Hey Kotlin, How it works?

package com.cwdoh.devfest2017
class Gugu {
fun print() {
for (i in 1..9) {
for (j in 1..9) {
print("$i * $j = ${i * j}")
}
}
}
}

package com.cwdoh.devfest2017
class Session {
val speaker = "cwdoh"
val title: String
= "Kotlin: How it works"
var room: Int? = null
fun description()
= "$speaker's talk: '$title' at room $room"
}

class Session {
var name = "cwdoh"
}
public final class Session {
@NotNull
private String name = "cwdoh";
@NotNull
public final String getName() {
return this.name;
}
public final void setName(@NotNull String var1) {
Intrinsics.checkParameterIsNotNull(var1, "<set-?>");
this.name = var1;
}
}

class Session {
val name = "cwdoh"
}
@NotNull
private final String name = "cwdoh";
@NotNull
return this.name;
}
}

class Session {
fun description() {
val talks = "$speaker's talks"
println(talks)
}
}
@NotNull
private final String speaker = "cwdoh";
@NotNull
public final String getSpeaker() {
return this.speaker;
}
public final void description() {
String talks = "" + this.speaker + "'s talks";
System.out.println(talks);
}
}

class Session {
var name: String = "cwdoh"
}
@NotNull
private String name = "cwdoh";
@NotNull
return this.name;
}
public final void setName(@NotNull String var1) {
Intrinsics.checkParameterIsNotNull(var1, "<set-?>");
this.name = var1;
}
}
public static void checkParameterIsNotNull(Object value, String paramName)
{
if (value == null) {
throwParameterIsNullException(paramName);
}
}

class Session {
fun hello(name: String) = "hello, " + name
}
@NotNull
public final String hello(@NotNull String name) {
Intrinsics.checkParameterIsNotNull(name, "name");
return "hello, " + name;
}
}
public static void checkParameterIsNotNull(Object value, String paramName)
{
if (value == null) {
throwParameterIsNullException(paramName);
}
}

class Session {
fun print() {
val name: String = "cwdoh"
print(hello(name))
}
}
@NotNull
}
public final void print() {
String name = "cwdoh";
String var2 = this.hello(name);
System.out.print(var2);
}
}

class Session {
fun print() {
val name: String? = null
print(hello(name!!))
}
}
@NotNull
}
public final void print() {
String name = (String)null;
Intrinsics.throwNpe();
String var2 = this.hello(name);
}
}
NullPointerException? 😎

class Session {
val title: String = "Kotlin: How it works"
var room: Int? = null
fun description() = "$speaker's talk: '$title' at room $room"
}
@NotNull
private final String speaker = "cwdoh";
@NotNull
private final String title = "Kotlin: How it works";
@Nullable
private Integer room;
…
@NotNull
public final String description() {
return "" + this.speaker + "'s talk: ‘"
+ this.title + "' at room " + this.room;
}
}

// access flags 0x11
public final description()Ljava/lang/String;
@Lorg/jetbrains/annotations/NotNull;() // invisible
L0
LINENUMBER 8 L0
NEW java/lang/StringBuilder
DUP
INVOKESPECIAL java/lang/StringBuilder.<init> ()V
LDC ""
INVOKEVIRTUAL java/lang/StringBuilder.append (Ljava/lang/String;)Ljava/lang/StringBuilder;
ALOAD 0
GETFIELD com/cwdoh/devfest2017/Session.speaker : Ljava/lang/String;
LDC "'s talk: '"
ALOAD 0
GETFIELD com/cwdoh/devfest2017/Session.title : Ljava/lang/String;
LDC "' at room "
ALOAD 0
GETFIELD com/cwdoh/devfest2017/Session.room : Ljava/lang/Integer;
INVOKEVIRTUAL java/lang/StringBuilder.append (Ljava/lang/Object;)Ljava/lang/StringBuilder;
INVOKEVIRTUAL java/lang/StringBuilder.toString ()Ljava/lang/String;
ARETURN

class NotOpenedClass
open class OpenedClass
public final class NotOpenedClass {
}
public class OpenedClass {
}

interface Interface
open class OpenClass
class ChildClass: OpenClass(), Interface
fun test() { val child = ChildClass() }
public final class ChildClass
extends OpenClass implements Interface {}
public interface Interface {}
public class OpenClass {}
public final class SimpleClassKt {
public static final void test() {
new ChildClass();
}
}

class Person1 constructor(name: String)
class Person2(name: String)
public final class Person1 {
public Person1(@NotNull String name) {
super();
}
}
public final class Person2 {
public Person2(@NotNull String name) {
super();
}
}

class Person constructor(val name: String)
public final class Person {
@NotNull
private final String name;
@NotNull
return this.name;
}
public Person(@NotNull String name) {
super();
this.name = name;
}
}

class Person constructor(val name: String) {
val greetings: String
init { greetings = "hello, $name” }
}
@NotNull private String greetings;
@NotNull private final String name;
@NotNull public final String getGreetings() { return this.greetings; }
@NotNull public final String getName() { return this.name; }
super();
this.name = name;
this.greetings = "hello, " + this.name;
}
}

class Person constructor(val name: String) {
val greetings: String
var age: Int = null
constructor(name: String, age: Int): this(name) { this.age = age }
init { greetings = "hello, $name” }
}
@NotNull
private final String greetings;
private int age;
…
super();
this.name = name;
this.age = ((Number)null).intValue();
this.greetings = "hello, " + this.name;
}
public Person(@NotNull String name, int age) {
this(name);
this.age = age;
}
}

open class Parent {
private val a = println("Parent.a")
constructor(arg: Unit=println("Parent primary constructor arg")) {
println("Parent primary constructor")
}
init { println("Parent.init") }
private val b = println("Parent.b")
}
class Child : Parent {
val a = println("Child.a")
init { println("Child.init 1") }
constructor(arg: Unit=println("Child primary constructor arg")) : super() {
println("Child primary constructor")
}
val b = println("Child.b")
constructor(arg: Int, arg2:Unit= println("Child secondary constructor arg")): this() {
println("Child secondary constructor")
}
init { println("Child.init 2") }
}
fun main(args: Array<String>) {
Child(1)
}
Child secondary constructor arg
Child primary constructor arg
Parent primary constructor arg
Parent.a
Parent.init
Parent.b
Parent primary constructor
Child.a
Child.init 1
Child.b
Child.init 2
Child primary constructor
Child secondary constructor

class Props {
var size: Int = 0
val isEmpty: Boolean
get() = this.size == 0
}
public final class Props {
private int size;
public final int getSize() {
return this.size;
}
public final void setSize(int var1) {
this.size = var1;
}
public final boolean isEmpty() {
return this.size == 0;
}
}

class Props {
var age: Int = 0
set(value: Int) {
age = if (value < 0) 0 else value
}
}
private int age;
public final int getAge() {
return this.age;
}
public final void setAge(int value) {
this.setAge(value < 0? 0:value);
}
}

class Props {
var age: Int = 0
private set
}
private int age;
public final int getAge() {
return this.age;
}
private final void setAge(int var1) {
this.age = var1;
}
}

class MainActivity : AppCompatActivity() {
private var mWelcomeTextView: TextView? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
mWelcomeTextView
= findViewById(R.id.msgView) as TextView
}
}

private lateinit var mWelcomeTextView: TextView
mWelcomeTextView
= findViewById(R.id.msgView) as TextView
}
}

private val mWelcomeTextView: TextView
// Where am I?????
// mWelcomeTextView =
// findViewById(R.id.msgView) as TextView
}
}

private val messageView : TextView by lazy {
// following code will be executed at first access
findViewById(R.id.message_view) as TextView
}
}
fun onSayHello() {
messageView.text = "Hello"
}
}

class Delegate {
operator fun getValue(
thisRef: Any?,
property: KProperty<*>
): String {
// do something
// return value
}
operator fun setValue(
thisRef: Any?,
property: KProperty<*>, value: String
) {
// do something
// assign
}
}

class Demo {
val myName : String by lazy { "John" }
}
public final class Demo {
// $FF: synthetic field
static final KProperty[] $$delegatedProperties = new KProperty[]{ … };
@NotNull
private final Lazy myName$delegate;
@NotNull
public final String getMyName() {
Lazy var1 = this.myName$delegate;
KProperty var3 = $$delegatedProperties[0];
return (String)var1.getValue();
}
public Demo() {
this.myName$delegate = LazyKt.lazy((Function0)null.INSTANCE);
}
}

class Demo {
val myName : String by lazy { getNameFromPreference() }
} initializerdelegate

myName
Lazy<T>
getValue()
{ getNameFromPreference() }initializer
class Demo {
}

myName
Lazy<T>
getValue() UNINITIALIZED_VALUE
class Demo {
}

myName
Lazy<T>
getValue() “John”
class Demo {
}

myName
Lazy<T>
getValue() “John”
initializer null
class Demo {
}

private val messageView : TextView by lazy {
// I’ll be initialized lazily at first access
findViewById(R.id.message_view) as TextView
}
}
fun onSayHello() {
messageView.text = "Hello"
}
}

val messageView: TextView by lazy { findViewById(R.id.message_view) as TextView }
property delegate

interface Base {
fun printX()
}
class BaseImpl(val x: Int) : Base {
override fun printX() { print(x) }
}

interface A {
fun hello(): String
}
class B : A {
override fun hello() = "Hello!!"
}
class C : A by B()

public interface A {
@NotNull
String hello();
}
public final class B implements A {
@NotNull
public String hello() {
return "Hello!!";
}
}
public final class C implements A {
// $FF: synthetic field
private final B $$delegate_0 = new B();
@NotNull
public String hello() {
return this.$$delegate_0.hello();
}
}

fun String.hello() : String {
return "Hello, $this"
}
val whom = "cwdoh"
println(whom.hello())
}
// Result
Hello, cwdoh

open class C
class D: C()
fun C.foo() = "c"
fun D.foo() = "d"
fun printFoo(c: C) {
println(c.foo())
}
class Demo {
fun run() {
printFoo(D())
}
}
public class C {}
public final class D extends C {}
@NotNull
public static final String foo(@NotNull C $receiver) {
Intrinsics.checkParameterIsNotNull($receiver, "$receiver");
return "c";
}
@NotNull
public static final String foo(@NotNull D $receiver) {
return "d";
}
public static final void printFoo(@NotNull C c) {
Intrinsics.checkParameterIsNotNull(c, "c");
String var1 = foo(c);
System.out.println(var1);
}
}
public final class Demo {
public final void run() {
SimpleClassKt.printFoo((C)(new D()));
}
}

class Person {
fun hello() {
println("hello!")
}
}
fun Person.hello() {
println(" ?!!")
}
fun main(args: Array<String>)
{
Person().hello()
}
// Result
hello!
public final void hello() {
String var1 = "hello!";
}
}
public static final void hello(@NotNull Person $receiver) {
Intrinsics.checkParameterIsNotNull(
$receiver, "$receiver");
String var1 = " ?!!";
}
public static final void main(@NotNull String[] args) {
Intrinsics.checkParameterIsNotNull(args, "args");
(new Person()).hello();
}
}

class D {
fun bar() {
println("D.bar()")
}
}
class C {
fun baz() {
println("C.bar()")
}
fun D.foo() {
bar() // calls D.bar
baz() // calls C.baz
}
fun caller(d: D) {
d.foo()
}
}
public final class C {
public final void baz() {
String var1 = "C.bar()";
}
public final void foo(@NotNull D $receiver) {
$receiver.bar();
this.baz();
}
public final void caller(@NotNull D d) {
Intrinsics.checkParameterIsNotNull(d, "d");
this.foo(d);
}
}
public final class D {
public final void bar() {
String var1 = "D.bar()";
}
}

data class Length(var centimeters: Int = 0)
var Length.meters: Float
get() {
return centimeters / 100.0f
}
set(meters: Float) {
this.centimeters = (meters * 100.0f).toInt()
}

data class Length(var centimeters: Int = 0)
var Length.meters: Float
get() {
return centimeters / 100.0f
}
set(meters: Float) {
this.centimeters = (meters * 100.0f).toInt()
}
public final class Length {
private int centimeters;
...
}
public final class ExtensionsKt {
public static final float getMeters(
@NotNull Length $receiver) {
return (float)$receiver.getCentimeters() / 100.0F;
}
public static final void setMeters(
@NotNull Length $receiver, float meters) {
$receiver.setCentimeters((int)(meters * 100.0F));
}
...
}

fun Any?.toString(): String
{
if (this == null)
return “null"
return toString()
}
@NotNull
public static final String
toString(@Nullable Object $receiver) {
return $receiver == null?
"null":$receiver.toString();
}
}

fun Any?.toString(): String {
println("Extension is called.")
if (this == null) return "null"
return toString()
}
val var1 : Any? = null
println(var1.toString())
val str1 : String? = null
println(str1.toString())
var str2 : String? = "hello"
var str3 : String = "world"
}
@NotNull
public static final String toString(@Nullable Object $receiver) {
String var1 = "Extension is called.";
return $receiver == null?"null":$receiver.toString();
}
public static final void main(@NotNull String[] args) {
Intrinsics.checkParameterIsNotNull(args, “args");
Object var1 = null;
String str1 = toString(var1);
System.out.println(str1);
str1 = (String)null;
String str2 = toString(str1);
str2 = "hello";
String str3 = toString(str2);
str3 = "world";
String var5 = str3.toString();
}
}
Extension is called.
null
null
hello
world

fun sing() {
println("We will we will rock you")
println("(Sing it!)")
}
fun beatbox() {
println("pv zk bschk pv zk")
}
fun ensemble() {
sing()
beatbox()
sing()
beatbox()
}
public static final void sing() {
String var0
= "We will we will rock you";
var0 = "(Sing it!)";
var0 = "We will we will rock you";
}
public static final void beatbox() {
String var0 = "pv zk bschk pv zk";
}
public static final void ensemble() {
sing();
beatbox();
sing();
beatbox();
}
}

fun sing() {
println("(Sing it!)")
}
fun beatbox() {
println("pv zk bschk pv zk")
}
fun ensemble() {
sing()
beatbox()
sing()
beatbox()
}
public static final void sing() {
String var1 = "We will we will rock you";
…
}
public static final void beatbox() {
…
}
public static final void ensemble() {
String var0
= "We will we will rock you";
beatbox();
beatbox();
}
}

fun log(message: () -> String) {
println(message())
}
fun test() {
log { "Lorem ipsum dolor sit amet, consectetur ..." }
}
public static final void log(@NotNull Function0 message) {
Intrinsics.checkParameterIsNotNull(message, "message");
Object var1 = message.invoke();
}
log((Function0)null.INSTANCE);
}
}

inline fun trace(message: String) {}
fun doSomething() {
print("I'm doing something!")
trace("doSomething() is doing something!")
}
public static final void trace(@NotNull String message) {
}
public static final void doSomething() {
String var0 = "I'm doing something!";
var0 = "doSomething() is doing something!";
}
}

inline fun log(message: () -> String) {
println(message())
}
fun test() {
log { "Lorem ipsum dolor sit amet, consectetur ..." }
}
public static final void log(@NotNull Function0 message) {
Object var2 = message.invoke();
}
String var0 = "Lorem ipsum dolor sit amet, consectetur ...";
}
}

inline fun trace(message: ()-> String) {}
fun doSomething() {
trace {
val receiver = "nurimaru"
val sender = "cwdoh"
"$sender wanna give $receiver big thank you for good tips."
}
}
public static final boolean isDebug() {
return true;
}
public static final void trace(@NotNull Function0 message) {
}
public static final void doSomething() {
}
}

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Hey Kotlin, How it works?

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