Compose Camp Day 1

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Compose Camp
Android Basics with Compose:
Unit 1 Pathway 1

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Compose Camp is a hands-on introduction to
learning how you can build Android apps with
Jetpack Compose.
What is Compose Camp?

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● Basic computer literacy
● Basic math skills
● Computer & headphones
● Internet connection
● (Optional) Android device & USB cable
Prerequisites

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● Build your first Android apps
● Set up Android Studio on your computer
● Learn the basics of the Kotlin programming language
● Learn Jetpack Compose
● Discover resources to continue learning
Compose Camp Learning Objectives

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1. Why are you here?
2. What are you goals?
3. How do you plan to achieve them?

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TOPIC TIME
Presentation 4:00 - 4:15
Your first program in
Kotlin
4:15 - 4:30
Create and use variables
in Kotlin
4:30 - 4:50
Break 4:50 - 5:00
Create and use
functions in Kotlin
5:00 - 5:30
Practice problems 5:30 - 5:45
Wrap up 5:45 - 6:00
Day 1 Schedule

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Android Basics
with Compose Course

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Unit 1: Your first
Android App

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A Pathway

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Take a Quiz

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Earn badges!

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Google Developer
Profile
Carrie Sawyer

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Session Overview

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Kotlin Programming
Language
Use Kotlin to start writing Android apps.
Kotlin helps developers be more
productive.

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Kotlin Playground
Write and run Kotlin code in
the browser.

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Program
A series of instructions for a
computer to perform some
action.
fun main() {
println("Hello, world!")
}
Output:
Hello, world!

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Code
Step by step instructions for
what the computer should do.
fun main() {
println("Hello, world!")
}
Output:
Hello, world!

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main Function
The main function is the entry
point, or starting point, of the
program.
Start here
fun main() {
println("Hello, world!")
}
Output:
Hello, world!

19. This work is licensed under the Apache 2.0 License
Functions
A function is a segment of a program that
performs a specific task.
You can have many functions in your program or
only a single one.

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Defining a function
Functions begin with the fun
keyword.
fun displayIntroduction() {
}

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Defining a function
Functions have a name so that
they can be called.
fun displayIntroduction() {
}

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Defining a function
Functions need a set of parentheses
after the function name in order to
surround the function inputs.
fun displayIntroduction() {
}

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Defining a function
The curly braces make up the
function body and contain the
instructions needed to execute
a task.
fun displayIntroduction() {
}

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Putting it together
fun displayIntroduction() {
// We will fill this out!
}
Output:
Hi I’m Meghan and I am 28 years old

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A container for a single piece of data.
Variables

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My name is and I am years old
Variables
name age

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My name is and I am years old
Variables
Name value: Meghan
Age value: 28
Output:
My name is Meghan and I
am 28 years old
Name value: Janet
Age value: 49
Output:
My name is Janet and I
am 49 years old
name age

28. This work is licensed under the Apache 2.0 License
Basic data types
Kotlin Data type What kind of data it can contain Example literal values
String Text
“Add contact”
“Search”
Int Whole integer number
32
-59873
Double Decimal number
2.0
-37123.9999
Float
Decimal number (less precise than a Double).
Has an f or F at the end of the number.
5.0f
-1630.209f
Boolean
true or false. Use this data type when there
are only two possible values.
true
false

29. This work is licensed under the Apache 2.0 License
val keyword
Use when you expect the variable value will
not change.
Example: name
var keyword
Use when you expect the variable value can
change.
Example: age
Defining a variable

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Defining a variable
Variables start with a var or val
keyword.
fun displayIntroduction() {
val name: String = "Meghan"
var age: Int = 28
}

31. This work is licensed under the Apache 2.0 License
Defining a variable
All variables must have a name.
fun displayIntroduction() {
val name: String = "Meghan"
var age: Int = 28
}

32. This work is licensed under the Apache 2.0 License
Defining a variable
Data type is the type of data
that the variable holds.
fun displayIntroduction() {
val name: String = "Meghan"
var age: Int = 28
}

33. This work is licensed under the Apache 2.0 License
Defining a variable
The initial value is the value that
is stored in the variable.
fun displayIntroduction() {
val name: String = "Meghan"
var age: Int = 28
}

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Putting it together
fun displayIntroduction() {
val name = "Meghan"
val age = 28
println("Hi I'm $name and I am $age years old")
}

35. This work is licensed under the Apache 2.0 License
Putting it together
fun main() {
displayIntroduction()
}
fun displayIntroduction() {
val name = "Meghan"
val age = 28
println("Hi I'm $name and I am $age years old")
}
Output:
Hi I’m Meghan and I am 28 years old

36. This work is licensed under the Apache 2.0 License
Let’s get started

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g.co/android/basics-compose
Start here:

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Unit 1: Pathway 1

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Work on Unit 1, Pathway 1
Have a Question?
Just ask

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Break

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Work on Unit 1, Pathway 1
Have a Question?
Just ask

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Welcome back
And congrats!

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What’s coming next:

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Share what you’ve
learned using
.#ComposeCamp
on social media
For a chance to be
featured by Android,
submit your tips on
learning Compose to
goo.gle/compose-tips

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Learn More

47. This work is licensed under the Apache 2.0 License
See you at the next Compose Camp Session!
Optional resources to check out:
● Official Android Developers Site: developer.android.com
● Official Android Developers Blog (for announcements)
● Android Developers Medium Blog (for more technical articles)
● Android Developers YouTube channel
● Follow @AndroidDev on Twitter
● Follow @AndroidDev on LinkedIn
● Subscribe to the Android Developer Newsletter