lawrenceching/kotlin.kt

## kotlin.kt
package com.example

import java.util.*
import kotlinx.coroutines.*
import kotlin.system.measureTimeMillis

val title = "Kotlin Demo"
var content = "A 20-mins Kotlin sharing"

var optional: String? = null


// String and template

// language=html
val html = """
    <html>
        <head>
            <title>$title</title>
        </head>
        <body>
            $content
        </body>
    </html>
""".trimIndent()


// For Loop

fun forLoop() {

    for(i in 0..9) {
        println(i)
    }

    for(i in 0..10 step 2) {
        println(i)
    }

    for(i in 10 downTo 0 step 2) {
        println(i)
    }


    for(i in listOf("A", "B", "C")) {
        println(i)
    }

    listOf("A", "B", "C").forEach {
        println(it)
    }

}


fun switchExpr() {

    val id = 1;
    when (id) {
        1 -> println(id)
        2, 3 -> println(id)
        in 4..5 -> println(id)
        !in 4..5 -> println(id)
        is Int -> println(id)
        else -> println(id)
    }


    fun Int.isEven(): Boolean {
        return true
    }

    fun isPrime(x: Int): Boolean {
        return true
    }
    when {
        id.isEven() -> println(id)
        isPrime(id) -> println(id)
    }


}


fun collection() {


    val list = listOf<Int>(1, 2, 3)
    val set = setOf<String>("A", "B", "C")
    var map = mapOf<Int, String>(
            1 to "A",
            2 to "B"
    )


    val mutalbeList = arrayListOf(1)
    val mutableSet = hashSetOf("ABC")
    val mutableMap = hashMapOf("OOO" to 123)

    list.map { it * 10 }
            .filter(
                    fun(number: Int): Boolean {
                        return number > 1
                    }
            )

}


fun functions() {

    fun say(msg: String) {
        println("Hello, $msg")
    }

    say("Lawrence")
    say("Mike")
    say("Jay")


    data class QuoteRequest(
            val id: String,
            val currency: String,
            val product: String,
            val reasonCode: String = "N/A")

    val quoteRequest = QuoteRequest(
            id = UUID.randomUUID().toString(),
            product = "SPOT",
            currency = "EURUSD"
    )


    fun QuoteRequest.toJSON(): String {
        return """
            {
                "id": "${this.id}",
                "currency": "${this.currency}",
                "product": "${this.product}",
                "reasonCode": "${this.reasonCode}",
            }
        """.trimIndent()
    }

}


fun classes() {


    class User {
        private val name: String
        private var age: Int

        constructor(name: String, age: Int) {
            this.name = name;
            this.age = age
        }

        fun getName(): String {
            return this.name
        }

        fun getAge(): Int {
            return this.age
        }

        fun setAge(age: Int) {
            this.age = age
        }
    }


    class Instance {

        var instanceId: String
        get() {
            return "ID_15123123"
        }
        set(value) {
            instanceId = value
        }

    }


    class Service {
        fun start() {}
        fun stop() {}
    }
//    class DemoTest {
//
//        lateinit var service: Service
//
//        @Before
//        fun setUp() {
//            service = Service()
//            service.start()
//        }
//
//        @After
//        fun tearDown() {
//            service.stop()
//        }
//
//    }
}


fun coroutines() {

    GlobalScope.launch { // launch a new coroutine in background and continue
        delay(1000L) // non-blocking delay for 1 second (default time unit is ms)
        println("World!") // print after delay

    }
    println("Hello,") // main thread continues while coroutine is delayed
    Thread.sleep(2000L)

    runBlocking {

        fun doSomethingSync(): String {

            return "Something"
        }

        val something = async {
            delay(3000L)
            doSomethingSync()
        }

        val otherThing = async {
            delay(3000)
            listOf(1,2,3).findLast { it >= 2 }
        }

        val duration = measureTimeMillis {
            println("${something.await()} is ${otherThing.await()}")
        }

        println("Duration: $duration")

    }


}
	package com.example

	import java.util.*
	import kotlinx.coroutines.*
	import kotlin.system.measureTimeMillis

	val title = "Kotlin Demo"
	var content = "A 20-mins Kotlin sharing"

	var optional: String? = null








	// String and template

	// language=html
	val html = """
	<html>
	<head>
	<title>$title</title>
	</head>
	<body>
	$content
	</body>
	</html>
	""".trimIndent()












	// For Loop

	fun forLoop() {

	for(i in 0..9) {
	println(i)
	}

	for(i in 0..10 step 2) {
	println(i)
	}

	for(i in 10 downTo 0 step 2) {
	println(i)
	}


	for(i in listOf("A", "B", "C")) {
	println(i)
	}

	listOf("A", "B", "C").forEach {
	println(it)
	}

	}















	fun switchExpr() {

	val id = 1;
	when (id) {
	1 -> println(id)
	2, 3 -> println(id)
	in 4..5 -> println(id)
	!in 4..5 -> println(id)
	is Int -> println(id)
	else -> println(id)
	}



	fun Int.isEven(): Boolean {
	return true
	}

	fun isPrime(x: Int): Boolean {
	return true
	}
	when {
	id.isEven() -> println(id)
	isPrime(id) -> println(id)
	}


	}





	fun collection() {


	val list = listOf<Int>(1, 2, 3)
	val set = setOf<String>("A", "B", "C")
	var map = mapOf<Int, String>(
	1 to "A",
	2 to "B"
	)


	val mutalbeList = arrayListOf(1)
	val mutableSet = hashSetOf("ABC")
	val mutableMap = hashMapOf("OOO" to 123)

	list.map { it * 10 }
	.filter(
	fun(number: Int): Boolean {
	return number > 1
	}
	)

	}










	fun functions() {

	fun say(msg: String) {
	println("Hello, $msg")
	}

	say("Lawrence")
	say("Mike")
	say("Jay")



	data class QuoteRequest(
	val id: String,
	val currency: String,
	val product: String,
	val reasonCode: String = "N/A")

	val quoteRequest = QuoteRequest(
	id = UUID.randomUUID().toString(),
	product = "SPOT",
	currency = "EURUSD"
	)


	fun QuoteRequest.toJSON(): String {
	return """
	{
	"id": "${this.id}",
	"currency": "${this.currency}",
	"product": "${this.product}",
	"reasonCode": "${this.reasonCode}",
	}
	""".trimIndent()
	}

	}










	fun classes() {


	class User {
	private val name: String
	private var age: Int

	constructor(name: String, age: Int) {
	this.name = name;
	this.age = age
	}

	fun getName(): String {
	return this.name
	}

	fun getAge(): Int {
	return this.age
	}

	fun setAge(age: Int) {
	this.age = age
	}
	}


	class Instance {

	var instanceId: String
	get() {
	return "ID_15123123"
	}
	set(value) {
	instanceId = value
	}

	}




	class Service {
	fun start() {}
	fun stop() {}
	}
	// class DemoTest {
	//
	// lateinit var service: Service
	//
	// @Before
	// fun setUp() {
	// service = Service()
	// service.start()
	// }
	//
	// @After
	// fun tearDown() {
	// service.stop()
	// }
	//
	// }
	}




	fun coroutines() {

	GlobalScope.launch { // launch a new coroutine in background and continue
	delay(1000L) // non-blocking delay for 1 second (default time unit is ms)
	println("World!") // print after delay

	}
	println("Hello,") // main thread continues while coroutine is delayed
	Thread.sleep(2000L)

	runBlocking {

	fun doSomethingSync(): String {

	return "Something"
	}

	val something = async {
	delay(3000L)
	doSomethingSync()
	}

	val otherThing = async {
	delay(3000)
	listOf(1,2,3).findLast { it >= 2 }
	}

	val duration = measureTimeMillis {
	println("${something.await()} is ${otherThing.await()}")
	}

	println("Duration: $duration")

	}







	}