This document outlines the schedule and content for a Compose Camp. The camp will cover introductory Kotlin topics like variables, functions, conditionals, and null safety over 4 sessions from October 11-14, 2022. Session topics include an intro to Kotlin, building a birthday card app, a dice roller app, and a calculator app. The document provides code examples for variables, functions, if/else statements, when expressions, nullability, and repeat functions. Camp leaders include Kaustubh Narwade, Sujal Goswami, and Rishabh Sachan.
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Kaustubh Narwade
GitHub
Camp leaders
Sujal Goswami
GitHub
Rishabh Sachan
GitHub
4. This work is licensed under the Apache 2.0 License
Camp Schedule
TOPIC TIME
Intro (Online) 0:00 - 0:00
Birthday Wish Card App (Offline) 0:00 - 0:00
Dice Roller App (Offiline) 0:00 - 0:00
Calculator (Online) 0:00 - 0:00
Sessions Date
Intro Session | Compose Camp 11th October, 2022
Birthday Wish Card App 12th October, 2022
Dice Roller App 13th October, 2022
Calculator App 14th October, 2022
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Recap
● Variables
● functions
● Android Studio
● Birthday wish card
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Recap
● Conditionals
● When statement
● Nullability
● Function types
● Repeat function
● Dice Roller App
7. This work is licensed under the Apache 2.0 License
8. This work is licensed under the Apache 2.0 License
Variables
fun main() {
val cartTotal = 0
cartTotal = 20
println("Total: $cartTotal")
}
Val cannot be reassignd
fun main() {
var cartTotal = 0
cartTotal = 20
println("Total: $cartTotal")
}
9. This work is licensed under the Apache 2.0 License
Functions
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Use if/else statements to express conditions
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When statement
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fun main() {
val x: Any = 20
when (x) {
2, 3, 5, 7 -> println("x is a prime number between 1 and 10.")
in 1..10 -> println("x is a number between 1 and 10, but not a prime number.")
is Int -> println("x is an integer number, but not between 1 and 10.")
else -> println("x isn't an integer number.")
}
}
Some Keywords
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if/else & when as
expressions
fun main() {
val trafficLightColor = "Black"
val message =
if (trafficLightColor == "Red") "Stop"
else if (trafficLightColor == "Yellow") "Slow"
else if (trafficLightColor == "Green") "Go"
else "Invalid traffic-light color"
println(message)
}
fun main() {
val trafficLightColor = "Amber"
val message = when(trafficLightColor) {
"Red" -> "Stop"
"Yellow", "Amber" -> "Proceed with caution."
"Green" -> "Go"
else -> "Invalid traffic-light color"
}
println(message)
}
14. This work is licensed under the Apache 2.0 License
Nullability
In Kotlin, there's a distinction between nullable and non-nullable types:
•Nullable types are variables that can hold null.
•Non-null types are variables that can't hold null.
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Handle nullable variables
• Use the ?. safe-call operator fun main() {
var favoriteActor: String? = "Sandra Oh"
println(favoriteActor?.length)
}
• Use the ?: Elvis operator
fun main() {
val favoriteActor: String? = "Sandra Oh"
val lengthOfName = favoriteActor?.length ?: 0
println("The number of characters in your
favorite actor's name is $lengthOfName.")
}
