Exemplos de como trabalhar com datas no Kotlin

DateExtension.kt

import java.text.SimpleDateFormat
import java.util.*
import java.util.concurrent.TimeUnit

fun String.stringToDate(format: String = "yyyy-MM-dd HH:mm:ss"): Date =
    SimpleDateFormat(format, Locale.getDefault()).parse(this)

fun Date.dateToString(format: String = "yyyy-MM-dd HH:mm:ss"): String =
    SimpleDateFormat(format, Locale.getDefault()).format(this)

infix fun Date.difHoursTo(dateTo: Date): Long =
    TimeUnit.MILLISECONDS.toHours(dateTo.time - this.time)

infix fun Date.difMinutesTo(dateTo: Date): Long =
    TimeUnit.MILLISECONDS.toMinutes(dateTo.time - this.time)

infix fun Date.difSecondsTo(dateTo: Date): Long =
    TimeUnit.MILLISECONDS.toSeconds(dateTo.time - this.time)

fun Date.add(field: Int, amount: Int): Date {
    Calendar.getInstance().apply {
        time = this@add
        add(field, amount)
        return time
    }
}

fun Date.addYears(years: Int): Date =
    add(Calendar.YEAR, years)

fun Date.addMonths(months: Int): Date =
    add(Calendar.MONTH, months)

fun Date.addDays(days: Int): Date =
    add(Calendar.DAY_OF_MONTH, days)

fun Date.addHours(hours: Int): Date =
    add(Calendar.HOUR_OF_DAY, hours)

fun Date.addMinutes(minutes: Int): Date =
    add(Calendar.MINUTE, minutes)

fun Date.addSeconds(seconds: Int): Date =
    add(Calendar.SECOND, seconds)