This android developer tutorial explains the basics of android.  Important concepts about activity, content providers and services.

STEP 1:

Before starting Android , you should have basic knowledge of the below technologies :

a) Object oriented programming concepts

b) Some experience in java programming

c) Experience with eclipse.

STEP 2:

In order to start the programming in Android you will have to first download ADT from the

http://developer.android.com/sdk/index.html
Download the latest android studio for windows.

Let us check some more information about Android

Android Architecture

a) Android runs on top of Linux

b) Dalvik virtual machine optimized for mobile devices.

c) Integrated browser

d) Optimized graphics

e) sql lite database for data storage.

The first version of android was android 2.0 and after that there are many different versions released for android.

1) All android applications are written in java programming language.

2) All android applications are compiled into an android package file called .apk file.

3) Every application runs into its own sandbox.

4) Every application consists of

a) A manifest file

b) Components

c) Resources

We will discuss each one of them separately:

1) Components : Components consists of

a) Activities : Activities are basically single screen that allows user to interact with it.

For example : For sending email, the user clicks on compose button. The form that opens on clicking
compose button is an activity.

The screen that opens to show users inbox is again an activity.

So every screen the user interacts with is an activity in android.

* An application consists of many activities.

* When a new activity starts, the other one is  pushed on the back stack.

* user can move back and forth ,by clicking different buttons to show different activities or  user screen.
* The GUI of the activity is created using java or xml file

2) Services :

Services performs operations that take lot of time and it runs on the background along with the component.
* Services do not have any user interface.

* Services are basically used to accomplish long operations in the background.

3) Content Providers:

*Content providers are basically used to store and retrieve data and make it accesible to all the applications.

* It shares the data among the applications.

* Data is stored as simple tables in the database.

4) Broadcast Receivers:

*Broad cast receivers are basically the components that responds to the system wide broadcast annoucement.

For example : When battery is low, broadcast receiver, receives the message and notifies to the user.

* it displays the message on the status bar.

* Broadcast receivers has no user interface of its own.

* Application can also generate broadcast, so other application listen to that and can respond to the broadcast.

5) Android manifest file:

This is the most important file for creating android application. The name of the android manifest file is (AndroidManifest.xml)
* It explains about the android application to the android system.

* It also defines the permission of the application so that android system knows about the permission.

* It defines all the activities, content providers, components that are used in the system.

This android developer tutorial explains the basics of all the android files.

Please click on the  below link to go to the next chapter of android developer tutorial.

Android tutorials