The document provides an overview of Android architecture and app development. It discusses that Android is built on a Linux kernel and consists of libraries, runtime, and core applications. It also covers creating layouts with UI components like ImageView, EditText, Button. Additionally, it summarizes running and debugging apps, activity navigation, and the activity lifecycle.

1. Android
Starting App Development

2. Contents
Android Architecture
Creating New Layouts
UI components
Running and Debugging apps
Activity Navigation

4. Android Architecture
Linux Kernel
Libraries
Android Runtime and Core libraries
Application Framework
Applications

6. Linux Kernel
Provides Basic System Functionality such as process management, memory
management and device management.
Provides all device drivers to communicate all different hardware in device like
Camera, Sensors, Bluetooth, WiFi, Audio and others.

7. Basic Libraries
Low level libraries which provide basic features like SQLite Database, web
browser, LibC, library for playing and recording Audio/Video etc.
Mainly written in C/C++.
Interact with device drivers to handle all the basic features of the OS.

8. Android Core Libraries
Java based libraries that are specific to Android.
Interact with Basic libraries to perform desired functionality such as handling
recording of Audio and Video.
User interface building, Graphics design(2D and 3D) and Database access.

9. Dalvik Virtual Machine
Each application run in its own instance of Dalvik Virtual machine.
Multiple instances of Dalvik VM’s can run efficiently.

10. Application Framework
Application Manager
Activity Manager
Notification Manager
Location Manager
..and others

11. Applications
All built in apps
And the third party apps
***

12. “Till 29th September, 2015 Android activations were 1.4
billion.”

13. Let’s Make Layouts - some basics
Height and Width - “match_parent” or “wrap_content” or digital value in “dp”
Unique id - “@+id/xxx”
Naming convention for Id’s - “@+id/tv_login_username”,
“@+id/button_login_submit”
Naming convention for layouts - activity_login.xml, activity_settings.xml

14. ImageView
<ImageView
android:id="@+id/iv_orders_list_footer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_margin="20dp"
android:src="@drawable/icon"
/>

15. Drawables
Located in res/drawable/filename.png
Support different size/resolution devices.
hdpi, mdpi, xhdpi, xxhdpi.
Referred in xml as “@drawable/abc” (for abc.png)
Usually prefer PNG images, can also use JPG images.

16. EditText
<EditText
android:id="@+id/et_login_password"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/passcode"
android:inputType="textPassword"
android:maxLength="30"
android:textSize="24dp"/>

17. Button
<Button
android:id="@+id/button_login_submit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:backgroundTint="@color/primary_dark"
android:text="Login"
android:textColor="@color/primary_text"
android:textSize="24dp"/>

18. Button
OnClickListener
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Do the required task
}
});

19. Hands On
Login screen
***

20. “Android share in Chinese mobile market is 76.5%”

21. Running and Debugging
Android Studio features - Clean, Build, Run
Android Emulator(Android Virtual Device)
Third Party Simulator - Genymotion
Displaying Logs
***

22. “Average daily Android subscription is 1.5 million.”

23. Activities
Every Activity will inherit an “Activity”.
Inheritance

24. Inheritance

25. Inheritance
Extending a class.
Accessing inherited methods and member variables.
Overriding methods.

26. Start Another Activity - Intents
Intent - “A message either to start another Activity or to communicate to another
Activity.”
Intent Actions - What it should do?
Passing Arguments to next Activity

27. Sending Data To Activity
Intent Parameters

28. Arrangement of Activities - Backstack

29. Why Activities are Important
Application performance and behaviour.
Interview Questions!!

30. Activity Lifecycle

31. Activity Lifecycle - Callback methods
onCreate
onStart
onResume
onPause
onStop
onDestroy

32. Activity Lifecycle
onCreate
onStart
onResume
onPause
onStop
onDestroy

33. ListView

34. PlayStore

36. But Not To Worry...
800,0000 apps have < 100 downloads.
Another 700,000 have < 1000 downloads.
Another 400,000 have < 10,000 downloads.
Only 35,000 apps are downloaded more than 500,000.
###

37. Paramvir Singh, Android Developer and Trainer
Paramvir.singh88@gmail.com
https://in.linkedin.com/in/paramvir-singh-android-developer-b45b5321