Android APIs
public abstract class

Filter

extends Object
java.lang.Object
   ↳ android.widget.Filter

Class Overview

A filter constrains data with a filtering pattern.

Filters are usually created by Filterable classes.

Filtering operations performed by calling filter(CharSequence) or filter(CharSequence, android.widget.Filter.FilterListener) are performed asynchronously. When these methods are called, a filtering request is posted in a request queue and processed later. Any call to one of these methods will cancel any previous non-executed filtering request.

See also:

Summary

Nested Classes
interface Filter.FilterListener

Listener used to receive a notification upon completion of a filtering operation. 

class Filter.FilterResults

Holds the results of a filtering operation. 

Public Constructors
Filter()

Creates a new asynchronous filter.

Public Methods
CharSequence convertResultToString(Object resultValue)

Converts a value from the filtered set into a CharSequence.

final void filter(CharSequence constraint, Filter.FilterListener listener)

Starts an asynchronous filtering operation.

final void filter(CharSequence constraint)

Starts an asynchronous filtering operation.

Protected Methods
abstract Filter.FilterResults performFiltering(CharSequence constraint)

Invoked in a worker thread to filter the data according to the constraint.

abstract void publishResults(CharSequence constraint, Filter.FilterResults results)

Invoked in the UI thread to publish the filtering results in the user interface.

[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public Filter ()

Added in API level 1

Creates a new asynchronous filter.

Public Methods

public CharSequence convertResultToString (Object resultValue)

Added in API level 1

Converts a value from the filtered set into a CharSequence. Subclasses should override this method to convert their results. The default implementation returns an empty String for null values or the default String representation of the value.

Parameters
resultValue the value to convert to a CharSequence
Returns
CharSequence a CharSequence representing the value

public final void filter (CharSequence constraint, Filter.FilterListener listener)

Added in API level 1

Starts an asynchronous filtering operation. Calling this method cancels all previous non-executed filtering requests and posts a new filtering request that will be executed later.

Upon completion, the listener is notified.

Parameters
constraint the constraint used to filter the data
listener a listener notified upon completion of the operation

public final void filter (CharSequence constraint)

Added in API level 1

Starts an asynchronous filtering operation. Calling this method cancels all previous non-executed filtering requests and posts a new filtering request that will be executed later.

Parameters
constraint the constraint used to filter the data

Protected Methods

protected abstract Filter.FilterResults performFiltering (CharSequence constraint)

Added in API level 1

Invoked in a worker thread to filter the data according to the constraint. Subclasses must implement this method to perform the filtering operation. Results computed by the filtering operation must be returned as a Filter.FilterResults that will then be published in the UI thread through publishResults(CharSequence, android.widget.Filter.FilterResults).

Contract: When the constraint is null, the original data must be restored.

Parameters
constraint the constraint used to filter the data
Returns
Filter.FilterResults the results of the filtering operation

protected abstract void publishResults (CharSequence constraint, Filter.FilterResults results)

Added in API level 1

Invoked in the UI thread to publish the filtering results in the user interface. Subclasses must implement this method to display the results computed in performFiltering(CharSequence).

Parameters
constraint the constraint used to filter the data
results the results of the filtering operation