尝试做一些 A* 的东西，我经常NullPointerException在第 129 行得到一个...
public class GameMap {
int tileW = 64;
int tileH = 36;
int tiles = 2304;
ArrayList<Node> nodes = new ArrayList<Node>();
public GameMap(int width, int height) {
int widthtest = 640;
int heighttest = 360;
for (int y = 0; y<tileH; y++){
for (int x = 0; x<tileW; x++){
nodes.add(new Node(x,y,false,null,10000));
//System.out.println("node added at x:" + x + " and y:" + y + " w/tilenum: " + nodes.size());
}
}
}
public void blockNode(int x, int y){
int tilenum = tileNum(x,y);
nodes.get(tilenum).blocked = true;
System.out.println("blocked node " + tilenum);
}
public int tileNum(int x, int y){
int tilenum = x+(y*64);
return tilenum;
}
public ArrayList<Node> findPath(int sx, int sy, int tx, int ty){
ArrayList<Node> open = new ArrayList<Node>();
ArrayList<Node> closed = new ArrayList<Node>();
ArrayList<Node> path = new ArrayList<Node>();
ArrayList<Node> adjList = new ArrayList<Node>();
Node startNode = new Node(sx, sy, false, null, getF(sx,sy,tx,ty));
Node endNode = new Node(tx, ty, false, null, 0);
Node currentNode = null;
open.add(startNode);
while(currentNode != endNode && open.size()>0 && endNode.parent == null){
currentNode = findBestNode(open);
adjList = getAdj(currentNode);
if(currentNode.equals(endNode)){
continue;
}
else{
open.remove(currentNode);
closed.add(currentNode);
for(int i = 0 ; i<adjList.size() ; i++){
if(adjList.get(i).blocked || closed.contains(adjList.get(i))){
continue;
}
if(!open.contains(adjList.get(i))){
open.add(adjList.get(i));
adjList.get(i).parent = currentNode;
}
else{
int newDistance = getF(currentNode.x, currentNode.y, tx, ty);
if(newDistance < currentNode.fscore){
adjList.get(i).parent = currentNode;
adjList.get(i).fscore = newDistance;
}
}
}
}
}
if(endNode.parent != null){
path = generatePath(startNode, endNode);
}
return path;
}
private ArrayList<Node> generatePath(Node startNode, Node endNode) {
ArrayList<Node> path = new ArrayList<Node>();
Node currentNode = endNode;
while(currentNode != startNode){
path.add(currentNode);
currentNode = currentNode.parent;
}
return path;
}
private Node findBestNode(ArrayList<Node> open) {
int lowF = 10000;
Node currentNode = null;
for (int i = 0 ; i<open.size() ; i++){
if(open.get(i).fscore < lowF){
lowF = open.get(i).fscore;
currentNode = open.get(i);
}
}
return currentNode;
}
private int getF(int sx, int sy, int tx, int ty){
int dx = Math.abs(tx - sx);
int dy = Math.abs(ty - sy);
int f = dx+dy;
return f;
}
private ArrayList<Node> getAdj(Node node){
ArrayList<Node> adj;
adj = new ArrayList<Node>();
for (int y = -1; y<2; y++){
for (int x = -1; x<2; x++){
if(node.x+x>-1 && node.y+y>-1){
Node theNode = nodes.get(tileNum(node.x+x, node.y+y));
//adj.add(theNode);
System.out.println(theNode);
adj.add(theNode);
}
}
}
return adj;
}
}
这是我的节点类
public class Node{
int x;
int y;
boolean blocked;
Node parent;
int fscore;
public Node(int x, int y, boolean blocked, Node parent, int fscore) {
this.x = x;
this.y = y;
this.blocked = blocked;
this.parent = parent;
this.fscore = fscore;
}
}
和游戏类：
public class Game {
public Game() {
GameMap gm = new GameMap(640,360);
gm.blockNode(63, 32);
System.out.println(gm.findPath(0, 0, 4, 2));
}
public static void main(String[] args){
Game game = new Game();
}
}
提前感谢您的帮助！
129号线在
ArrayList getAdj(节点节点){
确切的行是：
如果（节点.x+x>-1 && 节点.y+y>-1）{
希望我没有咬得比我能咀嚼的更多。我正在尝试创建节点周围所有相邻节点的数组列表。