What is Android? - Question of the Era ........

1.1. Android Operation System

Android is an operating system based on Linux with a Java programming interface.

The Android Software Development Kit (Android SDK) provides all necessary tools to develop Android applications. This includes a compiler, debugger and a device emulator, as well as its own virtual machine to run Android programs.

Android is currently primarily developed by Google.

Android allows background processing, provides a rich user interface library, supports 2-D and 3-D graphics using the OpenGL libraries, access to the file system and provides an embedded SQLite database.

Android applications consist of different components and can re-use components of other applications. This leads to the concept of a task in Android; an application can re-use other Android components to archive a task. For example you can trigger from your application another application which has itself registered with the Android system to handle photos. In this other application you select a photo and return to your application to use the selected photo.

Android is the newest mobile device operating system, we will be able to confidently create your own mobile device programs after learning android. Android applications are developed in Java and run on the Linux 2.6 kernel.

                                              

Open Handset Alliance and Android

The Open Handset Alliance is a group of hardware and software developers, including Google, NTT DoCoMo,

Sprint Nextel, and HTC, whose goal is to create a more open cell phone environment.

The first product to be released under the alliance is the mobile device operating

system, Android.

With the release of Android, Google made available a host of development tools

and tutorials to aid would-be developers onto the new system. Help files, the platform

software development kit (SDK), and even a developers’ community can be found at

Google’s Android website, http://code.google.com/android. This site should be your

starting point, and I highly encourage you to visit the site.

hardware platforms have been announced for Android to run on. HTC, LG

Electronics, Motorola, and Samsung are members of the Open Handset Alliance, under

which Android has been released, so we can only hope that they have plans for a few

Android-based devices in the near future. With its release in November 2007, the system

itself is still in a software-only beta.

Introduction to Android

Android, as a system, is a Java-based operating system that runs on the Linux 2.6 kernel.

The system is very lightweight and full featured. Figure 1-1 shows the unmodified

Android home screen.

Figure

Android applications are developed using Java and can be ported rather easily to the

new platform.

1.2. Google Play (Android Market)

Google offers the Google Play service in which programmers can offer their Android application to Android users. Google phones include the Google Play application which allows to install applications.

Google Play also offers an update service, e.g. if a programmer uploads a new version of his application to Google Play, this service will notify existing users that an update is available and allow to install it.

Google Play used to be called Android Market.

1.3. Security and permissions

During deployment on an Android device, the Android system will create a unique user and group ID for every Android application. Each application file is private to this generated user, e.g. other applications cannot access these files.

In addition each Android application will be started in its own process.

Therefore by means of the underlying Linux operating system, every Android application is isolated from other running applications.

If data should be shared, the application must do this explicitly, e.g. via a service or a ContentProvider.

Android also contains a permission system. Android predefines permissions for certain tasks but every application can define additional permissions.

An Android application declare its required permissions in its AndroidManifest.xml configuration file. For example an application may declare that it requires access to the Internet.

Permissions have different levels. Some permissions are automatically granted by the Android system, some are automatically rejected.

In most cases the requested permissions will be presented to the user before installation of the application. The user needs to decide if these permissions are given to the application.

If the user denies a permission required by the application, this application cannot be installed. The check of the permission is only performed during installation, permissions cannot be denied or granted after the installation.

Not all users pay attention to the required permissions during installation. But some users do and they write negative reviews on Google Play.