Foggy day

val intSrc = Observable.just(1, 2, 3) intSrc.subscribe(::println) val strSrc = intSrc.map { value -> value * 10 } strSrc.subscribe(::println) val src = Observable.just("A", "B", "C", "D") src.flatMap { s -> Observable.just(s + 2, s + 3) } src.subscribe(::println) val flatMap = Observable.range(2, 3).flatMap { x -> Observable.range(1, 9).map { y -> String.format("%d*%d=%d", x, y, x * y) } } flatM..

val items: PublishSubject = PublishSubject.create() items.onNext(1) items.onNext(2) items.onNext(3) items.filter { i -> i % 2 == 0 }.subscribe(::println) items.onNext(4) items.onNext(5) items.onNext(6) items.onNext(7) items.onNext(8)

class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) val lists = listOf('a', 'f', 'd', 'w') println("toString : ${toString(lists)}") println("add : ${add(10, 15)}") println("addSecond : ${addSecond(10, 15)}") println("factorialFirst : ${Factorial.factoria..

class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) val a = "A" val b = "B" val c = "C" val d = "D" println("func : ${func(a, b, c, d)}") println("curriedFunc : ${curriedFunc()(b)(c)(d)(a)}") println("curriedString : ${curriedString(a)(b)(c)(d)}") } fun ..

class KotlinPlayGroundActivity : AppCompatActivity() { val x = 5 val y = 7 override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) println("jhFun_1 : ${jhFun_1(x)}") println("jhFun_2 : ${jhFun_2(x)}") println("jhFun_3 : ${jhFun_3(x)}") println("jhFun_4 : ${jhFun_4(x, y)}") println("jhFun_5 : ${jhFun_5(x)}") prin..

If you want to display multiple lines, you can use triple quotes(""") and trimMargin(). println("""Example of Jinhan : It is about String |First line |Second line |Third line |Fourth line """.trimMargin())

class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) val message = "It is test" val length: Int = if (message is String) message.length else 100 println("length : $length") val value: Int = when (message) { is String -> message.length else -> 100 } printl..

class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) val lists = listOf(1, 2, 3, 4, 5, 6, 7) println("multiplyMap : ${multiplyMap(lists)} ") println("multiplyMapSecond : ${multiplyMapSecond(lists)}") println("multiplyFold : ${multiplyFold(lists)} ") print..

Fold function have initial value. initial is 1 in this example. so, result of calFold is 25. But reduce function don't have initial value. so, result of calRecude is 24, because value of List position zero is 0. class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_pla..

class KotlinPlayGroundActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_kotlin_play_ground) println("calculate : ${calculate(3, 4)}") println("calculate2 : ${calculate2(5, 10)}") println("calculate3 : ${calculate3(20, 41)}") } fun calculate(a: Int, b: Int): Int { return a + b } fun calculate2(..