Why Kotlin


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Speed of Innovation

Java has gone through a major ramp up regarding speed of innovation. Currently Java is releasing a new major version of the Java language every 6 months.

This is good news for all java developers, but there is one Problem: most businesses are not able to keep up with that speed, and therefore most businesses are still on JVM 8 (or even older versions).

Kotlin has its own release cycle, and is happily running on older JVM versions. This allows for innovations like coroutines

Note: the following snippet does not run on tech.io, because the used docker image is rather old...

import kotlinx.coroutines.*
import java.text.SimpleDateFormat
import java.util.*

fun main() = runBlocking {
    val deferred1 = async { computation1() }
    val deferred2 = async { computation2() }
    printCurrentTime("Awaiting computations...")
    val result = deferred1.await() + deferred2.await()
    printCurrentTime("The result is $result")

suspend fun computation1(): Int {
    delay(1000L) // simulated computation
    printCurrentTime("Computation1 finished")
    return 131

suspend fun computation2(): Int {
    printCurrentTime("Computation2 finished")
    return 9

fun printCurrentTime(message: String) {
    val time = (SimpleDateFormat("hh:mm:ss")).format(Date())
    println("[$time] $message")

Go to https://pl.kotl.in/1RO1ygMUT to see it in action

Kotlin has some other advanced features. One of the most interessting ones are smart casts.

Try to initialize the var x once as String and once as Int. The Kotlin compiler is intelligent enough to cast to the respective type

// {...}
var x: Any //no special type
//TODO: intialize string here
print(x.length) // smart casting here
//TODO: intialize int here
print(x*2) // smart casting here
// {...}

Other examples and the generall differences to Java can be found on the kotlin website

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