CSC207H Fall 2010 Quiz 1 Solution
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1.
a) static, because then that variable is shared and accessible from all
instances of the class. That means that it can be incremented in the
constructor.

b) Yes. Java scoping rules say that if a variable name is not found in an object
(as an instance variable), then the class itself is examined to see if there is
a static variable of that name.

c) No. Only instance methods -- not instance variables, and nothing static --
can be overriden. In all these other cases, if a variable or method of the same
name is declared, it shadows the one in the superclass.

2.
a) ((P) a2).y

b) ((C) a3).y

c) It cannot be done.

d) a3.r()

e) For the assignment statement a3 = a1;
     First evaluate the right-hand side -- a1's value is 0xA2 -- and then store
     the value in the variable on the left-hand side. This place 0xA2 into a3's
     box.

   For the assignment statement a3.y = ((P) a2).y;
     First evaluate the right-hand side -- ((P) a2).y's value is 6 -- and then
     store the value in the variable on the left-hand side. Entertainingly, a3.y
     and ((P) a2).y resolve to the same variable.

3.
a) It calls JFrame's constructor, which sets the title of the window.

b)
  - MooingWindow no longer implements ActionListener.
  
  - BListener implements ActionListener.
  
  - The BListener constructor needs to be told the MooingWindow, and that needs
    to be saved as an instance variable.
  
  - The actionPerformed method needs to be moved to BListener, and "this"
    replaced with the instance variable.
  
  - In the MooingWindow constructor, BListener needs to be instantiated and
    added to myButton as an actionListener.