Further abstraction techniques - Objects First with Java: A Practical Introduction Using BlueJ - page 331

Exercise 10.9 Check to see that setting the useShared field in Randomizer to false
breaks the repeatability of the simulations seen in Exercise 10.8. Be sure to restore it to true
afterwards, because repeatability will be an important element in later testing.

Now that we have a broad, external understanding of what this project does, we will look in
detail at the implementation of the Rabbit , Fox , and Simulator classes.

10.2.2 The Rabbit class
The source code of the Rabbit class is shown in Code 10.1.

Code 10.1
The Rabbit class

// import statements and class comment omitted

public class Rabbit
{
// Characteristics shared by all rabbits (class variables).

// The age at which a rabbit can start to breed.
private static final int BREEDING_AGE = 5;
// The age to which a rabbit can live.
private static final int MAX_AGE = 40;
// The likelihood of a rabbit breeding.
private static final double BREEDING_PROBABILITY = 0.12;
// The maximum number of births.
private static final int MAX_LITTER_SIZE = 4;
// A shared random number generator to control breeding.
private static final Random rand = Randomizer.getRandom();

// Individual characteristics (instance fields).

// The rabbit's age.
private int age;
// Whether the rabbit is alive or not.
private boolean alive;
// The rabbit's position.
private Location location;
// The field occupied.
private Field field;

/**
* Create a new rabbit. A rabbit may be created with age
* zero (a newborn) or with a random age.
*