Sometimes we would like a class that has just a single unique instance. Create a class Mer...

Sometimes we would like a class that has just a single unique instance. Create a class Merlin that has one attribute, theWizard, which is static and of type Merlin. The class has only one constructor and two methods, as follows:

• Merlin—a private constructor. Only this class can invoke this constructor; no other class or program can create an instance of Merlin.

• summon—a static method that returns theWizard if it is not null; if theWizard is null, this method creates an instance of Merlin using the private constructor and assigns it to theWizard before returning it.

• consult—a non-static method that returns the string "Pull the sword from the stone".