I have an activity that extends ExpandableListActivity. I use
SimpleCursorTreeAdapter to fill ExpandableListView.
My layout contains list view and empty view.
On app start ExpandableListActivity automatically chooses the right
view to display.
My steps:
1. App starts, there is no data. (empty view on the screen)
2. Insert some data into db.
3. Call adapter.notifyDataSetChanged(); But empty view is still on the
screen and there is no any item in my list view.
Then I restart app:
5. List view appears. I expand all groups and scroll to the bottom.
6. I click on the item in the list. New activity appears.
7. Click back button. All groups are collapsed and we are at the top
of the screen. Scroll position and expanded groups are not
remembered.
8. Delete all data from db and call adapter.notifyDataSetChanged();
9. Child views have disappeared, but top-level groups are still
visible.
Questions:
1. What can I do to replace empty view with list view?
2. What can I do to do to save state of groups and scroll position of
the list view?
Code:
public class MainActivity extends ExpandableListActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
dbHelper = new DBOpenHelper(this);
rubricsDbAdapter = new RubricsDBAdapter(dbHelper);
rubricsDbAdapter.open();
itemsDbAdapter = new ItemsDBAdapter(dbHelper);
itemsDbAdapter.open();
rubricsCursor = rubricsDbAdapter.getAllItemsCursor();
startManagingCursor(rubricsCursor);
// Cache the ID column index
rubricIdColumnIndex = rubricsCursor.getColumnIndexOrThrow
(RubricsDBAdapter.KEY_ID);
// Set up our adapter
mAdapter = new MyExpandableListAdapter(rubricsCursor,
this,
android.R.layout.simple_expandable_list_item_1,
android.R.layout.simple_expandable_list_item_1,
new String[] {RubricsDBAdapter.KEY_NAME},
new int[] {android.R.id.text1},
new String[] {ItemsDBAdapter.KEY_NAME},
new int[] {android.R.id.text1});
setListAdapter(mAdapter);
}
public boolean onChildClick(ExpandableListView parent, View v, int
groupPosition, int childPosition, long id) {
Intent i = new Intent(this, ItemViewActivity.class);
i.putExtra(ItemsDBAdapter.KEY_ID, id);
startActivity(i);
return super.onChildClick(parent, v, groupPosition,
childPosition, id);
}
private void updateMyData() {
int i;
int k;
long rubricId;
for (i = 1; i <= 5; i++) {
rubricId = rubricsDbAdapter.insert("rubric " + i);
for (k = 1; k <= 5; k++) {
itemsDbAdapter.insert("item " + i + "-" + k,
rubricId);
}
}
mAdapter.notifyDataSetChanged();
}
private void deleteMyData() {
rubricsDbAdapter.deleteAll();
itemsDbAdapter.deleteAll();
mAdapter.notifyDataSetChanged();
}
public class MyExpandableListAdapter extends
SimpleCursorTreeAdapter
{
public MyExpandableListAdapter(Cursor cursor, Context context,
int groupLayout,
int childLayout, String[] groupFrom, int[] groupTo,
String[] childrenFrom,
int[] childrenTo) {
super(context, cursor, groupLayout, groupFrom, groupTo,
childLayout, childrenFrom,
childrenTo);
}
@Override
protected Cursor getChildrenCursor(Cursor notebookCursor) {
// Given the group, we return a cursor for all the
children within that group
long id = notebookCursor.getLong(rubricIdColumnIndex);
Cursor itemsCursor = itemsDbAdapter.getRubricItemsCursor
(id);
startManagingCursor(itemsCursor);
return itemsCursor;
}
}
}
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