Object.GetType（）是否可以返回null？

Question

Merely curious.

Is there any time when calling .GetType() on an object will return null?

Hypothetical usage:

public Type MyMethod( object myObject )
{
    return myObject.GetType();
}

Answer 1

GetType on an object can never return null - at the very least it will be of type object. if myObject is null, then you'll get an exception when you try to call GetType() anyway

Answer 2

No, it will not return null . But here is a gotcha to be aware of!

static void WhatAmI<T>() where T : new() { 
    T t = new T(); 
    Console.WriteLine("t.ToString(): {0}", t.ToString());
    Console.WriteLine("t.GetHashCode(): {0}", t.GetHashCode());
    Console.WriteLine("t.Equals(t): {0}", t.Equals(t)); 

    Console.WriteLine("t.GetType(): {0}", t.GetType()); 
} 

Here's the output for a certain T :

t.ToString():
t.GetHashCode(): 0
t.Equals(t): True

Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object.

What is T ? Answer: any Nullable<U> .

(Credit orginal concept to Marc Gravell.)

Answer 3

If the myObject parameter is null, then you won't be able to call GetType() on it. A NullReferenceException will be thrown. Otherwise, I think you will fine.

Answer 4

http://msdn.microsoft.com/en-us/library/system.object.gettype(VS.85).aspx

MSDN only lists a type object as the return value.

I'd imagine other than that all you can get is a "not set to an instance of an object" exception (or maybe its null reference) Because MSDN does say INSTANCE.

Answer 5

基本上，不，它不能（永远不会返回null），也不会。