c# - 列表框无法显示子类变量

Question

我正在做一个项目，用户输入动物的值(姓名、年龄、性别等)，用户输入的值显示在列表框中 这些类相互继承。以下是继承的工作方式:

Animal class is the parent for all classes.

Mammal class inherit from Animal class.

Dog class inherit from Mammal class.

Cat class inherit from Mammal class

Reptile class inherit from Animal class

Snake class inherit from Reptile class

Lizard class inherit from Reptile class

Animal 的变量是id、name、age、gender。

哺乳动物的变量是 dentry

Dog 的变量是barkLevel

用户可以选择要创建的动物。有一个显示动物类型(哺乳动物和爬行动物)的列表框，旁边有一个列表框，根据用户选择的动物类型显示其动物。

例如，如果用户在列表框中选择哺乳动物，它旁边的列表框会显示狗和猫。

这一切都很好，这不是问题所在。

问题:

输入值显示在结果列表中，但不显示子类变量。结果列表框正在显示Id、姓名、年龄、性别但不是 dentry 或吠声水平。没有错误信息或任何东西。它只是不显示子类变量。

这是我的主窗体:

    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Windows.Forms;

    namespace Assign_1
    {
        public partial class MainForm : Form
        {
            private Dog m_dog = new Dog();
            private Cat m_cat = new Cat();
            private Snake m_snake = new Snake();
            private Lizard m_lizard = new Lizard();
            private AnimalManager animalmgr  = null;
            private Animal m_animal = new Animal();
            private Mammal m_mammal = new Mammal();
            public MainForm()
            {

                //Visual Studio initializations
                InitializeComponent();

                //My initializations
                InitializeGUI();
                Gendercmb.DataSource = Enum.GetValues(typeof(GenderType));
                Categorylst.DataSource = Enum.GetValues(typeof(Categorytype));
                animalmgr = new AnimalManager();

            }

            private void InitializeGUI()
            {
                ReadInput();
            }

            private void ReadInput()
            {
                m_animal.Name = ReadName();
                m_animal.Age = ReadAge();
                m_mammal.Teeth = ReadTeeth();
                m_dog.BarkLevel = ReadBarklevel();

                m_animal.Gender = this.Gendercmb.GetItemText(this.Gendercmb.SelectedItem);


            }
            private int ReadAge()
            {
                int age = 0;

                int.TryParse(Agetxt.Text, out age);

                return age;
            }
            private int ReadBarklevel()
            {
                int bark = 0;

                int.TryParse(barktxt.Text, out bark);

                return bark;

            }
            private int ReadTeeth()
            {
                int teeth = 0;

                int.TryParse(teethtxt.Text, out teeth);

                return teeth;
            }

            private string ReadName()
            {
                string name = "";
                name = Nametxt.Text;
                return name;
            }

            private void addMammal(Mammal values)
            {

                ReadInput();

                switch ((MammalType)Animallst.SelectedIndex)
                {
                     case MammalType.Dog:
                        {

                            // Use a copy constructor to set a dog with common data
                            Dog m_dog = new Dog(values);
                            // If more data in GUI to fill in for this animal, do it here
                            //Then send it to the manager for adding to the list
                            animalmgr.add(m_dog);
                            break;
                       } 
                    case MammalType.Cat:
                        {
                            Cat m_cat = new Cat(values);
                            animalmgr.add(m_cat);
                            break;
                        }
                }
            }

            private void AddReptile(Reptile values)
            {
                ReadInput();

                switch ((ReptileType)Animallst.SelectedIndex)
                {
                    case ReptileType.Snake:
                        {

                            // Use a copy constructor to set a snake with common data
                            Snake m_snake = new Snake(values);
                            // If more data in GUI to fill in for this animal, do it here
                            //Then send it to the manager for adding to the list
                            animalmgr.add(m_snake);
                            break;
                        }
                    case ReptileType.Lizard:
                        {
                            Lizard m_lizard = new Lizard();
                            animalmgr.add(m_lizard);
                            break;
                        }
                }
            }

            //When user clicks "Add to list"
            private void button1_Click(object sender, EventArgs e)
            {
                ReadInput();
                System.Windows.Forms.MessageBox.Show(m_dog.BarkLevel.ToString());

                switch ((Categorytype)Categorylst.SelectedIndex)
                {
                    case Categorytype.Mammal:
                        {
                            Mammal mammal = new Mammal(m_animal);
                            addMammal(mammal);
                            break;
                        }
                    case Categorytype.Reptile:
                        {
                            Reptile m_reptile = new Reptile(m_animal);
                            AddReptile(m_reptile);
                            break;
                        }


                }
                UpdateResults();
            }
            private void UpdateResults()
            {

                Resultlst.Items.Clear();  //Erase current list
                //Get one elemnet at a time from manager, and call its 
                //ToString method for info - send to listbox
                for (int index = 0; index < animalmgr.ElementCount; index++)
                {
                    Animal animal = animalmgr.GetElementAtPosition(index);
 toString method.
                    Resultlst.Items.Add(animal.ToString()); // <--- Here is the problem
                }
            }
        }
    }

这是我的动物管理类:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Assign_1
{
    class AnimalManager
    {
     //   private List<Animal> m_animalList;
        private List<Animal> m_animal;
        private List<Mammal> m_mammal;
        public AnimalManager()
        {
            //In this list objects off diff animals of all species are saved
            //   m_animalList = new List<Animal>();
            m_animal = new List<Animal>();
            m_mammal = new List<Mammal>();
        }


        public void add(Animal ObjIn)
        {
            m_animal.Add(ObjIn);
        }

        public bool IsIndexValid(int index)
        {
            return ((index >= 0) && (index < m_animal.Count));
        }

        public Animal GetElementAtPosition(int index)
        {
            //We choose to return a copy
        if (IsIndexValid(index))
            {
                if (m_animal[index] is Mammal)
                    return new Mammal((Mammal)m_animal[index]);
                if (m_animal[index] is Reptile)
                    return new Reptile((Reptile)m_animal[index]);
                return null;
            }
            else
                return null;
        }

        public int ElementCount
        {
            get { return m_animal.Count; }
        }
    }
}

更新:

我现在知道问题是 Resultlst.Items.Add(animal.ToString()); 我需要以某种方式包含哺乳动物和狗对象(取决于所选动物)，但我不知道'知道怎么做。

Answer 1

据我所知，您实际上从未返回过您的子类。假设您在 m_animal 中拥有所有的猫、狗、蛇和蜥蜴，当您通过基类构造函数运行它们时，您实际上正在丢失子类的属性。尝试直接返回对象:

public Animal GetElementAtPosition(int index)
{
    if (IsIndexValid(index))
        return m_animal[index];
    else
        return null;
}

如果您在所有类中重写了 ToString()，您应该会得到预期的结果。