while (cursor.moveToNext()) 在 android studio 中只运行一次

Question

我想在点击每个日期时显示不同的文本，我检查了日志，似乎在我点击一次后 while 语句不起作用..有什么想法吗？

这是我的代码

 calendar.setOnDateChangeListener(new CalendarView.OnDateChangeListener() {
        @Override
        public void onSelectedDayChange(@NonNull CalendarView calendarView, int year, int month, int dayOfMonth) {
            tapDate = year + "/" + (month + 1) + "/" + dayOfMonth;
            selectedDate.setText(tapDate);
            Log.d(TAG, "onSelectedDayChange: tapDate"+ tapDate);

            while (cursor.moveToNext()) {
                item = new Shelf_items();
                item.setBookTitle(cursor.getString(0));
                item.setWriteDate(cursor.getString(1));
                Log.d(TAG, "onSelectedDayChange: while runs");

                if(item.getWriteDate().equals(tapDate)){
                    mShelf.add(item);
                    Log.d(TAG, "onSelectedDayChange: mshelf item"+item);

                    for(Shelf_items i: mShelf){
                        i_result = i.getBookTitle() + " / ";
                    }
                    f_result +=i_result;
                    Log.d(TAG, "onSelectedDayChange: for 문: "+i_result);
                }
                bookName.setText(f_result);
            }
            cursor.close();
            
        }

    });

Answer 1

如果要再次遍历游标结果集，需要将游标倒回到开头。替换

while (cursor.moveToNext()) {
    ...
}

与

if (cursor.moveToFirst()) {
    do {
        ...
    } while (cursor.moveToNext());
}

并删除 cursor.close()，因为您还没有完成光标。

while (cursor.moveToNext()) 在 android studio 中只运行一次

while (cursor.moveToNext()) runs only once in android studio

calendar

android-cursor

android-sqlite