Cursor not binding text correctly with custom adapter

问题

My Custom Adapter that extends SimpleCursorAdapter for my ListFragment does not display the items in my database correctly. it does not display the text in the TextView, what else do I have to do to the cursor for it to show the correct text?

I thought I had to override the bindView but that had no effect

Setting the adapter:

public void populateList(){

        String[] fields = new String[] {BowlersDB.NAME};
        Cursor c = getActivity().getContentResolver().query(BowlersDB.CONTENT_URI,
                new String[] {BowlersDB.ID,BowlersDB.NAME},null,null,BowlersDB.NAME + " COLLATE LOCALIZED ASC");

mAdapter = new CheckAdapter(getActivity(),R.layout.check_listview,c,fields,new int[] {R.id.nameCheckTV});


        setListAdapter(mAdapter);   

        getLoaderManager().initLoader(0,null,this);
    }

Adapter:

public class CheckAdapter extends SimpleCursorAdapter{

    Context context;
    Cursor c;

    public CheckAdapter(Context context, int layout, Cursor c,String[] from, int[] to) {
        super(context, layout, c, from, to);
        this.context = context;
        this.c = c;
        // TODO Auto-generated constructor stub
    }

    @Override
    public void bindView(View view,Context context,Cursor cursor){
        String st = cursor.getString(cursor.getColumnIndex(BowlersDB.NAME));

        TextView tv = (TextView)view.findViewById(R.id.nameCheckTV);
        tv.setText(st);
    }

    @Override
    public View getView(final int position,View convertView,ViewGroup parent){
        if(convertView == null){
            LayoutInflater inflator = getLayoutInflater();
            convertView = inflator.inflate(R.layout.check_listview,null);
        }

        CheckBox cb = (CheckBox)convertView.findViewById(R.id.checkBox1);   
            cb.setOnClickListener(new OnClickListener(){

                @Override
                public void onClick(View v) {
                    CheckBox check = (CheckBox)v.findViewById(R.id.checkBox1);
                    int pos = position;
                    if(check.isChecked()){
                        mCheckedItems.add(position);
                    }else if(!check.isChecked()){
                        for(int i=0;i< mCheckedItems.size();i++){
                            if(mCheckedItems.get(i) == position){
                                mCheckedItems.remove(i);
                            }
                        }
                    }
                }

            });
        return convertView;
    }

}

回答1:

I think I got it. Check out the implementation for CursorAdapter.getView(). Notice how bindView() and newView() are called within getView(). It looks like by overriding getView() you are ensuring that your CursorAdapter never calls bindView(). Either put everything ONLY in getView() or ONLY in newView() and bindView(), but not both.

EDIT I:

Four things:

I've read up on CursorAdapters and it looks like you want to override bindView() instead of getView(). It looks like getView() is called twice for each row that's to be displayed and this is somehow preventing the cursor from being updated and thus always points to the first row. I think this is why your ListView only displays the first row. Further, the default CursorAdapter implementation for a ListView will recycle views for you, so overriding getView() really isn't necessary (check out this answer for more info).
When creating your mAdapter, you should pass a null Cursor into the constructor. The Cursor will be delivered in onLoadFinished (when the Loader has finished the query) and will be bound to the adapter with swapCursor(cursor).

Your onCreateLoader() method will create (or start) the Loader that will perform the initial query. Make sure it looks something like this,

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { BowlersDB.ID, BowlersDB.NAME };

    CursorLoader cursorLoader = new CursorLoader(getActivity(),
            BowlersDB.CONTENT_URI, projection, null, null, null);
    return cursorLoader;
}

Make sure you make use of the correct SimpleCursorAdapter constructor... the one you are currently using is deprecated! (pass 0as a flag... the CursorLoader will register a content observer for you so you don't need to pass in anything special).

EDIT II:

To clarify, the bindView() method is where you populate your row's widgets with the data from the Cursor's current position. You are handed the Cursor pre-positioned at the proper row. You need to pull data out of the Cursor and pour it into your desired widgets. In other words, you'll need to query for the row's id (instead of using the "position" argument in getView()). Try setting the onClickListener in bindView() with something like:

final int rowId = cursor.getInt(cursor.getColumnIndex("_id"));

CheckBox cb = (CheckBox)convertView.findViewById(R.id.checkBox1);   
cb.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        int position = rowId;
        /* you now know this row's position. do what you need to do. */
    }
});

来源：https://stackoverflow.com/questions/8902141/cursor-not-binding-text-correctly-with-custom-adapter

标签

android

android-listview

android-cursoradapter

android-loadermanager

android-cursor