Kotlin Cheatsheet – Syntax, Functions & OOP Paling Sering Digunakan

#1 fun main() { }

Fungsi utama program Kotlin

#2 println("Hello")

Menampilkan output ke console

#3 print("Hello")

Menampilkan output tanpa newline

#4 val name="John"

Membuat variabel immutable (tidak bisa diubah)

#5 var age=25

Membuat variabel mutable

#6 val number:Int=10

Variabel dengan tipe data eksplisit

#7 val price:Double=10.5

Variabel tipe Double

#8 val isActive:Boolean=true

Variabel boolean

#9 val letter:Char='A'

Variabel karakter

#10 val text:String="Hello Kotlin"

Variabel string

#11 val map=mapOf("a" to 1)

Membuat map

#12 numbers.size

Mengambil jumlah item list

#13 numbers.first()

Mengambil item pertama

#14 numbers.last()

Mengambil item terakhir

#15 numbers.contains(2)

Memeriksa item dalam list

#16 numbers.add(4)

Menambahkan item ke list mutable

#17 numbers.remove(1)

Menghapus item dari list

#18 if(condition){ }

Percabangan if

#19 if(condition) a else b

If expression

#20 when(x){1->println()}

Percabangan when

#21 when(x){1->'A' 2->'B' else->'C'}

When expression

#22 for(i in 1..5){ }

Loop range

#23 for(item in list){ }

Loop list

#24 while(condition){ }

Loop while

#25 do{ }while(condition)

Loop do while

#26 break

Menghentikan loop

#27 continue

Melanjutkan ke iterasi berikutnya

#28 fun greet(name:String="Guest")

Default parameter

#29 fun printAll(vararg items:String)

Varargs parameter

#30 class Person

Membuat class

#31 class Person(val name:String)

Class dengan property

#32 class Person{var age=0}

Class dengan properti mutable

#33 val p=Person("John")

Membuat instance class

#34 p.name

Mengakses property

#35 sealed class Result

Sealed class

#36 object Singleton

Singleton object

#37 companion object

Static member dalam class

#38 interface Animal

Membuat interface

#39 class Dog:Animal

Implementasi interface

#40 open class Animal

Class yang bisa diwarisi

#41 class Dog:Animal()

Inheritance class

#42 override fun speak()

Override method

#43 abstract class Shape

Abstract class

#44 abstract fun draw()

Abstract function

#45 this.name

Mengakses property class

#46 super.method()

Memanggil method parent

#47 constructor(name:String)

Constructor sekunder

#48 init{ }

Block inisialisasi class

#49 val length=text.length

Mengambil panjang string

#50 text.uppercase()

Mengubah string menjadi uppercase

#51 text.lowercase()

Mengubah string menjadi lowercase

#52 text.contains("a")

Memeriksa substring

#53 text.split("

),Memecah string"

#54 val a:Int?=null

Nullable type

#55 a?.length

Safe call operator

#56 a?:0

Elvis operator

#57 a!!

Non-null assertion

#58 list.map{it*2}

Transformasi list

#59 list.filter{it>2}

Filter list

#60 list.forEach{println(it)}

Iterasi list

#61 list.sum()

Menjumlahkan list

#62 list.sorted()

Mengurutkan list

#63 list.sortedDescending()

Urut descending

#64 list.distinct()

Menghapus duplikat

#65 list.take(3)

Ambil beberapa item

#66 list.drop(2)

Buang beberapa item

#67 try{ }catch(e:Exception){ }

Error handling

#68 finally{ }

Block finally

#69 throw Exception("Error")

Throw exception

#70 typealias UserId=Int

Alias tipe data

#71 fun String.addExclamation()

Extension function

#72 infix fun Int.add(x:Int)

Infix function

#73 operator fun plus()

Operator overloading

#74 tailrec fun factorial()

Recursive function optimized

#75 lateinit var name:String

Late initialization

#76 lazy{compute()}

Lazy initialization

#77 by lazy{value}

Delegated property lazy

#78 by observable()

Delegated observable property

#79 run{ }

Scope function run

#80 let{ }

Scope function let

#81 apply{ }

Scope function apply

#82 also{ }

Scope function also

#83 with(obj){ }

Scope function with

#84 list.indices

Index list

#85 list.isEmpty()

Cek list kosong

#86 list.isNotEmpty()

Cek list tidak kosong

Kotlin Cheatsheet – Syntax, Functions & OOP Paling Sering Digunakan

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