类概念（访问属性然后访问方法的类） [英] Class concept (a class accessing property then accessing method)

问题描述

Hello Everyone



我有一个名为Car的课程：

Hello Everyone

I have a class called Car:

Public Class Car
    'Property
    Public theColor() As Color

    'Method
    Public speed As Double
    Public Function run()
        Return speed
    End Function
End Class

在另一个类中我创建一个Ca实例r类：

In another class I create an instance of Car Class:

Public Class SUV
    Dim newCar As New Car

    Private Sub setColor()
        'set theColor property
        newCar.theColor = Color.Red
    End Sub

    Private Sub testDrive()
        'call run() function
        newCar.run()
    End Sub
End Class

从上面的代码中，

如果我想设置一个类的属性我只写一个实例和属性：

newCar.theColor = Color.Red

此外，如果我想调用类的方法，我只需编写一个实例，然后调用函数或子函数：

newCar.run（）



但是我不明白一行代码怎么会这样，例如：

From the code above,
If I want to set a property of a class I just write an instance and the property:
newCar.theColor = Color.Red
Also if I want to call a method of a class I just write an instance then call the function or sub:
newCar.run()

But I dont understand how can a line of code be like this, for example:

Dim dgv As New DataGridView
dgv.Rows.Add()

上面的代码显示实例（dgv）调用属性（Rows）而不是调用方法（添加（））





回到我班级（汽车和SUV）

怎么写如果我想调用这样的方法，我班上的代码？

The code above show that an instance (dgv) call property (Rows) than call a method (Add())


Back to my class (the Car And SUV)
How to write the code in my class if i want to call the method like this?

newCar.theColor.resetColor()

和另一个代码：

And another code:

newCar.theColor.setColor() = Color.Red

如果问题标题与我提出的问题不符，我很抱歉。



谢谢



我的尝试：



我不知道如何尝试解决上面的问题

I am sorry if the question's title isnt match with what i've asked.

Thanks

What I have tried:

I have no idea how to to try to solve my question above

推荐答案

当你写这个：

When you write this:

Dim dgv As New DataGridView
dgv.Rows.Add(obj)

您创建DataGridView的实例，然后使用它：

dgv.Rows 是DataGridView的一个属性，它返回DataGridViewRowCollection类的一个实例，它是DGV中的行：MSDN [ ^ ]

DataGridViewRowCollection有一个方法添加，它会在集合中添加一行，因此对于DGV。

要做类似的事情，你需要额外的课程：

You create an instance of the DataGridView, and then use it:
dgv.Rows is a Property of DataGridView which returns a n instance of the DataGridViewRowCollection class which is the rows in the DGV: MSDN[^]
The DataGridViewRowCollection has a Method Add which adds a row to the collection, and hence to the DGV.
To do something similar, you'd need an extra class:

Public Class MyColor
	Public Sub ResetColor()
	End Sub
End Class
Public Class Car
	Public Property TheColor() As MyColor
		Get
			Return m_TheColor
		End Get
		Set
			m_TheColor = Value
		End Set
	End Property
	Private m_TheColor As MyColor
End Class
...
Public Sub myMethod()
	Dim newCar As New Car()
	newCar.TheColor.ResetColor()
End Sub

引用：

我们是否采用类似的方式在另一种语言中创建属性或方法？像java或c＃。这是OOP概念的一部分吗？我在学习编程时错过了什么？

an we do the similiar way to create property or method in another language? like java or c#. And is this a part of OOP concept? what did i miss in my learning of programming?

是的。例如，C＃中的上述内容是：

Yes. For example, the above in C# is:

public class MyColor
    {
    public void ResetColor()
        {
        }
    }
public class Car
    {
    public MyColor TheColor { get; set; }
    }
...
    public void myMethod()
        {
        Car newCar = new Car();
        newCar.TheColor.ResetColor();
        }

这是类似的Java代码。

属性不是OOP的严格组成部分 - 它们是只是涉及方法调用的语法糖，让你将属性视为一个变量 - 但大多数OOP语言实现它们。



你错过了什么？ ：笑：我不知道，我不在那里！

And it's similar code for Java.
Properties aren't strictly part of OOPs - they are just "syntactic sugar" for the method calls involved that let you treat the property as a variable - but most OOPs languages implement them.

What did you miss? :laugh: I don't know, I wasn't there!

我强烈建议您阅读继承 [ ^ ]和 Polimorphism [ ^ ]。



A 汽车类必须是基类。 Suv 类应继承自 Car （因为它是一种 Car ）。我是对的吗？



例如：

I'd strongly recommend to read about Inheritance[^] and Polimorphism[^].

A Car class have to be a base class. A Suv class should inherits from Car (as it is a type of Car). Am i right?

For example:

Public Class Car
	
	Private dc As Integer = 5
	Private c As Drawing.Color = Drawing.Color.Gray
	
	Public Sub New ()
		'default constructor
		
	End Sub
	
	Public Sub New (ByVal doorsCount As Integer, ByVal color As Drawing.Color)
		dc = doorsCount
		c=  color
	End Sub
	
	Public Property DoorsCount As Integer
		Get
			Return dc
		End Get
		Set (ByVal value As Integer)
			dc = value
		End Set
	End Property
	
	Public Property Color As Drawing.Color
		Get
			Return c
		End Get
		Set (ByVal value As Drawing.Color)
			c = value
		End Set
	End Property

End Class

Public Class Suv
	Inherits Car
	
	Public Sub New ()
		'default constructor
		MyBase.DoorsCount = 4
                MyBase.Color = Drawing.Color.Green		
	End Sub
	
	Public Sub New (ByVal doorsCount As Integer, ByVal color As Drawing.Color)
		MyBase.DoorsCount = doorsCount
		MyBase.Color =  color
	End Sub
	
	
End Class

---

用法：

---

Usage:

Dim carcar As Car = New Car()
Console.WriteLine(New String("-", 25))
Console.WriteLine("Car details:")
Console.WriteLine("  - doors: {0}", carcar.DoorsCount)
Console.WriteLine("  - color: {0}", carcar.Color.ToString())


Dim suvcar As Suv = New Suv()
Console.WriteLine(New String("-", 25))
Console.WriteLine("Suv details:")
Console.WriteLine("  - doors: {0}", suvcar.DoorsCount)
Console.WriteLine("  - color: {0}", suvcar.Color.ToString())

suvcar.DoorsCount = 3
suvcar.Color = Drawing.Color.Yellow

Console.WriteLine(New String("-", 25))
Console.WriteLine("Suv details:")
Console.WriteLine("  - doors: {0}", suvcar.DoorsCount)
Console.WriteLine("  - color: {0}", suvcar.Color.ToString())

结果：

Result:

-------------------------
Car details:
  - doors: 5
  - color: Color [Gray]
-------------------------
Suv details:
  - doors: 4
  - color: Color [Green]
-------------------------
Suv details:
  - doors: 3
  - color: Color [Yellow]

---

如您所见，您不需要在自定义方法中使用getter / setter。你可以只用属性来实现。



试试吧！祝你好运！

---

As you can see, you don't need getter/setter inside custom method. You can achieve that using only properties.

Try! Good luck!

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