Components of Android

A component is a piece of code that has a well-defined life cycle like Activity, Intent, Service etc.

 The fundamental components of Android are activities, views, intent, service, content providers, fragments and AndroidManifest.xml.

 Activity is a class that represents a single screen. It is like a Frame in AWT.

 View is the UI element such as Button, TextView, Label etc. Anything that you see on display screen is View.

 Intent is used to invoke the components. It is mainly used to:
  • Start the service
  • Launch an activity
  • Display a webpage
  • Broadcast a message
  • Dial a phone call etc.
Service is a background process that runs for a long time.
There are two types of services local and remote. Local service is accessed from within the application and remote service is accessed remotely from another application running on the same device.

 Content Providers are used to share data between the applications.

Fragments are part of an activity. An activity can display one or more fragments on the screen at the same time.

AndroidManifest.xml contains information about activities, content providers, services, permissions etc. It is like web.xml file in J2EE.

Android Virtual Device(AVD)
It is the device that used to run, debug and test an android application without the need of mobile or tablet. It can be created in different configurations to emulate different types of real devices. It also known as an Emulator.

Comments

Post a Comment

Popular posts from this blog

MVC Architecture in Android

Image
MVC represents Model-View-Controller Model : Manage the behavior and data of the application R esponds to requests for information about its state (usually from the view) Responds to instructions to change state (usually from the controller) Allows the views to produce updated output View : T ypically a user interface element O ne to one correspondence with a display surface Present the model to the user Generates the output representation to the user Controller : Controls both model and view Accepts input from the user and instructs the model and the view to perform actions based on that input Update view when model changes Update model when user manipulate the input
Read more

Get Current Location using GPS/Network Provider

Hello to all, Today I teach you that how can we get current location. In android's new SDK tools, LocationManager class does not give any network provider's status. It always gives null value. Still it works in some of the android devices rarely. So that's why I include code for both network provider and gps provider for getting current location. Create one service class name LocationFinder  and implements it LocationListener . All the code which is related to Location, is doing in that service class and from MainActivity , call its method through its instance in onResume() method. The reason you know, why its called in onResume(), because when you enable GPS and come back in activity, then its again check Location's status. In the code, if GPS not enable, I show settings alert pop-up, to go settings menu. When you enable GPS, you will get current location after 2-3 seconds. If not, come again to activity and surely get location. Make sure, must add persmi...
Read more

SQLiteDatabase (Without SqliteOpenHelper class)

Image
SQLite is a open-source relational database, that is used to perform database operations such as creating, storing, manipulating, retrieving and deleting data from the database. SQLitedatabase is used in android in two way: Using SQLiteOpenHelper class Without SQLiteOpenHelper class Here we are going to see the example of sqlitedatabase without SQLiteOpenHelper class. In this example, we will do following: Create a database Create a table Insert values into table Retrieve values Update values Delete values Create a database: SQLiteDatabase db=openOrCreateDatabase(DB_NAME, Context.MODE_PRIVATE, null); This opens a database defined in the constant DB_NAME, if it already exists. Else it creates a new database and open it. Create a table: db.execSQL("CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, DESIGNATION TEXT, CONTACT NUMBER, AREA TEXT, CITY TEXT);"); This creates ...
Read more