Getting the selected View from ListView

Question

I am using a CursorAdapter to handle my ListActivity:

public class Mclass extends ListActivity{
...
TheAdapter mAdapter;
public static HashMap<Long, Boolean> shown = new HashMap<Long, Boolean>();
...

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);
         Boolean tmp = shown.get(id); 
        if (tmp == null) { // if null we don't have this key in the hashmap so we added with the value true
            shown.put(id, true);
        } else {
            shown.put(id, !tmp.booleanValue()); // if the value exists in the map then inverse it's value
        }
    mAdapter.notifyDataSetChanged();
         }

}

and my adapter class that extends CursorAdapter and overrides bindView:

@Override
public void bindView(View view, Context context, Cursor cursor) {
    String listText= cursor
            .getString(cursor
                    .getColumnIndexOrThrow(DataHandler.MY_TEXT));

long id = cursor.getLong(cursor.getColumnIndexOrThrow(DataHandler.ROW_ID)); 
    if (Mclass.shown.get(id) != null) {
        TextView m_text = (TextView) view
                .findViewById(R.id.my_text);
        if (m_text != null) {
            m_text.setVisibility(Mclass.shown.get(id)? View.VISIBLE:
                     View.GONE);

            if (m_text.isShown())
                m_text.setText("STRING");
   }
}

My list item layout is defined in a xml file list_item.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#DDDDDD"
android:orientation="horizontal" >

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/my_image"
        android:layout_width="wrap_content"
        android:layout_height="0dip"
        android:layout_weight="1"
        android:paddingRight="1dip"
        android:paddingTop="1dip"
</LinearLayout>

/*
 *I want to toggle this text view's visibility
 */
<TextView
    android:id="@+id/my_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:visibility="gone"//VISIBILITY defined here
    android:paddingBottom="2dip"
    android:paddingLeft="4dip"
    android:paddingRight="4dip"
    android:paddingTop="5dip" />
 </LinearLayout>

How can I toggle the visibility of the TextView in my layout within onListItemClick? I've tried:

TextView mTextView = (TextView) v.findViewById(R.id.my_text);
mTextView.setVisibility(mTextView.isShown()? View.GONE: View.VISIBLE);
mAdapter.notifyDataSetChanged();

but it seems to be choosing which list items to toggle at random, regardless of the one I click.

Answer 1

You'll have to store the id's of the rows you'll hide. You could make a field in your activity to store those ids:

HashMap<Long, Boolean> positionHide = new HashMap<Long, Boolean>();

where the key is the long id of the row and the boolean object represents the status of the TextView(false- it is gone, true it is visible). In the onListItemClick() add the ids of the clicked rows to that field:

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
         Boolean tmp = positionHide.get(id); 
        if (tmp == null) { // if null we don't have this key in the hashmap so we added with the value true
            status.put(id, true);
        } else {
            status.put(id, !tmp.booleanValue()); // if the value exists in the map then inverse it's value
        }
        mAdapter.notifyDataSetChanged();
    }

also modify the bindView() method:

@Override
public void bindView(View view, Context context, Cursor cursor) {
    String listText = cursor.getString(cursor
            .getColumnIndexOrThrow(DataHandler.MY_TEXT));
    long pos = cursor.getLong(cursor.getColumnIndex(DataHandler.ID)); // DataHandler.ID will point to the column _id
TextView m_text = (TextView) view.findViewById(R.id.my_text);

    if(status.get(pos) == null) {
//id is not yet in the hashmap so the value is 
//by default false, the TextView is invisible
    m_text.setVisibility(View.GONE);

    } else {
        // we have the value in the
        // Hashmap so see what it is and set the
    // textview visibility from this value

        if (tmp.booleanValue()) {
          m_text.setVisibility(View.VISIBLE);
             } else {
                 m_text.setVisibility(View.GONE);
                   }
          }
    if (m_text != null)
     m_text.setText(listText);  

}

For this to work you'll need to have in your database the column _id INTEGER PRIMARY KEY AUTOINCREMENT(and also added to the query).

Answer 2

Well you shouldn't use ListView for any active View, try using TableLayout or LinearLayout instead. Look at this blog post for more details on this, however it's for CheckBoxes,but holds true for any active View.

Answer 3

You're problem is that views are reused in list view. This meens that even if you have a list consisting of 100 items, there will be only 10 or so view instances (depending on how much can be fitted on the screen). If you can seen the method bindView takes a view to reuse as parameter.

What you have done, is taken a view that displays for example the 23rd item in the list, and hide the text box. When the 23rd item is scrolled out of the screen, it's view gets reused, but only the values are replaced with the 33rd item's data, the visiblity and other parameters you set for the View you're reusing remains the same.

What you should do is add a status boolean to all list items, and in the adapter's bindView toggle the text boxes visibility according to the currently wanted state of the item.

The other important thing to see is that when you click on the item, the bindView method is not called. So you should also toggle the visibility in the onClick method, to make the change instantious. If you miss this, the view's apparance will change only after the item is scrolled out and scrolled in again - that's when the bindView checks for the visibility boolean.

It would be more elegent to notify the DataSetObservers of the change in the "data", and let the ListView call the bindView for all visible items, but its also more resource consuming.

HashMap<Long, Boolean> positionHide = new HashMap<Long, Boolean>();
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
         Boolean tmp = positionHide.get(id); 
        if (tmp == null) { // if null we don't have this key in the hashmap so we added with the value true
            positionHide.put(id, true);
            tmp = true;
        } else {
                        tmp = !tmp.booleanValue();
            positionHide.put(id, !tmp.booleanValue()); // if the value exists in the map then inverse it's value
        }
        // You should also hide the text view, because bindView will not be called until the list item is scrolled out and in again
                TextView m_text = (TextView) view.findViewById(R.id.my_text);
        if (m_text != null) {
              if(tmp) {
                            // We should hide the text view
                            m_text.setVisibility(View.GONE);
                  } else {
                        // We should display the text view
                            m_text.setVisibility(View.VISIBLE);
                  }
        } 
    }


@Override
public void bindView(View view, Context context, Cursor cursor) {
    String listText = cursor.getString(cursor
            .getColumnIndexOrThrow(DataHandler.MY_TEXT));
            TextView m_text = (TextView) view.findViewById(R.id.my_text);
    if (m_text != null) {
          m_text.setText(listText);
          long pos = cursor.getLong(cursor.getColumnIndex(DataHandler.ID)); // DataHandler.ID will point to the column _id
          if((positionHide.get(pos) != null)&&(positionHide.get(pos))) {
                        // We should hide the text view
                        m_text.setVisibility(View.GONE);
              } else {
                    // We should display the text view
                        m_text.setVisibility(View.VISIBLE);
              }
            }
}

For this to work you'll need to have in your database the column _id INTEGER PRIMARY KEY AUTOINCREMENT(and also added to the query).