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Android » Basics

ANDROID APPLICATION DEVELOPMENT  

Introduction:

Before knowing about Android You need to know about some basic concept. So first we have discussed that concept after that we will start Android

  • ⦁Operating System (OS) : 

An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. 
A mobile operating system, also referred to as mobile OS, is the operating system that operates a Smartphone, tablet, PDA, or other digital mobile devices. Modern mobile operating systems combine the features of a personal computer operating system with touch screen, cellular, Bluetooth, Wife, GPS mobile navigation, camera, video camera, speech recognition, voice recorder, music player, Near field communication, personal digital assistant (PDA), and other features. Means mobile operating system as the name also says operating system.


Example & Symbol of Mobile Operating System 

  • ⦁Symbin 

  • ⦁iPhone 

  • ⦁Windows Phone

  • ⦁Android 

  • ⦁Open Source:

The term "open source" refers to something that can be modified because its design is publicly accessible.
While it originated in the context of computer software development, today the term "open source" designates a set of values—what we call the open source way. Open source projects, products, or initiatives are those that embrace and celebrate open exchange, collaborative participation, rapid prototyping, transparency, meritocracy, and community development.
WHAT IS OPEN SOURCE SOFTWARE ?
Open source software is software whose source code is available for modification or enhancement by anyone.
"Source code" is the part of software that most computer users don't ever see; it's the code computer programmers can manipulate to change how a piece of software—a "program" or "application"—works. Programmers who have access to a computer program's source code can improve that program by adding features to it or fixing parts that don't always work correctly.
What's the difference between open source software and other types of software?
Some software has source code that cannot be modified by anyone but the person, team, or organization who created it and maintains exclusive control over it. This kind of software is frequently called "proprietary software" or "closed source" software, because its source code is the property of its original authors, who are the only ones legally allowed to copy or modify it. Microsoft Word and Adobe Photoshop are examples of proprietary software. In order to use proprietary software, computer users must agree (usually by signing a license displayed the first time they run this software) that they will not do anything with the software that the software's authors have not expressly permitted.
Open source software is different. Its authors make its source code available to others who would like to view that code, copy it, learn from it, alter it, or share it. LibreOffice and the GNU Image Manipulation Program are examples of open source software. As they do with proprietary software, users must accept the terms of a license when they use open source software—but the legal terms of open source licenses differ dramatically from those of proprietary licenses. Open source software licenses promote collaboration and sharing because they allow other people to make modifications to source code and incorporate those changes into their own projects. Some open source licenses ensure that anyone who alters and then shares a program with others must also share that program's source code without charging a licensing fee for it. In other words, computer programmers can access, view, and modify open source software whenever they like—as long as they let others do the same when they share their work. In fact, they could be violating the terms of some open source licenses if they don't do this.
So as the Open Source Initiative explains, "open source doesn't just mean access to the source code." It means that anyone should be able to modify the source code to suit his or her needs, and that no one should prevent others from doing the same. The Initiative's definition of "open source" contains several other important provisions.


ANDROID ( OPERATING SYSTEM )  


Android is a mobile operating system (OS) based on the Linux kernel and currently developed by Google. With a user interface based on direct manipulation , Android is designed primarily for touchscreen mobile devices such as smartphones and tablet computers , with specialized user interfaces for televisions (Android TV) , cars (Android Auto) , and wrist watches (Android Wear).
Android's source code is released by Google under open source licenses, although most Android devices ultimately ship with a combination of open source and proprietary software, including proprietary software developed and licensed by Google. Initially developed by Android, Inc., which Google bought in 2005, Android was unveiled in 2007, along with the founding of the Open Handset Alliance(OHA) – a consortium of hardware , software, and telecommunication companies devoted to advancing open standards for mobile devices.


WHY ANDROID :
⦁A Simple and powerful SDK
⦁No Licensing , Distribution , or Development fees
⦁Development Over Many Platform Linux ,Windows
⦁ Excellent Documentation
⦁Growing Developer Community 


History:


Android, Inc. was founded in Palo Alto, California in October 2003 by Andy Rubin , Rich Miner , Nick Sears , and Chris White to develop “smarter mobile devices that are more aware of its owner's location and preferences “ . The early intentions of the company were to develop an advanced operating system for digital cameras. Though, when it was realized that the market for the devices was not large enough, the company diverted its efforts toward producing a smartphone operating system that would rival Symbian and Microsoft Windows Mobile. 
On November 5, 2007, the Open Handset Alliance, a consortium of technology companies including Google, device manufacturers such as HTC, Sony and Samsung, wireless carriers such as Sprint Nextel and T-Mobile, and chipset makers such as Qualcomm and Texas Instruments, unveiled itself, with a goal to develop open standards for mobile devices. That day, Android was unveiled as its first product, a mobile device platform built on the Linux kernel version 2.6.25. The first commercially available smartphone running Android was the HTC Dream, released on October 22, 2008.
In 2010, Google launched its Nexus series of devices – a line of smartphones and tablets running the Android operating system, and built by manufacturing partners. HTC collaborated with Google to release the first Nexus smartphone,[the Nexus One. Google has since updated the series with newer devices, such as the Nexus 5 phone (made by LG) and the Nexus 7 tablet (made by Asus).
In 2014, Google launched Android One, a standardized smartphone, mainly targeting customers in the developing world. Android One smartphones running the latest version of Android (e.g. the latest Android 5.1) close to the stock version of the operating system. As of March 3, 2015, the newest version of the Android operating system, 5.1, is available for selected devices including the Android One series, the Nexus 6 phablet, and the Nexus 9 tablet.
In May 2015, Google announced Project Brillo as a cut-down version of Android that uses its lower levels (excluding the user interface), intended for the "Internet of Things" (IoT) embedded systems.


Android devices boot to the homescreen, the primary navigation and information "hub" on Android devices that is analogous to the desktop found on PCs . Android homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content such as the weather forecast, the user's email inbox, or a news ticker directly on the homescreen. A homescreen may be made up of several pages that the user can swipe back and forth between, though Android's homescreen interface is heavily customisable, allowing the user to adjust the look and feel of the device to their tastes. Third-party apps available on Google Play and other app stores can extensively re-theme the homescreen, and even mimic the look of other operating systems, such as Windows Phone. Most manufacturers, and some wireless carriers, customise the look and feel of their Android devices to differentiate themselves from their competitors.

  • Application :

Applications ("apps"), which extend the functionality of devices, are written using the Android software development kit (SDK) and, often, the Java programming language that has complete access to the Android APIs. Java may be combined with C/C++, together with a choice of non-default runtimes that allow better C++ support; the Go programming language is also supported since its version 1.4, which can also be used exclusively although with a restricted set of Android APIs. The SDK includes a comprehensive set of development tools, including a debugger , software libraries , a handset emulator based on QEMU , documentation, sample code, and tutorials. Initially, Google's supported integrated development environment (IDE) was Eclipse using the Android Development Tools (ADT) plugin; in December 2014, Google released Android Studio, based on IntelliJ IDEA, as its primary IDE for Android application development. Other development tools are available, including a native development kit (NDK) for applications or extensions in C or C++, Google App Inventor, a visual environment for novice programmers, and various cross platform mobile web applications frameworks. In January 2014, Google unveiled an framework based on Apache Cordova for porting Chrome ,HTML 5 ,web applications to Android, wrapped in a native application shell.
Android has a growing selection of third-party applications, which can be acquired by users by downloading and installing the application's APK (Android application package) file, or by downloading them using an application store program that allows users to install, update, and remove applications from their devices. Google Play Store is the primary application store installed on Android devices that comply with Google's compatibility requirements and license the Google Mobile Services software. Google Play Store allows users to browse, download and update applications published by Google and third-party developers.

  • Linux Kernel:

Android's kernel is based on one of the Linux kernel's long-term support (LTS) branches. Since April 2014, Android devices mainly use versions 3.4 or 3.10 of the Linux kernel. The specific kernel version depends on the actual Android device and its hardware platform ,  Android has used various kernel versions since the version 2.6.25 that was used in Android 1.0.


This is the Kernel on which Android is based. This layer contain all low level drivers for various hardware component of an android devices. IPC – it stands for inter process communication. Binder means bind two process.


  • Open-Source Community:



Android has an active community of developers and enthusiasts who use the Android Open Source Project (AOSP) source code to develop and distribute their own modified versions of the operating system. These community-developed releases often bring new features and updates to devices faster than through the official manufacturer/carrier channels, albeit without as extensive testing or quality assurance, provide continued support for older devices that no longer receive official updates; or bring Android to devices that were officially released running other operating systems, such as the HP TouchPad.



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