BikDecimal

A Kotlin Multiplatform library providing arbitrary-precision decimal arithmetic across Android, iOS, and JVM platforms.

Features

• Multiplatform Support: Works seamlessly on Android, iOS, and JVM
• Arbitrary Precision: Handle decimal numbers with high precision without floating-point errors
• Easy to Use: Kotlin operator overloading for natural arithmetic operations
• Type Safe: Strongly typed decimal numbers with platform-native implementations

Supported Platforms

• Android (using java.math.BigDecimal)
• JVM (using java.math.BigDecimal)
• iOS (using NSDecimalNumber)

Installation

Add the dependency to your commonMain source set:

kotlin {
  sourceSets {
    commonMain.dependencies {
      implementation("jp.co.tanocee:bikdecimal:1.0.0")
    }
  }
}

Usage

Basic Arithmetic Operations

import jp.co.tanocee.bikdecimal.BikDecimal

val a = BikDecimal("123.45")
val b = BikDecimal("67.89")

val sum = a + b           // 191.34
val difference = a - b    // 55.56
val product = a * b       // 8382.2205
val quotient = a / b      // 1.818...

Constructors

// From String
val fromString = BikDecimal("999.99")

// From Double
val fromDouble = BikDecimal(3.14159)

// From Long
val fromLong = BikDecimal(42L)

Constants

val zero = BikDecimal.ZERO  // 0
val one = BikDecimal.ONE    // 1

Comparison

val x = BikDecimal("100")
val y = BikDecimal("200")

when {
  x < y -> println("x is less than y")
  x > y -> println("x is greater than y")
  x == y -> println("x equals y")
}

// Or use compareTo directly
x.compareTo(y)  // Returns negative, zero, or positive

Conversions

val value = BikDecimal("123.456")

val asString = value.toPlainString()  // "123.456"
val asDouble = value.toDouble()       // 123.456
val asLong = value.toLong()           // 123

Extension Functions

// String to BikDecimal with default value
val valid = "100.5".toBikDecimal()        // BikDecimal("100.5")
val invalid = "invalid".toBikDecimal()    // BikDecimal.ZERO (default)
val custom = "invalid".toBikDecimal(BikDecimal.ONE)  // BikDecimal.ONE

// Sum of collection
data class Product(val name: String, val price: String)
val products = listOf(
  Product("Apple", "1.20"),
  Product("Banana", "0.80"),
  Product("Orange", "1.50")
)

val total = products.sumOf { it.price.toBikDecimal() }  // 3.50

Negative Values

val value = BikDecimal("42.5")
val negated = value.negative()  // -42.5

Sample Application

The sample module contains a Compose Multiplatform application demonstrating all features of BikDecimal. You can run it to see interactive examples of:

• Basic arithmetic operations
• Different constructor types
• Comparison operations
• Conversion methods
• Collection operations with sumOf

Running the Sample App

Android:

./gradlew :sample:assembleDebug

iOS: Open the project in Xcode and run the sample target.

Project Structure

• bikdecimal-core - The core library with multiplatform implementation
  • commonMain - Common API and extension functions
  • androidMain - Android implementation using java.math.BigDecimal
  • jvmMain - JVM implementation using java.math.BigDecimal
  • iosMain - iOS implementation using NSDecimalNumber
• sample - Sample application demonstrating library usage

Building

To build the library:

./gradlew :bikdecimal-core:build

To build the entire project including the sample app:

./gradlew build

License

LICENSE