JAVA版A星算法实现

  1 import java.util.ArrayDeque;
  2 import java.util.ArrayList;
  3 import java.util.Collections;
  4 import java.util.HashMap;
  5 import java.util.Iterator;
  6 import java.util.Map.Entry;
  7 import java.util.Queue;
  8 
  9 public class TestPath {
 10     class Point implements Comparable<Point> {
 11         int x;  // 坐标x
 12         int y;  // 坐标y
 13         int f = 200; // 估值数 f = g + h
 14         int g = 100;  // 与父节点的距离
 15         int h = 100;  // 与目标点的距离
 16         boolean canWalk;  // 是否可以通行
 17         Point parent = null;
 18 
 19         Point(int x, int y, boolean canWalk) {
 20             this.x = x;
 21             this.y = y;
 22             this.canWalk = canWalk;
 23         }
 24 
 25         @Override
 26         public int compareTo(Point o) {
 27             return new Integer(f).compareTo(new Integer(o.f));
 28         }
 29 
 30     }
 31 
 32     public static void main(String[] args) {
 33         int arr[][] = {  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 
 34                                 { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0 },
 35                                 { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0 },
 36                                 { 0, 0, 0, 1, 1, 0, 0, 0, 0, 0 }, 
 37                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
 38                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 
 39                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 
 40                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
 41                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
 42                                 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } };
 43         Point[][] paths = new Point[10][10];
       // 生成路径对象数组
44 for (int i = 0; i < 10; i++) { 45 for (int j = 0; j < 10; j++) { 46 boolean canWalk = arr[i][j] == 1 ? false : true; 47 paths[i][j] = new TestPath().new Point(i, j, canWalk); 48 } 49 }
      // 起始点
50 Point bp = paths[0][0];
      // 目标点
51 Point ep = paths[2][4]; 52 AStart(paths, bp, ep); 53 Point tmp = ep; 54 while (tmp.parent != bp) { 55 tmp = tmp.parent; 56 System.out.println(tmp.x + "," + tmp.y); 57 } 58 59 } 60 61 static void AStart(Point[][] paths, Point beginP, Point endP) {
       // 待遍历列表
62 ArrayList<Point> openList = new ArrayList<>(100); 63 beginP.g = 0; 64 beginP.h = (Math.abs(beginP.x - endP.x) + Math.abs(beginP.y - endP.y)) * 10; 65 beginP.f = beginP.g + beginP.h; 66 endP.h = 0; 67 openList.add(beginP); 68 ArrayList<Point> closeList = new ArrayList<>(100); 69 //Iterator<Point> iter = openList.iterator(); 70 while (openList.size() != 0) { 71 Point p = openList.get(0); 72 System.out.println("p: x="+p.x + ",y="+p.y + ",g="+p.g + ",h="+ p.h +",f="+p.f); 73 if (p.h == 0) { 74 System.out.println("=========end==========="); 75 System.out.println(p.x + "," + p.y); 76 return; 77 }
          // 遍历周边相邻路径
78 for (int i = -1; i <= 1; i++) { 79 for (int j = -1; j <= 1; j++) { 80 if (p.x + i < 0 || p.x + i > 9 || p.y + j < 0 || p.y + j > 9) { // 超出地图范围 81 continue; 82 } 83 if (i == 0 && j == 0) { // 本身 84 continue; 85 } 86 Point tmp = paths[p.x + i][p.y + j];
              // 如果已经遍历过了,跳过
87 if (!tmp.canWalk || closeList.contains(tmp)) { 88 continue; 89 }
              // 下一个路径点的g值,相邻的加10,对角的加14(10和14是自己定义的值)
90 int newG = 0; 91 if ( i != 0 && j != 0) { 92 newG = p.g + 14; 93 } else { 94 newG = p.g + 10; 95 } 96 System.out.println("newg="+newG);
              // 下一个路径点与目标点的h值
97 tmp.h = (Math.abs(tmp.x - endP.x) + Math.abs(tmp.y - endP.y)) * 10; 98 if (openList.contains(tmp)) { 99 if (tmp.g > newG) { // 在待遍历列表中,并且与当前的路径点距离更近,则更换上级路径点 100 tmp.parent = p; 101 tmp.g = newG; 102 tmp.f = tmp.g + tmp.h; 103 } 104 } else {// 加入待遍历列表 105 tmp.parent = p; 106 tmp.g = newG; 107 openList.add(tmp); 108 } 109 tmp.f = tmp.g + tmp.h; // 更新f值 110 System.out.println(tmp.x + "," + tmp.y + "," + tmp.g+","+tmp.h+","+tmp.f+",("+tmp.parent.x + ","+ tmp.parent.y+")"); 111 } 112 }
          // 遍历完之后从待遍历列表中移除,加入到已遍历列表中
113 closeList.add(p); 114 openList.remove(p);
          // 按f值排序
115 Collections.sort(openList); 116 //iter = openList.iterator(); 117 } 118 } 119 120 }
原文地址:https://www.cnblogs.com/taixuyingcai/p/5227864.html