Formats numbers and dates based on locale settings with native API usage for consistent, locale-aware formatting. Offers lightweight, efficient, customizable number, currency, and percentage formatting.
FormatK is a Kotlin Multiplatform library for formatting numbers and dates based on locale. It supports JVM, Android, JavaScript (WASM & JS), and Apple platforms.
FormatK supports the following Kotlin Multiplatform targets:
dependencies {
implementation("com.bngdev:formatk:0.0.2")
}
dependencies {
implementation 'com.bngdev:formatk:0.0.2'
}
Replace <VERSION> with the latest release available on Maven Central.
Format numbers into human-readable formats with precision, locale-specific grouping, and customizable rules.
To format plain numbers based on locale:
import java.time.format.FormatStyle
// Instantiate a formatter for a specific locale
val localeInfo = LocaleInfo("en", "US") // English (US)
val numberFormatter = NumberFormaterProvider.getFormater(localeInfo, FormatStyle.DECIMAL)
// Format numbers as decimals
val formattedDecimal = numberFormatter.format(654321.987)
println(formattedDecimal) // Output: 654,321.987
When dealing with monetary values, FormatK can produce locale-appropriate numbers with currency symbols, decimal places, and grouping.
val numberFormatter = NumberFormaterProvider.getFormater(localeInfo, FormatStyle.CURRENCY)
val formattedCurrency = numberFormatter.format(654321.987)
println(formattedCurrency) // Output: $654,321.99
For more control, use custom currency codes and settings:
import com.bngdev.formatk.number.NumberFormaterSettings
val customCurrencySettings = NumberFormaterSettings(currencyCode = "GBP")
val numberFormatter = NumberFormaterProvider.getFormater(localeInfo, FormatStyle.CURRENCY, customCurrencySettings)
val formattedGBP = numberFormatter.format(654321.987)
println(formattedGBP) // Output: £654,321.99
To represent numbers as percentages:
val numberFormatter = NumberFormaterProvider.getFormater(localeInfo, FormatStyle.PERCENT)
val formattedPercentage = numberFormatter.format(0.975)
println(formattedPercentage) // Output: 97.5%
Percentages are automatically scaled to the 0 - 100% range.
NumberFormaterSettings offers various options to tweak the formatting rules as per your needs:
Example:
val customSettings = NumberFormaterSettings(
useGrouping = false, // Disable grouping (e.g., no commas)
minimumFractionDigits = 1,
maximumFractionDigits = 3,
roundingMode = RoundingMode.FLOOR
)
val numberFormatter = NumberFormaterProvider.getFormater(localeInfo, FormatStyle.DECIMAL, customSettings)
val formattedNumber = numberFormatter.format(12345.6789)
println(formattedNumber) // Output: 12345.678
You can retrieve default formatting configurations based on a locale and desired style using the built-in interface:
val defaultSettings = NumberFormaterProvider.getInstance(localeInfo).getDefaultSettings(FormatStyle.CURRENCY)
println(defaultSettings.useGrouping) // Output: true
FormatK includes a robust suite of tests to ensure seamless functionality across different locales, number styles, and edge cases. The testing framework validates multiple key areas of the library.
We welcome contributions!
FormatK is released under the Apache License, Version 2.0, January 2004.
For questions, suggestions, or issues, feel free to open an issue or reach out on Discussions.
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