I was to create a code where I mimic the functions of a robot. Turning and moving and such. I feel as if I'm approaching this in all the wrong ways... When I was writing this I thought I understood the gist of it, if the direction in the constructor is this then if it turn the new direction is this. I tested this and of course I ended up with some real incorrect results. I'm absolutely sure that I don't actually use any of these functions for my object. Can I get a tip about how to work this kind of code?
import java.awt.Point;
public class Robot
{
private int x;
private int y;
private int d;
private int p;
public static final int NORTH = 0;
public static final int SOUTH = 1;
public static final int EAST = 2;
public static final int WEST = 3;
/**
* Constructor for objects of class Robot
* #param theX the x coordinate
* #param theY the y coordinate
* #param theDirection the direction the robot is facing
*/
public Robot(int theX, int theY, int theDirection)
{
x = theX;
y = theY;
d = theDirection;
}
public void turnLeft()
{
if(d == NORTH) {
d = WEST;
}
if(d == WEST) {
d = SOUTH;
}
if(d == SOUTH) {
d = EAST;
}
if(d == EAST) {
d = NORTH;
}
}
public String getDirection()
{
if(d == NORTH) {
return "N";
}
if(d == SOUTH) {
return "S";
}
if(d == WEST) {
return "W";
}
if(d == EAST) {
return "E";
}
return "";
}
}
Testing
Robot rob = new Robot(20, 20, Robot.SOUTH);
rob.turnLeft;
System.out.println(rob.getDirection);
this return S when I think it should actually return E.
You need else if. When you turn left you assign a new value to d which is matching the condition of the following if statements.
Your turnLeft method is not quite right.
Here's the code by using if:
public void turnLeft() {
if (d == NORTH) {
d = WEST;
} else if (d == WEST) {
d = SOUTH;
} else if (d == SOUTH) {
d = EAST;
} else if (d == EAST) {
d = NORTH;
}
}
Here's the code by using switch..case
public void turnLeft() {
switch (d) {
case NORTH: d = WEST; break;
case WEST: d = SOUTH; break;
case SOUTH: d = EAST; break;
case EAST: d = NORTH; break;
}
}
Enum
public enum Direction {
private String name;
private String indicator;
public Direction(String name, String indicator) {
this.name = name;
this.indicator= indicator;
}
// getters
NORTH("North", "N"),
EAST("East", "E"),
SOUTH("South", "S"),
WEST("West", "W");
}
Next you can easily do this:
turnLeft() {
switch (d) {
case Direction.NORTH: return Direction.WEST;
case Direction.WEST: return Direction.SOUTH;
case Direction.SOUTH: return Direction.EAST;
case Direction.EAST: return Direction.NORTH;
}
}
getDirection() {
return d.getIndicator();
}
This way you can get rid of the four static int (NORTH, WEST, EAST, SOUTH) and change int d into Direction d. I would really recommend using an enum for this. Just to be typesafe.
What's the p var that you're using?
Your current direction is stored in d
...
d = theDirection;
...
You should try with this one:
public void turnLeft()
{
if(d == NORTH) {
d = WEST;
}
if(d == WEST) {
d = SOUTH;
}
if(d == SOUTH) {
d = EAST;
}
if(d == EAST) {
d = NORTH;
}
}
EDIT:
Just to clarify.
You wrote something like
if(p == SOUTH) {
d = EAST;
}
So you're checking if p is SOUTH and not d.
You're not using p anywhere so it will never be SOUTH, that's why your turnLeft() method does absolutely nothing!
1st) you should really clean up your p and d stuff ;) i suggest to call d "direction"
2nd) you should rearrange your int constants for directions in clockwise order. so you could reduce your turnLeft() method to a single line of code. You could order them this way:
public static final int NORTH = 0;
public static final int EAST = 1;
public static final int SOUTH = 2;
public static final int WEST = 3;
3rd) for testing you should use JUnit:
#Test
public void turnLeft() {
Robot rob = new Robot(20, 20, Robot.SOUTH);
rob.turnLeft;
assertEquals("E", rob.getDirection);
rob.turnLeft;
assertEquals("N", rob.getDirection);
rob.turnLeft;
assertEquals("W", rob.getDirection);
rob.turnLeft;
assertEquals("S", rob.getDirection);
}
In case someone ever neeeded, here is a solution for turning either way:
public enum Direction {
UP,
LEFT,
DOWN,
RIGHT;
Direction turnLeft() {
int turnLeft = 1;
return getDirectionByOrdinalMovingClockwise(turnLeft);
}
Direction turnRight() {
int turnRight = -1;
return getDirectionByOrdinalMovingClockwise(turnRight);
}
Direction turnAround() {
int turnAround = 2;
return getDirectionByOrdinalMovingClockwise(turnAround);
}
private Direction getDirectionByOrdinalMovingClockwise(int moveBy) {
var thisDirectionOrdinal = ordinal();
int newDirectionOrdinal = (thisDirectionOrdinal + moveBy) % enumElementsCount();
if (newDirectionOrdinal < 0) {
newDirectionOrdinal = enumElementsCount() + newDirectionOrdinal;
}
return values()[newDirectionOrdinal];
}
private int enumElementsCount() {
return values().length;
}
}
Related
I have an A* pathfinding algorithm that I've used for a Spigot plugin which worked fine. I then added a requirements system so it won't try and pathfind through places it shouldn't. Now it seems REALLY slow, and it looks like it has nothing to do with the requirements code itself, and more to do with the algorithm having many more incorrect paths when calculating. I seem to be getting 1500ms+ on this, which is definitely not good xD
Here is the pathfinder code:
public Path calculate(PathfinderGoal goal, PathScorer scorer, List<PathRequirement> requirements, int maxNodes) {
PathNode start = toNode(npc.getLocation());
PathNode end = toNode(goal.getLocation());
List<PathNode> open = new ArrayList<>() {{ add(start); }};
List<PathNode> navigated = new ArrayList<>();
start.setF(scorer.computeCost(start, end));
Timer timer = new Timer().start();
while (!open.isEmpty()) {
PathNode current = null;
for (PathNode node : open) {
if (current == null || node.getH() < current.getH()) {
current = node;
}
}
if (scorer.computeCost(current, end) < 1 || (navigated.size() >= maxNodes && maxNodes != -1)) {
navigated.add(navigated.size() < maxNodes ? end : current);
return reconstruct(navigated, navigated.size() - 1);
}
open.remove(current);
current.close();
for (PathNode node : current.getNeighbors()) {
if (node.isClosed()) {
continue;
}
double tentG = current.getG() + scorer.computeCost(current, node);
if (!open.contains(node) || tentG < node.getG()) {
boolean requirementsMet = true;
for (PathRequirement requirement : requirements) {
requirement.setNavigated(navigated);
if (!navigated.isEmpty() && !requirement.canMoveToNewNode(navigated.get(navigated.size() - 1), node)) {
requirementsMet = false;
break;
}
}
if (!navigated.contains(current)) {
navigated.add(current);
}
node.setG(tentG);
node.setH(scorer.computeCost(node, end));
node.setF(tentG + node.getH());
if (!open.contains(node) && requirementsMet) {
open.add(node);
}
}
}
Bukkit.broadcastMessage("Open Set Size: " + open.size());
Bukkit.broadcastMessage(timer.stop() + "ms");
}
return null;
}
private Path reconstruct(List<PathNode> navigated, int index) {
final PathNode current = navigated.get(index);
Path withCurrent = new Path(new ArrayList<>() {{ add(current); }});
if (index > 0 && navigated.contains(current)) {
return reconstruct(navigated, index - 1).append(withCurrent);
}
return withCurrent;
}
And here is the PathNode class:
public PathNode(Pathfinder pathfinder, int x, int y, int z) {
this.pathfinder = pathfinder;
this.x = x;
this.y = y;
this.z = z;
}
#Override
public boolean equals(Object other) {
if (!(other instanceof PathNode otherNode)) {
return false;
}
return otherNode.x == x && otherNode.y == y && otherNode.z == z;
}
public List<PathNode> getNeighbors() {
return new ArrayList<>() {
{
for (int x = -1; x <= 1; x++) {
for (int y = -1; y <= 1; y++) {
for (int z = -1; z <= 1; z++) {
add(new PathNode(pathfinder, PathNode.this.x + x, PathNode.this.y + y, PathNode.this.z + z));
}
}
}
}
};
}
public Location getLocation() {
return new Location(pathfinder.getNPC().getLocation().getWorld(), x, y, z);
}
public double getF() {
return F;
}
public void setF(double f) {
this.F = f;
}
public double getG() {
return G;
}
public void setG(double g) {
this.G = g;
}
public double getH() {
return H;
}
public void setH(double h) {
this.H = h;
}
public boolean isClosed() {
return closed;
}
public void close() {
this.closed = true;
}
Valid Requirements Class:
public class ValidPathRequirement extends PathRequirement {
#Override
public boolean canMoveToNewNode(PathNode from, PathNode to) {
Block fromBlock = from.getLocation().getBlock();
Block toBlock = to.getLocation().getBlock();
boolean validHeight = toBlock.getType().isAir() && toBlock.getRelative(BlockFace.UP).getType().isAir(); // checks if is player height
boolean validGround = toBlock.getRelative(BlockFace.DOWN).getType().isSolid(); // is there a block underneath that they can stand on?
boolean validFromPrev = toBlock.getLocation().subtract(fromBlock.getLocation()).getY() <= 1; // is it max one block higher than the last one?
// is this one causing issues?
Location fromLocDist = from.getLocation().clone();
Location toLocDist = to.getLocation().clone();
toLocDist.setY(fromLocDist.getY());
boolean validDistance = fromLocDist.distance(toLocDist) <= 1;
return validHeight && validGround && validFromPrev;
}
}
Without looking at the rest of the algorithm, the first thing that stands out is that your data structures are incorrect. The "open" list needs to be a Priority Queue, and "closed" (or "navigated") should be a set.
just wondering if there's a way to refactor the below code? I'm new to Java and trying to have DRY code - the below I've written but seems like a lot of conditionals to check
void printDirection() {
if (yDirection > 0) {
if (xDirection < 0) {
println("Travelling South-West");
} else {
println("Travelling South-East");
}
} else if (yDirection < 0) {
if (xDirection <0) {
println("Travelling North-West");
} else {
println("Travelling North-East");
}
}
}
Thanks in advance for any help!
You can evaluate the north/south and the east/west conditions individually, and glue the directions into your message.
System.out.printf("Travelling %s-%s%n", (yDirection < 0 ? "North" : "South"),
(xDirection < 0 ? "West" : "East"));
I assume from the code in your question that you're only concerned about those four complementary directions (not due north, due east, stationary etc.).
If you really want to make it DRY, it can be done using the operator ? but It's neither easy to read nor recommanded. It's used in programming contest where the goal is to go as fast as possible.
It follows the scheme :
(Condition?WhatHappenIfConditionIsTrue:WhatHappenIfConditionIsFalse);
You can use it in assignment :
int i = (a>0)?a:0;
in that case, if a>0 then i=a, else a=0
In your case, I would do it like that
void printDirection()
{
System.out.println("Travelling " + (yDirection > 0?"South":"North") + "-" + (xDirection>0?"East":"West"));
}
Some suggestiones:
1. Due to x,y combination; there are five states; you can use enum type to define these status;
2. If you want to reduce if...else statementes in your code, please refer to Status Machine Design Pattern; but i think, under your case, the status is so simple, do not need to make it too complicated
public class Status {
public enum Direction {
SOUTH_WEST((x, y) -> y > 0 && x < 0, "Travelling South-West")
, SOUTH_EAST((x, y) -> y >0 && x > 0, "Travelling South-East")
, NORTH_EAST((x, y) -> x > 0 && y < 0, "Travelling North-East")
, NORTH_WEST((x,y) -> x < 0 && y < 0, "Travelling North-West"), CENTER((x,y) -> x == 0 && y == 0, "");
BiPredicate<Integer, Integer> bp;
String desc;
public BiPredicate<Integer, Integer> getBp() {
return bp;
}
public void setBp(BiPredicate<Integer, Integer> bp) {
this.bp = bp;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
private Direction(BiPredicate<Integer, Integer> bp, String desc) {
this.bp = bp;
this.desc = desc;
}
public static Direction getDirection(int x, int y) {
for (Direction direction : Direction.values()) {
if(direction.getBp().test(x, y)) {
return direction;
}
}
return null;
}
}
public static void main(String[] args) {
Direction d = Direction.getDirection(3, 4);
System.out.println(d.getDesc());
/* if(d == Direction.SOUTH_WEST){
System.out.println("do some thing");
} else if(d == Direction.SOUTH_EAST){
System.out.println("do some thing");
} else if(d == Direction.NORTH_EAST){
System.out.println("do some thing");
} else if(d == Direction.NORTH_WEST){
System.out.println("do some thing");
}*/
}
}
I'm attempting to create a game "dungeon" map generator in Java in the style of roguelike etc. games. I generate rooms randomly, and then connect them with corridors. I'm trying to use A* pathfinding in corridor creation. I currently am creating just one corridor between rooms in the indices 1 and 2, if there is more than one room.
For some reason, the corridor creation seems to fail when I try to generate more than 1 maps ("floors"). The amount of floors is specified as a command-line parameter. Thus far, when I've generated just one floor, everything works perfectly. My gut feeling says that there's something about the floors that messes up my algorithm.
I thought that maybe an outside view of the project could help. There is quite a lot of code, but I'd be very grateful if someone took the time to review it. I can provide more information if it's needed.
THE RESULTS
The result, when correct, should look like this:
Map 1
# wall
. floor
+ door
$ corridor
..............................
..............................
..............................
..............................
..............................
..............................
..............................
..............................
...........$$$$$$$$$$.........
...........$......##+#######..
.....######$......#........#..
.....#....#$......#........#..
.....#....#$......#........#..
.....#....#$......#........#..
.....#....#$......#........#..
.....#....#$......#........#..
.....#....#$......#........#..
.....##+###$......##########..
.......$$$$$..................
..............................
The buggy result looks like this (the corridor does not go door-to-door, it just ends in a random location):
...........$$$...#########....
...........$#+##.#.......#....
...........$#..#.#.......#....
...........$#..#.#.......+....
###+###....$#..#.#.......#....
#.....#....$#..#.#.......#....
#.....#....$#..#.#.......#....
#.....#....$#..#.#########....
#.....#....$####..............
#.....#....$..................
#.....#....$..................
#######....$..................
...........$..................
...........$..................
...........$..................
...........$..................
...........$..................
...........$..................
.......$$$$$..................
..............................
THE CODE
AStar.java:
/**
* See https://www.raywenderlich.com/4946/introduction-to-a-pathfinding
*/
public class AStar {
private List<AStarSquare> openList;
private List<AStarSquare> closedList;
private Exporter debugExporter;
private static final Coords[] squareOffsetsToCheck = new Coords[] {
new Coords(0, 1),
new Coords(1, 0),
new Coords(0, -1),
new Coords(-1, 0)
};
public AStar() {
openList = new ArrayList<>();
closedList = new ArrayList<>();
debugExporter = new Exporter();
}
public List<Coords> findPath(Coords start, Coords end, Map map) {
List<Coords> path = new ArrayList<>(); // each square on the generated path
AStarSquare currentSquare = new AStarSquare(start, null); // current square around which possible squares are evaluated - start point
closedList.add(currentSquare); // add start point to closed list
createUpdateOpenSquares(currentSquare, start, end, map); // create open squares for first iteration
calculateScores(start, end, map); // calculate scores for first iteration
int loopGuard = 0;
// loop until break
while(true) {
if(openList.size() == 0) {
break;
}
currentSquare = getLowestOpenSquare(); // get the square with the lowest score
if(isAdjacentToDoor(currentSquare.getCoords(), end) /*|| currentSquare.getCoords().equalz(end) || loopGuard >= 1000*/) // end point reached or no possible next squares
break; // - exclude last square (door)
openList.remove(currentSquare);
closedList.add(currentSquare);
createUpdateOpenSquares(currentSquare, start, end, map); // create and/or update squares next to the current square
calculateScores(start, end, map);
map.setDebugCorridor(formulatePath(currentSquare));
loopGuard++;
}
path = formulatePath(currentSquare);
return path;
}
private void createUpdateOpenSquares(AStarSquare currentSquare, Coords start, Coords end, Map map) {
for(Coords squareOffsetToCheck : squareOffsetsToCheck) {
Coords coordsToCheck = currentSquare.getCoords().vectorAdd(squareOffsetToCheck);
if(map.isFloor(coordsToCheck)
&& !map.isInsideRoom(coordsToCheck)
&& isWithinMap(map, coordsToCheck)
&& !isClosed(coordsToCheck)) {
AStarSquare openSquare = getOpen(coordsToCheck);
if(openSquare == null)
openList.add(new AStarSquare(coordsToCheck, currentSquare));
else // is open
openSquare.setPrevious(currentSquare);
}
}
}
private boolean isClosed(Coords coords) {
for(AStarSquare closed : closedList) {
if(closed.getCoords().equalz(coords))
return true;
}
return false;
}
private AStarSquare getOpen(Coords coords) {
for(AStarSquare open : openList) {
if(open.getCoords().equalz(coords))
return open;
}
return null;
}
private boolean isWithinMap(Map map, Coords coords) {
if(coords.getX() < 0
|| coords.getY() < 0
|| coords.getX() >= map.getW()
|| coords.getY() >= map.getH())
return false;
return true;
}
private boolean isAdjacentToDoor(Coords coords, Coords end) {
for(Coords squareOffset : squareOffsetsToCheck) {
Coords offsetSquare = coords.vectorAdd(squareOffset);
if(offsetSquare.equalz(end))
return true;
}
return false;
}
private void calculateScores(Coords start, Coords end, Map map) {
for(AStarSquare square : openList) {
square.calculateScores(map, start, end);
}
}
private AStarSquare getLowestOpenSquare() {
AStarSquare lowestScore = null;
for(AStarSquare square : openList) {
// if lowestScore not set or if square.f is lower than lowestScore.f, set square to lowestScore
if(lowestScore == null || lowestScore.getF() > square.getF())
lowestScore = square;
}
return lowestScore;
}
// exclude first square (door)
private List<Coords> formulatePath(AStarSquare currentSquare) {
List<Coords> path = new ArrayList<>();
while(currentSquare.getPrevious() != null) {
path.add(currentSquare.getCoords());
currentSquare = currentSquare.getPrevious();
}
return path;
}
}
AStarSquare.java:
/**
* See https://www.raywenderlich.com/4946/introduction-to-a-pathfinding
*/
public class AStarSquare {
private Coords coords;
private AStarSquare previous;
private int g, h;
private boolean calculated;
public AStarSquare() {
g = h = 0;
calculated = false;
}
public AStarSquare(Coords coords) {
this();
this.coords = coords;
previous = null;
}
public AStarSquare(Coords coords, AStarSquare previous) {
this();
this.coords = coords;
this.previous = previous;
}
public void calculateScores(Map map, Coords start, Coords destination) {
g = previous.getG() + 1; // g = distance from start point
h = destination.getDistance(coords); // h = estimated (=shortest) distance from the current location to the destination
calculated = true;
}
}
Main class:
public class DungeonMapGenerator {
public static void main(String[] args) {
List<String> argsList = Arrays.asList(args);
if(!argsList.contains("-w")
|| !argsList.contains("-h")
|| !argsList.contains("-f")) {
System.out.println("Usage: java -jar DungeonMapGenerator.jar -w [width] -h [height] -f [floors] -[export option]");
System.exit(1);
}
int width = 0, height = 0, floors = 0;
for(int i = 0; i < args.length; i++) {
if(args[i].equalsIgnoreCase("-w"))
width = tryParseInt(args, i + 1, 30);
else if(args[i].equalsIgnoreCase("-h"))
height = tryParseInt(args, i + 1, 20);
else if(args[i].equalsIgnoreCase("-f"))
floors = tryParseInt(args, i + 1, 1);
}
Generator mapGenerator = new Generator(width, height, floors);
List<Map> maps = mapGenerator.generateMaps();
Exporter mapExporter = new Exporter();
if(argsList.contains("-c"))
mapExporter.exportToConsole(maps);
else
System.out.println("No export option selected, quitting");
}
private static int tryParseInt(String[] args, int index, int deflt) {
int res;
if(index >= args.length) // index out of range
res = deflt;
try {
res = Integer.parseInt(args[index], 10);
} catch(NumberFormatException ex) {
res = deflt;
}
return res;
}
}
Generator.java
public class Generator {
private static final int
MIN_ROOMS = 1,
MAX_ROOMS = 5,
MIN_DIM = 3, // dim = min and max room dimensions
MAX_DIM = 10;
private AStar pathfinder;
private Random random;
private int mapWidth, mapHeight, floors;
public Generator(int mapWidth, int mapHeight, int floors) {
pathfinder = new AStar();
random = new Random(System.currentTimeMillis());
this.mapWidth = mapWidth;
this.mapHeight = mapHeight;
this.floors = floors;
}
public List<Map> generateMaps() {
List<Map> mapList = new ArrayList<>();
for(int i = 0; i < floors; i++) {
Map map = new Map(i + 1, mapWidth, mapHeight, generateRooms(mapWidth, mapHeight), null);
generateDoors(map, map.getRooms());
debugFindPath(map);
mapList.add(map);
}
return mapList;
}
private List<Room> generateRooms(int mapWidth, int mapHeight) {
List<Room> roomList = new ArrayList<>();
int nRooms = random.nextInt(5) + 1;
for(int i = 0; i < nRooms; i++) {
Room room = null;
do {
int w = 0, h = 0, x = 0, y = 0;
w = getRandomDim();
h = getRandomDim();
x = random.nextInt(mapWidth - w);
y = random.nextInt(mapHeight - h);
room = new Room(x, y, w, h);
} while(roomsOverlap(room, roomList));
roomList.add(room);
}
return roomList;
}
private boolean roomsOverlap(Room room, List<Room> rooms) {
for(Room listRoom : rooms) {
if(room.overlapsWithRoom(listRoom))
return true;
}
return false;
}
private int getRandomDim() {
return random.nextInt(MAX_DIM - MIN_DIM + 1) + MIN_DIM;
}
private void generateDoors(Map map, List<Room> roomList) {
for(int i = 0; i < roomList.size(); i++) {
Door door = new Door(roomList.get(i));
do {
door.setSide(getRandomCardinal());
door.setDistNW(getRandomDistNW(roomList.get(i), door.getSide()));
} while(!validateDoor(map, door));
roomList.get(i).setDoors(Arrays.asList(new Door[] { door }));
map.getDoors().add(door);
}
}
private Cardinal getRandomCardinal() {
int cardinalInt = random.nextInt(4);
Cardinal cardinal;
switch(cardinalInt) {
case 1:
cardinal = Cardinal.EAST;
break;
case 2:
cardinal = Cardinal.SOUTH;
break;
case 3:
cardinal = Cardinal.WEST;
case 0:
default:
cardinal = Cardinal.NORTH;
break;
}
return cardinal;
}
private int getRandomDistNW(Room room, Cardinal cardinal) {
int distNW = 0;
if(cardinal == Cardinal.NORTH || cardinal == Cardinal.SOUTH)
distNW = random.nextInt(room.getW() - 2) + 1; // exclude corners
else if(cardinal == Cardinal.EAST || cardinal == Cardinal.WEST)
distNW = random.nextInt(room.getH() - 2) + 1; // exclude corners
return distNW;
}
private boolean validateDoor(Map map, Door door) {
Coords doorCoordsOnMap = door.getCoordsOnMap();
if(door.getSide() == Cardinal.NORTH
&& (door.getParent().getTop() == 0
// check if adjacent to another room
|| map.isWall(new Coords(doorCoordsOnMap.getX(), doorCoordsOnMap.getY() - 1))))
return false;
else if(door.getSide() == Cardinal.EAST
&& (door.getParent().getRight() == mapWidth - 1
// check if adjacent to another room
|| map.isWall(new Coords(doorCoordsOnMap.getX() + 1, doorCoordsOnMap.getY()))))
return false;
else if(door.getSide() == Cardinal.SOUTH
&& (door.getParent().getBottom() == mapHeight - 1
// check if adjacent to another room
|| map.isWall(new Coords(doorCoordsOnMap.getX(), doorCoordsOnMap.getY() + 1))))
return false;
else if(door.getSide() == Cardinal.WEST
&& (door.getParent().getLeft() == 0
// check if adjacent to another room
|| map.isWall(new Coords(doorCoordsOnMap.getX() - 1, doorCoordsOnMap.getY()))))
return false;
return true;
}
private void debugFindPath(Map map) {
if(map.getRooms().size() == 1)
return;
map.setDebugCorridor(pathfinder.findPath(
map.getRooms().get(0).getDoors().get(0).getCoordsOnMap(),
map.getRooms().get(1).getDoors().get(0).getCoordsOnMap(),
map
));
}
}
Room.java
public class Room {
private Coords topLeft;
private int w, h;
private List<Door> doors;
public Room(int topLeftX, int topLeftY, int w, int h) {
topLeft = new Coords(topLeftX, topLeftY);
this.w = w;
this.h = h;
doors = new ArrayList<>();
}
public boolean overlapsWithRoom(Room otherRoom) {
return !(otherRoom.getLeft() > this.getRight()
|| otherRoom.getRight() < this.getLeft()
|| otherRoom.getTop() > this.getBottom()
|| otherRoom.getBottom() < this.getTop());
}
#Override
public String toString() {
return "Room ~ top: " + getTop() + " right: " + getRight()
+ " bottom: " + getBottom() + " left: " + getLeft()
+ " width: " + w + " height: " + h;
}
public boolean isWall(Coords coords) { /*** TESTAA!!! ***/
if(
// x is either left or right, y is between top and bottom
((coords.getX() == topLeft.getX() || coords.getX() == topLeft.getX() + w)
&& coords.getY() >= topLeft.getY() && coords.getY() < topLeft.getY() + h + 1)
||
// y is either top or bottom, x is between left and right
((coords.getY() == topLeft.getY() || coords.getY() == topLeft.getY() + h)
&& coords.getX() >= topLeft.getX() && coords.getX() < topLeft.getX() + w)
)
return true;
return false;
}
}
Door.java
(Cardinal is a simple enum containing NORTH, EAST, SOUTH and WEST)
public class Door {
private Room parent;
private Cardinal side;
private int distNW = 0;
public Door(Room parent) {
this.parent = parent;
this.side = null;
}
public Door(Room parent, Cardinal side) {
this.parent = parent;
this.side = side;
}
public Coords getCoordsOnMap() {
Coords coords = null;
if(side == Cardinal.NORTH)
coords = new Coords(parent.getLeft() + distNW, parent.getTop());
else if(side == Cardinal.EAST)
coords = new Coords(parent.getRight(), parent.getTop() + distNW);
else if(side == Cardinal.SOUTH)
coords = new Coords(parent.getLeft() + distNW, parent.getBottom());
else if(side == Cardinal.WEST)
coords = new Coords(parent.getLeft(), parent.getTop() + distNW);
return coords;
}
}
In AStar, your A* pathfinding algorithm adds to its opened and closed lists before returning the chosen path
When pathfinding with different start/end destinations or a different map, those lists will need to be reset
The issue is that you're reusing the AStar object for each path you're trying to find, causing conflicts with old searches
To fix it, use a new AStar object for every path you search, or add a method to clear the old data
I removed this line from the Generator constructor:
public Generator(int mapWidth, int mapHeight, int floors) {
// pathfinder = new AStar(); // REMOVED THIS LINE
...
}
And I added the following line to the Generator.generateMaps method:
public List<Map> generateMaps() {
List<Map> mapList = new ArrayList<>();
for(int i = 0; i < floors; i++) {
pathfinder = new AStar(); // ADDED THIS LINE
Map map = new Map(i + 1, mapWidth, mapHeight, generateRooms(mapWidth, mapHeight), null);
generateDoors(map, map.getRooms());
debugFindPath(map);
mapList.add(map);
}
return mapList;
}
And now everything seems to work.
Another option is to add the following lines to AStar.findPath():
public List<Coords> findPath(Coords start, Coords end, Map map) {
openList = new ArrayList<>();
closedList = new ArrayList<>();
...
}
I've been trying to make a program that will solve a 2D integer maze. I keep getting a stackOverFlowError. I incorporated cases to set preferences in movement i.e North, South, East, West. I cannot find the issue in my recursive method.
import java.util.*;
import java.awt.*;
public class Runner
{
private static int[][] maze = MazeReader.getMaze("C:\\Users\\owner\\Desktop\\myMaze.txt");
private static int[][] solution = new int[maze.length][maze[0].length];
private static Point[] prefs = new Point[4];
private static int goalX, goalY, startX, startY;
/*
* if (x,y outside maze) return false
if (x,y is goal) return true
if (x,y not open) return false
mark x,y as part of solution path
if (FIND-PATH(North of x,y) == true) return true
if (FIND-PATH(East of x,y) == true) return true
if (FIND-PATH(South of x,y) == true) return true
if (FIND-PATH(West of x,y) == true) return true
unmark x,y as part of solution path
return false
*/
private static boolean FIND_PATH(int x, int y)
{
if(x<0||x>=maze.length||y<0||y>=maze[0].length){return false;}
if(x==goalX&&y==goalY){return true;}
if(maze[x][y]==1){return false;}
solution[x][y] = 2;
if(FIND_PATH(x+(int)prefs[0].getX(),y+(int)prefs[0].getY())){return true;}
else if(FIND_PATH(x+(int)prefs[1].getX(),y+(int)prefs[1].getY())){return true;}
else if(FIND_PATH(x+(int)prefs[2].getX(),y+(int)prefs[2].getY())){return true;}
else if(FIND_PATH(x+(int)prefs[3].getX(),y+(int)prefs[3].getY())){return true;}
else {solution[x][y] = 0;}
return false;
}
/*
* Locate the start position (call it startx, starty).
Call FIND-PATH(startx, starty).
*/
private static void solve(int sx, int sy, int gx, int gy, char p1, char p2, char p3, char p4)
{
establishPrefs(p1,p2,p3,p4);
startX = sx;
startY = sy;
goalX = gx;
goalY = gy;
if(FIND_PATH(startX,startY))
{
solution[startX][startY] = 3;
solution[goalX][goalY] = 4;
}
else{System.out.println("No Solution Found");}
FIND_PATH(startX,startY);
}
private static void establishPrefs(char p1, char p2, char p3, char p4)
{
switch(p1)
{
case 'N': prefs[0] = new Point(0,1);break;
case 'S': prefs[0] = new Point(0,-1);break;
case 'E': prefs[0] = new Point(1,0);break;
case 'W': prefs[0] = new Point(-1,0);break;
}
switch(p2)
{
case 'N': prefs[1] = new Point(0,1);break;
case 'S': prefs[1] = new Point(0,-1);break;
case 'E': prefs[1] = new Point(1,0);break;
case 'W': prefs[1] = new Point(-1,0);break;
}
switch(p3)
{
case 'N': prefs[2] = new Point(0,1);break;
case 'S': prefs[2] = new Point(0,-1);break;
case 'E': prefs[2] = new Point(1,0);break;
case 'W': prefs[2] = new Point(-1,0);break;
}
switch(p4)
{
case 'N': prefs[3] = new Point(0,1);break;
case 'S': prefs[3] = new Point(0,-1);break;
case 'E': prefs[3] = new Point(1,0);break;
case 'W': prefs[3] = new Point(-1,0);break;
}
}
private static Point[] getPrefs(){return prefs;}
public static void main(String[] args)
{
MazeReader.display(maze);
solve(0,0,0,2,'S','E','N','W');
MazeReader.display(solution);
}
}
Although you are marking solution[x][y] as part of your solution path, you are not checking if you are returning to a previous point on your solution. In essence, you end up going in circles.
You must not follow paths that lead you into a position that is currently part of your tentative solution.
if(maze[x][y]==1){return false;}
if(solution[x][y] == 2) {return false;} // <-- Add
solution[x][y] = 2;
I am working on a robot maze where the robot finds the target without bumping into walls. As a "backtrack" method, I need the robot to go in the opposite direction as it did when it first came across a junction. This is my code:
import uk.ac.warwick.dcs.maze.logic.IRobot;
import java.util.ArrayList;
import java.util.*;
import java.util.Iterator;
public class Explorer {
private int pollRun = 0; // Incremented after each pass.
private RobotData robotData; // Data store for junctions.
private ArrayList<Integer> nonWallDirections;
private ArrayList<Integer> passageDirections;
private ArrayList<Integer> beenbeforeDirections;
private Random random = new Random();
int [] directions = {IRobot.AHEAD, IRobot.LEFT, IRobot.RIGHT, IRobot.BEHIND};
public void controlRobot (IRobot robot) {
// On the first move of the first run of a new maze.
if ((robot.getRuns() == 0) && (pollRun ==0))
robotData = new RobotData();
pollRun++; /* Increment poll run so that the data is not reset
each time the robot moves. */
int exits = nonwallExits(robot);
int direction;
nonWallDirections = new ArrayList<Integer>();
passageDirections = new ArrayList<Integer>();
beenbeforeDirections = new ArrayList<Integer>();
// Adding each direction to the appropriate state ArrayList.
for(int item : directions) {
if(robot.look(item) != IRobot.WALL) {
nonWallDirections.add(item);
}
}
for(int item : directions) {
if(robot.look(item) == IRobot.PASSAGE) {
passageDirections.add(item);
}
}
for(int item : directions) {
if(robot.look(item) == IRobot.BEENBEFORE) {
beenbeforeDirections.add(item);
}
}
// Calling the appropriate method depending on the number of exits.
if (exits < 2) {
direction = deadEnd(robot);
} else if (exits == 2) {
direction = corridor(robot);
} else {
direction = junction(robot);
robotData.addJunction(robot);
robotData.printJunction(robot);
}
robot.face(direction);
}
/* The specification advised to have to seperate controls: Explorer and Backtrack
and a variable explorerMode to switch between them.
Instead, whenever needed I shall call this backtrack method.
If at a junction, the robot will head back the junction as to when it first approached it.
When at a deadend or corridor, it will follow the beenbefore squares until it
reaches an unexplored path. */
public int backtrack (IRobot robot) {
if (nonwallExits(robot) > 2) {
return robotData.reverseHeading(robot);
} else {
do {
return nonWallDirections.get(0);
} while (nonwallExits(robot) == 1);
}
}
// Deadend method makes the robot follow the only nonwall exit.
public int deadEnd (IRobot robot) {
return backtrack(robot);
}
/* Corridor method will make the robot follow the one and only passage.
The exception is at the start. Sometimes, the robot will start with
two passages available to it in which case it will choose one randomly.
If there is no passage, it will follow the beenbefore squares
until it reaches an unexplored path.*/
public int corridor (IRobot robot) {
if (passageExits(robot) == 1) {
return passageDirections.get(0);
} else if (passageExits(robot) == 2) {
int randomPassage = random.nextInt(passageDirections.size());
return passageDirections.get(randomPassage);
} else {
return backtrack(robot);
}
}
/* Junction method states if there is more than one passage, it will randomly select one.
This applies to crossroads as well as essentially they are the same.
If there is no passage, it will follow the beenbefore squares until it reaches an unexplored
path. */
public int junction(IRobot robot) {
if (passageExits(robot) == 1) {
return passageDirections.get(0);
} else if (passageExits(robot) > 1) {
int randomPassage = random.nextInt(passageDirections.size());
return passageDirections.get(randomPassage);
} else {
return backtrack(robot);
}
}
// Calculates number of exits.
private int nonwallExits (IRobot robot) {
int nonwallExits = 0;
for(int item : directions) {
if(robot.look(item) != IRobot.WALL) {
nonwallExits++;
}
}
return nonwallExits;
}
// Calculates number of passages.
private int passageExits (IRobot robot) {
int passageExits = 0;
for(int item : directions) {
if(robot.look(item) == IRobot.PASSAGE) {
passageExits++;
}
}
return passageExits;
}
// Calculates number of beenbefores.
private int beenbeforeExits (IRobot robot) {
int beenbeforeExits = 0;
for(int item : directions) {
if(robot.look(item) == IRobot.PASSAGE) {
beenbeforeExits++;
}
}
return beenbeforeExits;
}
// Resets Junction Counter in RobotData class.
public int reset() {
return robotData.resetJunctionCounter();
}
}
class RobotData {
/* It was advised in the specification to include the variable:
private static int maxJunctions = 10000;
However, as I am not using arrays, but ArrayLists, I do not
need this. */
private static int junctionCounter = 0;
private ArrayList<Junction> junctionList = new ArrayList<Junction>();
private Iterator<Junction> junctionIterator = junctionList.iterator();
// Resets the Junction counter.
public int resetJunctionCounter() {
return junctionCounter = 0;
}
// Adds the current junction to the list of arrays.
public void addJunction(IRobot robot) {
Junction newJunction = new Junction(robot.getLocation().x, robot.getLocation().y, robot.getHeading());
junctionList.add(newJunction);
junctionCounter++;
}
// Gets the junction counter for Junction info method in Junction class.
public int getJunctionCounter (IRobot robot) {
return junctionCounter;
}
// Prints Junction info.
public void printJunction(IRobot robot) {
String course = "";
switch (robot.getHeading()) {
case IRobot.NORTH:
course = "NORTH";
break;
case IRobot.EAST:
course = "EAST";
break;
case IRobot.SOUTH:
course = "SOUTH";
break;
case IRobot.WEST:
course = "WEST";
break;
}
System.out.println("Junction " + junctionCounter + " (x=" + robot.getLocation().x + ", y=" + robot.getLocation().y +") heading " + course);
}
/* Iterates through the junction arrayList to find the
heading of the robot when it first approached the junction. */
public int searchJunction(IRobot robot) {
Junction currentJunction = junctionIterator.next();
while (junctionIterator.hasNext()) {
if ((((currentJunction.x)==(robot.getLocation().x))) && ((currentJunction.y)==(robot.getLocation().y)))
break;
}
return currentJunction.arrived;
}
// Returns the reverse of the heading the robot had when first approaching the junction.
public int reverseHeading(IRobot robot) {
int firstHeading = searchJunction(robot);
int reverseHeading = 1; // Random integer to Iniitalise variable.
switch (firstHeading) {
case IRobot.NORTH:
if (robot.getHeading() == IRobot.NORTH)
reverseHeading = IRobot.BEHIND;
else if (robot.getHeading() == IRobot.EAST)
reverseHeading = IRobot.RIGHT;
else if (robot.getHeading() == IRobot.SOUTH)
reverseHeading = IRobot.AHEAD;
else
reverseHeading = IRobot.LEFT;
break;
case IRobot.EAST:
if (robot.getHeading() == IRobot.NORTH)
reverseHeading = IRobot.LEFT;
else if (robot.getHeading() == IRobot.EAST)
reverseHeading = IRobot.BEHIND;
else if (robot.getHeading() == IRobot.SOUTH)
reverseHeading = IRobot.RIGHT;
else
reverseHeading = IRobot.AHEAD;
break;
case IRobot.SOUTH:
if (robot.getHeading() == IRobot.NORTH)
reverseHeading = IRobot.AHEAD;
else if (robot.getHeading() == IRobot.EAST)
reverseHeading = IRobot.LEFT;
else if (robot.getHeading() == IRobot.SOUTH)
reverseHeading = IRobot.BEHIND;
else
reverseHeading = IRobot.RIGHT;
break;
case IRobot.WEST:
if (robot.getHeading() == IRobot.NORTH)
reverseHeading = IRobot.RIGHT;
else if (robot.getHeading() == IRobot.EAST)
reverseHeading = IRobot.AHEAD;
else if (robot.getHeading() == IRobot.SOUTH)
reverseHeading = IRobot.LEFT;
else
reverseHeading = IRobot.BEHIND;
break;
}
return reverseHeading;
}
}
class Junction {
int x;
int y;
int arrived;
public Junction(int xcoord, int ycoord, int course) {
x = xcoord;
y = ycoord;
arrived = course;
}
}
Whenever it is backtracking and reaches a junction it has already visited, it freezes and this comes up.
`java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor41.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at uk.ac.warwick.dcs.maze.controllers.PolledControllerWrapper.start(PolledControllerWrapper.java:70)
at uk.ac.warwick.dcs.maze.logic.ControllerThread.run(ControllerThread.java:46)
Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
at java.util.ArrayList$Itr.next(ArrayList.java:851)
at RobotData.searchJunction(Explorer.java:242)
at RobotData.reverseHeading(Explorer.java:255)
at Explorer.backtrack(Explorer.java:74)
at Explorer.junction(Explorer.java:122)
at Explorer.controlRobot(Explorer.java:56)
... 5 more`
I don't think your searchJunction() is right or safe, the ConcurrentModificationException might be thrown due to the incorrect iterator through junctionList . The problem should be more about the iterator rather than reflection.
You might try:
private Iterator<Junction> junctionIterator = junctionList.iterator(); doesn't make much sense since the list is empty when initialize a RobotData object. Try to move it into searchJunction()
Check hasNext() first then invoke next()
public int searchJunction(IRobot robot) {
Iterator<Junction> junctionIterator = junctionList.iterator();
while (junctionIterator.hasNext()) {
Junction currentJunction = junctionIterator.next();
if ((((currentJunction.x)==(robot.getLocation().x))) && ((currentJunction.y)==(robot.getLocation().y)))
break;
}
return currentJunction.arrived;
}
It looks like that issue is in following code -
`public int searchJunction(IRobot robot) {
Junction currentJunction = junctionIterator.next();
while (junctionIterator.hasNext()) {
if ((((currentJunction.x)==(robot.getLocation().x))) && ((currentJunction.y)==(robot.getLocation().y)))
break;
}
return currentJunction.arrived;
}
You are calling junctionIterator.next() before calling junctionIterator.hasNext(). Iterator specification says that you should call next() only after calling hasNext()