Mumbai University > Information Technology > Sem 5 > Open Source Technology

Marks: 5M

Year: Dec 2015

• Activity is an application component that allows user to perform an operation.
• User performs various operation as making call, clicking photos, sending messages, viewing a map. For each operation an activity is created.
• The main objective is to interact with users.
• Activity plays crucial role as they are used to create a display for users.
• Activity is composed of views that handles layout and provides text element, button, forms, graphics to device screen.

Creating Activity

• We can create an activity by creating a java class that extends Activity class.

• Each activity needs to create window for which user components are loaded. For this SetContentView() method is used.

• Activities are displayed as full screen, but you can set different views such as floating by using WindowIsFloating or embedded by using ActivityGroupClass.

Startind an activity

• Android API provides startActivity(Intent) method to start a new activity.

• When new activity is invoked it is placed at the top of activity stack by pushing other activities.

• StartActivity() method accepts single argument.

• OnCreate() is called during creation of activity
• OnStart() is called when user can visualize activity.
• OnResume() is called when activity starts interaction with user.
• OnPause() is called when user is not able to see the activity.
• OnStop() is called when activity is not visible.
• OnRestart is called when activity is stopped.
• OnDestroy() is called to destroy activity.