scala - Scala AnyRef.clone 执行浅复制还是深复制？

Question

在 Scala 中，AnyRef.clone 执行浅复制还是深复制？

Answer 1

简短回答:浅薄。

不太简短的答案:除非被重写，否则 AnyRef.clone() 使用 Java 的 Object.clone() 作为其实现。

关于 Object.clone() 的 Javadoc:

The method clone for class Object performs a specific cloning operation. First, if the class of this object does not implement the interface Cloneable, then a CloneNotSupportedException is thrown. Note that all arrays are considered to implement the interface Cloneable. Otherwise, this method creates a new instance of the class of this object and initializes all its fields with exactly the contents of the corresponding fields of this object, as if by assignment; the contents of the fields are not themselves cloned. Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.

请注意:

1. AnyRef.clone() 与 Java 中的对应项一样，具有“ protected ”访问级别，因此它无法从任何地方调用。
2. 您需要实现 Cloneable 才能使 clone() 正常工作。

长答案:阅读《Effective Java》，第二版，第 11 条:明智地覆盖克隆

摘要:不要使用它。有更好的选择。