我是C#的新手,正在努力了解基本概念.预先感谢您的帮助.我下面有一些示例类(在这个窗口中键入,因此可能会有一些错误),并有两个问题：
>是否可以调用派生类方法,该方法使用相同的名称在基类方法中执行代码,然后在派生类方法中执行代码？每个派生类都需要为RunCheck执行基类代码,然后执行特定于其类的特殊代码.我可以在基类中命名RunCheck(),然后在调用派生类的RunCheck()时调用它,但是我必须记住在派生类中的RunCheck()上调用它.
>在Program.cs中,如果在不传递的派生类的字段中,我想输出一个空值的所有字段,我将通过什么？
这是我的代码：
class baseCheck
{
public DateTime StartTime { get; set; }
public DateTime LastRun { get; set; }
public int Runs { get; set; }
//Others
public void RunCheck()
{
if (Started != null)
started = DateTime.Now;
LastRun = DateTime.Now;
Runs++;
}
}
class FileCheck : baseCheck
{
public string FileName { get; set; }
public void RunCheck()
{
//I want all the code in the base class to run plus
//any code I put here when calling this class method
}
}
class DirectoryCheck : baseCheck
{
public string DirectoryName { get; set; }
public void RunCheck()
{
//I want all the code in the base class to run plus
//any code I put here when calling this class method
}
}
//Program.cs
static void Main()
{
//Create derived class - either DirectoryCheck or FileCheck
//depending on what the user chooses.
if (Console.ReadLine()=="F")
{
FileCheck c = new FileCheck();
}
else
{
DirectoryCheck c = new DirectoryCheck();
}
PrintOutput(c);
}
private void PrintOut(What do I put here?)
{
Console.WriteLine("Started: {0}",f.StartTime)
Console.WriteLine("Directory: {0}",f.DirectoryName)
Console.WriteLine("File: {0}",f.FileName}
}
解决方法
只需在DirectoryCheck类中调用base.RunCheck()：
public class DirectoryCheck : baseCheck
{
public string DirectoryName { get; set; }
public void RunCheck()
{
//I want all the code in the base class to run plus
//any code I put here when calling this class method
base.RunCheck();
Console.WriteLine("From DirectoryCheck");
}
}
还有你当前的实现,你隐藏基类RunCheck()方法 – 你应该重写它 – 这会将基类中的方法签名更改为
public virtual void RunCheck()
并在派生类中
public override void RunCheck()
我怀疑你真正想要的是像Non Virtual interface模式(NVI) – 在基类中暴露一个受保护的虚拟方法,子类可以覆盖,但是在基类上实际上是调用该方法的公共方法 – 这种方法允许您扩展您在该呼叫之前和之后所做的工作.
在你的例子中,它将如下所示：
class BaseCheck
{
private DateTime Started { get; set; }
public DateTime StartTime { get; set; }
public DateTime LastRun { get; set; }
public int Runs { get; set; }
//Others
public void RunCheck()
{
if (Started != null)
Started = DateTime.Now;
LastRun = DateTime.Now;
Runs++;
CoreRun();
}
protected virtual void CoreRun()
{
}
}
public class DirectoryCheck : BaseCheck
{
public string DirectoryName { get; set; }
protected override void CoreRun()
{
//I want all the code in the base class to run plus
//any code I put here when calling this class method
Console.WriteLine("From DirectoryCheck");
}
}
