❔ Create new instance of type unknown at runtime?

Say I have a base class,

abstract class Letter

abstract class Letter

with child classes

, and

.

If I have a variable:

Letter myLetter

Letter myLetter

which is of unknown type (can be any of

, or

, the only guarantee is it's a child of

Letter

Letter

), how can I create a new instance of whatever class

myLetter

myLetter

is?

I need to create a new instance (must call default constructor as well) of whatever

myLetter

myLetter

is and store it in another variable (say

myLetter2

myLetter2

)