Question

i am using custom cursor adapter to get catagories in listview from SQlite view and also want to show specific rows count saved with same category name.i try many times but unfortuntely can’t succeed.

here the Query which i used

int GetTasksCountByCategory(String cat)
 {

     Cursor cur = mDb.rawQuery(" SELECT Count(*) FROM  ViewTasks where Category_name = "+"'"+"cat"+"'", null);
     int x = 0;
     if (cur.moveToFirst())
     {
         x = cur.getInt(0);
     }

        cur.close();
        return x;    
 }

and my Adapter class

public class cursorAdapter2 extends CursorAdapter{
    private Context mContext;
    DbAdapter myAdapter = new DbAdapter(mContext);

    @SuppressWarnings("deprecation")
    public cursorAdapter2(Context context, Cursor c) {
        super(context, c);
        mContext=context;
        // TODO Auto-generated constructor stub
    }

    @Override
    public View newView(Context arg0, Cursor arg1, ViewGroup arg2) {
        // TODO Auto-generated method stub
         LayoutInflater inflater = LayoutInflater.from(arg2.getContext());
         View retView = inflater.inflate(R.layout.list, arg2, false);

        return retView;
    }

    @SuppressWarnings("unused")
    @Override
    public void bindView(View view, Context arg1, Cursor cursor) {
        // TODO Auto-generated method stub
        TextView category = (TextView) view.findViewById(R.id.txtLastcatId);
        category.setText(cursor.getString(cursor.getColumnIndex(DbAdapter.KEY_CATEGORY_NAME)));

         String getCat = (String) category.getText();
           int i = myAdapter.GetTasksCountByCategory(getCat);
        Button count = (Button) view.findViewById(R.id.button2);
        count.setText(Integer.toString(i));

        Button img = (Button) view.findViewById(R.id.button1);
    }

}

in this i get null pointer exception
anyone plz help me
thanx in advance

Answer 1

two things. first the assignment of DbAdapter myAdapter should be done in the class’ constructor…when mContext has a value.

public cursorAdapter2(Context context, Cursor c) {
    super(context, c);
    mContext=context;
    myAdapter = new DbAdapter(mContext);
}

secondly modify the query from….

Cursor cur = mDb.rawQuery(" SELECT Count(*) FROM  ViewTasks where Category_name = "+"'"+"cat"+"'", null);

to

Cursor cur = mDb.rawQuery("SELECT Count(*) FROM ViewTasks where Category_name = ?", new String[] { cat } );

you are passing in the string "cat" not the variable cat.