Question

我写了一个Cursor，它将在databasehelper类中读取表中的所有信息，并为其分配一个自定义列表视图，我希望每个元素都对应相应的字段。但是，Cursor仅打印最后一个元素，并且仅限于3次迭代。

这是数据库助手类：

nditer

} 这是片段函数调用它：

public Cursor getPrograss(){
SQLiteDatabase db = this.getReadableDatabase ();
StatsitcsHelper object = new StatsitcsHelper ();

Cursor cursor =  db.rawQuery ("select * from " + TABLE_PROGGRES, null);

cursor.moveToFirst();
if (cursor!= null && cursor.getCount() > 0 &&  !cursor.isAfterLast()){

    cursor.moveToNext();
}
return cursor;

这是适配器：

    public void ShowStatstics() {

    DatabaseHelper db = new DatabaseHelper (getActivity ());
    Cursor cursor =  db.getPrograss ();


    String DataA = cursor.getString(cursor.getColumnIndex(COL_P_Date));
    String WeightA =  cursor.getString(cursor.getColumnIndex(COL_P_Weight));
    String PercentA = cursor.getString(cursor.getColumnIndex(COL_P_Percentage));



    String[] Prograss = {DataA,WeightA,PercentA};

    ListAdapter listAdapter = new StatisticsAdapter (getActivity (),Prograss);
    lest.setAdapter (listAdapter);
}

Answer 1

你可以像这样创建一个POJO类，

public class Data {
    String date;
    String weight;
    String percentage;
}

然后在你的方法中你可以返回ArrayList并显示在下面的列表中，

public ArrayList<Data> getPrograss() {
    SQLiteDatabase db = this.getReadableDatabase();
    StatsitcsHelper object = new StatsitcsHelper();

    Cursor cursor =  db.rawQuery ("select * from " + TABLE_PROGGRES, null);

    ArrayList<Data> datas = new ArrayList<>();

    if(cursor != null) {
        cursor.moveToFirst();

        for (int i = 0; i < cursor.getCount(); i++) {

            cursor.moveToPosition(i);

            Data data = new Data();
            data.date = cursor.getString(cursor.getColumnIndex(COL_P_Date));
            data.weight = cursor.getString(cursor.getColumnIndex(COL_P_Weight));
            data.percentage = cursor.getString(cursor.getColumnIndex(COL_P_Percentage));

            datas.add(data);
        }

        cursor.close();
    }

    return datas;
}

你的适配器类看起来像这样，

class StatisticsAdapter  extends ArrayAdapter<Data> {
    public StatisticsAdapter(@NonNull Context context, ArrayList<Data> resource) {
        super (context, R.layout.listview_layout ,resource);
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        LayoutInflater ListInflate = LayoutInflater.from(getContext ());

        Data data = getItem(position);

        View customView = ListInflate.inflate (R.layout.listview_layout,parent,false);

        String first = data.date;
        TextView date = (TextView) customView.findViewById (R.id.List_Date);

        String Second = data.weight;
        TextView Weight = (TextView) customView.findViewById (R.id.List_Weight);

        String Thierd = data.percentage;
        TextView Percent = (TextView) customView.findViewById (R.id.List_Percentage);

        date.setText (first);
        Weight.setText (Second);
        Percent.setText (Thierd);

        return customView;

    }
}

你可以从你的方法创建适配器，

public void showStatstics() {
    DatabaseHelper db = new DatabaseHelper (getActivity ());
    ArrayList<Data> datas =  db.getPrograss ();

    ListAdapter listAdapter = new StatisticsAdapter (getActivity (),datas);
    lest.setAdapter (listAdapter);
}

游标不会遍历所有数据库表

1 个答案: