Fundamental blocks of an Android Application

This article will provide an overview of the android application components from a developer's point of view.

In order to develop an Android application, we need to first know what components make up an android app. There are four fundamental components which form an Android App. These building blocks, which are implemented as JAVA classes, are:

• Activity Class - Activities provide the GUI to the user of the application, enabling the user to enter and receive data. Therefore, we can say this component works in the foreground, i.e, is visible to the user.

• Service Class -  Services allow the different processes to request operations and share data.

• Broadcast receiver - This block can be considered like a dormant component, waiting for an event to occur, like a message to be received, or battery level going below 5% etc. and take actions like show notifications.
  
  
  
  
  Consider, the watchman of your Apartment. He sits at the main gate of the complex, dormant. While you are inside your flat unaware of any activity occurring outside. Now say, some friend decides to visit you. This friend reaches the complex gates. The watchman sitting there, stops the visitor, finds out which flat this visitor wants to go to, and then notifies you through intercom that - You have a visitor! In this case the watchman acts like the Broadcast receiver of an Android application.

• Content Provider - We have discussed the Content Provider before (read here). Content Provider enables data sharing between Android applications. It allows data to be centralised at one place like a database, however, it has many more other functions than being just a database.

Now that we have some idea of the organisation of our application, next we will delve into details in the next post.

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LEARN ANDROID FOR FREE

Want to have your own android app some day?

A lot of us want to learn writing Android Apps. But where does one start?

It looks like a daunting and never ending task. There are a million resources to learn from, but when you look at the never-ending list of documentation they have, it seems like you are drowning in a sea of information and yet starving for a drop of practical knowledge. Following this, many have given up there quest for Learning Android.

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However, the truth is you don't have to read tons and tons of documentation of Android Manual and resources to learn Android. You can learn Android for free and within a short time.

Don't get confused. Start learning for free.

If you are looking for a guide to learning Android the practical way, you have found the right place. My posts have the gist of all the documentation. And you need nothing except a laptop/PC and this blog will set you rolling.

How to use this blog to learn Android App Development free

Book mark this page . Start here and follow this list in order. I will keep updating as and when needed.

1. How to develop a mobile application using Android
2. Basics of Android
3. The Android Application Framework

4. Fundamental Blocks of an Android Application

5. to be continued..

Hope this Android Application Development tutorial is helping. If not, please lets us know.

Do you have Questions? Arguments? doubts?... we'll try our best to resolve

How to develop a mobile application using Android

So, You want to develop your own mobile application that would run on Android. You are at the right page. This and a lot more posts will teach beginners how to develop an android app for free.

To start off here is what you will need:

1. Basic knowledge of the Android System. Read this post.
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2. Android SDK which can be downloaded here

3. JAVA programming language. If you don't know that, don't worry. This blog will help you cope with that.

Once you are done with the above requisites, you are all set to learn how to develop your own android application. Keep following this blog.

BASICS OF ANDROID

To learn how to develop a Mobile Application using Android, We need to first understand the basics of Android. This and the following few posts will provide a guide or tutorial for Android mobile app development.

Overview of The  Android Stack 

The Android is a platform which support mobile devices such as phones and tablets. It has several layers that manage everything from sensors to the applications you see on the screen (and the android app that you are going to develop).

Shown below is a representation of Android stack

The Android System Stack

Android has:

• LINUX KERNEL as the bottom layer

• which provides the operating system services.

• THE SYSTEM LIBRARIES and the ANDROID RUNTIME SYSTEM above it

• C/C++ libraries that make many operations easier for the programmer and also help improve performance
• ANDROID RUNTIME : JAVA libararies and the Dalvik Virtual Machine (Explained below)

• next up is a rich APPLICATION FRAMEWORK

• reusable software that can be used by many applications, like buttons and icons
• Deeper Look into Application Framework

• and  at the top of all these the APPLICATIONS that we use. This is the interface of the USER and the rest of the android system

THE DALVIK VIRTUAL MACHINE (DVM)

Android programs are generally written in JAVA. However they are not executed bythe JAVA virtual machine. They actually run on the Dalvik Virtual Machine. 

Applications programmed in JAVA are compiled using a JAVA compiler to generate the JAVA byte code. In order to make it executable in the DVM, the JAVA bytecode is converted to a DEX format using appropriate tools. This DEX code, with other packages of the application, is installed on the target device and when run, it is executed by the Dalvik Virtual Machine. 

WHY DVM and NOT JVM?
JVM is not designed to run on mobile devices where resources like CPU, memory and power are limited. DVM is particularly designed for this purpose. Hence while developing an Android app, the developer has to worry less about the constrained resources.

Next,  Let us have a closer look at the android application framework.

Hope this Android Application Development tutorial is helping. If not, please lets us know.

Do you have Questions? Arguments? doubts?... we'll try our best to resolve
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