[Android] Important Classes

1. Activity
   
   1. ActivityManager
      Features:
      
      • Return information about the memory usage of one or more processes
      • Returns a list of any processes that are currently in an error condition.
      • Return a list of the tasks that the user has recently launched
      • Returns a list of application processes that are running on the device
      • Return a list of the services that are currently running
      • Return a list of the tasks that are currently running
      • Kill all background processes associated with the given package
   2. Activity Types
   1. Activity
      
   2. ActivityGroup
      
      • TabActivity
        TabHost, TabWidget
        
      • xxx
        
   3. ListActivity
   4. xxx
      
   3. xxx
      
2. Service
   IBinder, Binder, Messenger, ServiceConnection
   
3. BroadcastReceiver
4. Date Storage
1. File
   
2. SQLite
   
3. Content Provider
   
   • ContentResolver
     ContentObserver 
     
   • xxx
     
4. xxx
   
5. Intent & IntentFilter
   
   1. Intent
      An intent is an abstract description of an operation to be performed. It can be used to launch an Activity, to send broadcast receiver, and to communicate with a background Service.
   2. IntentFilter
      Structured description of Intent values to be matched. An IntentFilter can match against actions, categories, and data (either via its type, scheme, and/or path) in an Intent. It also includes a "priority" value which is used to order multiple matching filters
      
6. ComponentName
   Identifier for a specific application component (Activity, Service, BroadcastReceiver, or ContentProvider). the package and class inside of the package are used to identify a component.
   
7. Notify User
   
   1. Status Bar
      NotificationManager, Notification, PendingIntent
      
   2. Toast
   3. Dialog
      
      1. AlertDialog
         AlertDialog.Builder,
         
         • ProgressDialog
           Can be shown as a horizontal progress bar, or a ciruclar and spinning progress bar
         • TimePickerDialog
         • DatePickerDialog
           
      2. xxx
   4. xxx
      
8. TelephonyManager
1. Features:
1. Get call state
2. Get cell location
3. Get device id: IMEI or MEID
4. Get device software version
5. Get Phone number
6. Get operator
7. 
   
2. Need to declare proper permission
   
3. ...
   
9. WallpaperManager
   
10. SearchManager
11. Schedule Task
    
    1. AlarmManager
12. Key
    
    1. KeyguardManager
       A class that can be used to lock and unlock the keyboard.
       
    2. xxx
       
13. Blue Tooth
    
    1. BluetoothAdapter
    2. BluetoothDevice
    3. BluetoothServerSocket
    4. BluetoothSocket
14. Device Administrate
    Implement the features as the application Settings > Security location > Screen unlock pattern. you can find the sample DeviceAdminSample.java within SDK 2.2.
    
    1. DevicePolicyManager
    2. DeviceAdminReceiver
15. ...