Create a Notepad and To-do list combined app in Android

3 « Prev Page

8. The Manage tab

The Manage tab is similar to the Browse tab except it uses an ExpandableListView and SimpleCursorTreeAdapter. Each group item represents a category where as child items within it are the notes.

---

The implementaion of an expandable list is very easy since Android provides ExpandableListActivity which already implements the functionality to expand/collapse a group item.

Android provides ListActivity for implementing a list. However, we didn't use it while developing the Browse tab since there is a known issue in the SDK. In brief, the id of the views i.e. @android:id/list conflict when used together with ExpandableListActivity in a TabHost.

Here is an outline of the ManageActivity class.

	public class ManageActivity extends ExpandableListActivity {
		
		@Override
		public void onCreate(Bundle savedInstanceState) {
			super.onCreate(savedInstanceState);
			setContentView(R.layout.tab_manage);
		}    
		
		@Override
		protected void onResume() {
			super.onResume();
			
			Cursor c = Category.list(SmartPad.db);
			startManagingCursor(c);
			SimpleCursorTreeAdapter adapter = new CategoryTreeAdapter(this, c);
			setListAdapter(adapter);        
		}	
		
		//--------------------------------------------------------------------------

		private class CategoryTreeAdapter extends SimpleCursorTreeAdapter {
			
			public CategoryTreeAdapter(Context context, Cursor cursor) {
				super(
						context, 
						cursor, 
						R.layout.row_category, 
						new String[]{Category.COL_NAME}, 
						new int[]{android.R.id.text1}, 
						R.layout.row_category_note, 
						new String[]{Note.COL_TITLE}, 
						new int[]{android.R.id.text1});
			}

			@Override
			protected Cursor getChildrenCursor(Cursor groupCursor) {
				int columnIndex = groupCursor.getColumnIndex(Category.COL_ID);
				String categoryId = groupCursor.getString(columnIndex);
				Cursor c = Note.list(SmartPad.db, categoryId);
				startManagingCursor(c);
				return c;
			}

			@Override
			protected void bindGroupView(View view, Context context, Cursor cursor, boolean isExpanded) {
				super.bindGroupView(view, context, cursor, isExpanded);

				((TextView)view.findViewById(android.R.id.text1))
					.setCompoundDrawablesWithIntrinsicBounds(R.drawable.folder, 0, 0, 0);
			}
			
			@Override
			protected void bindChildView(View view, Context context, Cursor cursor, boolean isLastChild) {
				super.bindChildView(view, context, cursor, isLastChild);

				((TextView)view.findViewById(android.R.id.text1))
					.setCompoundDrawablesWithIntrinsicBounds(R.drawable.file, 0, 0, 0);
			}
			
		}
	}
					

SimpleCursorTreeAdapter is an abstract class and we need to provide implementation for getChildrenCursor() method. Additionally, we have overridden bindGroupView() and bindChildView() to set icon next to the title.

---

The content view for this tab is almost similar to the Browse tab. Here is the portion which is different.

    <ExpandableListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="1"
        android:cacheColorHint="#00000000"
        android:divider="@android:color/transparent"
        android:drawSelectorOnTop="false"
        android:groupIndicator="@null" />			
						

Notice that you can specify your own groupIndicator in the ExpandableListView otherwise the default indicator is shown. However, we chose to remove it by setting it as @null.

9. The Preferences screen

The tools button at the bottom of the Manage tab navigates user to the Settings screen.

---

Create a new Activity and make it extend PreferenceActivity. Here is the code.

	public class SettingsActivity extends PreferenceActivity {
		
		private static final String TAG = "SettingsActivity";

		@Override
		public void onCreate(Bundle savedInstanceState) {
			super.onCreate(savedInstanceState);
			addPreferencesFromResource(R.xml.settings);
		}
	}					
					

The settings.xml file was created earlier while developing the Application class.

---

Declare the SettingsActivity in AndroidManifest.xml

	<activity android:name=".SettingsActivity"></activity>
					

Edit the tab_manage.xml to specify onClick function for the settings button.

	<ImageButton
		android:id="@+id/settings_btn"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:onClick="onClick"
		android:layout_margin="5dip"
		android:background="@drawable/btn_bg"
		android:src="@drawable/preferences" />
					

Add onClick() method to ManageActivity.

	public void onClick(View v) {
		switch (v.getId()) {
		case R.id.new_btn:
			// TODO show dialog for new category
			break;
			
		case R.id.settings_btn:
			Intent intent = new Intent();
			intent.setClass(this, SettingsActivity.class);
			startActivity(intent);			
			break;			
		}
	}					
					

---

In the next chapter we discuss how the flow of the application is implemented and the various menus and dialogs.

Next Page » 3