(C#) 访问/修改列表中的对象

Question

新来的，我已经学习 c# 大约一个月了。

不管怎样，我已经搜索 StackOverflow 几天了，但找不到我的问题的具体答案...

//Here's my Class

public class Guy
{
     public static int ID { get; set; }
     public static int LifeExpectancy { get; set; }
     public static bool Living { get; set; }

     public Guy(int id, int lifeExpectancy, bool living)
     {
         ID = id;
         LifeExpectancy = lifeExpectancy;
         Living = living;
     }
}

我要做的是创建特定数量的“someGuy”对象，然后使用这种方法将它们放入公共列表中......

public static List<Guy> Guys = new List<Guy>();

public static void makeSomeGuys(int howManyGuys)
{
    for (int i = 0, i <= howManyGuys; i++)
    {
        int id = i;
        int lifeExpectancy = 80;
        bool alive = true;

        Guys.Add(New Guy(id, lifeExpectancy, alive));

        Console.WriteLine("Made a new Guy {0}", id);         
    }
    return; 
}

问题按重要性排序：

如何访问特定对象及其参数？ （从“Guys”列表访问。）

如何在另一个类中访问此列表中的对象？ （我不是绝对需要，我很好奇）

我可以使用参数在列表中搜索对象吗？ （而不是像...humanPopulation[number]）

我应该为修改了参数的对象创建一个新列表吗？ （而不是将其留在原始列表中）

是否可以从列表中删除项目？ （一般来说，这是人们做的事情吗？如果是，为什么？）

我真的只需要回答第一个问题。其余的只是奖金。谢谢！

Answer 1

首先你需要从 Guy 类的属性中移除 static 修饰符，即：

public int ID { get; set; }
public int LifeExpectancy { get; set; }
public bool Living { get; set; }

因为 static 导致属性成为类本身的属性，而不是类的实例（个体“人”）。

获取第一个人（第零个人）的预期寿命：

Console.WriteLine(Guys[0].LifeExpectancy);

获取第五个人的预期寿命：

Console.WriteLine(Guys[4].LifeExpectancy);

Answer 2

using System;
using System.Collections.Generic;
using System.Linq;

namespace test
{
    public class Guy
    {
        private int m_ID;
        private int m_LifeExpectancy;
        private bool m_Living;

        public int ID
        {
            get { return m_ID; }
            set { m_ID = value; }
        }
        public int LifeExpectancy
        {
            get { return m_LifeExpectancy; }
            set { m_LifeExpectancy = value; }
        }
        public bool Living
        {
            get { return m_Living; }
            set { m_Living = value; }
        }

        public Guy(int id, int lifeExpectancy, bool living)
        {
            ID = id;
            LifeExpectancy = lifeExpectancy;
            Living = living;
        }
    }

    public class MyFactory
    {
        public IList<Guy> MakeSomeGuys(int howManyGuys)
        {

            IList<Guy> localGuys = new List<Guy>();

            for (int i = 0; i <= howManyGuys; i++)
            {

                int id = i;
                int lifeExpectancy = 80;
                bool alive = true;

                localGuys.Add(new Guy(id, lifeExpectancy, alive));

                Console.WriteLine("Made a new Guy {0}", id);
            }


            return localGuys;
        }
    }

    public class program
    {
        public void Main()
        {
            MyFactory mf = new MyFactory();
            IList<Guy> guys = mf.MakeSomeGuys(5);

            //How do I access a specific object as well as its parameters? (Accessing from the list "Guys".)
            int GetFirstGuyId = guys.FirstOrDefault().ID; //LEARN LINQ

            //How do I access an object from this list in another class? (Not that I absolutely need to, I'm curious)
            //you need to learn about object oriented encapsulation for better understanding.

            //Can I search for an object in a list by using its parameters? (As opposed to doing something like...humanPopulation[number])
            Guy guyById = guys.Where(g => g.ID == 5).FirstOrDefault(); // returns the first match (need to learn lambda expression)

            //Should I create a new list for objects that have had their parameters modified? (As opposed to leaving it in the original list)
            // you need to learn about passing values by value / reference (by reference you already changing the original!).

            //Is it possible to remove items from a list? (Just in general, is that a thing people do? if so, why?)
            //yes
            guys.Remove(guyById);

        }
    }
}

Answer 3

你可能是 C# 和 OO 编程的新手，所以我在这个答案中包含了一些很好的链接。

仅关于问题 1：

首先，您的Guy 类属性未正确封装。确保您正确地确定了ID、LifeExpectancy 和Living 属性的范围，如this 文章中所示。

如果您想访问一个特定项，即具有特定 ID 的 Guy，则最好使用像 Dictionary 这样的关联容器。

如果您对List 容器感到满意，则需要在Guys 上使用Find 方法，如链接中的示例所示。您会注意到文档中的术语 谓词，this 链接将详细说明。