java游标。getCount（）给定错误

Question

当我尝试使用游标时，我正在做一个安卓项目。getCount（）；这给了我一个错误：

cannot resolve symbol getCount();

这是我的密码

class GetNotesFromDbTask extends AsyncTask<Void, Void, Boolean> {

@Override
protected Boolean doInBackground(Void... params) {
    return null;
}

@Override
protected void onPreExecute() {
    ProgressDialog dialog = new ProgressDialog(NoteDetail.this);
    dialog.setTitle("Loading");
    dialog.setMessage("Please wait..");
    dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
    dialog.setCancelable(false);
    dialog.show();
}


SQLiteDatabase db = helpers.getReadableDatabase();
String[] projection = {
        NoteContract.FeedEntry._ID,
        NoteContract.FeedEntry.NOTES_TITLE,
        NoteContract.FeedEntry.NOTES_ID,
        NoteContract.FeedEntry.NOTES_BODY,

};

String sortOrder =
        NoteContract.FeedEntry.NOTES_ID + " DESC";

Cursor cursor = db.query(
        NoteContract.FeedEntry.TABLE_NAME,  // The table to query
        projection,                               // The columns to return
        null,                                // The columns for the WHERE clause
        null,                            // The values for the WHERE clause
        null,                                     // don't group the rows
        null,                                     // don't filter by row groups
        sortOrder                                 // The sort order
);


if(cursor.getCount()>0) //here i am getting error

{

}

我也定义了游标，我不明白它为什么不工作

还有

我试过if(cursor !=null)

它在对我说

cursor unknown class

Answer 1

您的代码应该在类内部的方法中，而不是在类级别本身

前面的行在语法上是有效的，因为它们是变量声明和初始化。if条件在类级别无效

Answer 2

            class GetNotesFromDbTask extends AsyncTask<Void, Void, Boolean> {

            @Override
            protected Boolean doInBackground(Void... params) {
      SQLiteDatabase db = helpers.getReadableDatabase();
            String[] projection = {
                    NoteContract.FeedEntry._ID,
                    NoteContract.FeedEntry.NOTES_TITLE,
                    NoteContract.FeedEntry.NOTES_ID,
                    NoteContract.FeedEntry.NOTES_BODY,

            };

            String sortOrder =
                    NoteContract.FeedEntry.NOTES_ID + " DESC";

            Cursor cursor = db.query(
                    NoteContract.FeedEntry.TABLE_NAME,  // The table to query
                    projection,                               // The columns to return
                    null,                                // The columns for the WHERE clause
                    null,                            // The values for the WHERE clause
                    null,                                     // don't group the rows
                    null,                                     // don't filter by row groups
                    sortOrder                                 // The sort order
            );


            if(cursor.getCount()>0) //here i am getting error

            {

            }
                return null;
            }

            @Override
            protected void onPreExecute() {
                ProgressDialog dialog = new ProgressDialog(NoteDetail.this);
                dialog.setTitle("Loading");
                dialog.setMessage("Please wait..");
                dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
                dialog.setCancelable(false);
                dialog.show();
            }

            }  // this line add asynctask class end 

          protected void onCreate(Bundle savedInstanceState) {

            GetNotesFromDbTask  gnfd=new GetNotesFromDbTask ();
            //asynctask run onpre ->onbackground->onpost
gnfd.execute();


        }