android.app
Class ExpandableListActivity

java.lang.Object
  android.content.Context
      android.content.ContextWrapper
          android.view.ContextThemeWrapper
              android.app.Activity
                  android.app.ExpandableListActivity

All Implemented Interfaces:

ComponentCallbacks, KeyEvent.Callback, LayoutInflater.Factory, View.OnCreateContextMenuListener, Window.Callback, ExpandableListView.OnChildClickListener, ExpandableListView.OnGroupCollapseListener, ExpandableListView.OnGroupExpandListener

public class ExpandableListActivity
extends Activity
implements View.OnCreateContextMenuListener, ExpandableListView.OnChildClickListener, ExpandableListView.OnGroupCollapseListener, ExpandableListView.OnGroupExpandListener

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 R.id.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.

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

 <?xml version="1.0" encoding="UTF-8"?>
 <LinearLayout
         android:orientation="vertical"
         android:layout_width="fill_parent" 
         android:layout_height="fill_parent"
         android:paddingLeft="8"
         android:paddingRight="8">
 
     <ExpandableListView id="android:list"
               android:layout_width="fill_parent" 
               android:layout_height="fill_parent"
               android:background="#00FF00"
               android:layout_weight="1"
               android:drawSelectorOnTop="false"/>
 
     <TextView id="android:empty"
               android:layout_width="fill_parent" 
               android:layout_height="fill_parent"
               android:background="#FF0000"
               android:text="No data"/>
 </LinearLayout>
 

Row Layout

The ExpandableListAdapter set in the ExpandableListActivity via setListAdapter(ExpandableListAdapter) provides the Views for each row. This adapter has separate methods for providing the group Views and child Views. There are a couple provided ExpandableListAdapters that simplify use of adapters: SimpleCursorTreeAdapter and SimpleExpandableListAdapter.

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 Cursors and the SimpleExpandableListAdapter fetches data from Lists of Maps.

Android provides some standard row layout resources. These are in the R.layout 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.

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:orientation="vertical">
 
     <TextView id="text1"
         android:textSize="16"
         android:textStyle="bold"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"/>
 
     <TextView id="text2"
         android:textSize="16"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"/>
 </LinearLayout>
 

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 ExpandableListAdapter interface. Android provides two standard list adapters: SimpleExpandableListAdapter for static data (Maps), and SimpleCursorTreeAdapter for Cursor query results.

See Also:

setListAdapter(android.widget.ExpandableListAdapter), ExpandableListView

Field Summary

(package private) ExpandableListAdapter	mAdapter
(package private) boolean	mFinishedStart
(package private) ExpandableListView	mList

Fields inherited from class android.app.Activity

DEFAULT_KEYS_DIALER, DEFAULT_KEYS_DISABLE, DEFAULT_KEYS_SEARCH_GLOBAL, DEFAULT_KEYS_SEARCH_LOCAL, DEFAULT_KEYS_SHORTCUT, FOCUSED_STATE_SET, mActivityInfo, mCalled, mConfigChangeFlags, mCurrentConfig, mDecor, mEmbeddedID, mFinished, mMainThread, mParent, mResultCode, mResultData, mStartedActivity, RESULT_CANCELED, RESULT_FIRST_USER, RESULT_OK

Fields inherited from class android.content.Context

ACTIVITY_SERVICE, ALARM_SERVICE, AUDIO_SERVICE, BIND_AUTO_CREATE, BIND_DEBUG_UNBIND, BLUETOOTH_SERVICE, CLIPBOARD_SERVICE, CONNECTIVITY_SERVICE, CONTEXT_IGNORE_SECURITY, CONTEXT_INCLUDE_CODE, KEYGUARD_SERVICE, LAYOUT_INFLATER_SERVICE, LOCATION_SERVICE, MODE_APPEND, MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITEABLE, NOTIFICATION_SERVICE, POWER_SERVICE, SEARCH_SERVICE, SENSOR_SERVICE, STATUS_BAR_SERVICE, TELEPHONY_SERVICE, VIBRATOR_SERVICE, WALLPAPER_SERVICE, WIFI_SERVICE, WINDOW_SERVICE

Constructor Summary

ExpandableListActivity()

Method Summary

ExpandableListAdapter	getExpandableListAdapter() Get the ExpandableListAdapter associated with this activity's ExpandableListView.
ExpandableListView	getExpandableListView() Get the activity's expandable list view widget.
long	getSelectedId() Gets the ID of the currently selected group or child.
long	getSelectedPosition() Gets the position (in packed position representation) of the currently selected group or child.
boolean	onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) Override this for receiving callbacks when a child has been clicked.
void	onContentChanged() Updates the screen state (current list and other views) when the content changes.
void	onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) Override this to populate the context menu when an item is long pressed.
void	onGroupCollapse(int groupPosition) Override this for receiving callbacks when a group has been collapsed.
void	onGroupExpand(int groupPosition) Override this for receiving callbacks when a group has been expanded.
protected void	onRestoreInstanceState(Bundle state) Ensures the expandable list view has been created before Activity restores all of the view states.
void	setListAdapter(ExpandableListAdapter adapter) Provide the adapter for the expandable list.
boolean	setSelectedChild(int groupPosition, int childPosition, boolean shouldExpandGroup) Sets the selection to the specified child.
void	setSelectedGroup(int groupPosition) Sets the selection to the specified group.

Methods inherited from class android.app.Activity

addContentView, attach, closeOptionsMenu, createPendingResult, dismissDialog, dispatchActivityResult, dispatchKeyEvent, dispatchTouchEvent, dispatchTrackballEvent, finalize, findViewById, finish, finishActivity, finishActivityFromChild, finishFromChild, getActivityToken, getApplication, getCallingActivity, getCallingPackage, getChangingConfigurations, getComponentName, getCurrentFocus, getInstanceCount, getIntent, getLastNonConfigurationInstance, getLayoutInflater, getLocalClassName, getMenuInflater, getParent, getPreferences, getRequestedOrientation, getSystemService, getTaskId, getTitle, getTitleColor, getVolumeControlStream, getWallpaperDesiredMinimumHeight, getWallpaperDesiredMinimumWidth, getWindow, getWindowManager, isChild, isFinishing, isResumed, isTaskRoot, managedCommitUpdates, managedQuery, managedQuery, moveTaskToBack, onActivityResult, onApplyThemeResource, onChildTitleChanged, onConfigurationChanged, onContextItemSelected, onContextMenuClosed, onCreate, onCreateDescription, onCreateDialog, onCreateOptionsMenu, onCreatePanelMenu, onCreatePanelView, onCreateThumbnail, onCreateView, onDestroy, onKeyDown, onKeyMultiple, onKeyUp, onLowMemory, onMenuItemSelected, onMenuOpened, onNewIntent, onOptionsItemSelected, onOptionsMenuClosed, onPanelClosed, onPause, onPostCreate, onPostResume, onPrepareDialog, onPrepareOptionsMenu, onPreparePanel, onRestart, onResume, onRetainNonConfigurationInstance, onSaveInstanceState, onSearchRequested, onStart, onStop, onTitleChanged, onTouchEvent, onTrackballEvent, onWindowAttributesChanged, onWindowFocusChanged, openContextMenu, openOptionsMenu, performRestart, performRestoreInstanceState, performResume, performSaveInstanceState, performStart, performStop, registerForContextMenu, removeDialog, requestWindowFeature, runOnUiThread, setContentView, setContentView, setContentView, setDefaultKeyMode, setFeatureDrawable, setFeatureDrawableAlpha, setFeatureDrawableResource, setFeatureDrawableUri, setIntent, setParent, setPersistent, setProgress, setProgressBarIndeterminate, setProgressBarIndeterminateVisibility, setProgressBarVisibility, setRequestedOrientation, setResult, setResult, setSecondaryProgress, setTitle, setTitle, setTitleColor, setVolumeControlStream, showDialog, startActivity, startActivityForResult, startActivityFromChild, startActivityIfNeeded, startManagingCursor, startNextMatchingActivity, startSearch, stopManagingCursor, takeKeyEvents, unregisterForContextMenu

Methods inherited from class android.view.ContextThemeWrapper

attachBaseContext, getTheme, setTheme

Methods inherited from class android.content.ContextWrapper

bindService, checkCallingOrSelfPermission, checkCallingOrSelfUriPermission, checkCallingPermission, checkCallingUriPermission, checkPermission, checkUriPermission, checkUriPermission, clearWallpaper, createPackageContext, databaseList, deleteDatabase, deleteFile, enforceCallingOrSelfPermission, enforceCallingOrSelfUriPermission, enforceCallingPermission, enforceCallingUriPermission, enforcePermission, enforceUriPermission, enforceUriPermission, fileList, getApplicationContext, getAssets, getBaseContext, getCacheDir, getClassLoader, getContentResolver, getDatabasePath, getDir, getFilesDir, getFileStreamPath, getMainLooper, getPackageCodePath, getPackageManager, getPackageName, getPackageResourcePath, getResources, getSharedPreferences, getWallpaper, grantUriPermission, openFileInput, openFileOutput, openOrCreateDatabase, peekWallpaper, registerReceiver, registerReceiver, removeStickyBroadcast, revokeUriPermission, sendBroadcast, sendBroadcast, sendOrderedBroadcast, sendOrderedBroadcast, sendStickyBroadcast, setWallpaper, setWallpaper, startInstrumentation, startService, stopService, unbindService, unregisterReceiver

Methods inherited from class android.content.Context

getString, getString, getText, obtainStyledAttributes, obtainStyledAttributes, obtainStyledAttributes, obtainStyledAttributes

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mAdapter

ExpandableListAdapter mAdapter

mList

ExpandableListView mList

mFinishedStart

boolean mFinishedStart

Constructor Detail

ExpandableListActivity

public ExpandableListActivity()

Method Detail

onCreateContextMenu

public void onCreateContextMenu(ContextMenu menu,
                                View v,
                                ContextMenu.ContextMenuInfo menuInfo)

Override this to populate the context menu when an item is long pressed. menuInfo will contain a AdapterView.AdapterContextMenuInfo whose position is a packed position that should be used with ExpandableListView.getPackedPositionType(long) and the other similar methods.

Called when a context menu for the view is about to be shown. Unlike Activity.onCreateOptionsMenu(Menu), this will be called every time the context menu is about to be shown and should be populated for the view (or item inside the view for AdapterView subclasses, this can be found in the menuInfo)).

Use Activity.onContextItemSelected(android.view.MenuItem) to know when an item has been selected.

It is not safe to hold onto the context menu after this method returns. Called when the context menu for this view is being built. It is not safe to hold onto the menu after this method returns.

Specified by:

onCreateContextMenu in interface View.OnCreateContextMenuListener

Overrides:

onCreateContextMenu in class Activity

Parameters:

menu - The context menu that is being built

v - The view for which the context menu is being built

menuInfo - Extra information about the item for which the context menu should be shown. This information will vary depending on the class of v.

onChildClick

public boolean onChildClick(ExpandableListView parent,
                            View v,
                            int groupPosition,
                            int childPosition,
                            long id)

Override this for receiving callbacks when a child has been clicked.

Callback method to be invoked when a child in this expandable list has been clicked.

Specified by:

onChildClick in interface ExpandableListView.OnChildClickListener

Parameters:

parent - The ExpandableListView where the click happened

v - The view within the expandable list/ListView that was clicked

groupPosition - The group position that contains the child that was clicked

childPosition - The child position within the group

id - The row id of the child that was clicked

Returns:

True if the click was handled

onGroupCollapse

public void onGroupCollapse(int groupPosition)

Override this for receiving callbacks when a group has been collapsed.

Specified by:

onGroupCollapse in interface ExpandableListView.OnGroupCollapseListener

Parameters:

groupPosition - The group position that was collapsed

onGroupExpand

public void onGroupExpand(int groupPosition)

Override this for receiving callbacks when a group has been expanded.

Specified by:

onGroupExpand in interface ExpandableListView.OnGroupExpandListener

Parameters:

groupPosition - The group position that was expanded

onRestoreInstanceState

protected void onRestoreInstanceState(Bundle state)

Ensures the expandable list view has been created before Activity restores all of the view states.

Overrides:

onRestoreInstanceState in class Activity

Parameters:

state - the data most recently supplied in Activity.onSaveInstanceState(android.os.Bundle).

See Also:

Activity.onRestoreInstanceState(Bundle)

onContentChanged

public void onContentChanged()

Updates the screen state (current list and other views) when the content changes.

Specified by:

onContentChanged in interface Window.Callback

Overrides:

onContentChanged in class Activity

See Also:

Activity.onContentChanged()

setListAdapter

public void setListAdapter(ExpandableListAdapter adapter)

Provide the adapter for the expandable list.

getExpandableListView

public ExpandableListView getExpandableListView()

Get the activity's expandable list view widget. This can be used to get the selection, set the selection, and many other useful functions.

See Also:

ExpandableListView

getExpandableListAdapter

public ExpandableListAdapter getExpandableListAdapter()

Get the ExpandableListAdapter associated with this activity's ExpandableListView.

getSelectedId

public long getSelectedId()

Gets the ID of the currently selected group or child.

Returns:

The ID of the currently selected group or child.

getSelectedPosition

public long getSelectedPosition()

Gets the position (in packed position representation) of the currently selected group or child. Use ExpandableListView.getPackedPositionType(long), ExpandableListView.getPackedPositionGroup(long), and ExpandableListView.getPackedPositionChild(long) to unpack the returned packed position.

Returns:

A packed position representation containing the currently selected group or child's position and type.

setSelectedChild

public boolean setSelectedChild(int groupPosition,
                                int childPosition,
                                boolean shouldExpandGroup)

Sets the selection to the specified child. If the child is in a collapsed group, the group will only be expanded and child subsequently selected if shouldExpandGroup is set to true, otherwise the method will return false.

Parameters:

groupPosition - The position of the group that contains the child.

childPosition - The position of the child within the group.

shouldExpandGroup - Whether the child's group should be expanded if it is collapsed.

Returns:

Whether the selection was successfully set on the child.

setSelectedGroup

public void setSelectedGroup(int groupPosition)

Sets the selection to the specified group.

Parameters:

groupPosition - The position of the group that should be selected.