Thursday, 20 June 2013

An Overview of Android OS


Most people still think that the Android project has been developed by Google. But it is not. OS Android has created a small innovative company Android Inc. in Silicon Valley in the United States. And when, in 2005, Google acquired the project Android, everyone was very surprised and did not believe in the success of the event. Many natural questions arose why the success of contact with non-core segment of the market, the outlook for which is very vague? However, time has proved the correctness of the strategy of Google, which proved that the mobile operating system can be successfully developed and maintained on an open platform. Currently, Google continues to invest significant money and resources into the project Android, which turned out to be extremely successful. So in July 2010 they have activated daily 160,000 mobile devices running Android, which is already very good, considering that the first device running Android appeared in October 2008. With this project in less than two years, Google has radically changed the situation in the mobile market! 

The openness of the Android OS platform developers has never been so easy to make money on their own. After all, Android users do not know about you, but they know and trust Google to it. Anyone can publish your application on online  Android Market, which is controlled by Google. Therefore, it is Google and guarantees the quality of the applications at online Android Market. It is natural that people are willing to buy the application on this site.

Application Development

Why develop your own applications for the Android OS ? And why not? Do you want to make your application to be made ​​available to millions of users around the world? Do you want to publish your application as soon as it is debugged and tested? Want to make money in intellectual work? Want to work on an open platform? If your answer to at least one of these questions is yes, it means that you do make sense to develop applications for the Android OS .

As an application developer, you will get the opportunity to create applications for a brand new market, the daily increasing by leaps and bounds. It is predicted that the next few years, Android will surely overtake other platforms on the market of software for mobile devices. With such a large number of users has never been so easy to write applications that will be loaded by real people. Service Android Market will give your application into the hands of those users. Users no longer need to wander around the Internet looking for the right application, which you can now simply download and install directly on the gadget. Service Android Market is now pre-installed on almost all mobile devices running OS Android. That's why most people are not looking for the right applications to the Internet, and the Android Market. From the statistics of site Android Market. it can be clearly seen that the number of downloads each application increases almost daily. This applies to both free and paid applications. A part of OS Android platform comes with a very large number of libraries API (ready-routines). It is the presence of routines greatly facilitated the process of creating rich applications and allows them to create in a short time.


The Android operating system is an open platform. This means that it is not tied to a single hardware manufacturer or service provider. This open platform allows OS Android rapidly gain market share. All equipment manufacturers and service providers can share equally in its capabilities by producing at its base devices and services and then selling them to the public. Source OS Android is available at and after the download is available to view, modify, and apply to everyone. Nothing prevents you to study the source code, it is good to analyze it, and understand how to address the desired task / function. This open source code enables mobile device manufacturers to create for their own user interfaces and integrate them with any innovations. This puts all the developers in the same competitive conditions.

OS Android can run on devices with different processors, with different size and resolution of the screen. Of course the specific parameters of the mobile device (e.g. screen size and resolution) are major factors that affect the operation of the device as a whole. Therefore, OS Android comes with a set of tools that help you to create applications tailored to the specific values ​​of the parameters a mobile device. For example, if your application requires a front facing camera, the Android Market, it will only be displayed for those types of mobile devices, which really is such a camera, and with the required parameters.

Using Java

To create an application for the Android OS, one does not have to be a rocket scientist. Programming for Android is quite an easy job because it uses language Java. Knowledge of the basic elements of Java makes it easy to create simple applications on Android. Of course, to create professional kind of application, it needs a different level of knowledge of the language Java. But writing applications for OS Android has become quite feasible task.

In Android applications, almost everything is done with the help of Java, but in some infrastructure components are used- such as tools XML. It is recommended to familiarize yourself with the basic elements of XML. It is enough to know the structure of the document XML, descriptions and attributes, all the rest is not necessary. If you have experience with XML and Java, so much the better. In any case, you can safely possible to continue to explore this series of articles to build your application Android.

As I said, the Android application written in Java, but not in a fully functional form, in which professional developers create their own applications - J2TT, but on a small subset of the language that is compatible with the Dalvik virtual machine . In addition to this subset has eliminated all of the classes that simply do not make sense for mobile devices. In subsequent articles, I will continue to step through the story of how you can create YOUR application environment OS Android.

Activities and Intentions

Android application consists of one or more operations (activities). It must contain at least one activity. For greater clarity, now you can imagine the activity as a container of a user interface that contains both the user interface itself, and the code that creates it. In other words, the activity is a schematic representation  of Android-apps. For example, a specific screen that the user sees. Android-application can have multiple operations and can switch between them at runtime.

Intentions (intents) - these are the messages on the platform Android. Intention consists of actions to be performed (view, edit, dial, etc.) and data. In other words, it's asynchronous messages that allow an application to request functions from other activities .

Action (action) - a combination of operations that will be performed in the preparation of intentions, and data on which to perform the operation. For example, such data may be options contact from your address book. Intentions are used to run activities and communication between the different parts of the system Android. The application can either transmit or receive intentions .

Transfer of intent does not necessarily mean that anything will happen in the application. To do this, you must register the receiver's intentions, which constantly listens to all intent and tells the manager of Android, what exactly needs to be done. If several of these receivers can receive one intention, you should create a user-friendly tool select the desired intent . A classic example of such a tool of choice - image gallery. In this case, the application displays the number of thumbnails and when you click on a thumbnail, it loads the selected image from the Internet.

By default, many registered receiver processes the general intent . For example, one aim would be to create an e-mail, and others - start another application. Intention can find several receivers, so the user is usually provided by the tool of choice, which asks specifically what should be done - to create an e-mail or launch another application.


In contrast to the full-featured computers that allow the user to move the pointer (cursor) on the screen, mobile devices running OS Android allow you to select commands by touching (usually a finger) to the control on the screen. But how to simulate a right click to select a particular menu? Instead of clicking the right button, OS Android introduces the concept of a long press (another name - a long click). It is realized by touching the icon or button and retaining pin in this position for several seconds. Only then will open a context menu. As a developer, you can specify the contents of the context menu and specify commands in this menu, and which are subject to the selection of appropriate elements. In addition, you can allow the user to click / select different elements of the menu using two fingers. 

However, it should be remembered that the fingers of the people can be very different, so the controls must be of sufficient size and suitable not only for tiny fingers of a charming girl, but for podgy fingers of obese people also. In other words, distance between adjacent elements in the context menu should be large enough that would work comfortably while using a thin stylus as well as fingers of various sizes.

1 comment:

  1. Thank you for your introduction ^.^

    I have one question.

    Does that mean we don't need to type any Linux command in using Android mobile operating system ?