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17
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Counter.ctxt Executable file
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#BlueJ class context
comment0.params=name
comment0.target=Counter(java.lang.String)
comment0.text=\n\ Provide\ a\ name\ for\ one\ of\ the\ simulation\ types.\n\ @param\ name\ \ A\ name,\ e.g.\ "Fox".\n
comment1.params=
comment1.target=java.lang.String\ getName()
comment1.text=\n\ @return\ The\ short\ description\ of\ this\ type.\n
comment2.params=
comment2.target=int\ getCount()
comment2.text=\n\ @return\ The\ current\ count\ for\ this\ type.\n
comment3.params=
comment3.target=void\ increment()
comment3.text=\n\ Increment\ the\ current\ count\ by\ one.\n
comment4.params=
comment4.target=void\ reset()
comment4.text=\n\ Reset\ the\ current\ count\ to\ zero.\n
numComments=5

60
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Counter.java Executable file
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import java.awt.Color;
/**
* Provide a counter for a participant in the simulation.
* This includes an identifying string and a count of how
* many participants of this type currently exist within
* the simulation.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Counter
{
// A name for this type of simulation participant
private String name;
// How many of this type exist in the simulation.
private int count;
/**
* Provide a name for one of the simulation types.
* @param name A name, e.g. "Fox".
*/
public Counter(String name)
{
this.name = name;
count = 0;
}
/**
* @return The short description of this type.
*/
public String getName()
{
return name;
}
/**
* @return The current count for this type.
*/
public int getCount()
{
return count;
}
/**
* Increment the current count by one.
*/
public void increment()
{
count++;
}
/**
* Reset the current count to zero.
*/
public void reset()
{
count = 0;
}
}

41
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Field.ctxt Executable file
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#BlueJ class context
comment0.params=depth\ width
comment0.target=Field(int,\ int)
comment0.text=\n\ Represent\ a\ field\ of\ the\ given\ dimensions.\n\ @param\ depth\ The\ depth\ of\ the\ field.\n\ @param\ width\ The\ width\ of\ the\ field.\n
comment1.params=
comment1.target=void\ clear()
comment1.text=\n\ Empty\ the\ field.\n
comment10.params=location
comment10.target=java.util.List\ adjacentLocations(Location)
comment10.text=\n\ Return\ a\ shuffled\ list\ of\ locations\ adjacent\ to\ the\ given\ one.\n\ The\ list\ will\ not\ include\ the\ location\ itself.\n\ All\ locations\ will\ lie\ within\ the\ grid.\n\ @param\ location\ The\ location\ from\ which\ to\ generate\ adjacencies.\n\ @return\ A\ list\ of\ locations\ adjacent\ to\ that\ given.\n
comment11.params=
comment11.target=int\ getDepth()
comment11.text=\n\ Return\ the\ depth\ of\ the\ field.\n\ @return\ The\ depth\ of\ the\ field.\n
comment12.params=
comment12.target=int\ getWidth()
comment12.text=\n\ Return\ the\ width\ of\ the\ field.\n\ @return\ The\ width\ of\ the\ field.\n
comment2.params=location
comment2.target=void\ clear(Location)
comment2.text=\n\ Clear\ the\ given\ location.\n\ @param\ location\ The\ location\ to\ clear.\n
comment3.params=animal\ row\ col
comment3.target=void\ place(java.lang.Object,\ int,\ int)
comment3.text=\n\ Place\ an\ animal\ at\ the\ given\ location.\n\ If\ there\ is\ already\ an\ animal\ at\ the\ location\ it\ will\n\ be\ lost.\n\ @param\ animal\ The\ animal\ to\ be\ placed.\n\ @param\ row\ Row\ coordinate\ of\ the\ location.\n\ @param\ col\ Column\ coordinate\ of\ the\ location.\n
comment4.params=animal\ location
comment4.target=void\ place(java.lang.Object,\ Location)
comment4.text=\n\ Place\ an\ animal\ at\ the\ given\ location.\n\ If\ there\ is\ already\ an\ animal\ at\ the\ location\ it\ will\n\ be\ lost.\n\ @param\ animal\ The\ animal\ to\ be\ placed.\n\ @param\ location\ Where\ to\ place\ the\ animal.\n
comment5.params=location
comment5.target=java.lang.Object\ getObjectAt(Location)
comment5.text=\n\ Return\ the\ animal\ at\ the\ given\ location,\ if\ any.\n\ @param\ location\ Where\ in\ the\ field.\n\ @return\ The\ animal\ at\ the\ given\ location,\ or\ null\ if\ there\ is\ none.\n
comment6.params=row\ col
comment6.target=java.lang.Object\ getObjectAt(int,\ int)
comment6.text=\n\ Return\ the\ animal\ at\ the\ given\ location,\ if\ any.\n\ @param\ row\ The\ desired\ row.\n\ @param\ col\ The\ desired\ column.\n\ @return\ The\ animal\ at\ the\ given\ location,\ or\ null\ if\ there\ is\ none.\n
comment7.params=location
comment7.target=Location\ randomAdjacentLocation(Location)
comment7.text=\n\ Generate\ a\ random\ location\ that\ is\ adjacent\ to\ the\n\ given\ location,\ or\ is\ the\ same\ location.\n\ The\ returned\ location\ will\ be\ within\ the\ valid\ bounds\n\ of\ the\ field.\n\ @param\ location\ The\ location\ from\ which\ to\ generate\ an\ adjacency.\n\ @return\ A\ valid\ location\ within\ the\ grid\ area.\n
comment8.params=location
comment8.target=java.util.List\ getFreeAdjacentLocations(Location)
comment8.text=\n\ Get\ a\ shuffled\ list\ of\ the\ free\ adjacent\ locations.\n\ @param\ location\ Get\ locations\ adjacent\ to\ this.\n\ @return\ A\ list\ of\ free\ adjacent\ locations.\n
comment9.params=location
comment9.target=Location\ freeAdjacentLocation(Location)
comment9.text=\n\ Try\ to\ find\ a\ free\ location\ that\ is\ adjacent\ to\ the\n\ given\ location.\ If\ there\ is\ none,\ return\ null.\n\ The\ returned\ location\ will\ be\ within\ the\ valid\ bounds\n\ of\ the\ field.\n\ @param\ location\ The\ location\ from\ which\ to\ generate\ an\ adjacency.\n\ @return\ A\ valid\ location\ within\ the\ grid\ area.\n
numComments=13

206
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Field.java Executable file
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import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
/**
* Represent a rectangular grid of field positions.
* Each position is able to store a single animal.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Field
{
// A random number generator for providing random locations.
private static final Random rand = Randomizer.getRandom();
// The depth and width of the field.
private int depth, width;
// Storage for the animals.
private Object[][] field;
/**
* Represent a field of the given dimensions.
* @param depth The depth of the field.
* @param width The width of the field.
*/
public Field(int depth, int width)
{
this.depth = depth;
this.width = width;
field = new Object[depth][width];
}
/**
* Empty the field.
*/
public void clear()
{
for(int row = 0; row < depth; row++) {
for(int col = 0; col < width; col++) {
field[row][col] = null;
}
}
}
/**
* Clear the given location.
* @param location The location to clear.
*/
public void clear(Location location)
{
field[location.getRow()][location.getCol()] = null;
}
/**
* Place an animal at the given location.
* If there is already an animal at the location it will
* be lost.
* @param animal The animal to be placed.
* @param row Row coordinate of the location.
* @param col Column coordinate of the location.
*/
public void place(Object animal, int row, int col)
{
place(animal, new Location(row, col));
}
/**
* Place an animal at the given location.
* If there is already an animal at the location it will
* be lost.
* @param animal The animal to be placed.
* @param location Where to place the animal.
*/
public void place(Object animal, Location location)
{
field[location.getRow()][location.getCol()] = animal;
}
/**
* Return the animal at the given location, if any.
* @param location Where in the field.
* @return The animal at the given location, or null if there is none.
*/
public Object getObjectAt(Location location)
{
return getObjectAt(location.getRow(), location.getCol());
}
/**
* Return the animal at the given location, if any.
* @param row The desired row.
* @param col The desired column.
* @return The animal at the given location, or null if there is none.
*/
public Object getObjectAt(int row, int col)
{
return field[row][col];
}
/**
* Generate a random location that is adjacent to the
* given location, or is the same location.
* The returned location will be within the valid bounds
* of the field.
* @param location The location from which to generate an adjacency.
* @return A valid location within the grid area.
*/
public Location randomAdjacentLocation(Location location)
{
List<Location> adjacent = adjacentLocations(location);
return adjacent.get(0);
}
/**
* Get a shuffled list of the free adjacent locations.
* @param location Get locations adjacent to this.
* @return A list of free adjacent locations.
*/
public List<Location> getFreeAdjacentLocations(Location location)
{
List<Location> free = new LinkedList<>();
List<Location> adjacent = adjacentLocations(location);
for(Location next : adjacent) {
if(getObjectAt(next) == null) {
free.add(next);
}
}
return free;
}
/**
* Try to find a free location that is adjacent to the
* given location. If there is none, return null.
* The returned location will be within the valid bounds
* of the field.
* @param location The location from which to generate an adjacency.
* @return A valid location within the grid area.
*/
public Location freeAdjacentLocation(Location location)
{
// The available free ones.
List<Location> free = getFreeAdjacentLocations(location);
if(free.size() > 0) {
return free.get(0);
}
else {
return null;
}
}
/**
* Return a shuffled list of locations adjacent to the given one.
* The list will not include the location itself.
* All locations will lie within the grid.
* @param location The location from which to generate adjacencies.
* @return A list of locations adjacent to that given.
*/
public List<Location> adjacentLocations(Location location)
{
assert location != null : "Null location passed to adjacentLocations";
// The list of locations to be returned.
List<Location> locations = new LinkedList<>();
if(location != null) {
int row = location.getRow();
int col = location.getCol();
for(int roffset = -1; roffset <= 1; roffset++) {
int nextRow = row + roffset;
if(nextRow >= 0 && nextRow < depth) {
for(int coffset = -1; coffset <= 1; coffset++) {
int nextCol = col + coffset;
// Exclude invalid locations and the original location.
if(nextCol >= 0 && nextCol < width && (roffset != 0 || coffset != 0)) {
locations.add(new Location(nextRow, nextCol));
}
}
}
}
// Shuffle the list. Several other methods rely on the list
// being in a random order.
Collections.shuffle(locations, rand);
}
return locations;
}
/**
* Return the depth of the field.
* @return The depth of the field.
*/
public int getDepth()
{
return depth;
}
/**
* Return the width of the field.
* @return The width of the field.
*/
public int getWidth()
{
return width;
}
}

23
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/FieldStats.ctxt Executable file
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#BlueJ class context
comment0.params=
comment0.target=FieldStats()
comment0.text=\n\ Construct\ a\ FieldStats\ object.\n
comment1.params=field
comment1.target=java.lang.String\ getPopulationDetails(Field)
comment1.text=\n\ Get\ details\ of\ what\ is\ in\ the\ field.\n\ @return\ A\ string\ describing\ what\ is\ in\ the\ field.\n
comment2.params=
comment2.target=void\ reset()
comment2.text=\n\ Invalidate\ the\ current\ set\ of\ statistics;\ reset\ all\ \n\ counts\ to\ zero.\n
comment3.params=animalClass
comment3.target=void\ incrementCount(java.lang.Class)
comment3.text=\n\ Increment\ the\ count\ for\ one\ class\ of\ animal.\n\ @param\ animalClass\ The\ class\ of\ animal\ to\ increment.\n
comment4.params=
comment4.target=void\ countFinished()
comment4.text=\n\ Indicate\ that\ an\ animal\ count\ has\ been\ completed.\n
comment5.params=field
comment5.target=boolean\ isViable(Field)
comment5.text=\n\ Determine\ whether\ the\ simulation\ is\ still\ viable.\n\ I.e.,\ should\ it\ continue\ to\ run.\n\ @return\ true\ If\ there\ is\ more\ than\ one\ species\ alive.\n
comment6.params=field
comment6.target=void\ generateCounts(Field)
comment6.text=\n\ Generate\ counts\ of\ the\ number\ of\ foxes\ and\ rabbits.\n\ These\ are\ not\ kept\ up\ to\ date\ as\ foxes\ and\ rabbits\n\ are\ placed\ in\ the\ field,\ but\ only\ when\ a\ request\n\ is\ made\ for\ the\ information.\n\ @param\ field\ The\ field\ to\ generate\ the\ stats\ for.\n
numComments=7

128
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/FieldStats.java Executable file
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import java.awt.Color;
import java.util.HashMap;
/**
* This class collects and provides some statistical data on the state
* of a field. It is flexible: it will create and maintain a counter
* for any class of object that is found within the field.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class FieldStats
{
// Counters for each type of entity (fox, rabbit, etc.) in the simulation.
private HashMap<Class, Counter> counters;
// Whether the counters are currently up to date.
private boolean countsValid;
/**
* Construct a FieldStats object.
*/
public FieldStats()
{
// Set up a collection for counters for each type of animal that
// we might find
counters = new HashMap<>();
countsValid = true;
}
/**
* Get details of what is in the field.
* @return A string describing what is in the field.
*/
public String getPopulationDetails(Field field)
{
StringBuffer buffer = new StringBuffer();
if(!countsValid) {
generateCounts(field);
}
for(Class key : counters.keySet()) {
Counter info = counters.get(key);
buffer.append(info.getName());
buffer.append(": ");
buffer.append(info.getCount());
buffer.append(' ');
}
return buffer.toString();
}
/**
* Invalidate the current set of statistics; reset all
* counts to zero.
*/
public void reset()
{
countsValid = false;
for(Class key : counters.keySet()) {
Counter count = counters.get(key);
count.reset();
}
}
/**
* Increment the count for one class of animal.
* @param animalClass The class of animal to increment.
*/
public void incrementCount(Class animalClass)
{
Counter count = counters.get(animalClass);
if(count == null) {
// We do not have a counter for this species yet.
// Create one.
count = new Counter(animalClass.getName());
counters.put(animalClass, count);
}
count.increment();
}
/**
* Indicate that an animal count has been completed.
*/
public void countFinished()
{
countsValid = true;
}
/**
* Determine whether the simulation is still viable.
* I.e., should it continue to run.
* @return true If there is more than one species alive.
*/
public boolean isViable(Field field)
{
// How many counts are non-zero.
int nonZero = 0;
if(!countsValid) {
generateCounts(field);
}
for(Class key : counters.keySet()) {
Counter info = counters.get(key);
if(info.getCount() > 0) {
nonZero++;
}
}
return nonZero > 1;
}
/**
* Generate counts of the number of foxes and rabbits.
* These are not kept up to date as foxes and rabbits
* are placed in the field, but only when a request
* is made for the information.
* @param field The field to generate the stats for.
*/
private void generateCounts(Field field)
{
reset();
for(int row = 0; row < field.getDepth(); row++) {
for(int col = 0; col < field.getWidth(); col++) {
Object animal = field.getObjectAt(row, col);
if(animal != null) {
incrementCount(animal.getClass());
}
}
}
countsValid = true;
}
}

38
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Fox.ctxt Executable file
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#BlueJ class context
comment0.params=randomAge\ field\ location
comment0.target=Fox(boolean,\ Field,\ Location)
comment0.text=\n\ Create\ a\ fox.\ A\ fox\ can\ be\ created\ as\ a\ new\ born\ (age\ zero\n\ and\ not\ hungry)\ or\ with\ a\ random\ age\ and\ food\ level.\n\ \n\ @param\ randomAge\ If\ true,\ the\ fox\ will\ have\ random\ age\ and\ hunger\ level.\n\ @param\ field\ The\ field\ currently\ occupied.\n\ @param\ location\ The\ location\ within\ the\ field.\n
comment1.params=newFoxes
comment1.target=void\ hunt(java.util.List)
comment1.text=\n\ This\ is\ what\ the\ fox\ does\ most\ of\ the\ time\:\ it\ hunts\ for\n\ rabbits.\ In\ the\ process,\ it\ might\ breed,\ die\ of\ hunger,\n\ or\ die\ of\ old\ age.\n\ @param\ field\ The\ field\ currently\ occupied.\n\ @param\ newFoxes\ A\ list\ to\ return\ newly\ born\ foxes.\n
comment10.params=
comment10.target=boolean\ canBreed()
comment10.text=\n\ A\ fox\ can\ breed\ if\ it\ has\ reached\ the\ breeding\ age.\n
comment11.params=
comment11.target=void\ setDead()
comment11.text=\n\ Indicate\ that\ the\ fox\ is\ no\ longer\ alive.\n\ It\ is\ removed\ from\ the\ field.\n
comment2.params=
comment2.target=boolean\ isAlive()
comment2.text=\n\ Check\ whether\ the\ fox\ is\ alive\ or\ not.\n\ @return\ True\ if\ the\ fox\ is\ still\ alive.\n
comment3.params=
comment3.target=Location\ getLocation()
comment3.text=\n\ Return\ the\ fox's\ location.\n\ @return\ The\ fox's\ location.\n
comment4.params=newLocation
comment4.target=void\ setLocation(Location)
comment4.text=\n\ Place\ the\ fox\ at\ the\ new\ location\ in\ the\ given\ field.\n\ @param\ newLocation\ The\ fox's\ new\ location.\n
comment5.params=
comment5.target=void\ incrementAge()
comment5.text=\n\ Increase\ the\ age.\ This\ could\ result\ in\ the\ fox's\ death.\n
comment6.params=
comment6.target=void\ incrementHunger()
comment6.text=\n\ Make\ this\ fox\ more\ hungry.\ This\ could\ result\ in\ the\ fox's\ death.\n
comment7.params=
comment7.target=Location\ findFood()
comment7.text=\n\ Look\ for\ rabbits\ adjacent\ to\ the\ current\ location.\n\ Only\ the\ first\ live\ rabbit\ is\ eaten.\n\ @return\ Where\ food\ was\ found,\ or\ null\ if\ it\ wasn't.\n
comment8.params=newFoxes
comment8.target=void\ giveBirth(java.util.List)
comment8.text=\n\ Check\ whether\ or\ not\ this\ fox\ is\ to\ give\ birth\ at\ this\ step.\n\ New\ births\ will\ be\ made\ into\ free\ adjacent\ locations.\n\ @param\ newFoxes\ A\ list\ to\ return\ newly\ born\ foxes.\n
comment9.params=
comment9.target=int\ breed()
comment9.text=\n\ Generate\ a\ number\ representing\ the\ number\ of\ births,\n\ if\ it\ can\ breed.\n\ @return\ The\ number\ of\ births\ (may\ be\ zero).\n
numComments=12

227
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Fox.java Executable file
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import java.util.List;
import java.util.Iterator;
import java.util.Random;
/**
* A simple model of a fox.
* Foxes age, move, eat rabbits, and die.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Fox
{
// Characteristics shared by all foxes (class variables).
// The age at which a fox can start to breed.
private static final int BREEDING_AGE = 15;
// The age to which a fox can live.
private static final int MAX_AGE = 150;
// The likelihood of a fox breeding.
private static final double BREEDING_PROBABILITY = 0.08;
// The maximum number of births.
private static final int MAX_LITTER_SIZE = 2;
// The food value of a single rabbit. In effect, this is the
// number of steps a fox can go before it has to eat again.
private static final int RABBIT_FOOD_VALUE = 9;
// A shared random number generator to control breeding.
private static final Random rand = Randomizer.getRandom();
// Individual characteristics (instance fields).
// The fox's age.
private int age;
// Whether the fox is alive or not.
private boolean alive;
// The fox's position.
private Location location;
// The field occupied.
private Field field;
// The fox's food level, which is increased by eating rabbits.
private int foodLevel;
/**
* Create a fox. A fox can be created as a new born (age zero
* and not hungry) or with a random age and food level.
*
* @param randomAge If true, the fox will have random age and hunger level.
* @param field The field currently occupied.
* @param location The location within the field.
*/
public Fox(boolean randomAge, Field field, Location location)
{
age = 0;
alive = true;
this.field = field;
setLocation(location);
if(randomAge) {
age = rand.nextInt(MAX_AGE);
foodLevel = rand.nextInt(RABBIT_FOOD_VALUE);
}
else {
// leave age at 0
foodLevel = rand.nextInt(RABBIT_FOOD_VALUE);
}
}
/**
* This is what the fox does most of the time: it hunts for
* rabbits. In the process, it might breed, die of hunger,
* or die of old age.
* @param field The field currently occupied.
* @param newFoxes A list to return newly born foxes.
*/
public void hunt(List<Fox> newFoxes)
{
incrementAge();
incrementHunger();
if(alive) {
giveBirth(newFoxes);
// Move towards a source of food if found.
Location newLocation = findFood();
if(newLocation == null) {
// No food found - try to move to a free location.
newLocation = field.freeAdjacentLocation(location);
}
// See if it was possible to move.
if(newLocation != null) {
setLocation(newLocation);
}
else {
// Overcrowding.
setDead();
}
}
}
/**
* Check whether the fox is alive or not.
* @return True if the fox is still alive.
*/
public boolean isAlive()
{
return alive;
}
/**
* Return the fox's location.
* @return The fox's location.
*/
public Location getLocation()
{
return location;
}
/**
* Place the fox at the new location in the given field.
* @param newLocation The fox's new location.
*/
private void setLocation(Location newLocation)
{
if(location != null) {
field.clear(location);
}
location = newLocation;
field.place(this, newLocation);
}
/**
* Increase the age. This could result in the fox's death.
*/
private void incrementAge()
{
age++;
if(age > MAX_AGE) {
setDead();
}
}
/**
* Make this fox more hungry. This could result in the fox's death.
*/
private void incrementHunger()
{
foodLevel--;
if(foodLevel <= 0) {
setDead();
}
}
/**
* Look for rabbits adjacent to the current location.
* Only the first live rabbit is eaten.
* @return Where food was found, or null if it wasn't.
*/
private Location findFood()
{
List<Location> adjacent = field.adjacentLocations(location);
Iterator<Location> it = adjacent.iterator();
while(it.hasNext()) {
Location where = it.next();
Object animal = field.getObjectAt(where);
if(animal instanceof Rabbit) {
Rabbit rabbit = (Rabbit) animal;
if(rabbit.isAlive()) {
rabbit.setDead();
foodLevel = RABBIT_FOOD_VALUE;
return where;
}
}
}
return null;
}
/**
* Check whether or not this fox is to give birth at this step.
* New births will be made into free adjacent locations.
* @param newFoxes A list to return newly born foxes.
*/
private void giveBirth(List<Fox> newFoxes)
{
// New foxes are born into adjacent locations.
// Get a list of adjacent free locations.
List<Location> free = field.getFreeAdjacentLocations(location);
int births = breed();
for(int b = 0; b < births && free.size() > 0; b++) {
Location loc = free.remove(0);
Fox young = new Fox(false, field, loc);
newFoxes.add(young);
}
}
/**
* Generate a number representing the number of births,
* if it can breed.
* @return The number of births (may be zero).
*/
private int breed()
{
int births = 0;
if(canBreed() && rand.nextDouble() <= BREEDING_PROBABILITY) {
births = rand.nextInt(MAX_LITTER_SIZE) + 1;
}
return births;
}
/**
* A fox can breed if it has reached the breeding age.
*/
private boolean canBreed()
{
return age >= BREEDING_AGE;
}
/**
* Indicate that the fox is no longer alive.
* It is removed from the field.
*/
private void setDead()
{
alive = false;
if(location != null) {
field.clear(location);
location = null;
field = null;
}
}
}

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Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Location.ctxt Executable file
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#BlueJ class context
comment0.params=row\ col
comment0.target=Location(int,\ int)
comment0.text=\n\ Represent\ a\ row\ and\ column.\n\ @param\ row\ The\ row.\n\ @param\ col\ The\ column.\n
comment1.params=obj
comment1.target=boolean\ equals(java.lang.Object)
comment1.text=\n\ Implement\ content\ equality.\n
comment2.params=
comment2.target=java.lang.String\ toString()
comment2.text=\n\ Return\ a\ string\ of\ the\ form\ row,column\n\ @return\ A\ string\ representation\ of\ the\ location.\n
comment3.params=
comment3.target=int\ hashCode()
comment3.text=\n\ Use\ the\ top\ 16\ bits\ for\ the\ row\ value\ and\ the\ bottom\ for\n\ the\ column.\ Except\ for\ very\ big\ grids,\ this\ should\ give\ a\n\ unique\ hash\ code\ for\ each\ (row,\ col)\ pair.\n\ @return\ A\ hashcode\ for\ the\ location.\n
comment4.params=
comment4.target=int\ getRow()
comment4.text=\n\ @return\ The\ row.\n
comment5.params=
comment5.target=int\ getCol()
comment5.text=\n\ @return\ The\ column.\n
numComments=6

73
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Location.java Executable file
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/**
* Represent a location in a rectangular grid.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Location
{
// Row and column positions.
private int row;
private int col;
/**
* Represent a row and column.
* @param row The row.
* @param col The column.
*/
public Location(int row, int col)
{
this.row = row;
this.col = col;
}
/**
* Implement content equality.
*/
public boolean equals(Object obj)
{
if(obj instanceof Location) {
Location other = (Location) obj;
return row == other.getRow() && col == other.getCol();
}
else {
return false;
}
}
/**
* Return a string of the form row,column
* @return A string representation of the location.
*/
public String toString()
{
return row + "," + col;
}
/**
* Use the top 16 bits for the row value and the bottom for
* the column. Except for very big grids, this should give a
* unique hash code for each (row, col) pair.
* @return A hashcode for the location.
*/
public int hashCode()
{
return (row << 16) + col;
}
/**
* @return The row.
*/
public int getRow()
{
return row;
}
/**
* @return The column.
*/
public int getCol()
{
return col;
}
}

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Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/README.TXT Executable file
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Project: foxes-and-rabbits-v1
Authors: Michael Kölling and David J. Barnes
This project is part of the material for chapter 10 of the book
Objects First with Java - A Practical Introduction using BlueJ
Sixth edition
David J. Barnes and Michael Kölling
Pearson Education, 2016
A predator-prey simulation involving foxes and rabbits in
an enclosed rectangular field.
This is the first version of the simulation. This version
does not use inheritance.
How to start:
Create a Simulator object.
Then call one of:
+ simulateOneStep - for a single step.
+ simulate - and supply a number (say 10) for that many steps.
+ runLongSimulation - for a simulation of 500 steps.

32
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Rabbit.ctxt Executable file
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#BlueJ class context
comment0.params=randomAge\ field\ location
comment0.target=Rabbit(boolean,\ Field,\ Location)
comment0.text=\n\ Create\ a\ new\ rabbit.\ A\ rabbit\ may\ be\ created\ with\ age\n\ zero\ (a\ new\ born)\ or\ with\ a\ random\ age.\n\ \n\ @param\ randomAge\ If\ true,\ the\ rabbit\ will\ have\ a\ random\ age.\n\ @param\ field\ The\ field\ currently\ occupied.\n\ @param\ location\ The\ location\ within\ the\ field.\n
comment1.params=newRabbits
comment1.target=void\ run(java.util.List)
comment1.text=\n\ This\ is\ what\ the\ rabbit\ does\ most\ of\ the\ time\ -\ it\ runs\ \n\ around.\ Sometimes\ it\ will\ breed\ or\ die\ of\ old\ age.\n\ @param\ newRabbits\ A\ list\ to\ return\ newly\ born\ rabbits.\n
comment2.params=
comment2.target=boolean\ isAlive()
comment2.text=\n\ Check\ whether\ the\ rabbit\ is\ alive\ or\ not.\n\ @return\ true\ if\ the\ rabbit\ is\ still\ alive.\n
comment3.params=
comment3.target=void\ setDead()
comment3.text=\n\ Indicate\ that\ the\ rabbit\ is\ no\ longer\ alive.\n\ It\ is\ removed\ from\ the\ field.\n
comment4.params=
comment4.target=Location\ getLocation()
comment4.text=\n\ Return\ the\ rabbit's\ location.\n\ @return\ The\ rabbit's\ location.\n
comment5.params=newLocation
comment5.target=void\ setLocation(Location)
comment5.text=\n\ Place\ the\ rabbit\ at\ the\ new\ location\ in\ the\ given\ field.\n\ @param\ newLocation\ The\ rabbit's\ new\ location.\n
comment6.params=
comment6.target=void\ incrementAge()
comment6.text=\n\ Increase\ the\ age.\n\ This\ could\ result\ in\ the\ rabbit's\ death.\n
comment7.params=newRabbits
comment7.target=void\ giveBirth(java.util.List)
comment7.text=\n\ Check\ whether\ or\ not\ this\ rabbit\ is\ to\ give\ birth\ at\ this\ step.\n\ New\ births\ will\ be\ made\ into\ free\ adjacent\ locations.\n\ @param\ newRabbits\ A\ list\ to\ return\ newly\ born\ rabbits.\n
comment8.params=
comment8.target=int\ breed()
comment8.text=\n\ Generate\ a\ number\ representing\ the\ number\ of\ births,\n\ if\ it\ can\ breed.\n\ @return\ The\ number\ of\ births\ (may\ be\ zero).\n
comment9.params=
comment9.target=boolean\ canBreed()
comment9.text=\n\ A\ rabbit\ can\ breed\ if\ it\ has\ reached\ the\ breeding\ age.\n\ @return\ true\ if\ the\ rabbit\ can\ breed,\ false\ otherwise.\n
numComments=10

175
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Rabbit.java Executable file
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import java.util.List;
import java.util.Random;
/**
* A simple model of a rabbit.
* Rabbits age, move, breed, and die.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
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 new born) or with a random age.
*
* @param randomAge If true, the rabbit will have a random age.
* @param field The field currently occupied.
* @param location The location within the field.
*/
public Rabbit(boolean randomAge, Field field, Location location)
{
age = 0;
alive = true;
this.field = field;
setLocation(location);
if(randomAge) {
age = rand.nextInt(MAX_AGE);
}
}
/**
* This is what the rabbit does most of the time - it runs
* around. Sometimes it will breed or die of old age.
* @param newRabbits A list to return newly born rabbits.
*/
public void run(List<Rabbit> newRabbits)
{
incrementAge();
if(alive) {
giveBirth(newRabbits);
// Try to move into a free location.
Location newLocation = field.freeAdjacentLocation(location);
if(newLocation != null) {
setLocation(newLocation);
}
else {
// Overcrowding.
setDead();
}
}
}
/**
* Check whether the rabbit is alive or not.
* @return true if the rabbit is still alive.
*/
public boolean isAlive()
{
return alive;
}
/**
* Indicate that the rabbit is no longer alive.
* It is removed from the field.
*/
public void setDead()
{
alive = false;
if(location != null) {
field.clear(location);
location = null;
field = null;
}
}
/**
* Return the rabbit's location.
* @return The rabbit's location.
*/
public Location getLocation()
{
return location;
}
/**
* Place the rabbit at the new location in the given field.
* @param newLocation The rabbit's new location.
*/
private void setLocation(Location newLocation)
{
if(location != null) {
field.clear(location);
}
location = newLocation;
field.place(this, newLocation);
}
/**
* Increase the age.
* This could result in the rabbit's death.
*/
private void incrementAge()
{
age++;
if(age > MAX_AGE) {
setDead();
}
}
/**
* Check whether or not this rabbit is to give birth at this step.
* New births will be made into free adjacent locations.
* @param newRabbits A list to return newly born rabbits.
*/
private void giveBirth(List<Rabbit> newRabbits)
{
// New rabbits are born into adjacent locations.
// Get a list of adjacent free locations.
List<Location> free = field.getFreeAdjacentLocations(location);
int births = breed();
for(int b = 0; b < births && free.size() > 0; b++) {
Location loc = free.remove(0);
Rabbit young = new Rabbit(false, field, loc);
newRabbits.add(young);
}
}
/**
* Generate a number representing the number of births,
* if it can breed.
* @return The number of births (may be zero).
*/
private int breed()
{
int births = 0;
if(canBreed() && rand.nextDouble() <= BREEDING_PROBABILITY) {
births = rand.nextInt(MAX_LITTER_SIZE) + 1;
}
return births;
}
/**
* A rabbit can breed if it has reached the breeding age.
* @return true if the rabbit can breed, false otherwise.
*/
private boolean canBreed()
{
return age >= BREEDING_AGE;
}
}

11
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Randomizer.ctxt Executable file
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#BlueJ class context
comment0.params=
comment0.target=Randomizer()
comment0.text=\n\ Constructor\ for\ objects\ of\ class\ Randomizer\n
comment1.params=
comment1.target=java.util.Random\ getRandom()
comment1.text=\n\ Provide\ a\ random\ generator.\n\ @return\ A\ random\ object.\n
comment2.params=
comment2.target=void\ reset()
comment2.text=\n\ Reset\ the\ randomization.\n\ This\ will\ have\ no\ effect\ if\ randomization\ is\ not\ through\ a\ shared\ Random\ generator.\n
numComments=3

51
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Randomizer.java Executable file
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import java.util.Random;
/**
* Provide control over the randomization of the simulation. By using the shared, fixed-seed
* randomizer, repeated runs will perform exactly the same (which helps with testing). Set
* 'useShared' to false to get different random behaviour every time.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Randomizer
{
// The default seed for control of randomization.
private static final int SEED = 1111;
// A shared Random object, if required.
private static final Random rand = new Random(SEED);
// Determine whether a shared random generator is to be provided.
private static final boolean useShared = true;
/**
* Constructor for objects of class Randomizer
*/
public Randomizer()
{
}
/**
* Provide a random generator.
* @return A random object.
*/
public static Random getRandom()
{
if(useShared) {
return rand;
}
else {
return new Random();
}
}
/**
* Reset the randomization.
* This will have no effect if randomization is not through a shared Random generator.
*/
public static void reset()
{
if(useShared) {
rand.setSeed(SEED);
}
}
}

26
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Simulator.ctxt Executable file
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#BlueJ class context
comment0.params=
comment0.target=Simulator()
comment0.text=\n\ Construct\ a\ simulation\ field\ with\ default\ size.\n
comment1.params=depth\ width
comment1.target=Simulator(int,\ int)
comment1.text=\n\ Create\ a\ simulation\ field\ with\ the\ given\ size.\n\ @param\ depth\ Depth\ of\ the\ field.\ Must\ be\ greater\ than\ zero.\n\ @param\ width\ Width\ of\ the\ field.\ Must\ be\ greater\ than\ zero.\n
comment2.params=
comment2.target=void\ runLongSimulation()
comment2.text=\n\ Run\ the\ simulation\ from\ its\ current\ state\ for\ a\ reasonably\ long\ \n\ period\ (4000\ steps).\n
comment3.params=numSteps
comment3.target=void\ simulate(int)
comment3.text=\n\ Run\ the\ simulation\ for\ the\ given\ number\ of\ steps.\n\ Stop\ before\ the\ given\ number\ of\ steps\ if\ it\ ceases\ to\ be\ viable.\n\ @param\ numSteps\ The\ number\ of\ steps\ to\ run\ for.\n
comment4.params=
comment4.target=void\ simulateOneStep()
comment4.text=\n\ Run\ the\ simulation\ from\ its\ current\ state\ for\ a\ single\ step.\ Iterate\n\ over\ the\ whole\ field\ updating\ the\ state\ of\ each\ fox\ and\ rabbit.\n
comment5.params=
comment5.target=void\ reset()
comment5.text=\n\ Reset\ the\ simulation\ to\ a\ starting\ position.\n
comment6.params=
comment6.target=void\ populate()
comment6.text=\n\ Randomly\ populate\ the\ field\ with\ foxes\ and\ rabbits.\n
comment7.params=millisec
comment7.target=void\ delay(int)
comment7.text=\n\ Pause\ for\ a\ given\ time.\n\ @param\ millisec\ \ The\ time\ to\ pause\ for,\ in\ milliseconds\n
numComments=8

181
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/Simulator.java Executable file
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import java.util.Random;
import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.awt.Color;
/**
* A simple predator-prey simulator, based on a rectangular field containing
* rabbits and foxes.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class Simulator
{
// Constants representing configuration information for the simulation.
// The default width for the grid.
private static final int DEFAULT_WIDTH = 120;
// The default depth of the grid.
private static final int DEFAULT_DEPTH = 80;
// The probability that a fox will be created in any given grid position.
private static final double FOX_CREATION_PROBABILITY = 0.02;
// The probability that a rabbit will be created in any given position.
private static final double RABBIT_CREATION_PROBABILITY = 0.08;
// Lists of animals in the field.
private List<Rabbit> rabbits;
private List<Fox> foxes;
// The current state of the field.
private Field field;
// The current step of the simulation.
private int step;
// A graphical view of the simulation.
private SimulatorView view;
/**
* Construct a simulation field with default size.
*/
public Simulator()
{
this(DEFAULT_DEPTH, DEFAULT_WIDTH);
}
/**
* Create a simulation field with the given size.
* @param depth Depth of the field. Must be greater than zero.
* @param width Width of the field. Must be greater than zero.
*/
public Simulator(int depth, int width)
{
if(width <= 0 || depth <= 0) {
System.out.println("The dimensions must be >= zero.");
System.out.println("Using default values.");
depth = DEFAULT_DEPTH;
width = DEFAULT_WIDTH;
}
rabbits = new ArrayList<>();
foxes = new ArrayList<>();
field = new Field(depth, width);
// Create a view of the state of each location in the field.
view = new SimulatorView(depth, width);
view.setColor(Rabbit.class, Color.ORANGE);
view.setColor(Fox.class, Color.BLUE);
// Setup a valid starting point.
reset();
}
/**
* Run the simulation from its current state for a reasonably long
* period (4000 steps).
*/
public void runLongSimulation()
{
simulate(4000);
}
/**
* Run the simulation for the given number of steps.
* Stop before the given number of steps if it ceases to be viable.
* @param numSteps The number of steps to run for.
*/
public void simulate(int numSteps)
{
for(int step=1; step <= numSteps && view.isViable(field); step++) {
simulateOneStep();
// delay(60); // uncomment this to run more slowly
}
}
/**
* Run the simulation from its current state for a single step. Iterate
* over the whole field updating the state of each fox and rabbit.
*/
public void simulateOneStep()
{
step++;
// Provide space for newborn rabbits.
List<Rabbit> newRabbits = new ArrayList<>();
// Let all rabbits act.
for(Iterator<Rabbit> it = rabbits.iterator(); it.hasNext(); ) {
Rabbit rabbit = it.next();
rabbit.run(newRabbits);
if(! rabbit.isAlive()) {
it.remove();
}
}
// Provide space for newborn foxes.
List<Fox> newFoxes = new ArrayList<>();
// Let all foxes act.
for(Iterator<Fox> it = foxes.iterator(); it.hasNext(); ) {
Fox fox = it.next();
fox.hunt(newFoxes);
if(! fox.isAlive()) {
it.remove();
}
}
// Add the newly born foxes and rabbits to the main lists.
rabbits.addAll(newRabbits);
foxes.addAll(newFoxes);
view.showStatus(step, field);
}
/**
* Reset the simulation to a starting position.
*/
public void reset()
{
step = 0;
rabbits.clear();
foxes.clear();
populate();
// Show the starting state in the view.
view.showStatus(step, field);
}
/**
* Randomly populate the field with foxes and rabbits.
*/
private void populate()
{
Random rand = Randomizer.getRandom();
field.clear();
for(int row = 0; row < field.getDepth(); row++) {
for(int col = 0; col < field.getWidth(); col++) {
if(rand.nextDouble() <= FOX_CREATION_PROBABILITY) {
Location location = new Location(row, col);
Fox fox = new Fox(true, field, location);
foxes.add(fox);
}
else if(rand.nextDouble() <= RABBIT_CREATION_PROBABILITY) {
Location location = new Location(row, col);
Rabbit rabbit = new Rabbit(true, field, location);
rabbits.add(rabbit);
}
// else leave the location empty.
}
}
}
/**
* Pause for a given time.
* @param millisec The time to pause for, in milliseconds
*/
private void delay(int millisec)
{
try {
Thread.sleep(millisec);
}
catch (InterruptedException ie) {
// wake up
}
}
}

17
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/SimulatorView.ctxt Executable file
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#BlueJ class context
comment0.params=height\ width
comment0.target=SimulatorView(int,\ int)
comment0.text=\n\ Create\ a\ view\ of\ the\ given\ width\ and\ height.\n\ @param\ height\ The\ simulation's\ height.\n\ @param\ width\ \ The\ simulation's\ width.\n
comment1.params=animalClass\ color
comment1.target=void\ setColor(java.lang.Class,\ java.awt.Color)
comment1.text=\n\ Define\ a\ color\ to\ be\ used\ for\ a\ given\ class\ of\ animal.\n\ @param\ animalClass\ The\ animal's\ Class\ object.\n\ @param\ color\ The\ color\ to\ be\ used\ for\ the\ given\ class.\n
comment2.params=animalClass
comment2.target=java.awt.Color\ getColor(java.lang.Class)
comment2.text=\n\ @return\ The\ color\ to\ be\ used\ for\ a\ given\ class\ of\ animal.\n
comment3.params=step\ field
comment3.target=void\ showStatus(int,\ Field)
comment3.text=\n\ Show\ the\ current\ status\ of\ the\ field.\n\ @param\ step\ Which\ iteration\ step\ it\ is.\n\ @param\ field\ The\ field\ whose\ status\ is\ to\ be\ displayed.\n
comment4.params=field
comment4.target=boolean\ isViable(Field)
comment4.text=\n\ Determine\ whether\ the\ simulation\ should\ continue\ to\ run.\n\ @return\ true\ If\ there\ is\ more\ than\ one\ species\ alive.\n
numComments=5

215
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/SimulatorView.java Executable file
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import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* A graphical view of the simulation grid.
* The view displays a colored rectangle for each location
* representing its contents. It uses a default background color.
* Colors for each type of species can be defined using the
* setColor method.
*
* @author David J. Barnes and Michael Kölling
* @version 2016.02.29
*/
public class SimulatorView extends JFrame
{
// Colors used for empty locations.
private static final Color EMPTY_COLOR = Color.white;
// Color used for objects that have no defined color.
private static final Color UNKNOWN_COLOR = Color.gray;
private final String STEP_PREFIX = "Step: ";
private final String POPULATION_PREFIX = "Population: ";
private JLabel stepLabel, population;
private FieldView fieldView;
// A map for storing colors for participants in the simulation
private Map<Class, Color> colors;
// A statistics object computing and storing simulation information
private FieldStats stats;
/**
* Create a view of the given width and height.
* @param height The simulation's height.
* @param width The simulation's width.
*/
public SimulatorView(int height, int width)
{
stats = new FieldStats();
colors = new LinkedHashMap<>();
setTitle("Fox and Rabbit Simulation");
stepLabel = new JLabel(STEP_PREFIX, JLabel.CENTER);
population = new JLabel(POPULATION_PREFIX, JLabel.CENTER);
setLocation(100, 50);
fieldView = new FieldView(height, width);
Container contents = getContentPane();
contents.add(stepLabel, BorderLayout.NORTH);
contents.add(fieldView, BorderLayout.CENTER);
contents.add(population, BorderLayout.SOUTH);
pack();
setVisible(true);
}
/**
* Define a color to be used for a given class of animal.
* @param animalClass The animal's Class object.
* @param color The color to be used for the given class.
*/
public void setColor(Class animalClass, Color color)
{
colors.put(animalClass, color);
}
/**
* @return The color to be used for a given class of animal.
*/
private Color getColor(Class animalClass)
{
Color col = colors.get(animalClass);
if(col == null) {
// no color defined for this class
return UNKNOWN_COLOR;
}
else {
return col;
}
}
/**
* Show the current status of the field.
* @param step Which iteration step it is.
* @param field The field whose status is to be displayed.
*/
public void showStatus(int step, Field field)
{
if(!isVisible()) {
setVisible(true);
}
stepLabel.setText(STEP_PREFIX + step);
stats.reset();
fieldView.preparePaint();
for(int row = 0; row < field.getDepth(); row++) {
for(int col = 0; col < field.getWidth(); col++) {
Object animal = field.getObjectAt(row, col);
if(animal != null) {
stats.incrementCount(animal.getClass());
fieldView.drawMark(col, row, getColor(animal.getClass()));
}
else {
fieldView.drawMark(col, row, EMPTY_COLOR);
}
}
}
stats.countFinished();
population.setText(POPULATION_PREFIX + stats.getPopulationDetails(field));
fieldView.repaint();
}
/**
* Determine whether the simulation should continue to run.
* @return true If there is more than one species alive.
*/
public boolean isViable(Field field)
{
return stats.isViable(field);
}
/**
* Provide a graphical view of a rectangular field. This is
* a nested class (a class defined inside a class) which
* defines a custom component for the user interface. This
* component displays the field.
* This is rather advanced GUI stuff - you can ignore this
* for your project if you like.
*/
private class FieldView extends JPanel
{
private final int GRID_VIEW_SCALING_FACTOR = 6;
private int gridWidth, gridHeight;
private int xScale, yScale;
Dimension size;
private Graphics g;
private Image fieldImage;
/**
* Create a new FieldView component.
*/
public FieldView(int height, int width)
{
gridHeight = height;
gridWidth = width;
size = new Dimension(0, 0);
}
/**
* Tell the GUI manager how big we would like to be.
*/
public Dimension getPreferredSize()
{
return new Dimension(gridWidth * GRID_VIEW_SCALING_FACTOR,
gridHeight * GRID_VIEW_SCALING_FACTOR);
}
/**
* Prepare for a new round of painting. Since the component
* may be resized, compute the scaling factor again.
*/
public void preparePaint()
{
if(! size.equals(getSize())) { // if the size has changed...
size = getSize();
fieldImage = fieldView.createImage(size.width, size.height);
g = fieldImage.getGraphics();
xScale = size.width / gridWidth;
if(xScale < 1) {
xScale = GRID_VIEW_SCALING_FACTOR;
}
yScale = size.height / gridHeight;
if(yScale < 1) {
yScale = GRID_VIEW_SCALING_FACTOR;
}
}
}
/**
* Paint on grid location on this field in a given color.
*/
public void drawMark(int x, int y, Color color)
{
g.setColor(color);
g.fillRect(x * xScale, y * yScale, xScale-1, yScale-1);
}
/**
* The field view component needs to be redisplayed. Copy the
* internal image to screen.
*/
public void paintComponent(Graphics g)
{
if(fieldImage != null) {
Dimension currentSize = getSize();
if(size.equals(currentSize)) {
g.drawImage(fieldImage, 0, 0, null);
}
else {
// Rescale the previous image.
g.drawImage(fieldImage, 0, 0, currentSize.width, currentSize.height, null);
}
}
}
}
}

182
Semester 1/Programming 1/Java/examples/projects/chapter12/foxes-and-rabbits-v1/package.bluej Executable file
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#BlueJ package file
dependency1.from=Field
dependency1.to=Randomizer
dependency1.type=UsesDependency
dependency10.from=Rabbit
dependency10.to=Location
dependency10.type=UsesDependency
dependency11.from=Rabbit
dependency11.to=Field
dependency11.type=UsesDependency
dependency12.from=FieldStats
dependency12.to=Field
dependency12.type=UsesDependency
dependency13.from=FieldStats
dependency13.to=Counter
dependency13.type=UsesDependency
dependency14.from=Simulator
dependency14.to=Field
dependency14.type=UsesDependency
dependency15.from=Simulator
dependency15.to=SimulatorView
dependency15.type=UsesDependency
dependency16.from=Simulator
dependency16.to=Rabbit
dependency16.type=UsesDependency
dependency17.from=Simulator
dependency17.to=Fox
dependency17.type=UsesDependency
dependency18.from=Simulator
dependency18.to=Randomizer
dependency18.type=UsesDependency
dependency19.from=Simulator
dependency19.to=Location
dependency19.type=UsesDependency
dependency2.from=Field
dependency2.to=Location
dependency2.type=UsesDependency
dependency3.from=SimulatorView
dependency3.to=FieldStats
dependency3.type=UsesDependency
dependency4.from=SimulatorView
dependency4.to=Field
dependency4.type=UsesDependency
dependency5.from=Fox
dependency5.to=Randomizer
dependency5.type=UsesDependency
dependency6.from=Fox
dependency6.to=Location
dependency6.type=UsesDependency
dependency7.from=Fox
dependency7.to=Field
dependency7.type=UsesDependency
dependency8.from=Fox
dependency8.to=Rabbit
dependency8.type=UsesDependency
dependency9.from=Rabbit
dependency9.to=Randomizer
dependency9.type=UsesDependency
objectbench.height=76
objectbench.width=955
package.editor.height=536
package.editor.width=847
package.editor.x=70
package.editor.y=80
package.numDependencies=19
package.numTargets=9
package.showExtends=true
package.showUses=true
project.charset=UTF-8
target1.editor.height=700
target1.editor.width=900
target1.editor.x=0
target1.editor.y=2
target1.height=50
target1.name=Field
target1.naviview.expanded=true
target1.showInterface=false
target1.type=ClassTarget
target1.typeParameters=
target1.width=80
target1.x=300
target1.y=190
target2.height=50
target2.name=Randomizer
target2.naviview.expanded=true
target2.showInterface=false
target2.type=ClassTarget
target2.typeParameters=
target2.width=90
target2.x=430
target2.y=450
target3.editor.height=700
target3.editor.width=900
target3.editor.x=0
target3.editor.y=2
target3.height=50
target3.name=Counter
target3.naviview.expanded=true
target3.showInterface=false
target3.type=ClassTarget
target3.typeParameters=
target3.width=80
target3.x=700
target3.y=180
target4.editor.height=700
target4.editor.width=900
target4.editor.x=0
target4.editor.y=2
target4.height=50
target4.name=Rabbit
target4.naviview.expanded=true
target4.showInterface=false
target4.type=ClassTarget
target4.typeParameters=
target4.width=80
target4.x=140
target4.y=390
target5.editor.height=700
target5.editor.width=900
target5.editor.x=0
target5.editor.y=2
target5.height=50
target5.name=SimulatorView
target5.naviview.expanded=true
target5.showInterface=false
target5.type=ClassTarget
target5.typeParameters=
target5.width=110
target5.x=500
target5.y=40
target6.editor.height=700
target6.editor.width=900
target6.editor.x=96
target6.editor.y=84
target6.height=50
target6.name=Simulator
target6.naviview.expanded=true
target6.showInterface=false
target6.type=ClassTarget
target6.typeParameters=
target6.width=80
target6.x=70
target6.y=110
target7.editor.height=700
target7.editor.width=900
target7.editor.x=0
target7.editor.y=2
target7.height=50
target7.name=Fox
target7.naviview.expanded=true
target7.showInterface=false
target7.type=ClassTarget
target7.typeParameters=
target7.width=80
target7.x=230
target7.y=340
target8.editor.height=700
target8.editor.width=900
target8.editor.x=0
target8.editor.y=2
target8.height=50
target8.name=FieldStats
target8.naviview.expanded=true
target8.showInterface=false
target8.type=ClassTarget
target8.typeParameters=
target8.width=80
target8.x=620
target8.y=110
target9.editor.height=700
target9.editor.width=900
target9.editor.x=0
target9.editor.y=2
target9.height=50
target9.name=Location
target9.naviview.expanded=true
target9.showInterface=false
target9.type=ClassTarget
target9.typeParameters=
target9.width=90
target9.x=430
target9.y=280