Further abstraction techniques - Objects First with Java: A Practical Introduction Using BlueJ - page 337

Exercise 10.14 Does increasing the maximum age for foxes lead to a significantly higher
numbers of foxes throughout a simulation, or is the rabbit population more likely to be reduced
to zero as a result?
Exercise 10.15 Experiment with different combinations of settings (breeding age, maximum
age, breeding probability, litter size, etc.) for foxes and rabbits. Do species always disappear
completely in some configurations? Are there configurations that are stable—i.e., that produce
a balance of numbers for a significant length of time?
Exercise 10.16 Experiment with different sizes of fields. (You can do this by using the
second constructor of Simulator .) Does the size of the field affect the likelihood of species
surviving?
Exercise 10.17 Compare the results of running a simulation with a single large field and two
simulations with fields that each have half the area of the single field. This models something
close to splitting an area in half with a freeway. Do you notice any significant differences in the
population dynamics between the two scenarios?
Exercise 10.18 Repeat the investigations of the previous exercise, but vary the proportions
of the two, smaller fields. For instance, try three-quarters and one quarter, or two-thirds and
one-third. Does it matter at all how the single field is split?
Exercise 10.19 Currently, a fox will eat at most one rabbit at each step. Modify the find-
Food method so that rabbits in all adjacent locations are eaten at a single step. Assess the im-
pact of this change on the results of the simulation. Note that the findFood method currently
returns the location of the single rabbit that is eaten, so you will need to return the location of
one of the eaten rabbits in your version. However, don't forget to return null if there are no
rabbits to eat.
Exercise 10.20 Following on from the previous exercise, if a fox eats multiple rabbits at a
single step, there are several different possibilities as to how we can model its food level. If we
add all the rabbit's food values, the fox will have a very high food level, making it unlikely to die
of hunger for a very long time. Alternatively, we could impose a ceiling on the fox's food level.
This models the effect of a predator that kills prey regardless of whether it is hungry or not.
Assess the impacts on the resulting simulation of implementing this choice.
Exercise 10.21 Challenge exercise Given the random elements in the simulation,
argue why the population numbers in an apparently stable simulation could ultimately
collapse.
10.2.4 The Simulator class: setup
The Simulator class is the central part of the application that coordinates all the other pieces.
Code 10.3 illustrates some of its main features.