EmmanuelGuther

Elvis Operator
When we have a nullable reference r, we can say "if r is not null, use it, otherwise use some non-null value x":

val l: Int = if (b != null) b.length else -1
Along with the complete if-expression, this can be expressed with the Elvis operator, written ?::

val l = b?.length ?: -1
If the expression to the left of ?: is not null, the elvis operator returns it, otherwise it returns the expression to the right. Note that the right-hand side expression is evaluated only if the left-hand side is null.

Note that, since throw and return are expressions in Kotlin, they can also be used on the right hand side of the elvis operator. This can be very handy, for example, for checking function arguments:

EmmanuelGuther

fun TextView.showCountIncrementAnimation(from: Int? = 0, to: Int?) {
    var duration: Long? = null
    val animator = ValueAnimator()
    animator.setObjectValues(from, to)// here you set the range, from 0 to "count" value
    animator.addUpdateListener { animation -> this.text = animation.animatedValue.toString() }
    duration = when (to) {
        in 0..4 -> 200
        in 5..10 -> 1000
        in 11..50 -> 3000
        else -> 2000

EmmanuelGuther

fun TextView.afterTextChangedDelayed(afterTextChanged: (String) -> Unit) {
    this.addTextChangedListener(object : TextWatcher {
        var timer: CountDownTimer? = null

        override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
        }

        override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
        }

EmmanuelGuther

fun generateRandomLocationInsideRadius(x0: Double, y0: Double, radius: Int): LatLng {
    val random = Random()
    // Convert radius from meters to degrees
    val radiusInDegrees = (radius / 111000f).toDouble()
    val u = random.nextDouble()
    val v = random.nextDouble()
    val w = radiusInDegrees * sqrt(u)
    val t = 2.0 * Math.PI * v
    val x = w * cos(t)
    val y = w * sin(t)

EmmanuelGuther

/** USAGE -> ('a'..'z').randomString(6) */
fun ClosedRange<Char>.randomString(lenght: Int) =
        (1..lenght)
                .map { (Random().nextInt(endInclusive.toInt() - start.toInt()) + start.toInt()).toChar() }
                .joinToString("")

EmmanuelGuther

private Object increaseVersionCode() {
    Properties versionProps = new Properties()
    def versionPropsFile = file('version.properties')
    if (versionPropsFile.exists())
        versionProps.load(new FileInputStream(versionPropsFile))
    def code = (versionProps['VERSION_CODE'] ?: "410").toInteger() + 1
    versionProps['VERSION_CODE'] = code.toString()
    versionProps.store(versionPropsFile.newWriter(), null)
    return code
}

EmmanuelGuther

    val fiveMinutes = (1000 * 60 * 5).toLong() //5m in milliseconds

EmmanuelGuther

fun Long.checkTimeIsOldThan(days: Int): Boolean {
    val daysInMillis = TimeUnit.DAYS.toMillis(days.toLong())
    val currentTime = Date().time
    val previousTime = this
    val differ = currentTime - previousTime
    return !(differ < daysInMillis && differ > -daysInMillis)
}

EmmanuelGuther

---------------------------     -----   ------------    --------------- ------- -----------     ----------------    ---         ----------
Device                          Inches  ResolutionPX    Density         DPI     ResolutionDP    AspectRatios        SysNavYorN  ContentResolutionDP
---------------------------     -----   ------------    --------------- ------- -----------     ----------------    ---         ----------                                                          
Galaxy Y                                 320 x  240     ldpi    0.75    120      427 x 320      4:3     1.3333                   427 x 320
?                                        400 x  240     ldpi    0.75    120      533 x 320      5:3     1.6667                   533 x 320
?                                        432 x  240     ldpi    0.75    120      576 x 320      9:5     1.8000                   576 x 320
Galaxy Ace                               480 x  320     mdpi    1       160      480 x 320      3:2     1.5000             

EmmanuelGuther

 internal fun handleChatMessages(messages: List<MessageModel>?) {
        hideProgress()
        adapter.collection = messages.orEmpty()
        animate { runLayoutAnimation() }
    }

 private fun animate(function: () -> Unit) {
        when {
            firstTimeCreated -> function.invoke()
        }