4
我有一個包含ForeignCollection吸氣劑&引領者收集增加,從ForeignCollection刪除對象
public class TextQuestion{
@ForeignCollectionField
private ForeignCollection<TextAnswer> answers;
....
我有一個封裝了DAO
public class TextQuestionService
{
private static TextQuestionService instance;
private static Dao<TextQuestion, Integer> textQuestionDAO;
private static DatabaseHelper dbHelper = new DatabaseHelper();
public void addAnswer(TextQuestion textQuestion, TextAnswer answer)
{
List<Answer> answers = (List)textQuestion.getAnswers();
if(answers == null)
{
try
{
answers = (List)textQuestionDAO.getEmptyForeignCollection("answers");
} catch (SQLException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
answers.add(answer);
}
,維修人員包裝類的實體我的問題是 如何從這個集合通過包裝服務類添加,刪除的項目? 以上是我的心血,但我剛剛完全喪失,鑄造到收藏列表等 問題是,當我要到答案添加到問題ForeignCollection如果答案集合不空就沒有問題,但我想建立問題,在堅持它之前添加答案。從前面的問題我知道我需要調用getEmptyForeignCollection,如果沒有從數據庫中檢索父項。必須有一個簡單的方法來做到這一點?任何工作類似的例子將是很好