如何创建一个列表℃的新型深复制（克隆）; T＆GT ;? [英] How create a new deep copy (clone) of a List<T>?

问题描述

在下面的一段code的，

In the following piece of code,

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace clone_test_01
{

    public partial class MainForm : Form
    {

        public class Book
        {
            public string title = "";

            public Book(string title)
            {
                this.title = title;
            }
        }


        public MainForm()
        {
            InitializeComponent();

            List<Book> books_1 = new List<Book>();
            books_1.Add(  new Book("One")  );
            books_1.Add(  new Book("Two")  );
            books_1.Add(  new Book("Three")  );
            books_1.Add(  new Book("Four")  );

            List<Book> books_2 = new List<Book>(books_1);

            books_2[0].title = "Five";
            books_2[1].title = "Six";

            textBox1.Text = books_1[0].title;
            textBox2.Text = books_1[1].title;
        }
    }

}

我用图书对象类型来创建一个列表＆LT; T＆GT; ，我和几个项目来填充它给他们一个独特的标题（从一到十二五）。

I use a Book object type to create a List<T> and I populate it with a few items giving them a unique title (from 'one' to 'five').

然后，我创建列表＆LT;图书＆GT; books_2 =新的List＆LT;图书＆GT;（books_1）。

从这一点来说，我知道这是列表对象的克隆，而是来自 book_2 在 books_1 。它通过在 books_2 的两个第一要素进行更改，然后检查在 book_1 的那些相同的元素证明文本框。

From this point, I know it's a clone of the list object, BUT the book objects from book_2 are still a reference from the book objects in books_1. It's proven by making changes on the two first elements of books_2, and then checking those same elements of book_1 in a TextBox.

books_1 [0] .title伪和books_2 [1] .title伪确实已更改为 books_2的新值[0] .title伪和books_2 [1] .title伪。

现在的问题

我们如何创建一个新的硬拷贝一个列表＆LT; T＆GT; ？这个想法是， books_1 和 books_2 成为完全相互独立的。

How do we create a new hard copy of a List<T>? The idea is that books_1 and books_2 become completely independent of each other.

我很失望，微软并没有提供像Ruby整齐，快速和容易的解决方案是用克隆做（）方法。

I'm disappointed Microsoft didn't offer a neat, fast and easy solution like Ruby are doing with the clone() method.

将是真正真棒从助手是用我的code和一个可行的解决方案，改变它，所以它可以编译和工作是什么。我认为这将真正帮助新手试图理解这个问题提供的解决方案。

What would be really awesome from helpers is to use my code and alter it with a workable solution so it can be compiled and work. I think it will truly help newbies trying to understand offered solutions for this issue.

编辑：请注意，图书类可能会更加复杂，并有更多的特性。我试图让事情变得简单。

Note that the Book class could be more complex and have more properties. I tried to keep things simple.

推荐答案

您需要创建新的图书对象，然后把那些在一个新的列表：

You need to create new Book objects then put those in a new List:

List<Book> books_2 = books_1.Select(book => new Book(book.title)).ToList();

更新：稍微简单... 列表＆LT; T＆GT; 有一个名为方法的 ConvertAll 返回一个新的列表：

Update: Slightly simpler... List<T> has a method called ConvertAll that returns a new list:

List<Book> books_2 = books_1.ConvertAll(book => new Book(book.title));

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