I'm creating a DateTimeFormatter to format a LocalDate with a pattern from DateFormat.getBestDateTimePattern(..). This works on all the devices we have in the office, but I'm seeing a lot of crashes in Crashlytics. I've managed to find out the pattern generated by getBestDateTimePattern() (d 'de' MMMM) and locale (spa (ESP)) from the crashes, but this combination works on all our devices, so a pattern/locale might not be the issue. Has anybody come across this?

fun dateTimeFormatterOfBestDateTimePattern(
    pattern: String,
    locale: Locale = Locale.getDefault()
): DateTimeFormatter {
    val datePattern = android.text.format.DateFormat.getBestDateTimePattern(locale, pattern)
    return DateTimeFormatter.ofPattern(datePattern)
        .withLocale(locale)
        .withZone(ZoneId.systemDefault())
}

val date = LocalDate.now()
val formatter = dateTimeFormatterOfBestDateTimePattern("MMMMd")
formatter.format(date)

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1
       at j$.time.zone.f.i(SourceFile:1107)
       at j$.time.format.A.<init>(SourceFile:581)
       at j$.time.format.DateTimeFormatter.format(SourceFile:1794)

I'm creating a DateTimeFormatter to format a LocalDate with a pattern from DateFormat.getBestDateTimePattern(..). This works on all the devices we have in the office, but I'm seeing a lot of crashes in Crashlytics. I've managed to find out the pattern generated by getBestDateTimePattern() (d 'de' MMMM) and locale (spa (ESP)) from the crashes, but this combination works on all our devices, so a pattern/locale might not be the issue. Has anybody come across this?

fun dateTimeFormatterOfBestDateTimePattern(
    pattern: String,
    locale: Locale = Locale.getDefault()
): DateTimeFormatter {
    val datePattern = android.text.format.DateFormat.getBestDateTimePattern(locale, pattern)
    return DateTimeFormatter.ofPattern(datePattern)
        .withLocale(locale)
        .withZone(ZoneId.systemDefault())
}

val date = LocalDate.now()
val formatter = dateTimeFormatterOfBestDateTimePattern("MMMMd")
formatter.format(date)

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1
       at j$.time.zone.f.i(SourceFile:1107)
       at j$.time.format.A.<init>(SourceFile:581)
       at j$.time.format.DateTimeFormatter.format(SourceFile:1794)

• android
• kotlin

• can you share the piece of code where you have used this dateTimeFormatterOfBestDateTimePattern? – Jayanta Sarkar Commented Mar 24 at 7:35
• I've edited the post – okycelt Commented Mar 24 at 7:53
• I don't think there is problem with dateFormatterOfBestdateTimePattern. As I tried this code and it works fine. Do check the the line number 1107 and 581 in your SourceFile. – Jayanta Sarkar Commented Mar 24 at 9:14

1 Answer 1

Updated code with added -> if conditions and Logs. Please try once

import java.time.LocalDate
import java.time.ZoneId
import java.time.format.DateTimeFormatter
import android.text.format.DateFormat
import android.util.Log
import java.util.*

fun dateTimeFormatterOfBestDateTimePattern(
    pattern: String,
    locale: Locale = Locale.getDefault()
): DateTimeFormatter {
     val datePattern = DateFormat.getBestDateTimePattern(locale, pattern)
     Log.d("DatePattern", "Pattern: $datePattern")
     if (datePattern.isEmpty()) {
        Log.e("DatePatternError", "Generated pattern is empty for locale: $locale. Using fallback pattern.")
        return DateTimeFormatter.ofPattern("MMMM d") // Default fallback pattern
            .withLocale(locale)
            .withZone(ZoneId.systemDefault())
    }

 
    return try {
        DateTimeFormatter.ofPattern(datePattern)
            .withLocale(locale)
            .withZone(ZoneId.systemDefault())
    } catch (e: Exception) {
      
        Log.e("DatePatternError", "Failed to create DateTimeFormatter with pattern: $datePattern", e)
        
      
        DateTimeFormatter.ofPattern("MMMM d")
            .withLocale(locale)
            .withZone(ZoneId.systemDefault())
    }
}

// Usage example
val date = LocalDate.now()
val formatter = dateTimeFormatterOfBestDateTimePattern("MMMMd", Locale("es", "ES"))
println(formatter.format(date))