Accessing a Private Constructor from Outside the Class in C#

by

New answer (nine years later)

There is now several overloads for Activator.CreateInstance that allow you to use non public constructors:

Activator.CreateInstance(typeof(YourClass), true);

true = use non public constructors.

.

Old answer

Default constructors are private for a reason. The developer doesn’t make it private for fun.

But if you still want to use the default constructor you get it by using reflection.

var constructor = typeof(Bob).GetConstructor(BindingFlags.NonPublic|BindingFlags.Instance, null, new Type[0], null);
var instance = (Bob)constructor.Invoke(null);

Edit

I saw your comment about testing. Never test protected or private methods / properties. You have probably done something wrong if you can’t manage to test those methods/properties through the public API. Either remove them or refactor the class.

Edit 2

Forgot a binding flag.

Leave a Comment