Copyright© Jeffrey Jongko, Ateneo de Manila University Editing ListAdapter Data part 2

Selection and Touch  Selection and Touch are two different interaction systems in Android  Selection is used when using Arrows/Fire keys  Touch is used when you tap using a touch screen  These two are independent of each other  It is a major UI design issue to be able to handle both cleanly  Usually, focuses on Touch since many phones no longer have arrow/fire keys

Example  When interaction with a ListView you can do the following  Use the arrow keys to move around and use the fire key to select the row  Tap the ListView and row directly  For now, we will focus on the use of Touch

Copyright© Jeffrey Jongko, Ateneo de Manila University Context Sensitive Menus

 Context Sensitive Menus are menus whose contents are dependent on the selected item (the context)  The Activity class is responsible for the creation of these menus and provides methods that need to be overridden (just like the Options menu)

General Steps  To enable Context Menus you need to do the following  Register which view needs context menus  Override onCreateContextMenu()  Override onContextItemSelected()

registerForContextMenu()  For a view to have a context menu, it must be registered to the activity using registerForContextMenu(View)  Any number of views can have context menus, just register them all

Example ListView lv = getListView(); lv.setTextFilterEnabled(true); // NOTE: REGISTER listview for context menu registerForContextMenu(lv);

onCreateContextMenu()  Works similar to the onCreateOptionsMenu()  Use a MenuInflater to initialize the menu based on an XML file  Alternatively you can invoke the menu’s add() method to add options programatically  E.g. for dynamic menus

public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); MenuInflater inflater = getMenuInflater(); // places the contents of the XML to the menu inflater.inflate(R.menu.context_menu, menu); }

Example XML <menu xmlns:android="

onContextItemSelected()  To handle selections override onContextItemSelected(MenuItem item)  Switch against the menuItem’s ID to determine which action was selected  Make sure to propagate the call to the superclass should none of the cases handle the option

AdapterContextMenuInfo  The MenuItem parameter contains a ContextMenuInfo object retrieved from using getMenuInfo()  For a ListView, it returns an AdapterContextMenuInfo instance  The main job of this class is to pass back the  following  target view – which specific view this menu is for  position of the view within the targetView  This will allow you to extract the specific object within the backing data  id of the view within the targetView

public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo(); switch (item.getItemId()) { case R.id.delete: // delete the currently selected row // NOTE: trigger the changes sampleList.remove(info.position); adapter.notifyDataSetChanged(); return true; default: return super.onContextItemSelected(item); }

Extras  Other menu features  Submenus  MenuGroups  Checkable menus  Shortcut keys  Check out file:///C:/android-sdk- windows/docs/guide/topics/ui/menus.html