Date extensions wrote in Kotlin

DateExtension.kt

import java.text.SimpleDateFormat
import java.util.*


/**
 * Pattern: yyyy-MM-dd HH:mm:ss
 */
fun Date.formatToServerDateTimeDefaults(): String{
    val sdf= SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault())
    return sdf.format(this)
}

fun Date.formatToTruncatedDateTime(): String{
    val sdf= SimpleDateFormat("yyyyMMddHHmmss", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Pattern: yyyy-MM-dd
 */
fun Date.formatToServerDateDefaults(): String{
    val sdf= SimpleDateFormat("yyyy-MM-dd", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Pattern: HH:mm:ss
 */
fun Date.formatToServerTimeDefaults(): String{
    val sdf= SimpleDateFormat("HH:mm:ss", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Pattern: dd/MM/yyyy HH:mm:ss
 */
fun Date.formatToViewDateTimeDefaults(): String{
    val sdf= SimpleDateFormat("dd/MM/yyyy HH:mm:ss", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Pattern: dd/MM/yyyy
 */
fun Date.formatToViewDateDefaults(): String{
    val sdf= SimpleDateFormat("dd/MM/yyyy", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Pattern: HH:mm:ss
 */
fun Date.formatToViewTimeDefaults(): String{
    val sdf= SimpleDateFormat("HH:mm:ss", Locale.getDefault())
    return sdf.format(this)
}

/**
 * Add field date to current date
 */
fun Date.add(field: Int, amount: Int): Date{
    val cal = Calendar.getInstance()
    cal.time=this
    cal.add(field, amount)

    this.time = cal.time.time

    cal.clear()

    return this
}

fun Date.addYears(years: Int): Date{
    return add(Calendar.YEAR, years)
}
fun Date.addMonths(months: Int): Date {
    return add(Calendar.MONTH, months)
}
fun Date.addDays(days: Int): Date{
    return add(Calendar.DAY_OF_MONTH, days)
}
fun Date.addHours(hours: Int): Date{
    return add(Calendar.HOUR_OF_DAY, hours)
}
fun Date.addMinutes(minutes: Int): Date{
    return add(Calendar.MINUTE, minutes)
}
fun Date.addSeconds(seconds: Int): Date{
    return add(Calendar.SECOND, seconds)
}