Question

我正在开发一个用户应该向动物输入值（项目名称，年龄，性别等等）的项目，并且用户输入的值应显示在列表框中这些类相互继承。以下是继承的工作原理：

Animal 类是所有类的父级。

哺乳动物类继承自 Animal 类。

Dog 类继承自 Mammal 类。

Cat 类继承自 Mammal 类

Reptile 类继承自 Animal 类

Snake 类继承自 Reptile 类

Lizard 类继承自 Reptile 类

用户可以选择要创建的动物。有一个列表框显示动物的类型（哺乳动物和爬行动物），旁边有一个列表框，根据用户选择的动物类型，它会显示动物。

例如，如果用户在列表框中选择 Mammal ，则旁边的列表框会显示 Dog 和 Cat 。

这是完美的，这不是问题。

问题是指用户在列表框中选择动物类型后输入动物值（名称和年龄）（例如哺乳动物，狗）并单击添加按钮，结果列表框在尝试添加哺乳动物时显示 Assign1_1.Mammal ，在尝试添加爬行动物时显示 Assign_1.Reptile

我想要它做的是在结果列表框中显示用户输入的值（名称和年龄），而只是显示 Assign1.Mammal 或 Assign1.Reptile 取决于所选择的动物。

这是我的MainForm代码：

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

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

            return age;
        }

        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();
                        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();

            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);

                Resultlst.Items.Add(animal.ToString());
            }
        }

这是我的动物经理班：

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_animal;
        private List<Mammal> m_mammal;
        public AnimalManager()
        {
            //In this list objects off diff animals of all species are saved
            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, why do I need type casting when copying?
        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; }
        }


    }
}

这是我的哺乳动物课：

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

namespace Assign_1
{
    class Mammal : Animal
    {
        private MammalType theMammal;
        private int teeth;


        public Mammal() : base()
             {

             }
        public Mammal(Animal other)
        {
            this.Name = other.Name;
            this.Age = other.Age;
            this.Gender = other.Gender;
            this.Id = other.Id;

        }

        public Mammal (MammalType type)
        {
            theMammal = type; 
        }

#region Props
        public MammalType TheMammal
        {
            get { return theMammal; }
            set { theMammal = value; }
        }


        public int Teeth
        {
            get { return teeth; }
            set { teeth = value; }
         }
#endregion


    }
}

这是我的Dog课程：

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

namespace Assign_1
{
    class Dog : Mammal
    {


        public Dog()
        {

        }
      public Dog(Mammal other)
    {
      this.Name = other.Name;
      this.Age = other.Age;
      this.Teeth = other.Teeth;
    }


    }
}

修改为了更简单，我只显示子类哺乳动物和狗。如果我能够弄清楚如何创建 Dog ，我也可以修复其他人。

Answer 1

您需要覆盖ToString() - 方法。请注意签名中的override关键字。

public override string ToString()
{
    //You can put anything here and it will be returned by the ToString()-method.
    return this.Name + ", " + this.Age;
}

将此代码放入Dog - 课程中。这将使dog.ToString()返回Name, Age。

此外，您实际上可以将此覆盖放在您的基类Animal中，它将被转移到所有子类。只要他们不自己覆盖ToString()，他们也会返回Name, Age。

Answer 2

您只需在班级中添加ToString()方法的覆盖覆盖返回您选择在ListBoxes中显示的值。

ListBox，当准备好显示项目时，使用添加到其items集合的类实例的ToString方法。如果没有ToString（），则使用基类Object.ToString()，该方法只返回类名

例如，您可以使用

更改Dog类

class Dog : Mammal
{
    public Dog()
    {
    }
    public Dog(Mammal other)
    {
       this.Name = other.Name;
       this.Age = other.Age;
       this.Teeth = other.Teeth;
    } 
    public override string ToString()
    {
       return string.Format("{0}, {1}, {2}", 
               this.Name, this.Age, this.Teeth);
    }
}

列表框显示的是类名而不是值

2 个答案: