光标初始化错误 [android]答案

【问题标题】：cursor initialization error [android]光标初始化错误 [android]
【发布时间】：2014-04-09 13:10:16
【问题描述】：

    public HashMap<String,String> getUserDetails(){
    HashMap<String,String> user = new HashMap<String,String>();
    String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;
    System.out.println("select query:"+selectQuery);
    System.out.println("entering into hashmap");

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);
    // Move to first row
    cursor.moveToFirst();
    System.out.println("cursor count is");
    System.out.println(cursor.getCount());
    if(cursor.getCount() > 0){
        System.out.println("enter into if of hashmap");
        user.put("username", cursor.getString(1));
        user.put("name", cursor.getString(2));
        user.put("email", cursor.getString(3));
        user.put("user_id", cursor.getString(4));
        user.put("country", cursor.getString(5));
        user.put("state", cursor.getString(6));
        user.put("city", cursor.getString(7));
        user.put("registered_on", cursor.getString(8));
      }
    cursor.close();
    db.close();
    // return user
    return user;
}

错误：无法从 CursorWindow 读取第 0 行第 8 列。确保 Cursor 在从中访问数据之前已正确初始化。

无法从 SQLiteDatabase 获取任何数据

谢谢

【问题讨论】：

将位置从 (1-8) 更改为 (0-7)

标签： android android-cursor

【解决方案1】：

在游标中，列索引从 0 开始。

也就是说，如果您想从第一列获取数据，那么您应该使用 cursor.getString(0) 而不是 cursor.getString(1)

所以你需要更换

 if(cursor.getCount() > 0){
        System.out.println("enter into if of hashmap");
        user.put("username", cursor.getString(1));
        user.put("name", cursor.getString(2));
        user.put("email", cursor.getString(3));
        user.put("user_id", cursor.getString(4));
        user.put("country", cursor.getString(5));
        user.put("state", cursor.getString(6));
        user.put("city", cursor.getString(7));
        user.put("registered_on", cursor.getString(8));
      }

通过以下代码....

 if(cursor.getCount() > 0){
        System.out.println("enter into if of hashmap");
        user.put("username", cursor.getString(0));
        user.put("name", cursor.getString(1));
        user.put("email", cursor.getString(2));
        user.put("user_id", cursor.getString(3));
        user.put("country", cursor.getString(4));
        user.put("state", cursor.getString(5));
        user.put("city", cursor.getString(6));
        user.put("registered_on", cursor.getString(7));
      }

在您的代码中，它试图从不存在的第 9 列中获取数据。

【讨论】：

【解决方案2】：

更改从 1.. 开始的光标索引从 0 到 7.，它将如下所示：

if(cursor.getCount() > 0){
        user.put("username", cursor.getString(0));
        user.put("name", cursor.getString(1));
        user.put("email", cursor.getString(2));
        user.put("user_id", cursor.getString(3));
        user.put("country", cursor.getString(4));
        user.put("state", cursor.getString(5));
        user.put("city", cursor.getString(6));
        user.put("registered_on", cursor.getString(7));
      }

【讨论】：

【解决方案3】：

尝试使用以下代码：使用 cursor.getString(0) 代替 cursor.getString(1)

public HashMap<String,String> getUserDetails(){
ArrayList<HashMap<String, String>> wordList;
String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;
System.out.println("select query:"+selectQuery);
System.out.println("entering into hashmap");

SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
 do
 {
  HashMap<String,String> user = new HashMap<String,String>();
  user.put("username", cursor.getString(0));
    user.put("name", cursor.getString(1));
    user.put("email", cursor.getString(2));
    user.put("user_id", cursor.getString(3));
    user.put("country", cursor.getString(4));
    user.put("state", cursor.getString(5));
    user.put("city", cursor.getString(6));
    user.put("registered_on", cursor.getString(7));
     wordList.add(user);
  }while(cursor.moveToNext);
    return wordList
}
  else
     {
       System.out.println("No data found");
       return null;
     }
  }

我们可以使用这段代码显示数据。

 ArrayList<HashMap<String, String>> result;
 result= Objectname.getdetails();
 for(i=0;i<result.size();i++)
    {
         HashMap<String,String> content = new HashMap<String, String>();
         content = result.get(i);
               String username=content.get("username").toString();
                String name=content.get("name").toString();
                String email=content.get("email").toString();
                String uid=content.get("user_id").toString();
                String country=content.get("country").toString();
                String state=content.get("state").toString();
                String city=content.get("city").toString();
                String reg=content.get("registered_on").toString();

    }

【讨论】：