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Android.App.ExpandableListActivity Class

An activity that displays an expandable list of items by binding to a data source implementing the ExpandableListAdapter, and exposes event handlers when the user selects an item.

See Also: ExpandableListActivity

Syntax

[Android.Runtime.Register("android/app/ExpandableListActivity", DoNotGenerateAcw=true)]
public class ExpandableListActivity : Activity, ExpandableListView+IOnChildClickListener, ExpandableListView+IOnGroupCollapseListener, ExpandableListView+IOnGroupExpandListener, IDisposable

Remarks

An activity that displays an expandable list of items by binding to a data source implementing the ExpandableListAdapter, and exposes event handlers when the user selects an item.

ExpandableListActivity hosts a ExpandableListView object that can be bound to different data sources that provide a two-levels of data (the top-level is group, and below each group are children). Binding, screen layout, and row layout are discussed in the following sections.

Screen Layout

ExpandableListActivity has a default layout that consists of a single, full-screen, centered expandable list. However, if you desire, you can customize the screen layout by setting your own view layout with setContentView() in onCreate(). To do this, your own view MUST contain an ExpandableListView object with the id "@android:id/list" (or NoType:android/R$id;Href=../../../reference/android/R.id.html#list if it's in code)

Optionally, your custom view can contain another view object of any type to display when the list view is empty. This "empty list" notifier must have an id "android:empty". Note that when an empty view is present, the expandable list view will be hidden when there is no data to display.

xml Example

 <?xml version="1.0" encoding="UTF-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:orientation="vertical"
         android:layout_width="match_parent" 
         android:layout_height="match_parent"
         android:paddingLeft="8dp"
         android:paddingRight="8dp">
 
     <ExpandableListView android:id="@id/android:list"
               android:layout_width="match_parent" 
               android:layout_height="match_parent"
               android:background="#00FF00"
               android:layout_weight="1"
               android:drawSelectorOnTop="false"/>
 
     <TextView android:id="@id/android:empty"
               android:layout_width="match_parent" 
               android:layout_height="match_parent"
               android:background="#FF0000"
               android:text="No data"/>
 </LinearLayout>
The IExpandableListAdapter set in the ExpandableListActivity via ExpandableListActivity.SetListAdapter(IExpandableListAdapter) provides the Views for each row. This adapter has separate methods for providing the group Views and child Views. There are a couple provided IExpandableListAdapters that simplify use of adapters: SimpleCursorTreeAdapter and SimpleExpandableListAdapter.

xml Example

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:orientation="vertical">
 
     <TextView android:id="@+id/text1"
         android:textSize="16sp"
         android:textStyle="bold"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"/>
 
     <TextView android:id="@+id/text2"
         android:textSize="16sp"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"/>
 </LinearLayout>

The following code demonstrates an (ugly) custom screen layout. It has a list with a green background, and an alternate red "no data" message.

Row Layout

With these, you can specify the layout of individual rows for groups and children in the list. These constructor takes a few parameters that specify layout resources for groups and children. It also has additional parameters that let you specify which data field to associate with which object in the row layout resource. The SimpleCursorTreeAdapter fetches data from ICursors and the SimpleExpandableListAdapter fetches data from ILists of IMaps.

Android provides some standard row layout resources. These are in the NoType:android/R$layout;Href=../../../reference/android/R.layout.html class, and have names such as simple_list_item_1, simple_list_item_2, and two_line_list_item. The following layout XML is the source for the resource two_line_list_item, which displays two data fields,one above the other, for each list row.

You must identify the data bound to each TextView object in this layout. The syntax for this is discussed in the next section.

Binding to Data

You bind the ExpandableListActivity's ExpandableListView object to data using a class that implements the IExpandableListAdapter interface. Android provides two standard list adapters: SimpleExpandableListAdapter for static data (Maps), and SimpleCursorTreeAdapter for Cursor query results.

See Also

[Android Documentation]

Requirements

Namespace: Android.App
Assembly: Mono.Android (in Mono.Android.dll)
Assembly Versions: 0.0.0.0
Since: Added in API level 1

The members of Android.App.ExpandableListActivity are listed below.

See Also: Activity

Public Constructors

Protected Constructors

A constructor used when creating managed representations of JNI objects; called by the runtime.

Public Properties

[read-only]
ExpandableListAdapterIExpandableListAdapter. Get the ExpandableListAdapter associated with this activity's ExpandableListView.
[read-only]
ExpandableListViewExpandableListView. Get the activity's expandable list view widget.
[read-only]
SelectedIdInt64. Gets the ID of the currently selected group or child.
[read-only]
SelectedPositionInt64. Gets the position (in packed position representation) of the currently selected group or child.

Protected Properties

[read-only]
override
ThresholdClassIntPtr. This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.
[read-only]
override
ThresholdTypeType. This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

Public Methods

OnChildClick(ExpandableListView, View, Int32, Int32, Int64) : Boolean
Override this for receiving callbacks when a child has been clicked.
OnGroupCollapse(Int32)
Override this for receiving callbacks when a group has been collapsed.
OnGroupExpand(Int32)
Override this for receiving callbacks when a group has been expanded.
SetListAdapter(IExpandableListAdapter)
Provide the adapter for the expandable list.
SetSelectedChild(Int32, Int32, Boolean) : Boolean
Sets the selection to the specified child.
SetSelectedGroup(Int32)
Sets the selection to the specified group.