Three Hierarchies for ButtonApp2

Class Hierarchy (= flat)

Main:

• Provides window and layout, also Panel for each Square

• Creates Canvas

• Creates Squares and the buttons that go with each Square

• Provide drawSquares()

  • Because we have the list of Square's
  • then delegate the work to each Square

Canvas:

• paintComponent() callback, passes job up to main

Square:

• Packages up the model or "application data" in ivars, i.e., location and fill of square

  • Has pointer to canvas for redraw

  • Can draw itself

  • Accepts "semantic" call from button routines

  • Uses enum ButtonAction

• "POJO" Plain Old Java Object

ButtonXXX:

• Initializes button with label, icon, etc

  • ButtonFill also updates its own label

• Remembers its Square, that it controls

• Each button has its own listener, sends semantic action to its Square

Aggregation Hierarchy

Main:

• Square(s), has pointer to Main

• ButtonXXX, has pointer to its Square

• Canvas, just creates it and passes its pointer

Uses ("Collaboration") Hierarchy

ButtonXXX:

• Calls Square for semantics on user pushbutton callbacks

Square:

• Calls Canvas for repaint after each semantic callback

Canvas:

• Calls Main to handle paintComponent() callback

Main:

• Calls Squares to redraw themselves

Note:

• Widgets needed later are kept as ivars

• Widgets needed only for creation are local variables, maybe passed to constructors