Introduction and features of android :
Android is a Linux based operating system it is designed primarily for touch screen mobile devices such as smart phones and tablet computers. The operating system have developed a lot in last 15 years starting from black and white phones to recent smart phones or mini computers. One of the most widely used mobile OS these days is android. The android is software that was founded in Palo Alto of California in 2003.
features of android:
- The android is a powerful operating system and it supports large number of applications in Smartphones.
- These applications are more comfortable and advanced for the users.
- The hardware that supports android software is based on ARM architecture platform.
- The android is an open source operating system means that it’s free and any one can use it.
- The android has got millions of apps available that can help you managing your life one or other way and it is available low cost in market at that reasons android is very popular.
- The android development supports with the full java programming language.
- Even other packages that are API and JSE are not supported.
- The first version 1.0 of android development kit (SDK) was released in 2008 and latest updated version is jelly bean.
Android Architecture:
The android is a operating system and is a stack of software components which is divided into five sections and four main layers that is.
- Linux kernel
- Libraries
- Android run time
Linux kernel function in android:
The android uses the powerful Linux kernel and it supports wide range of hardware drivers. The kernel is the heart of the operating system that manages input and output requests from software. This provides basic system functionalities like process management, memory management, device management like camera, keypad, display etc the kernel handles all the things. The Linux is really good at networking and it is not necessary to interface it to the peripheral hardware.
The kernel itself does not interact directly with the user but rather interacts with the shell and other programs as well as with the hard ware devices on the system.
Libraries:
The on top of a Linux kennel there is a set of libraries including open source web browser such as webkit, library libc. These libraries are used to play and record audio and video. The SQLite is a data base which is useful for storage and sharing of application data. The SSL libraries are responsible for internet security etc.
Android Runtime:
The android runtime provides a key component called Dalvik Virtual Machine which is a kind of java virtual machine. It is specially designed and optimized for android. The Dalvik VM is the process virtual machine in the android operating system. It is a software that runs apps on android devices.
The Dalvik VM makes use of Linux core features like memory management and multithreading which is in a java language. The Dalvik VM enables every android application to run it own process. The Dalvik VM executes the files in the .dex format.
Applications and Features in android :
You will find all the android applications at the top layer and you will write your application and install on this layer. Example of such applications are contacts, books, browsers, services etc. Each application perform a different role in the over all applications.
Features:
- Head set layout
- Storage
- Connectivity: GSM/EDGE, IDEN, CDMA, Bluetooth, WI-FI, EDGE,3G,NFC, LTE,GPS.
- Messaging: SMS, MMS, C2DM (could to device messaging), GCM (Google could messaging)
- Multilanguage support
- Multi touch
- Video calling
- Screen capture
- External storage
- Streaming media support
- Optimized graphics.
Advantages:
- Android is Linux based open source operating system , it can be developed by any one
- Easy access to the android apps
- You can replace the battery and mass storage, disk drive and UDB option
- Its supports all Google services
- The operating system is able to inform you of a new SMS and Emails or latest updates.
- It supports Multitasking
- Android phone can also function as a router to share internet
- Its free to customize
- Can install a modified ROM
- Its supports 2D and 3D graphics
Application frame work:
The application frame work layer provides many higher level services to applications such as windows manager, view system, package manager, resource manager etc. The application developers are allowed to make use of these services in their application.
Applications and Features:
You will find all the android applications at the top layer and you will write your application and install on this layer. Example of such applications are contacts, books, browsers, services etc. Each application perform a different role in the over all applications.
Advantage of android platform:
- Zero startup costs to begin development. The development tools for the platform are free to download, and Google only charges a small fee to distribute applications on the Android Market.
- Freedom to innovate. The Android OS is an open-source platform based on the Linux kernel and multiple open-source libraries. In addition to building applications to run on Android devices, developers are free to contribute to or extend the platform as well.
- Freedom to collaborate. Android developers are not required to sign an NDA and are encouraged to collaborate and share source code with each other. According to a survey by Black Duck Software, the number of open source mobile apps and libraries grew at a rate of 168% from 2008 to 2009, faster on Android than any other platform. This means more code that you can reuse in your own projects to bring them to market much faster.
- Open distribution model. Very few restrictions are placed on the content or functionality allowed in Google’s Android Market, and developers are free to distribute their applications through other distribution channels as well.
- Multi-platform support. There are a wide variety of hardware devices powered by the Android OS, including many different phones and tablet computers. Development for the platform can occur on Windows, Mac OS or Linux.
- Multi-carrier support. A large number of telecom carriers currently offer Android powered phones.
Assuming you have already installed the Eclipse ADT plugin, you will need to configure Eclipse for Android development by manually setting the filepath for the Android SDK. To do this, select Eclipse > Preferences from the main tool bar, and then select Android from the dialogue box that appears. Update the “SDK Location” option to point to the directory where you installed the SDK. You should now have the IDE configured for Android development.
The AndroidManifest.xml file
The AndroidManifest.xml file provides metadata about your application that the Android OS will need to run the app properly. The name of the application, used for both the app icon and the activity titlebar, and the app icon are defined under Application Attributes. You will notice that the Name field doesn’t actually contain the name text, but “@string/app_name” instead. This is a string reference and can be used anytime a string is expected. The actual string text is then defined in one of the XML files found under the res/values folder. The app creation wizard generated a file there called strings.xml.