Question

我正在尝试检索存储在数据库中的数据。

我想以arraylist格式检索它

 ArrayList (ProfileID, Name)

我有一个Databasehandler我正在尝试以下内容：

public ArrayList<String> getinviteDetails()
{
    String selectQuery = "SELECT  * FROM " + TABLE_DETAILS;

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);
    ArrayList<String> datalist = new ArrayList<String>();

    if (cursor.moveToLast()) 
    {
        datalist.add(cursor.getString(0));
        datalist.add(cursor.getString(1));
        datalist.add(cursor.getString(2));
        datalist.add(cursor.getString(3));
    }

    cursor.close();
    db.close();

    return datalist;
}

但这会像

一样得到保存

 ArrayList (ProfileID)
 ArrayList (Name)

我不确定如何以ArrayList（ProfileID，Name）格式存储它？有人可以帮我解决这个问题吗？

谢谢！

Answer 1

您不能在ArrayList中拥有键值对。使用HashMap代替它。http://developer.android.com/reference/java/util/HashMap.html 正确的方法应如下

public HashMap<String, String> getinviteDetails() {
        HashMap<String, String> datalist = new HashMap<String, String>();
        SQLiteDatabase db = null;
        Cursor cursor = null;
        try {
            db = this.getWritableDatabase();
            String selectQuery = "SELECT  * FROM " + TABLE_DETAILS;
            cursor = db.rawQuery(selectQuery, null);
            if (cursor != null) {
                // Loop all entries and fill datalist
                while (cursor.moveToNext()) {
                    String profileID = cursor.getString(cursor
                            .getColumnIndex(PROFILE_COLUMN_NAME));
                    String name = cursor.getString(cursor
                            .getColumnIndex(NAME_COLUMN_NAME));
                    datalist.put(profileID, name);
                }
            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            if (cursor != null) {
                cursor.close();
            }
            if (db != null) {
                db.close();
            }
        }
        return datalist;
    }

Answer 2

拥有如下的模型类：

class ModelProfileClass
{
   // Constructor for ProfileID and Name
   public ModelProfileClass (String PROFILE_ID, String UNAME)
   {
       this.profile_ID = PROFILE_ID;
       this.uname = UNAME;
   }
   // getters and setters for ProfileID and Name
   //get_PROFILEID(), get_UNAME() , set_PROFILEID(String profileID) , set_UNAME(String uname)
}

在你的主要课程中，

// Create a list of objects of ModelProfileClass
List<ModelProfileClass> profileList= new ArrayList<ModelProfileClass>();

Cursor cursor = db.rawQuery(selectQuery, null);

// looping through all rows and adding to list
if (cursor.moveToFirst()) {

//  For each iteration, making the object null
ModelProfileClass  profileObject= null;
do {

    // Constructor is invoked in the model class and so, the object values are set.
    profileObject= new ModelProfileClass(
                    cursor.getString(0) ,
                    cursor.getString(1)  

            );

                    // Adding current object to the object array list
            profileList.add(profileObject);
    } while (cursor.moveToNext()); // Do this till the last record.
    cursor.close();

如果您想要检索位置可用的记录，则必须使用：

String profileID = profileList.get(position).get_PROFILEID();
String uName = profileList.get(position).get_UNAME();

在Android中以特定格式从DB检索数据

2 个答案: