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我開始重構這個程序，我正在努力工作，並且遇到了一個主要障礙......我有一個類作爲一個核心，有大約6個其他較小（但仍然重要）的類一起工作來運行程序......我採用了一種方法[稱爲'填充（）']出核類，並用它[稱爲'PopulationGenerator']創建了一個全新的類，但是當我嘗試創建一個對象找不到意外循環的來源
：在覈級試圖創建對象之前......這裏的重構前的核上課的時候我會停留在新課改我從來沒有過這個問題永無止境的循環新創建的類的任何地方
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 grid position.
private static final double RABBIT_CREATION_PROBABILITY = 0.08;
// List of animals in the field.
private List<Animal> animals;
// 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 greater than zero.");
System.out.println("Using default values.");
depth = DEFAULT_DEPTH;
width = DEFAULT_WIDTH;
}
animals = new ArrayList<Animal>();
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 from its current state 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();
}
}
/**
* 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 animals.
List<Animal> newAnimals = new ArrayList<Animal>();
// Let all rabbits act.
for(Iterator<Animal> it = animals.iterator(); it.hasNext();) {
Animal animal = it.next();
animal.act(newAnimals);
if(! animal.isAlive()) {
it.remove();
}
}
// Add the newly born foxes and rabbits to the main lists.
animals.addAll(newAnimals);
view.showStatus(step, field);
}
/**
* Reset the simulation to a starting position.
*/
public void reset()
{
step = 0;
animals.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);
animals.add(fox);
}
else if(rand.nextDouble() <= RABBIT_CREATION_PROBABILITY) {
Location location = new Location(row, col);
Rabbit rabbit = new Rabbit(true, field, location);
animals.add(rabbit);
}
// else leave the location empty.
}
}
}
}
編輯：
下面是這同一類之後重構......
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.
*
* Update 10.40:
* Now *almost* decoupled from the concrete animal classes.
*
* @TWiSTED_CRYSTALS
*/
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 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;
//Population Generator class... coupled to fox and rabbit classes
private PopulationGenerator popGenerator;
// Lists of animals in the field. Separate lists are kept for ease of iteration.
private List<Animal> animals;
/**
* 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 greater than zero.");
System.out.println("Using default values.");
depth = DEFAULT_DEPTH;
width = DEFAULT_WIDTH;
}
animals = new ArrayList<Animal>();
field = new Field(depth, width);
// Create a view of the state of each location in the field.
//
// view.setColor(Rabbit.class, Color.orange); // PG
// view.setColor(Fox.class, Color.blue); // PG
// 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 from its current state 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();
}
}
/**
* 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 animals.
List<Animal> newAnimals = new ArrayList<Animal>();
// Let all animals act.
for(Iterator<Animal> it = animals.iterator(); it.hasNext();) {
Animal animal = it.next();
animal.act(newAnimals);
if(! animal.isAlive()) {
it.remove();
}
}
animals.addAll(newAnimals);
}
/**
* Reset the simulation to a starting position.
*/
public void reset()
{
PopulationGenerator popGenerator = new PopulationGenerator();
step = 0;
animals.clear();
popGenerator.populate();
// Show the starting state in the view.
view.showStatus(step, field);
}
public int getStep()
{
return step;
}
}
...和新的類
import java.util.ArrayList;
import java.util.Random;
import java.util.List;
import java.awt.Color;
public class PopulationGenerator
{
// 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 grid position.
private static final double RABBIT_CREATION_PROBABILITY = 0.08;
// Lists of animals in the field. Separate lists are kept for ease of iteration.
private List<Animal> animals;
// The current state of the field.
private Field field;
// A graphical view of the simulation.
private SimulatorView view;
/**
* Constructor
*/
public PopulationGenerator()
{
animals = new ArrayList<Animal>();
field = new Field(DEFAULT_DEPTH, DEFAULT_WIDTH);
}
/**
* Randomly populate the field with foxes and rabbits.
*/
public void populate()
{
// Create a view of the state of each location in the field.
view = new SimulatorView(DEFAULT_DEPTH, DEFAULT_WIDTH);
view.setColor(Rabbit.class, Color.orange); // PG
view.setColor(Fox.class, Color.blue); // PG
Simulator simulator = new Simulator();
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);
animals.add(fox);
}
else if(rand.nextDouble() <= RABBIT_CREATION_PROBABILITY) {
Location location = new Location(row, col);
Rabbit rabbit = new Rabbit(true, field, location);
animals.add(rabbit);
}
// else leave the location empty.
}
}
view.showStatus(simulator.getStep(), field);
}
}
這裏的Field類的PopulationGenerator電話...我沒有以任何方式改變這個班級
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.
*
* @TWiSTED_CRYSTALS
*/
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<Location>();
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<Location>();
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;
}
}
首先，你必須隔離問題的所在來這裏傾倒，可能有沒有相關的問題在所有代碼之前。使用調試器或println語句來隔離它。或者，如果您確定此問題存在於此代碼中，請告訴我們您爲什麼這麼想以及上述代碼轉儲位於何處。 –
爲什麼你的新課程不包括在內？我無法看到這段代碼中的任何循環都可能變得無窮無盡，所以問題可能就在於此。 –
@Mark：我知道。現在我們不得不猜測代碼中發生了什麼，他沒有向我們展示這些有點令人沮喪。在原始的海報上：再次，你有責任做一些基本的調試步驟，以便嘗試隔離問題，然後在這裏發佈**代碼。 –