Strange behavior of ListActivity and Activity

I'm implementing an application for android and I run into memory issues while populating a list view with data from the internet. A strange error that occurs seems to be caused by the lack of recycling of the rows as it should normally happen as it is stated at Google I/O 2009.

When I run the code at http://android.amberfog.com/?p=296, everything is running smoothly, the row views are recycled and the listView is optimally used.

I now want to use the listView within another activity that will have much more things inside, therefore a class that extends just ListActivity, is not enough. So, I have an Activity that has the following code:

public class MultipleItemsList extends Activity {
    private Context mContext;
    private MyCustomAdapter mAdapter;
    private ListView listView;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mContext = this;

        listView = (ListView) findViewById(R.id.listView);

        mAdapter = new MyCustomAdapter(mContext);

        for (int i = 1; i < 50; i++) {
            mAdapter.addItem("item " + i);
        }

        listView.setAdapter(mAdapter);
    }  
}

The main.xml is nothing fancy also:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView  
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:text="@string/hello"/>

    <ListView
        android:id="@+id/listView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

The ListActivity that the previous link proposes is the following:

public class MultipleItemsList extends ListActivity {
    private Context mContext;
    private MyCustomAdapter mAdapter;
    private ListView listView;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mContext = this;

        mAdapter = new MyCustomAdapter(mContext);

        for (int i = 1; i < 50; i++) {
            mAdapter.addItem("item " + i);
        }
        setListAdapter(mAdapter);
    }
}

The adapter is the following in both cases:

public class MyCustomAdapter extends BaseAdapter {
    private static final int TYPE_ITEM = 0;
    private static final int TYPE_SEPARATOR = 1;
    private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1;

    private ArrayList<String> mData = new ArrayList<String>();
    private LayoutInflater mInflater;

    private TreeSet<Integer> mSeparatorsSet = new TreeSet<Integer>();

    public static class ViewHolder {
        public TextView textView;
    }

    public MyCustomAdapter(Context context) {
        mInflater = LayoutInflater.from(context);
    }

    public void addItem(final String item) {
        mData.add(item);
        notifyDataSetChanged();
    }

    public void addSeparatorItem(final String item) {
        mData.add(item);
        // save separator position
        mSeparatorsSet.add(mData.size() - 1);
        notifyDataSetChanged();
    }

    @Override
    public int getItemViewType(int position) {
        return mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM;
    }

    @Override
    public int getViewTypeCount() {
        return TYPE_MAX_COUNT;
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public String getItem(int position) {
        return mData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        int type = getItemViewType(position);
        Log.d("myCA", "getView " + position + " " + convertView + " type = " + type);
        if (convertView == null) {
            holder = new ViewHolder();
            switch (type) {
                case TYPE_ITEM:
                    convertView = mInflater.inflate(R.layout.item1, null);
                    hol开发者_StackOverflowder.textView = (TextView)convertView.findViewById(R.id.text);
                    break;
                case TYPE_SEPARATOR:
                    convertView = mInflater.inflate(R.layout.item2, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.textSeparator);
                    break;
            }
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder)convertView.getTag();
        }
        holder.textView.setText(mData.get(position));
        return convertView;
    }
}

So, my question is why in the second case of the ListActivity the view recycling takes place without problems, while at the implementation of the Activity, recycling gets screwed up ?

The Log shows that when the ListActivity is used, everything is recycled correctly:

    07-13 10:14:25.277: DEBUG/myCA(2336): getView 0 null type = 0
    07-13 10:14:25.277: DEBUG/myCA(2336): getView 1 null type = 0
    07-13 10:14:25.277: DEBUG/myCA(2336): getView 2 null type = 0
    07-13 10:14:25.277: DEBUG/myCA(2336): getView 3 null type = 0
    07-13 10:14:25.287: DEBUG/myCA(2336): getView 4 null type = 0
    07-13 10:14:25.287: DEBUG/myCA(2336): getView 5 null type = 0
    07-13 10:14:27.887: DEBUG/myCA(2336): getView 6 null type = 0
    07-13 10:14:28.047: DEBUG/myCA(2336): getView 7 android.widget.LinearLayout@40522c30 type = 0
    07-13 10:14:28.267: DEBUG/myCA(2336): getView 8 android.widget.LinearLayout@405236b8 type = 0
...
...
...

At my implementation of Activity, I see the following:

07-13 10:11:47.517: DEBUG/myCA(2296): getView 0 null type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 1 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 2 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 3 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.527: DEBUG/myCA(2296): getView 4 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.527: DEBUG/myCA(2296): getView 5 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 0 android.widget.LinearLayout@405221e8 type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 1 null type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 2 null type = 0
07-13 10:11:47.557: DEBUG/myCA(2296): getView 3 null type = 0
...
...
...

where there is clearly problem with the recycling.

Am I missing something that would make the listView behave properly when the parent activity is just a simple activity and not a ListActivity ? Has anyone come across something like that in the past ?

Thanks for your time.

Both Activity and ListActivity should be fine. I believe you're leaking the entire activity through the mContext reference. Remove it and see what happens!