Android APIs
public abstract class

ContentObserver

extends Object
java.lang.Object
   ↳ android.database.ContentObserver
Known Direct Subclasses

Class Overview

Receives call backs for changes to content. Must be implemented by objects which are added to a ContentObservable.

Summary

Public Constructors
ContentObserver(Handler handler)
Creates a content observer.
Public Methods
boolean deliverSelfNotifications()
Returns true if this observer is interested receiving self-change notifications.
final void dispatchChange(boolean selfChange, Uri uri)
Dispatches a change notification to the observer.
final void dispatchChange(boolean selfChange)
This method was deprecated in API level 16. Use dispatchChange(boolean, Uri) instead.
void onChange(boolean selfChange, Uri uri)
This method is called when a content change occurs.
void onChange(boolean selfChange)
This method is called when a content change occurs.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public ContentObserver (Handler handler)

Added in API level 1

Creates a content observer.

Parameters
handler The handler to run onChange(boolean) on, or null if none.

Public Methods

public boolean deliverSelfNotifications ()

Added in API level 1

Returns true if this observer is interested receiving self-change notifications. Subclasses should override this method to indicate whether the observer is interested in receiving notifications for changes that it made to the content itself.

Returns
boolean True if self-change notifications should be delivered to the observer.

public final void dispatchChange (boolean selfChange, Uri uri)

Added in API level 16

Dispatches a change notification to the observer. Includes the changed content Uri when available.

If a Handler was supplied to the ContentObserver constructor, then a call to the onChange(boolean) method is posted to the handler's message queue. Otherwise, the onChange(boolean) method is invoked immediately on this thread.

Parameters
selfChange True if this is a self-change notification.
uri The Uri of the changed content, or null if unknown.

public final void dispatchChange (boolean selfChange)

Added in API level 1

This method was deprecated in API level 16.
Use dispatchChange(boolean, Uri) instead.

Dispatches a change notification to the observer.

If a Handler was supplied to the ContentObserver constructor, then a call to the onChange(boolean) method is posted to the handler's message queue. Otherwise, the onChange(boolean) method is invoked immediately on this thread.

Parameters
selfChange True if this is a self-change notification.

public void onChange (boolean selfChange, Uri uri)

Added in API level 16

This method is called when a content change occurs. Includes the changed content Uri when available.

Subclasses should override this method to handle content changes. To ensure correct operation on older versions of the framework that did not provide a Uri argument, applications should also implement the onChange(boolean) overload of this method whenever they implement the onChange(boolean, Uri) overload.

Example implementation:


 // Implement the onChange(boolean) method to delegate the change notification to
 // the onChange(boolean, Uri) method to ensure correct operation on older versions
 // of the framework that did not have the onChange(boolean, Uri) method.
 @Override
 public void onChange(boolean selfChange) {
     onChange(selfChange, null);
 }

 // Implement the onChange(boolean, Uri) method to take advantage of the new Uri argument.
 @Override
 public void onChange(boolean selfChange, Uri uri) {
     // Handle change.
 }
 

Parameters
selfChange True if this is a self-change notification.
uri The Uri of the changed content, or null if unknown.

public void onChange (boolean selfChange)

Added in API level 1

This method is called when a content change occurs.

Subclasses should override this method to handle content changes.

Parameters
selfChange True if this is a self-change notification.