Kotlin Basics & Introduction to Jetpack Compose.pptx

This work is licensed under the Apache 2.0 License
Compose Camp
27th September 2022
Introduction to Kotlin
& Jetpack compose

TAKSHIL KUNADIA
Facilitator
Camp Facilitators
APOORVA RUMALE
Co-facilitator

What the Camp is about?
Focus of this event will be around how to build
Android apps using Kotlin and Jetpack
Compose.

● 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

HISTORY OF ANDROID
● Andy Rubin founded Android Incorporation in
Palo Alto, California, United States in October,
2003.
● In 2005, Google acquired android Incorporation.
Since then, it is in the subsidiary of Google
Incorporation.
● Originally intended for camera but shifted to
smart phones later because of low market for
camera only.
● In 2007, Google announces the development of
android OS.
● In 2008, HTC launched the first android mobile.

APPLICATIONS
ANDROID ARCHITECTURE
• Applications is the top layer of android
architecture.
• The pre-installed applications like home,
contacts, camera, gallery etc and third party
applications downloaded from the play store
like chat applications, games etc. will be
installed on this layer only.
• It runs within the Android run time with the
help of the classes and services provided by
the application framework.

APPLICATION
FRAMEWORK
• Application Framework provides several
important classes which are used to create
an Android application.
• It provides a generic abstraction for
hardware access and also helps in
managing the user interface with application
resources.
• Generally, it provides the services with the
help of which we can create a particular
class and make that class helpful for the
Applications creation

RUNTIME
ENVIRONMENT
• Android Runtime environment is one of the
most important part of Android. It contains
components like core libraries and the Dalvik
virtual machine(DVM).
• Dalvik Virtual Machine (DVM) is a register-
based virtual machine and specially
designed and optimized for android to
ensure that a device can run multiple
instances efficiently.
• It depends on the layer Linux kernel for
threading and low-level memory
management. The core libraries enable us to
implement android applications using the
standard JAVA or Kotlin programming
languages.

NATIVE
LIBRARIES
• The Platform Libraries includes various
C/C++ core libraries and Java based
libraries to provide a support for android
development.
1. Media library provides support to play and record an
audio and video formats.
2. Surface manager responsible for managing access to
the display subsystem.
3. SGL and OpenGL both cross-language, cross-platform
application program interface (API) are used for 2D and
3D computer graphics.
4. SQLite provides database support
and FreeType provides font support.
5. Web-Kit This open source web browser engine provides
all the functionality to display web content and to simplify
page loading.
6. SSL (Secure Sockets Layer) is security technology to
establish an encrypted link between a web server and a
web browser.

LINUX KERNEL
• Linux Kernel is heart of the android
architecture. It manages all the available
drivers such as display drivers, camera
drivers, Bluetooth drivers, audio drivers,
memory drivers, etc. which are required
during the runtime.
• The Linux Kernel will provide an abstraction
layer between the device hardware and the
other components of android architecture. It
is responsible for management of memory,
power, devices etc.

Android Studio

Android Studio - Project View

Android Studio - Code View

Android Studio - Design View

Android Studio - Split View

Android Studio - Greeting function

The Android Emulator emulates Android devices on your computer
so that you can test your application on a variety of devices and
Android API levels without needing to have each physical device.
What is an emulator?

Creating an emulator

Running your app on
a physical device

Android Project Structure

● By default, Android Studio displays your project
files in the Android view.
● This view does not reflect the actual file hierarchy
on disk, but is organized by modules and file types
to simplify navigation between key source files of
your project, hiding certain files or directories that
are not commonly used.
Project files

src/
Contains all code and resource files for the module in the following
subdirectories:
androidTest/
Contains code for instrumentation tests that run on an Android device.
main/
Contains the "main" sourceset files: the Android code and
resources shared by all build variants
AndroidManifest.xml
Describes the nature of the application and each of its
components.

Java | kotlin/
Contains kotlin code sources.
gen/
Contains the kotlin files generated by Android Studio, such as your R.java file.
res/
Contains application resources, such as drawable files, layout files, and UI string.
assets/
Contains file that should be compiled into an .apk file as-is.
build.gradle (module)
This defines the module-specific build configurations.
build.gradle (project)
This defines your build configuration that apply to all modules. This file is integral
to the project, so you should maintain them in revision control with all other
source code.

Speed of coding
Kotlin and Java provide almost the same speed for coding.
Java has more coding processes than Kotlin, therefore, a
developer can spend less time thinking of a solution.
However, Kotlin has more laconic constructions, which
allow a developer to type less code.
Datatype
In Kotlin, the variable specification data type is not
required, while in Java, the variable data type is required.
Coding convention
In Kotlin, line breaks are used to format the code
construct, while Java uses the semicolon to end a
statement or declaration. As a result, the Kotlin coding
convention is easier than the Java convention.
Talent pool
According to the latest Developer Survey from
StackOverflow at the time of writing, Kotlin is one of the
most popular technologies, with around eight percent of
professional developers choosing Kotlin.
Incidentally, Kotlin brings more money to developers with
a revenue of $55k per year in comparison to $50k for Java.
Learning curve
While Java and Kotlin both have ample documentation,
Kotlin has a smoother learning curve.

Kotlin is the language that the
majority of professional Android
developers use to build apps.
Compose apps are written in
the Kotlin programming
language.

Kotlin Playground
Write and run Kotlin code in
the browser.

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

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

A container for a single piece of
data.
Variables

My name is and I am years old
Variables
name age

My name is and I am years old
Variables
Name value: Takshil
Age value: 23
Output:
My name is Takshil and I
am 23 years old
Name value: Apoorva Rumale
Age value: 22
Output:
My name is Apoorva and I
am 22 years old
name age

Basic data types
Kotlin Data type What kind of data it can contain Example literal values
String Text
“Add contact”
“Search”
Char Letter
‘T’
‘4’
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

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

Defining a variable
Variables start with a var or val
keyword.
fun displayIntroduction() {
val name: String = ”Takshil"
var age: Int = 23
}

Defining a variable
All variables must have a name.
val name: String = ”Takshil"
var age: Int = 23
}

Defining a variable
Data type is the type of data
that the variable holds.
val name: String = " Takshil "
var age: Int = 23
}

Defining a variable
The initial value is the value that
is stored in the variable.
val name: String = " Takshil "
var age: Int = 23
}

Naming Convention
● Names can contain letters, digits, underscores, and dollar signs
● Names should start with a letter
● Names can also begin with $ and _ (but we will not use it in this tutorial)
● Names are case sensitive ("myVar" and "myvar" are different variables)
● Names should start with a lowercase letter and it cannot contain whitespace
● Reserved words (like Kotlin keywords, such as var or String) cannot be used as names

Displaying Output
● print()
print prints its argument to the standard output.
● println()
println prints its arguments and adds a line break, so that the next thing you print appears
on the next line.

An array is a collection of similar
data types either of Int, String, etc.
Array in Kotlin is mutable in nature
with fixed size which means we can
perform both read and write
operations, on the elements of an
array.
Arrays

90
Kotlin arrays can be created using
arrayOf<dataType>()
Example – arrayof<int>()
arrayof<float>()
Kotlin Array
Declaration
90 77 36 50 86
Marks[]
0 1 2 3 4

CONDITIONALS

IF - ELSE
● Kotlin if
Use if to specify a block of code to be executed if a
condition is true.
Syntax:-
if (condition) {
// block of code to be executed if the condition is true
}
● Kotlin else
Use else to specify a block of code to be executed if the
condition is false.
Syntax:-
if (condition) {
// block of code to be executed if the condition is true
} else {
// block of code to be executed if the condition is false
}

ELSEIF
● Kotlin elseif
Use else if to specify a new condition if the first
condition is false.
Syntax:-
if (condition1) {
// block of code to be executed if condition1 is true
} else if (condition2) {
// block of code to be executed if the condition1 is false and
condition2 is true
} else {
// block of code to be executed if the condition1 is false and
condition2 is false
}

WHEN
● Kotlin when
Instead of writing many if..else expressions,
you can use the when expression, which is
much easier to read.
It is used to select one of many code blocks to
be executed.

KOTLIN FOR LOOPS
90 77 36 50 86
90 70 36 50 86
val marks = arrayOf(1, 5, 10, 15, 20)
for (x in marks) {
println(x)
}

KOTLIN FOR LOOPS
1 2 3 4 5
for (i in 1..5) {
println(i)
}

KOTLIN WHILE LOOPS
0 1 2 3 4
var i = 0
while (i < 5) {
println(i)
i++
}

KOTLIN DO-WHILE LOOPS
0 1 2 3 4
var i = 0
do {
println(i)
i++
} while (i < 5)

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.

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

Defining a function
Functions begin with the fun
keyword.
}

Defining a function
Functions have a name so that
they can be called.
}

Defining a function
Functions need a set of parentheses
after the function name in order to
surround the function inputs.
}

Defining a function
The curly braces make up the
function body and contain the
instructions needed to execute
a task.
}

Putting it together
// We will fill this out!
}
Output:
Hi I’m Takshil and I am 23 years old.

Putting it together
val name = " Takshil "
val age = 23
println("Hi I'm $name and I am $age years old")
}

Putting it together
fun main() {
displayIntroduction()
}
val name = ”Apoorva"
val age = 22
println("Hi I'm $name and I am $age years old")
}
Output:
Hi I’m Apoorva and I am 22 years old

Working of an Android App

Views in Android

A View is a simple building block of a user interface. It is a small rectangular box
that can be text, image, or even a button. It occupies the area on the screen in a
rectangular area and is responsible for drawing and event handling.
ViewGroup provides an invisible container to hold the views or layouts. ViewGroup
instances and views work together as a container for Layouts.
VIEWS IN ANDROID

I am Groot!

Activity Life Cycle

Activities are where all
the action happens,
because they are the
screens that allow the
user to interact with your
app.
ACTIVITY IN ANDROID

Intents in Android

● Android Intent is a messaging object used to request another app component to
perform an action. Intent facilitates users to communicate with app component
through several ways such as starting an activity, starting a service, delivering a
broadcast receiver, etc.
ACTIVITY IN ANDROID

Layouts
This work is
licensed under the
Apache 2.0 License

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/layout2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="#8ED3EB"
android:gravity="center"
android:orientation="vertical" >
<TextView
android:id="@+id/textView4"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="This is a TextView" />
</LinearLayout>
Example of Layout Code

Jetpack Compose is the
modern toolkit for building
native user interfaces for
Android apps.
Compose makes it easier and
faster to build UIs on Android.

Material Tents
This work is
licensed under the
Apache 2.0 License

Stargazing at State

Performance Peak
This work is licensed under
the Apache 2.0 License

Let’s talk about
Resources

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

Android Basics
with Compose Course

Unit 1: Your first
Android App

A Pathway

Take a Quiz

Earn badges!

Google Developer
Profile
Carrie Sawyer

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
● Kotlin 101 course

Learn More

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

THANK YOU
for participating Compose Camp Day 1
Do participate tomorrow as well

Kotlin Basics & Introduction to Jetpack Compose.pptx

In this document