Java Reference
In-Depth Information
Figure 19.2. A
Visualization
object lets a user paint a picture of a prospective factory.
When the user clicks Add or drags and releases a machine image, the
Visualization
object asks the
FactoryModel
object for a new memento. The
Visualization
object
stacks this memento. When the user clicks Undo, the
Visualization
object pops
amemento and calls the
FactoryModel
object's
restore()
method, passing in
the memento at the new top of the stack. The
FactoryModel
object creates a memento by
creating a list and populating it with clones of the current
MachineImage
objects in its
machines
list.
CHALLENGE 19.2
Write the code for the
createMemento()
method of
FactoryModel
so that
the method returns a
List
of clones of machine simulators.
The counterpart to a
createMemento()
method is a
restore()
method that restores the
state of the object according to the information in the memento. In this example, the memento
