Android App
DevelopmentAhmad Tayeb
Ahmad Tayeb
Lecturer @ Department of Information Technology, Faculty of Computing and
Information Technology, KAU
Master degree from Information Sciences and Technologies , B. Thomas
Golisano College of Computing and Information Sciences, Rochester Institute
of Technology , Rochester, NY, USA
http://ahmadt.com
Twitter: @ahmad_tayeb
Android
Android is a software package and Linux based operating system for mobile
devices such as tablet computers and smartphones.
It is developed by Google and later the OHA (Open Handset Alliance). Java
language is mainly used to write the android code even though other
languages can be used.
What is Open Handset Alliance (OHA) ?
It's a consortium of 84 companies such as google, samsung, AKM, synaptics,
KDDI, Garmin, Teleca, Ebay, Intel etc.
Features of Android
It is open-source.
Anyone can customize the
Android Platform.
There are a lot of mobile
applications that can be chosen
by the consumer.
Android Architecture
Linux kernel
Native libraries (middleware)
Android Runtime
Application Framework
Applications
Android Architecture
1) Linux kernel
It is the heart of android architecture that exists at the root of android
architecture.
Linux kernel is responsible for device drivers, power management, memory
management, device management and resource access.
Android Architecture
2) Native Libraries
On the top of Linux kernel, their are Native libraries such as WebKit, OpenGL,
FreeType, SQLite, Media, C runtime library (libc) etc.
The WebKit library is responsible for browser support, SQLite is for database,
FreeType for font support, Media for playing and recording audio and video
formats.
Android Architecture
3) Android Runtime
In android runtime, there are core libraries and DVM (Dalvik Virtual Machine)
which is responsible to run android application.
DVM is like JVM but it is optimized for mobile devices. It consumes less
memory and provides fast performance.
Android Architecture
4) Android Framework
On the top of Native libraries and android runtime, there is android
framework.
Android framework includes Android API's such as UI (User Interface),
telephony, resources, locations, Content Providers (data) and package
managers.
It provides a lot of classes and interfaces for android application
development.
Android Architecture
5) Applications
On the top of android framework, there are applications.
All applications such as home, contact, settings, games, browsers are using
android framework that uses android runtime and libraries.
Android runtime and native libraries are using Linux kernel.
Android Core Building Blocks
An android component is simply a piece of code that has a well defined life
cycle e.g. Activity, Receiver, Service etc.
The core building blocks or fundamental components of android are activities,
views, intents, services, content providers, fragments and
AndroidManifest.xml.
Android Core Building Blocks
Activity
An activity is a class that represents a single screen. It is like a Frame in AWT.
Android Core Building Blocks
View
A view is the UI element such as button, label, text field etc. Anything that
you see is a view.
Android Core Building Blocks
Intent
Intent is used to invoke components. It is mainly used to:
Start the service
Launch an activity
Display a web page
Display a list of contacts
Broadcast a message
Dial a phone call etc.
Android Core Building Blocks
Service
Service is a background process that can
run for a long time.
There are two types of services local and
remote.
Local service is accessed from within the
application whereas remote service is
accessed remotely from other
applications running on the same device.
Android Core Building Blocks
Broadcast Receiver
Broadcast Receiver handles communication
between Android OS and applications.
Broadcast Receivers simply respond to
broadcast messages from other applications
or from the system.
For example, applications can also initiate
broadcasts to let other applications know
that some data has been downloaded to the
device and is available for them to use, so
this is broadcast receiver who will intercept
this communication and will initiate
appropriate action.
Android Core Building Blocks
Content Provider
Content Providers are used to share data between the applications.
Android Core Building Blocks
Fragment
Fragments are like parts of activity.
An activity can display one or more fragments on the screen at the same
time.
Android Core Building Blocks
AndroidManifest.xml
It contains informations about activities, content providers, permissions etc.
It is like the web.xml file in Java EE.
Android Core Building Blocks
Android Virtual Device (AVD)
It is used to test the android application without the need for mobile or tablet
etc.
It can be created in different configurations to emulate different types of real
devices.
Prerequisites
Android programming is based on Java programming language so if you have
basic understanding on Java programming then it will be a fun to learn
Android application development.
Android Studio
Android Studio is the official IDE for android application development.
It works based on IntelliJ IDEA.
https://developer.android.com/studio/
Your First Android App ☺
Directory & Resource Type
Directory & Resource Type
Directory & Resource Type
Directory & Resource Type
Alternative Resources
Your application should provide alternative resources to support specific
device configurations.
For example, you should include alternative drawable resources ( i.e.images )
for different screen resolution and alternative string resources for different
languages.
At runtime, Android detects the current device configuration and loads the
appropriate resources for your application.
Alternative Resources
Steps
To specify configuration-specific alternatives for a set of resources, follow the
following steps:
Create a new directory in res/ named in the form <resources_name>-
<config_qualifier>. Here resources_name will be any of the resources mentioned
in the above table, like layout, drawable etc. The qualifier will specify an
individual configuration for which these resources are to be used.
Save the respective alternative resources in this new directory. The resource files
must be named exactly the same as the default resource files, but these files will
have content specific to the alternative. For example though image file name will
be same but for high resolution screen, its resolution will be high.
Alternative Resources
Configuration Qualifier Names
Android supports several configuration qualifiers and you can add multiple
qualifiers to one directory name, by separating each qualifier with a dash.
https://developer.android.com/guide/topics/resources/providing-resources
Android Activity Lifecycle
Intents
An Intent is a messaging object you can use to request an action from
another app component.
Although intents facilitate communication between components in
several ways, there are three fundamental use cases:
Starting an activity
Starting a service
Delivering a broadcast
There are two types of intents:
Explicit intents
Implicit intents
Intents Types
Explicit Intents
Explicit intents specify which application will satisfy the intent, by supplying
either the target app's package name or a fully-qualified component class
name.
You'll typically use an explicit intent to start a component in your own app,
because you know the class name of the activity or service you want to start.
For example, you might start a new activity within your app in response to a
user action, or start a service to download a file in the background.
Intents Types
Implicit Intents
Implicit intents do not name a specific component, but instead declare a
general action to perform, which allows a component from another app to
handle it.
For example, if you want to show the user a location on a map, you can use
an implicit intent to request that another capable app show a specified
location on a map.
References
https://www.techotopia.com/index.php/Handling_Android_Activity_State_Changes
https://developer.android.com/guide/topics/resources/providing-resources
https://developer.android.com/guide/components/intents-filters
http://donkcowan.com/blog/2013/4/21/android-activity-lifecycle-method-typical-uses
https://www.javatpoint.com/android-tutorial
https://www.tutorialspoint.com/android
https://www.devglan.com/android/android-service-example
https://devcfgc.com/introduction-to-android-content-providers-685ed2468935
Head First Android Development: A Brain-Friendly Guide 1st Edition, By Dawn Griffiths.
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