Optimize Android date and time formatting #315
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martinbonnin
approved these changes
May 27, 2024
cbeyls
commented
May 27, 2024
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| actual fun LocalDate.formatMediumDate(): String { | ||
| val dateFormat = SimpleDateFormat.getDateInstance(MEDIUM) | ||
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| val tz = TimeZone.getTimeZone("Europe/Paris") |
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Also note that the previous code may produce incorrect output because the LocalDate is transformed to a Date using the system default timezone but then formatted using the Paris timezone which may be different.
So if the Paris timezone is at the west of the current timezone, the previous day will be shown.
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The current Android code uses the legacy
java.text.SimpleDateFormatclass and creates a new instance of it for every formatting. This also requires unnecessary conversion of the date or time to the legacyDatefirst.This pull request uses the new thread-safe
DateTimeFormatterto formatLocalDateandLocalTime, the classes used internally by the kotlinx datetime types. Unwrapping the internal value is a free operation.In addition, cache the
DateTimeFormatterfor the currentLocaleusing a thread-safe custom memoization function. The cache will be invalidated when the default locale changes so the dates will always be localized properly.Note that
DateTimeFormatterand otherjava.timeAPIs are available before API 26 thanks to core library desugaring being enabled in the Android app configuration.Finally, upgrade the kotlinx datetime library to 0.6.0.