复制ObservableCollection项(Duplicate an ObservableCollection Item)

复制ObservableCollection项(Duplicate an ObservableCollection Item)

我想在observablecollection中复制一个列表项。 当我做：

TreasureCards[TreasureCards.Count - 1] = TreasureCards[CardPosition];

它会创建特定列表项的副本，但随后会在我的UI中进行链接。 因此，如果我更改新的重复项目的名称，它将更改原始名称。 我知道我可以逐个完成每个属性（见下文），但有没有办法只复制整个项目？

TreasureCards[TreasureCards.Count - 1].ame = TreasurecCards[CardPosition].ame; TreasureCards[TreasureCards.Count - 1].Type= TreasurecCards[CardPosition].Type; // etc

I want to duplicate a list item in an observablecollection. When I do:

TreasureCards[TreasureCards.Count - 1] = TreasureCards[CardPosition];

It creates a copy of the specific list item but then they are linked in my UI. So if I change the new duplicated item's name, it changes the originals name. I know I could do each of the properties one by one (see below) but is there a way to just copy the entire item?

TreasureCards[TreasureCards.Count - 1].ame = TreasurecCards[CardPosition].ame; TreasureCards[TreasureCards.Count - 1].Type= TreasurecCards[CardPosition].Type; // etc

最满意答案

您没有复制该对象。 您正在创建对该对象的新引用。 仍然只有一个对象; 现在，在您的集合中有两个对它的引用，对象的任何更改都会被两个引用反映出来。

要创建新对象，可以在从Object派生的任何内容上调用MemberwiseClone() 。 此方法返回一个新实例，复制原始对象中所有字段的值。 所以你要这样做：

TreasureCards[TreasureCards.Count - 1] = TreasureCards[CardPosition].MemberwiseClone();

这种方法有两个局限性。 首先，它是一个浅拷贝，即原始对象中的任何参考字段都复制了它们的值。 因此，如果a.Foo是对Bar对象的引用，则a.MemberwiseClone().Foo将引用相同的Bar对象。 其次，该方法只是复制字段; 它不会调用新对象的构造函数。 根据班级的设计，这要么不重要，要么是真正的大交易。

通常，使类实现ICloneable并显式实现Clone()方法更安全，例如：

public TreasureCard Clone() { return new TreasureCard { ame = this.ame, Type = this.Type, ... }; }

You aren't duplicating the object. You're creating a new reference to the object. There's still only one object; now there are two references to it in your collection, and any change to the object is reflected by both references.

To create a new object, you can call MemberwiseClone() on anything that derives from Object. This method returns a new instance, copying the values from all fields in the original object. So you'd do:

TreasureCards[TreasureCards.Count - 1] = TreasureCards[CardPosition].MemberwiseClone();

There are two limitati with this method. First, it's a shallow copy, any reference fields in the original object have their values copied. So if a.Foo is a reference to a Bar object, a.MemberwiseClone().Foo will refer to the same Bar object. Second, the method just copies the fields; it doesn't call the new object's ctructor. Depending on the design of the class, this is either unimportant or a Really Big Deal.

Usually, it's safer to make the class implement ICloneable and explicitly implement a Clone() method, e.g.:

public TreasureCard Clone() { return new TreasureCard { ame = this.ame, Type = this.Type, ... }; }