# ExpandableListAdapter
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
# ExpandableListAdapter
*** ** * ** ***
Kotlin\|[Java](https://developer.android.com/reference/android/widget/ExpandableListAdapter "View this page in Java")
```
interface ExpandableListAdapter
```
|------------------------------------------------------------------------------------------------------------------------------|
| [android.widget.ExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#) |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Known Direct Subclasses [BaseExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/BaseExpandableListAdapter) |----------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [BaseExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/BaseExpandableListAdapter) | Base class for a[ExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#)used to provide data and Views from some data to an expandable list view. | |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Known Indirect Subclasses [CursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/CursorTreeAdapter),[ResourceCursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/ResourceCursorTreeAdapter),[SimpleCursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/SimpleCursorTreeAdapter),[SimpleExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/SimpleExpandableListAdapter) |--------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [CursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/CursorTreeAdapter) | An adapter that exposes data from a series of[Cursor](https://developer.android.com/reference/kotlin/android/database/Cursor.html#)s to an[ExpandableListView](https://developer.android.com/reference/kotlin/android/widget/ExpandableListView)widget. | | [ResourceCursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/ResourceCursorTreeAdapter) | A fairly simple ExpandableListAdapter that creates views defined in an XML file. | | [SimpleCursorTreeAdapter](https://developer.android.com/reference/kotlin/android/widget/SimpleCursorTreeAdapter) | An easy adapter to map columns from a cursor to TextViews or ImageViews defined in an XML file. | | [SimpleExpandableListAdapter](https://developer.android.com/reference/kotlin/android/widget/SimpleExpandableListAdapter) | An easy adapter to map static data to group and child views defined in an XML file. | |
An adapter that links a[ExpandableListView](https://developer.android.com/reference/kotlin/android/widget/ExpandableListView)with the underlying data. The implementation of this interface will provide access to the data of the children (categorized by groups), and also instantiate[View](https://developer.android.com/reference/kotlin/android/view/View.html#)s for children and groups.
## Summary
| Public methods ||
|--------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| abstract[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [areAllItemsEnabled](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#areAllItemsEnabled())`()`
|
| abstract[Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)! | [getChild](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChild(kotlin.Int,%20kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `childPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Gets the data associated with the given child within the given group. |
| abstract[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [getChildId](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChildId(kotlin.Int,%20kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `childPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Gets the ID for the given child within the given group. |
| abstract[View](https://developer.android.com/reference/kotlin/android/view/View.html#)! | [getChildView](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChildView(kotlin.Int,%20kotlin.Int,%20kotlin.Boolean,%20android.view.View,%20android.view.ViewGroup))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `childPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `isLastChild:` `[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html)`, `convertView:` `[View](https://developer.android.com/reference/kotlin/android/view/View.html#)!`, `parent:` `[ViewGroup](https://developer.android.com/reference/kotlin/android/view/ViewGroup.html#)!`)` Gets a View that displays the data for the given child within the given group. |
| abstract[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [getChildrenCount](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChildrenCount(kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Gets the number of children in a specified group. |
| abstract[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [getCombinedChildId](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getCombinedChildId(kotlin.Long,%20kotlin.Long))`(`groupId:` `[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html)`, `childId:` `[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html)`)` Gets an ID for a child that is unique across any item (either group or child) that is in this list. |
| abstract[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [getCombinedGroupId](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getCombinedGroupId(kotlin.Long))`(`groupId:` `[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html)`)` Gets an ID for a group that is unique across any item (either group or child) that is in this list. |
| abstract[Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)! | [getGroup](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getGroup(kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Gets the data associated with the given group. |
| abstract[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | [getGroupCount](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getGroupCount())`()` Gets the number of groups. |
| abstract[Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | [getGroupId](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getGroupId(kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Gets the ID for the group at the given position. |
| abstract[View](https://developer.android.com/reference/kotlin/android/view/View.html#)! | [getGroupView](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getGroupView(kotlin.Int,%20kotlin.Boolean,%20android.view.View,%20android.view.ViewGroup))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `isExpanded:` `[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html)`, `convertView:` `[View](https://developer.android.com/reference/kotlin/android/view/View.html#)!`, `parent:` `[ViewGroup](https://developer.android.com/reference/kotlin/android/view/ViewGroup.html#)!`)` Gets a View that displays the given group. |
| abstract[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [hasStableIds](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#hasStableIds())`()` Indicates whether the child and group IDs are stable across changes to the underlying data. |
| abstract[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [isChildSelectable](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#isChildSelectable(kotlin.Int,%20kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`, `childPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Whether the child at the specified position is selectable. |
| abstract[Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | [isEmpty](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#isEmpty())`()`
|
| abstract[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [onGroupCollapsed](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#onGroupCollapsed(kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Called when a group is collapsed. |
| abstract[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [onGroupExpanded](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#onGroupExpanded(kotlin.Int))`(`groupPosition:` `[Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html)`)` Called when a group is expanded. |
| abstract[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [registerDataSetObserver](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#registerDataSetObserver(android.database.DataSetObserver))`(`observer:` `[DataSetObserver](https://developer.android.com/reference/kotlin/android/database/DataSetObserver.html#)!`)`
|
| abstract[Unit](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-unit/index.html) | [unregisterDataSetObserver](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#unregisterDataSetObserver(android.database.DataSetObserver))`(`observer:` `[DataSetObserver](https://developer.android.com/reference/kotlin/android/database/DataSetObserver.html#)!`)`
|
## Public methods
### areAllItemsEnabled
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun areAllItemsEnabled(): Boolean
```
**See Also**
- [android.widget.ListAdapter#areAllItemsEnabled()](https://developer.android.com/reference/kotlin/android/widget/ListAdapter#areAllItemsEnabled())
### getChild
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getChild(
groupPosition: Int,
childPosition: Int
): Any!
```
Gets the data associated with the given child within the given group.
| Parameters ||
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group that the child resides in |
| `childPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the child with respect to other children in the group |
| Return ||
|-----------------------------------------------------------------------------|-----------------------|
| [Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)! | the data of the child |
### getChildId
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getChildId(
groupPosition: Int,
childPosition: Int
): Long
```
Gets the ID for the given child within the given group. This ID must be unique across all children within the group. The combined ID (see[getCombinedChildId(long,long)](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getCombinedChildId(kotlin.Long,%20kotlin.Long))) must be unique across ALL items (groups and all children).
| Parameters ||
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group that contains the child |
| `childPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the child within the group for which the ID is wanted |
| Return ||
|------------------------------------------------------------------------------|----------------------------------|
| [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | the ID associated with the child |
### getChildView
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getChildView(
groupPosition: Int,
childPosition: Int,
isLastChild: Boolean,
convertView: View!,
parent: ViewGroup!
): View!
```
Gets a View that displays the data for the given child within the given group.
| Parameters ||
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group that contains the child |
| `childPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the child (for which the View is returned) within the group |
| `isLastChild` | [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html):Whether the child is the last child within the group |
| `convertView` | [View](https://developer.android.com/reference/kotlin/android/view/View.html#)!:the old view to reuse, if possible. You should check that this view is non-null and of an appropriate type before using. If it is not possible to convert this view to display the correct data, this method can create a new view. It is not guaranteed that the convertView will have been previously created by[getChildView(int,int,boolean,android.view.View,android.view.ViewGroup)](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChildView(kotlin.Int,%20kotlin.Int,%20kotlin.Boolean,%20android.view.View,%20android.view.ViewGroup)). |
| `parent` | [ViewGroup](https://developer.android.com/reference/kotlin/android/view/ViewGroup.html#)!:the parent that this view will eventually be attached to |
| Return ||
|---------------------------------------------------------------------------------|---------------------------------------------------------------|
| [View](https://developer.android.com/reference/kotlin/android/view/View.html#)! | the View corresponding to the child at the specified position |
### getChildrenCount
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getChildrenCount(groupPosition: Int): Int
```
Gets the number of children in a specified group.
| Parameters ||
|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group for which the children count should be returned |
| Return ||
|----------------------------------------------------------------------------|-------------------------------------------|
| [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | the children count in the specified group |
### getCombinedChildId
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getCombinedChildId(
groupId: Long,
childId: Long
): Long
```
Gets an ID for a child that is unique across any item (either group or child) that is in this list. Expandable lists require each item (group or child) to have a unique ID among all children and groups in the list. This method is responsible for returning that unique ID given a child's ID and its group's ID. Furthermore, if[hasStableIds()](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#hasStableIds())is true, the returned ID must be stable as well.
| Parameters ||
|-----------|----------------------------------------------------------------------------------------------------------------------------|
| `groupId` | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html):The ID of the group that contains this child. |
| `childId` | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html):The ID of the child. |
| Return ||
|------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | The unique (and possibly stable) ID of the child across all groups and children in this list. |
### getCombinedGroupId
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getCombinedGroupId(groupId: Long): Long
```
Gets an ID for a group that is unique across any item (either group or child) that is in this list. Expandable lists require each item (group or child) to have a unique ID among all children and groups in the list. This method is responsible for returning that unique ID given a group's ID. Furthermore, if[hasStableIds()](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#hasStableIds())is true, the returned ID must be stable as well.
| Parameters ||
|-----------|--------------------------------------------------------------------------------------------------|
| `groupId` | [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html):The ID of the group |
| Return ||
|------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | The unique (and possibly stable) ID of the group across all groups and children in this list. |
### getGroup
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getGroup(groupPosition: Int): Any!
```
Gets the data associated with the given group.
| Parameters ||
|-----------------|------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group |
| Return ||
|-----------------------------------------------------------------------------|----------------------------------------|
| [Any](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html)! | the data child for the specified group |
### getGroupCount
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getGroupCount(): Int
```
Gets the number of groups.
| Return ||
|----------------------------------------------------------------------------|----------------------|
| [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html) | the number of groups |
### getGroupId
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getGroupId(groupPosition: Int): Long
```
Gets the ID for the group at the given position. This group ID must be unique across groups. The combined ID (see[getCombinedGroupId(long)](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getCombinedGroupId(kotlin.Long))) must be unique across ALL items (groups and all children).
| Parameters ||
|-----------------|---------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group for which the ID is wanted |
| Return ||
|------------------------------------------------------------------------------|----------------------------------|
| [Long](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-long/index.html) | the ID associated with the group |
### getGroupView
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun getGroupView(
groupPosition: Int,
isExpanded: Boolean,
convertView: View!,
parent: ViewGroup!
): View!
```
Gets a View that displays the given group. This View is only for the group--the Views for the group's children will be fetched using[getChildView(int,int,boolean,android.view.View,android.view.ViewGroup)](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getChildView(kotlin.Int,%20kotlin.Int,%20kotlin.Boolean,%20android.view.View,%20android.view.ViewGroup)).
| Parameters ||
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group for which the View is returned |
| `isExpanded` | [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html):whether the group is expanded or collapsed |
| `convertView` | [View](https://developer.android.com/reference/kotlin/android/view/View.html#)!:the old view to reuse, if possible. You should check that this view is non-null and of an appropriate type before using. If it is not possible to convert this view to display the correct data, this method can create a new view. It is not guaranteed that the convertView will have been previously created by[getGroupView(int,boolean,android.view.View,android.view.ViewGroup)](https://developer.android.com/reference/kotlin/android/widget/ExpandableListAdapter#getGroupView(kotlin.Int,%20kotlin.Boolean,%20android.view.View,%20android.view.ViewGroup)). |
| `parent` | [ViewGroup](https://developer.android.com/reference/kotlin/android/view/ViewGroup.html#)!:the parent that this view will eventually be attached to |
| Return ||
|---------------------------------------------------------------------------------|---------------------------------------------------------------|
| [View](https://developer.android.com/reference/kotlin/android/view/View.html#)! | the View corresponding to the group at the specified position |
### hasStableIds
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun hasStableIds(): Boolean
```
Indicates whether the child and group IDs are stable across changes to the underlying data.
| Return ||
|------------------------------------------------------------------------------------|-------------------------------------------------------------|
| [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | whether or not the same ID always refers to the same object |
**See Also**
- [android.widget.Adapter#hasStableIds()](https://developer.android.com/reference/kotlin/android/widget/Adapter#hasStableIds())
### isChildSelectable
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun isChildSelectable(
groupPosition: Int,
childPosition: Int
): Boolean
```
Whether the child at the specified position is selectable.
| Parameters ||
|-----------------|------------------------------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the group that contains the child |
| `childPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):the position of the child within the group |
| Return ||
|------------------------------------------------------------------------------------|----------------------------------|
| [Boolean](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/index.html) | whether the child is selectable. |
### isEmpty
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun isEmpty(): Boolean
```
**See Also**
- [android.widget.ListAdapter#isEmpty()](https://developer.android.com/reference/kotlin/android/widget/Adapter#isEmpty())
### onGroupCollapsed
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun onGroupCollapsed(groupPosition: Int): Unit
```
Called when a group is collapsed.
| Parameters ||
|-----------------|-------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):The group being collapsed. |
### onGroupExpanded
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun onGroupExpanded(groupPosition: Int): Unit
```
Called when a group is expanded.
| Parameters ||
|-----------------|------------------------------------------------------------------------------------------------------|
| `groupPosition` | [Int](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-int/index.html):The group being expanded. |
### registerDataSetObserver
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun registerDataSetObserver(observer: DataSetObserver!): Unit
```
**See Also**
- [android.widget.Adapter#registerDataSetObserver(DataSetObserver)](https://developer.android.com/reference/kotlin/android/widget/Adapter#registerDataSetObserver(android.database.DataSetObserver))
### unregisterDataSetObserver
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels)
```
abstract fun unregisterDataSetObserver(observer: DataSetObserver!): Unit
```
**See Also**
- [android.widget.Adapter#unregisterDataSetObserver(DataSetObserver)](https://developer.android.com/reference/kotlin/android/widget/Adapter#unregisterDataSetObserver(android.database.DataSetObserver))