Question

I am having a problem where in the started Intent, the findViewById returns null.

Is there anything special I should know about starting a new intent?

It goes something like this for me:

//in the MainList class
Intent stuffList = new Intent(this, StuffList.class);

then in the new Stuff’s constructor:

public class StuffList extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          this.setContentView(R.layout.stuff_list);
          ...
          this.setListAdapter(new StuffAdapter(this, my_cursor));

and in the StuffAdapter I do my usual view and data retrieval.

Note the line where findViewById returns null:

class ViewWrapper{
    View base;
    TextView label = null;

    ViewWrapper(View base){
         this.base = base; }

    TextView getLabel(){
        if(label == null){
            label = (TextView)base.findViewById(R.id.my_label); // returns NULL
        }
        return label;}      
}

class StuffAdapter extends CursorAdapter{
        StuffAdapter(Context context, Cursor cursor){
            super(context, cursor);
        }       

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {
               LayoutInflater inflater = getLayoutInflater();
               View row = inflater.inflate(R.layout.stuff_list, parent, false);
               ViewWrapper wrapper = new ViewWrapper(row);

               row.setTag(wrapper);
               return(row);
        }       

        @Override
        public void bindView(View row, Context context, Cursor cursor) {
              ViewWrapper wrapper = (ViewWrapper)row.getTag();
              TextView label = wrapper.getLabel(); // also NULL
              //this throws exception of course
              label.setText(cursor.getString("title"));         
         }
}

The curious thing is that in the class that calls intent (MainList class), I do Exactly the same thing (i list a bunch of objects), and it Works! however when I try to do it in an Intent – it can’t seem to find the view by id.

For completeness I wanted to add that my list resource file is call “stuff_list.xml” and my row layout file is called “stuff_row.xml”.

Answer 1

Ok, the lesson is – don’t copy and paste your code.
The problem was precisely in the newView function, where I was trying to inflate a list instead of a row!

 View row = inflater.inflate(R.layout.stuff_list, parent, false);

but it should be:

 View row = inflater.inflate(R.layout.stuff_row, parent, false);