It’s a mobile platform that consists of an Operating System, Middleware, and some Key Applications, developed by Google in October 2003 and Allows writing managed code in the Java language.
it has its DVM (Dalvik Virtual Machine), which is used for executing the Android application.
Open Handset Alliance(OHA): it’s a business alliance of firms to develop open standards for mobile devices. ANDROID ARCHITECTURE: (application layer, application framework, libraries and runtime, kernel)
1-Kernel: it’s the core of Android architecture, which provides services like power management, memory management, security, etc.
It helps in software or hardware binding for better communication.
2-Libraries: Android libraries are in C/C++, which cannot be accessed directly. some Native libraries are: Surface Mgr. is responsible for composing different drawing surfaces on the screen.
Web Kit is for browser support., SQLite is for databases, Free Type is for font support, and Media is for playing and recording audio and video formats.
3-Run time: there are core libraries and DVM (Dalvik Virtual Machine) which is responsible for running Android applications, it consumes less memory and provides fast performance.
4-Application framework: it’s the toolkit that all applications use, which includes Android APIs such as telephony, locations, Content Providers (data), and package managers, which provides a lot of classes and interfaces for Android application development.
A: The activity manager manages the lifecycle of applications., and All the activities are controlled by the activity manager.
B: Resource manager provides access to non-code resources such as graphics etc.
C: Notification manager enables all applications to display custom alerts in the status bar.
D: Location manager: – It fires alerts when a user enters or leaves a specified geographical location. E: Package manager is used to retrieve the data about installed packages on the device.
F: Window manager:-It is used to create views and layouts.
G: Telephony manager is used to handle settings of network connection and all information about services on
device.
5- Application Layer: All the applications like camera, Google Maps, browser, sums, calendars, and contacts are
native applications. These applications work with end users with the help of an application framework.
Advantages of Android: The ability for anyone to customize the Google Android platform Has better notification and app market (1,80,000 applications), its Multitasking
support many applications, in which the user can change the screen display.
With Google Chrome you can open many windows at once, and Supports all Google services as well!
Dis- Advantage of Android: The Android Market has less control over the manager; Hackers keep on trying to steal your personal information.
Advertisement pop-ups, Wasteful Batteries (in the OS background there are lots of “processes” that will cause the battery to quickly and Very unstable and often hang or crash)
Development Environment = Eclipse + ADT + SDK
The Android developing environment includes the following tools (Eclipse IDE, Android Development Tools (ADT), and Android System Development Kit (SDK))
1: Eclipse IDE: used to create and debug Java code, and manage the various resources that normally are used in the making of an Android app.
2- ADT plugin: used to extend Eclipse so can easily reach the tools of the SDK through the use of menus, perspectives, and icons seamlessly integrated into Eclipse’s IDE.
3: SDK: it contains tools needed to transfer, profile, emulate, observe, and debug your applications which could run into any virtual or physical Android device.
Anatomy of Android Applications
An Android application consists of one or more core components ( Activity, Service, broadcast receiver, content provider )
1: Activity: The Android application consists of one or more activities, an activity usually shows a single (GUI), and only one activity known as main when the application is launched.
An activity may transfer control and data to another activity through an interprocess communication protocol called intents.
- Service: they are a special type of activity that do not have a (GUI ), and usually runs in the background for an indefinite period.
3:Broadcast receiver: it’s an Android component that allows to register and listen for device orientation
changes like sums message received, phone call received/pick/cut, battery status changed, and the Wi-Fi came on.
4. Content provider: is a class, which offers a standard set of “database-like“ methods to enable other applications to retrieve, delete, update, and insert data items.
activity stack: it schedules the Activities in the system, e.g.
the first started app will go to the last # of the list when the second app comes to the list …
Life Cycle Events: When progressing from one state to the other, the OS notifies the application of the changes by issuing calls to the following protected transition methods.
Every activity has three states (It is active or running, it is paused or It is stopped)
1: active or running; This is the activity that has “focus” and its graphical interface is responsive to the user’s interactions.
2: paused: if it has lost focus but is still visible to the user. Or; it is a live activity and can be killed by the system when available memory becomes extremely low.
3: stopped: in this state, the activity is not visible to the user, because the process is completely terminated!
