Question

My problem is thus: I need a way to ensure only one given class can instantiate another. I don’t want to have to make the other a nested inner class or something dumb like that. How do I do this? I forget offhand.

Answer 1

Make the constructor private. Create a static factory method that takes an instance of the class that is allowed access. Have the factory method create a suitable object and use a settor on the object that is allowed access to the created object to give that class the created copy.

public class AllowedAccess {     private SecureClass secure;     public setSecureClass( SecureClass secure )     {         this.secure = secure;     }      ... }  public class SecureClass {      private SecureClass() {}       public static void Create( AllowedAccess allowed )      {           allowed.setSecureClass( new SecureClass() );      }       ... } 

BTW, I’m suspicious of this design. Seems too highly coupled to me.