java - 数组列表，Java。这两个构造函数有什么区别

Question

我还是个 java 新手，你能告诉我这两个构造函数有什么区别吗？

首先:

public class Plan
{

   ArrayList<Point2D> points;

   public Plan(ArrayList<Ponto2D> points)
   {
       this.points = new Arraylist<Point2D>(points);
   }

}

还有这个: 第二:

public class Plan
{

    public Plan(ArrayList<Point2D> lpoints)
    {
        points = new ArrayList<Point2D>();
        for(Point2D p : lpoints) point.add(p.clone());
    }

}

Answer 1

第一个构造函数是浅拷贝，第二个是深拷贝。

S.Lott给出的答案对于 this question .

Shallow copies duplicate as little as possible. A shallow copy of a collection is a copy of the collection structure, not the elements. With a shallow copy, two collections now share the individual elements.

Deep copies duplicate everything. A deep copy of a collection is two collections with all of the elements in the original collection duplicated.