Kotlin Extensions

ActivityIntentState.kt

fun Activity.getStringFromIntentOrState(field: String, savedInstanceState: Bundle?): String? =
    when {
        intent.getStringExtra(field) != null -> intent.getStringExtra(field)
        savedInstanceState?.getString(field) != null -> savedInstanceState.getString(field)
        else -> null
    }

Keyboard.kt

fun Activity.hideKeyboard() {
    (getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager)
        ?.let { imm ->
            val view = currentFocus ?: View(this)
            imm.hideSoftInputFromWindow(view.windowToken, 0)
        }
}

fun Fragment.hideKeyboard() {
    activity?.hideKeyboard()
}

LocalDate.kt

fun LocalDate.toLocalDateTime(): LocalDateTime {
    return LocalDateTime.of(year, monthValue, dayOfMonth, 0, 0)
}

LocalDateTime.kt

fun LocalDateTime.getThisWeekDays(): List<LocalDateTime> {
    val fieldISO = WeekFields.of(Locale.getDefault()).dayOfWeek()
    return (1L..7L).map { with(fieldISO, it) }
}

fun LocalDateTime.getThisWeekDays(): List<LocalDateTime> {
    val fieldISO = WeekFields.of(Locale.TRADITIONAL_CHINESE).dayOfWeek()
    return (1L..7L).map { with(fieldISO, it) }
}

fun LocalDateTime.getThisMonthStartEndDay(): Pair<LocalDateTime, LocalDateTime> {
    val date = toLocalDate()
    val start = date.withDayOfMonth(1)
    val end = date.withDayOfMonth(date.month.length(date.isLeapYear))
    return start.toLocalDateTime() to end.toLocalDateTime()
}

fun LocalDateTime.getThisMonthAllDays(): List<LocalDateTime> {
    val (start, end) = LocalDateTime.now().getThisMonthStartEndDay()
    return (start.dayOfMonth..end.dayOfMonth).map {
        LocalDate.now().withDayOfMonth(it)
    }.map { it.toLocalDateTime() }
}

Zip.kt

fun File.makeZip(filePaths: List<String>) {
    ZipOutputStream(BufferedOutputStream(FileOutputStream(this))).use { out ->
        for (file in filePaths) {
            FileInputStream(file).use { fi ->
                BufferedInputStream(fi).use { origin ->
                    val entry = ZipEntry(file.substring(file.lastIndexOf("/") + 1))
                    out.putNextEntry(entry)
                    origin.copyTo(out, 1024)
                }
            }
        }
    }
}