java - 使用克隆或使用构造函数并分配哪一种更有效

Question

我有一个链接列表，我想复制该链接列表。克隆运行速度是否比创建新实例然后为其赋值更快？例如我有

LinkedList<MyClass> list = new LinkedList<MyClass>();
list.add(instance1);
list.add(instance2);

使用克隆:

LinkedList<MyClass> list2 = list.clone();

使用构造函数:

LinkedList<MyClass> list2 = new LinkedList<MyClass>();
   for(MyClass myclass : list){
   list2.add(myclass);
}

Answer 1

最好是使用浅复制构造函数。您编写了使用构造函数，而不是使用。您正在循环播放它。

我建议使用

List<MyClass> list2 = new LinkedList<MyClass>(list);

偶数Josh Bloch suggest the same

The truth of the matter is that you don't provide any capability to your clients by implementing Cloneable and providing a public clone method other than the ability to copy. This is no better than what you get if you provide a copy operation with a different name and you don't implement Cloneable. That's basically what you're doing with a copy constructor. The copy constructor approach has several advantages, which I discuss in the book. One big advantage is that the copy can be made to have a different representation from the original. For example, you can copy a LinkedList into an ArrayList.