委托代理action 的四种方式

1.

Action<T>Delegate

个人理解:和func一样,但是没有返回值

Eg1: 传统型

delegatevoid DisplayMessage(string message);

publicclassTestCustomDelegate
{
publicstaticvoid Main()
{
DisplayMessage messageTarget;

if(Environment.GetCommandLineArgs().Length > 1)
messageTarget =ShowWindowsMessage;
else
messageTarget =Console.WriteLine;

messageTarget("Hello,World!");
}

privatestaticvoid ShowWindowsMessage(string message)
{
MessageBox.Show(message);
}
}

Eg2;

publicstaticvoid Main()
{
Action<string> messageTarget;

if(Environment.GetCommandLineArgs().Length > 1)
messageTarget =ShowWindowsMessage;
else
messageTarget =Console.WriteLine;

messageTarget("Hello,World!");
}

privatestaticvoid ShowWindowsMessage(string message)
{
MessageBox.Show(message);
}
}

Eg3:

publicstaticvoid Main()
{
Action<string> messageTarget;

if(Environment.GetCommandLineArgs().Length > 1)
messageTarget = delegate(string s) {ShowWindowsMessage(s); };
else
messageTarget = delegate(string s) {Console.WriteLine(s); };

messageTarget("Hello,World!");
}

privatestaticvoid ShowWindowsMessage(string message)
{
MessageBox.Show(message);
}

Eg4:lamba

publicstaticvoid Main()
{
Action<string> messageTarget;

if(Environment.GetCommandLineArgs().Length > 1)
messageTarget = s =>ShowWindowsMessage(s);
else
messageTarget = s =>Console.WriteLine(s);

messageTarget("Hello,World!");
}

privatestaticvoid ShowWindowsMessage(string message)
{
MessageBox.Show(message);
}