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

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

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