Question

如何在android

中的sqlite数据库的列表视图中显示新项目

代码如下：

我的displayData（）方法：

private void displayData()
                {
        dataBase = mHelper.getWritableDatabase();
        Cursor mCursor = dataBase.rawQuery("SELECT * FROM "+ DbHelper.TABLE_NAME, null);
        userId.clear();
        Name.clear();
        Description.clear();
                Assignto.clear();
                Duration.clear();
                Priority.clear();
                Category.clear();
                Kudos.clear();
        if (mCursor.moveToFirst())
                  {
            do {
                userId.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.KEY_ID)));
                Name.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Name)));
                Description.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Description)));
                                Assignto.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Assignto)));
                                Duration.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Duration)));
                                Priority.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Priority)));
                                Category.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Category)));
                                Kudos.add(mCursor.getString(mCursor.getColumnIndex(DbHelper.Kudos)));                                       }
                     while (mCursor.moveToNext());
          }
CustomList adapter = new CustomList(tasklist.this,userId,Name,Description,Assignto,Duration,Priority,Category,Kudos,imageId);
        list.setAdapter(adapter);
        mCursor.close();
            }`

我的自定义列表适配器类：

 public View getView(int pos, View child, ViewGroup parent)
          {
           Holder mHolder;
            LayoutInflater layoutInflater;

        if (child == null)
            {
                    layoutInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                    child = layoutInflater.inflate(R.layout.list_single, null);
                    mHolder = new Holder();
                    mHolder.imageId=(ImageView) child.findViewById(R.id.img);
                    mHolder.txt_Name = (TextView) child.findViewById(R.id.txt_Name);
                    mHolder.txt_Description = (TextView) child.findViewById(R.id.txt_Description);
                    mHolder.txt_Assignto = (TextView) child.findViewById(R.id.txt_Assignto);
                    child.setTag(mHolder);
            }
           else {
                   mHolder = (Holder) child.getTag();
                }

            mHolder.imageId.setImageResource(imageId[pos]);
            mHolder.txt_Name.setText(Name.get(pos));
            mHolder.txt_Description.setText(Description.get(pos));
            mHolder.txt_Assignto.setText(Assignto.get(pos));
            return child;
      }
    public class Holder
     {

            ImageView imageId;
            TextView txt_Name;
            TextView txt_Description;
            TextView txt_Assignto;
    }

我试过＆＃34; desc＆＃34;在查询中但没有工作并显示错误。

Answer 1

您可以尝试moveToLast()方法，该方法将从最后一个开始显示您的数据

if(cursor.moveToLast()){
     do{
         //your operations here
     }while(cursor.moveToPrevious());
}

Answer 2

您是否在数据库中有row_ID等列是整数主键（使用自动增加或必须增加值）？如果您有此列，请尝试使用desc。

Cursor mCursor = dataBase.rawQuery("SELECT * FROM "+ DbHelper.TABLE_NAME + " order by userId DESC;", null);

columnName是主键列然后，结果是数据是输入数据的排序。

如果您的数据库没有整数主键值，例如row_id，我认为您必须创建此字段以获取选择一行或更多行数据。

Answer 3

您应该通过数据库的id列以相反的顺序获取数据。这里是Cursor查询的例子。你也可以通过rawquery获取它。

 db = helper.getReadableDatabase();
Cursor cursor = db.query(helper.Table_name,null,null,null,null,null,helper._id + " DESC ");

             // THE DESIRED COLUMNS TO BE BOUND
String[] columns = new String[] {helper.KeyName, helper.KeyVlue };
            // THE XML DEFINED VIEWS WHICH THE DATA WILL BE BOUND TO
 int[] to = new int[] { R.id.name, R.id.score };

            // CREATE THE ADAPTER USING THE CURSOR POINTING TO THE DESIRED DATA AS WELL AS THE LAYOUT INFORMATION
 MyCursorAdapter dataAdapter = new MyCursorAdapter(MainActivity.this, R.layout.simpl_list_item,cursor,columns,to,0);

            // SET THIS ADAPTER AS YOUR LISTACTIVITY'S ADAPTER   
 list.setAdapter(dataAdapter);

从android中的sqlite数据库列表视图中的列表顶部的新项目

3 个答案: