Kotlin library for data manipulation. It contains extension methods for ByteArray allowing to read numbers in big-endian and little-endian order in various formats, bit operators for Byte and Short, and methods for converting UUIDs to and from ByteArray.

Setting up

implementation("no.nordicsemi.kotlin:data:<version>")

Usage Examples

Reading Integers & Floats

val array = byteArrayOf(0x87.toByte(), 0x65, 0x43, 0x21, 0xFF.toByte(), 0x00, 0x01, 0x6C)

// Read Int32
val intVal = array.getInt(offset = 0, format = IntFormat.INT32, order = ByteOrder.BIG_ENDIAN)

// Read IEEE 11073 32-bit Float
val floatVal = array.getFloat(offset = 4, format = FloatFormat.IEEE_11073_32_BIT, order = ByteOrder.BIG_ENDIAN)

Bit operators

val value = 0b1010_1001.toByte()
assertTrue(value hasAllBitsSet 0b1000_0001)
assertTrue(value hasBitSet 0)

UUID

val uuid = UUID.randomUUID()
val array = uuid.toByteArray(order = ByteOrder.BIG_ENDIAN)
val recoveredUuid = array.toUuid(order = ByteOrder.BIG_ENDIAN)

---

ID

A lightweight module providing a standard interface for identifiable objects.

Setting up

implementation("no.nordicsemi.kotlin:id:<version>")

Usage

class Device(override val identifier: String) : Identifiable<String>

---

Log

A flexible logging facade that separates log production (Emitters) from log consumption (Sinks).

Key Features

• Lazy Evaluation: Messages are only computed if they pass the sink's filters.
• Strong Typing: Use your own enum class for log categories.
• Identifiable Emitters: Automatically includes source identifiers for multi-instance components.
• Relay: Easily forward logs from internal components to the main application sink.

Setting up

implementation("no.nordicsemi.kotlin:log:<version>")

Usage Example

1. Define Categories and Emitter

enum class MyCategory : Log.Category { NETWORK, UI }

// Emitter for a single instance component
class NetworkManager : Log.Emitter {
    var logger: Log.Sink<MyCategory>? = Log.Sink.Null

    fun connect() {
        // Message is only evaluated if logger is not null and filter passes
        logger?.i(MyCategory.NETWORK) { "Connecting to server..." }
    }
}

// IdentifiableEmitter for multi-instance components (e.g. connected devices)
class Device(override val identifier: String) : Identifiable<String>, Log.IdentifiableEmitter<String> {
    var logger: Log.Sink<MyCategory>? = Log.Sink.Null

    fun update() {
        // Automatically includes the identifier ("source") in log events
        logger?.d(MyCategory.UI) { "Updating UI" }
    }
}

2. Assign a Sink in the Application

val manager = NetworkManager()

// Log to console (Logcat on Android, println on JVM/Native)
// By default, it logs Level.INFO and above.
manager.logger = Log.Sink.Default() 

// Or customize the filter
manager.logger = Log.Sink.Default { category, level ->
    level >= Log.Level.DEBUG && category == MyCategory.NETWORK
}

// Or direct to a SharedFlow for reactive processing
val logFlow = Log.Sink.Flow<MyCategory>()
manager.logger = logFlow

---

Log Timber

Android addon for :log that forwards logs to Timber.

Setting up

implementation("no.nordicsemi.kotlin:log-timber:<version>")

Usage Example

import no.nordicsemi.kotlin.log.Log
import no.nordicsemi.kotlin.log.timber.Timber
import timber.log.Timber

enum class AppCategory : Log.Category { NETWORK }

fun createLogger(): Log.Sink<AppCategory> {
    Timber.plant(Timber.DebugTree())

    return Log.Sink.Timber { _, level ->
        level >= Log.Level.DEBUG
    }
}

---

License

The Kotlin Util Library is available under the BSD 3-Clause license.