Android ListView → Android ExpandableListView – Camposha

Android ListView

Android ListView

Android ListView

Android ExpandableListView

Android ExpandableListView Tutorial and Examples.

An ExpandableListView is a view that shows items in a vertically scrolling two-level list. You can imagine it’s a form of a ListView given the name or the fact that it derives from it, however ExpandableListView is obviously more complex in that it’s view items can be expanded and collapsed.

It allows two levels:

  1. groups which can individually be expanded
  2. children shown when the groups are expanded.

Powering ExpandableListView is the ExpandableListAdapter. It is this adapter that supplies items to populate our ExpandableListView.

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ExpandableListView API Definition.

ExpandableListView isn’t young, even if alot of developers haven’t used it yet. It has existed since the beginning of android, API level 1.

As a class it derives from [ListView](/android/listview:

public class ExpandableListView extends ListView 

Both reside in the android.widget package.

Here’s ExpandableListView‘s inheritance hierarchy:

java.lang.Object
   ↳    android.view.View
       ↳    android.view.ViewGroup
           ↳    android.widget.AdapterView<android.widget.ListAdapter>
               ↳    android.widget.AbsListView
                   ↳    android.widget.ListView
                       ↳    android.widget.ExpandableListView

States and Indicators

Beside the item views in your ExpandableListView normally you see an indicator. This visually notifies you that you need to either expand to see more content or close the child. They tell you the current state of the expandable listview.

These states can be:

  1. Expanded group.
  2. Collapsed group
  3. Child
  4. Last child).

These indicators can be set using the setChildIndicator(Drawable) or setGroupIndicator(Drawable) (or the corresponding XML attributes).

The default style for an ExpandableListView provides indicators which will be shown next to Views given to the ExpandableListView.

The layouts android.R.layout.simple_expandable_list_item_1 and android.R.layout.simple_expandable_list_item_2 (which should be used with SimpleCursorTreeAdapter) contain the preferred position information for indicators.

You can find more documentation about ExpandableListView here.

 

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