mirror of
https://github.com/LeCoupa/awesome-cheatsheets.git
synced 2026-01-24 20:28:02 -08:00
Merge 8e01273f3f into 88e5be6e4b
This commit is contained in:
Aasim Khan
GitHub
265
mobile/kotlin.kt
Normal file
265
mobile/kotlin.kt
Normal file
@@ -0,0 +1,265 @@
|
||||
// Kotlin is a statically typed programming language for modern multiplatform applications.
|
||||
// https://kotlinlang.org/
|
||||
|
||||
// Mutability
|
||||
var mutableString: String = "Adam"
|
||||
val immutableString: String = "Adam"
|
||||
val inferredString = "Adam"
|
||||
|
||||
// Strings
|
||||
val name = "Adam"
|
||||
val greeting = "Hello, " + name
|
||||
val greetingTemplate = "Hello, $name"
|
||||
val interpolated = "Hello, ${name.toUpperCase()}"
|
||||
|
||||
// Numbers
|
||||
val intNum = 10
|
||||
val doubleNum = 10.0
|
||||
val longNum = 10L
|
||||
val floatNum = 10.0F
|
||||
|
||||
// Booleans
|
||||
val trueBoolean = true
|
||||
val falseBoolean = false
|
||||
val andCondition = trueBoolean && falseBoolean
|
||||
val orCondition = trueBoolean || falseBoolean
|
||||
|
||||
// Static Fields
|
||||
class Person {
|
||||
companion object {
|
||||
val NAME_KEY = "name_key"
|
||||
}
|
||||
}
|
||||
|
||||
val key = Person.NAME_KEY
|
||||
|
||||
|
||||
// Nullable properties
|
||||
val cannotBeNull: String = null // Invalid
|
||||
val canBeNull: String? = null // Valid
|
||||
|
||||
val cannotBeNull: Int = null // Invalid
|
||||
val canBeNull: Int? = null // Valid
|
||||
|
||||
// Checking for null
|
||||
val name: String? = "Adam"
|
||||
|
||||
if (name != null && name.length > 0) {
|
||||
print("String length is ${name.length}")
|
||||
} else {
|
||||
print("String is empty.")
|
||||
}
|
||||
|
||||
// Safe Operator
|
||||
val nullableStringLength: Int? = nullableString?.length
|
||||
val nullableDepartmentHead: String? = person?.department?.head?.name
|
||||
|
||||
// Elvis Operator
|
||||
val nonNullStringLength: Int = nullableString?.length ?: 0
|
||||
val nonNullDepartmentHead: String = person?.department?.head?.name ?: ""
|
||||
val nonNullDepartmentHead: String = person?.department?.head?.name.orEmpty()
|
||||
|
||||
// Safe Casts
|
||||
// Will not throw ClassCastException
|
||||
val nullableCar: Car? = (input as? Car)
|
||||
|
||||
/// Collections
|
||||
|
||||
// Creation
|
||||
val numArray = arrayOf(1, 2, 3)
|
||||
val numList = listOf(1, 2, 3)
|
||||
val mutableNumList = mutableListOf(1, 2, 3)
|
||||
|
||||
// Accessing
|
||||
val firstItem = numList[0]
|
||||
val firstItem = numList.first()
|
||||
val firstItem = numList.firstOrNull()
|
||||
|
||||
// Maps
|
||||
val faceCards = mutableMapOf("Jack" to 11, "Queen" to 12, "King" to 13)
|
||||
val jackValue = faceCards["Jack"] // 11
|
||||
faceCards["Ace"] = 1
|
||||
|
||||
// Mutability
|
||||
val immutableList = listOf(1, 2, 3)
|
||||
val mutableList = immutableList.toMutableList()
|
||||
|
||||
val immutableMap = mapOf("Jack" to 11, "Queen" to 12, "King" to 13)
|
||||
val mutableMap = immutableMap.toMutableMap()
|
||||
|
||||
// Iterating
|
||||
for (item in myList) {
|
||||
print(item)
|
||||
}
|
||||
|
||||
myList.forEach {
|
||||
print(it)
|
||||
}
|
||||
|
||||
myList.forEachIndexed { index, item ->
|
||||
print("Item at $index is: $item")
|
||||
}
|
||||
|
||||
// Filtering & Searching
|
||||
val evenNumbers = numList.filter { it % 2 == 0 }
|
||||
val containsEven = numList.any { it % 2 == 0 }
|
||||
val containsNoEvens = numList.none { it % 2 == 0 }
|
||||
val containsNoEvens = numList.all { it % 2 == 1 }
|
||||
val firstEvenNumber: Int = numList.first { it % 2 == 0 }
|
||||
val firstEvenOrNull: Int? = numList.firstOrNull { it % 2 == 0 }
|
||||
// Note: it is the implicit name for a single parameter.
|
||||
|
||||
/// Functions
|
||||
|
||||
// Parameters & Return Types
|
||||
fun printName() {
|
||||
print("Adam")
|
||||
}
|
||||
|
||||
fun printName(person: Person) {
|
||||
print(person.name)
|
||||
}
|
||||
|
||||
fun getGreeting(person: Person): String {
|
||||
return "Hello, ${person.name}"
|
||||
}
|
||||
|
||||
fun getGreeting(person: Person): String = "Hello, ${person.name}"
|
||||
fun getGreeting(person: Person) = "Hello, ${person.name}"
|
||||
|
||||
// Higher Order Functions
|
||||
fun callbackIfTrue(condition: Boolean, callback: () -> Unit) {
|
||||
if (condition) {
|
||||
callback()
|
||||
}
|
||||
}
|
||||
|
||||
callbackIfTrue(someBoolean) {
|
||||
print("Condition was true")
|
||||
}
|
||||
|
||||
/ Extension Functions
|
||||
fun Int.timesTwo(): Int {
|
||||
return this * 2
|
||||
}
|
||||
|
||||
val four = 2.timesTwo()
|
||||
|
||||
// Default Parameters
|
||||
fun getGreeting(person: Person, intro: String = "Hello,") {
|
||||
return "$intro ${person.name}"
|
||||
}
|
||||
|
||||
// Returns "Hello, Adam"
|
||||
val hello = getGreeting(Person("Adam"))
|
||||
|
||||
// Returns "Welcome, Adam"
|
||||
val welcome = getGreeting(Person("Adam"), "Welcome,")
|
||||
|
||||
// Named Parameters
|
||||
class Person(val name: String = "", age: Int = 0)
|
||||
|
||||
// All valid
|
||||
val person = Person()
|
||||
val person = Person("Adam", 100)
|
||||
val person = Person(name = "Adam", age = 100)
|
||||
val person = Person(age = 100)
|
||||
val person = Person(age = 100, name = "Adam")
|
||||
|
||||
// Static Functions
|
||||
class Fragment(val args: Bundle) {
|
||||
companion object {
|
||||
fun newInstance(args: Bundle): Fragment {
|
||||
return Fragment(args)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
val fragment = Fragment.newInstance(args)
|
||||
// Companion Objects
|
||||
|
||||
|
||||
// Classes
|
||||
// Primary Constructor
|
||||
class Person(val name: String, val age: Int)
|
||||
val adam = Person("Adam", 100)
|
||||
|
||||
// Secondary Constructors
|
||||
class Person(val name: String) {
|
||||
private var age: Int? = null
|
||||
|
||||
constructor(name: String, age: Int) : this(name) {
|
||||
this.age = age
|
||||
}
|
||||
}
|
||||
|
||||
// Above can be replaced with default params
|
||||
class Person(val name: String, val age: Int? = null)
|
||||
|
||||
// Inheritance & Implementation
|
||||
open class Vehicle
|
||||
class Car : Vehicle()
|
||||
|
||||
interface Runner {
|
||||
fun run()
|
||||
}
|
||||
|
||||
class Machine : Runner {
|
||||
override fun run() {
|
||||
// ...
|
||||
}
|
||||
}
|
||||
// Control Flow
|
||||
If Statements
|
||||
if (someBoolean) {
|
||||
doThing()
|
||||
} else {
|
||||
doOtherThing()
|
||||
}
|
||||
|
||||
// For Loops
|
||||
for (i in 0..10) { } // 1 - 10
|
||||
for (i in 0 until 10) // 1 - 9
|
||||
(0..10).forEach { }
|
||||
for (i in 0 until 10 step 2) // 0, 2, 4, 6, 8
|
||||
|
||||
When Statements
|
||||
when (direction) {
|
||||
NORTH -> {
|
||||
print("North")
|
||||
}
|
||||
SOUTH -> print("South")
|
||||
EAST, WEST -> print("East or West")
|
||||
"N/A" -> print("Unavailable")
|
||||
else -> print("Invalid Direction")
|
||||
}
|
||||
While Loops
|
||||
while (x > 0) {
|
||||
x--
|
||||
}
|
||||
|
||||
do {
|
||||
x--
|
||||
} while (x > 0)
|
||||
|
||||
// Destructuring Declarations
|
||||
// Objects & Lists
|
||||
val person = Person("Adam", 100)
|
||||
val (name, age) = person
|
||||
|
||||
val pair = Pair(1, 2)
|
||||
val (first, second) = pair
|
||||
|
||||
val coordinates = arrayOf(1, 2, 3)
|
||||
val (x, y, z) = coordinates
|
||||
|
||||
// ComponentN Functions
|
||||
class Person(val name: String, val age: Int) {
|
||||
operator fun component1(): String {
|
||||
return name
|
||||
}
|
||||
|
||||
operator fun component2(): Int {
|
||||
return age
|
||||
}
|
||||
}
|
||||
186
mobile/swift.swift
Normal file
186
mobile/swift.swift
Normal file
@@ -0,0 +1,186 @@
|
||||
/********************************************************************************************
|
||||
* Swift CHEATSHEET
|
||||
* https://www.swift.org
|
||||
********************************************************************************************/
|
||||
|
||||
// Variables
|
||||
var myInt = 1
|
||||
var myExplicitInt: Int = 1 // explicit type
|
||||
var x = 1, y = 2, z = 3 // declare multiple integers
|
||||
myExplicitInt = 2 // set to another integer value
|
||||
|
||||
// Constants
|
||||
let myInt = 1
|
||||
myInt = 2 // compile-time error!
|
||||
|
||||
// Strings
|
||||
var myString = "a"
|
||||
let myImmutableString = "c"
|
||||
myString += "b" // ab
|
||||
myString = myString + myImmutableString // abc
|
||||
myImmutableString += "d" // compile-time error!
|
||||
|
||||
let count = 7
|
||||
let message = "There are \(count) days in a week"
|
||||
Logical Operators
|
||||
var happy = true
|
||||
var sad = !happy // logical NOT, sad = false
|
||||
var everyoneHappy = happy && sad // logical AND, everyoneHappy = false
|
||||
var someoneHappy = happy || sad // logical OR, someoneHappy = true
|
||||
|
||||
// Printing
|
||||
let name = "swift"
|
||||
println("Hello")
|
||||
println("My name is \(name)")
|
||||
print("See you ")
|
||||
print("later")
|
||||
/* Hello
|
||||
My name is swift
|
||||
See you later
|
||||
*/
|
||||
|
||||
// Arrays
|
||||
var colors = ["red", "blue"]
|
||||
var moreColors: String[] = ["orange", "purple"] // explicit type
|
||||
colors.append("green") // [red, blue, green]
|
||||
colors += "yellow" // [red, blue, green, yellow]
|
||||
colors += moreColors // [red, blue, green, yellow, orange, purple]
|
||||
|
||||
var days = ["mon", "thu"]
|
||||
var firstDay = days[0] // mon
|
||||
days.insert("tue", atIndex: 1) // [mon, tue, thu]
|
||||
days[2] = "wed" // [mon, tue, wed]
|
||||
days.removeAtIndex(0) // [tue, wed]
|
||||
Dictionaries
|
||||
var days = ["mon": "monday", "tue": "tuseday"]
|
||||
days["tue"] = "tuesday" // change the value for key "tue"
|
||||
days["wed"] = "wednesday" // add a new key/value pair
|
||||
|
||||
var moreDays: Dictionary = ["thu": "thursday", "fri": "friday"]
|
||||
moreDays["thu"] = nil // remove thu from the dictionary
|
||||
moreDays.removeValueForKey("fri") // remove fri from the dictionary
|
||||
Conditionals
|
||||
|
||||
// IF STATEMENT
|
||||
let happy = true
|
||||
if happy {
|
||||
println("We're Happy!")
|
||||
} else {
|
||||
println("We're Sad :('")
|
||||
}
|
||||
|
||||
// We're Happy!
|
||||
|
||||
let speed = 28
|
||||
if speed <= 0 {
|
||||
println("Stationary")
|
||||
} else if speed <= 30 {
|
||||
println("Safe speed")
|
||||
} else {
|
||||
println("Too fast!")
|
||||
}
|
||||
|
||||
// Safe speed
|
||||
|
||||
|
||||
// SWITCH STATEMENT
|
||||
let n = 2
|
||||
switch n {
|
||||
case 1:
|
||||
println("It's 1!")
|
||||
case 2...4:
|
||||
println("It's between 2 and 4!")
|
||||
case 5, 6:
|
||||
println("It's 5 or 6")
|
||||
default:
|
||||
println("Its another number!")
|
||||
}
|
||||
|
||||
// It's between 2 and 4!
|
||||
For Loops
|
||||
for var index = 1; index < 3; ++index {
|
||||
// loops with index taking values 1,2
|
||||
}
|
||||
for index in 1..3 {
|
||||
// loops with index taking values 1,2
|
||||
}
|
||||
for index in 1...3 {
|
||||
// loops with index taking values 1,2,3
|
||||
}
|
||||
|
||||
let colors = ["red", "blue", "yellow"]
|
||||
for color in colors {
|
||||
println("Color: \(color)")
|
||||
}
|
||||
// Color: red
|
||||
// Color: blue
|
||||
// Color: yellow
|
||||
|
||||
let days = ["mon": "monday", "tue": "tuesday"]
|
||||
for (shortDay, longDay) in days {
|
||||
println("\(shortDay) is short for \(longDay)")
|
||||
}
|
||||
// mon is short for monday
|
||||
// tue is short for tuesday
|
||||
While Loops
|
||||
var count = 1
|
||||
while count < 3 {
|
||||
println("count is \(count)")
|
||||
++count
|
||||
}
|
||||
// count is 1
|
||||
// count is 2
|
||||
|
||||
count = 1
|
||||
while count < 1 {
|
||||
println("count is \(count)")
|
||||
++count
|
||||
}
|
||||
//
|
||||
|
||||
|
||||
count = 1
|
||||
do {
|
||||
println("count is \(count)")
|
||||
++count
|
||||
} while count < 3
|
||||
// count is 1
|
||||
// count is 2
|
||||
|
||||
count = 1
|
||||
do {
|
||||
println("count is \(count)")
|
||||
++count
|
||||
} while count < 1
|
||||
|
||||
// count is 1
|
||||
|
||||
// Functions
|
||||
func iAdd(a: Int, b: Int) -> Int {
|
||||
return a + b
|
||||
}
|
||||
iAdd(2, 3) // returns 5
|
||||
|
||||
func eitherSide(n: Int) -> (nMinusOne: Int, nPlusOne: Int) {
|
||||
return (n-1, n+1)
|
||||
}
|
||||
eitherSide(5) // returns the tuple (4,6)
|
||||
|
||||
// Classes
|
||||
class Counter {
|
||||
var count: Int = 0
|
||||
func inc() {
|
||||
count++
|
||||
}
|
||||
func add(n: Int) {
|
||||
count += n
|
||||
}
|
||||
func printCount() {
|
||||
println("Count: \(count)")
|
||||
}
|
||||
}
|
||||
|
||||
var myCount = Counter()
|
||||
myCount.inc()
|
||||
myCount.add(2)
|
||||
myCount.printCount() // Count: 3
|
||||
Reference in New Issue
Block a user