将对象列表保存到ORMLite数据库

问题描述

我正在寻找一种使用ORMLite将对象列表保存到数据库的方法并阅读这个问题：

I am looking for a way to save a list of objects to the database with ORMLite and read upon this question: Best way to store several ArrayLists in ORMLite for ApplicationSettings

并且接受的答案对我有意义：

And the accepted answer makes sense to me:

public class YourClass {
    @GeneratedId
    private int id;

    @ForeignCollectionField
    private Collection<MyString> bunchOfStrings = new ArrayList<MyString>();
}

public class MyString{
     @DatabaseField(canBeNull = true, foreign = true)
     private YourClass yourClass;

     @DatabaseField
     private String text;
}

我唯一不理解的是这行私人收藏< MyString> bunchOfStrings = new ArrayList< MyString>（）。为什么我们将 ForeignCollectionField 保存为 Collection< MyString> 而不是 ArrayList< MyString> ？使用上面的 bunchOfStrings 对象时，我们是否总是需要将其强制转换为 ArrayList< MyString> ？

And the only thing that I don't understand is this line private Collection<MyString> bunchOfStrings = new ArrayList<MyString>(). Why do we save the ForeignCollectionField as Collection<MyString> instead of as ArrayList<MyString>? When working with the bunchOfStrings object above, do we always need to cast it to ArrayList<MyString>?

推荐答案

这是设计考虑因素，摘自

That was design consideration, excerpt from doc

The field type of orders must be either ForeignCollection<T> or Collection<T> – no other
collections are supported because they are much heavier with many methods to support

你不必初始化那个字段，Ormlite会这样做。因此，只有可用的方法是Collection或ForeignCollection

You dont have to initialize that field, Ormlite will do that. Hence, only available methods are ones present in Collection or ForeignCollection

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