java语言该怎么实现呢？

以下是Java语言的示例代码：

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.PriorityQueue;
import java.util.Set;

public class AStar {
    private final int[][] directions = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}}; // 四个方向
    private final int[][] grid; // 网格
    private final int rows; // 行数
    private final int cols; // 列数
    private final int[] start; // 起点坐标
    private final int[] end; // 终点坐标

    private int heuristic(int[] a, int[] b) { // 启发式函数
        return Math.abs(b[0] - a[0]) + Math.abs(b[1] - a[1]);
    }

    private boolean isInGrid(int row, int col) { // 判断坐标是否在网格内
        return row >= 0 && row < rows && col >= 0 && col < cols;
    }

    private boolean isObstacle(int row, int col) { // 判断坐标是否为障碍物
        return grid[row][col] == 1;
    }

    private List<int[]> getNeighbors(int row, int col) { // 获取相邻节点列表
        List<int[]> neighbors = new ArrayList<>();
        for (int[] dir : directions) {
            int r = row + dir[0];
            int c = col + dir[1];
            if (isInGrid(r, c) && !isObstacle(r, c)) {
                neighbors.add(new int[]{r, c});
            }
        }
        return neighbors;
    }

    public List<int[]> findPath() { // A*算法主函数
        PriorityQueue<int[]> openList = new PriorityQueue<>(Comparator.comparingInt(node -> node[2])); // open列表，按f值排序
        Set<String> closeSet = new HashSet<>(); // close列表，存储已访问的节点

        openList.offer(new int[]{start[0], start[1], 0, heuristic(start, end), -1}); // 将起点加入open列表
        while (!openList.isEmpty()) {
            int[] current = openList.poll(); // 选取f值最小的节点作为当前节点
            if (current[0] == end[0] && current[1] == end[1]) { // 到达终点，回溯得到路径
                List<int[]> path = new ArrayList<>();
                int curr = current[4];
                while (curr != -1) {
                    path.add(new int[]{curr / cols, curr % cols});
                    curr = current[4] = curr / cols;
                }
                return path;
            }
            closeSet.add(current[0] + "," + current[1]); // 将当前节点加入close列表
            for (int[] neighbor : getNeighbors(current[0], current[1])) { // 处理相邻节点
                String key = neighbor[0] + "," + neighbor[1];
                if (closeSet.contains(key)) { // 如果相邻节点已经在close列表中，忽略它
                    continue;
                }
                int g = current[2] + 1; // 计算相邻节点的g值
                int h = heuristic(neighbor, end); // 计算相邻节点的h值
                int f = g + h; // 计算相邻节点的f值
                int idx = neighbor[0] * cols + neighbor[1];
                for (int[] node : openList) { // 如果相邻节点已经在open列表中，更新它的f值和父节点
                    if (node[4] == idx) {
                        if (f < node[2] + node[3]) {
                            node[2] = g;
                            node[3] = h;
                            node[4] = current[0] * cols + current[1];
                        }
                        break;
                    }
                }
                if (!openList.contains(neighbor)) { // 否则，将相邻节点加入open列表中
                    openList.offer(new int[]{neighbor[0], neighbor[1], g, h, current[0] * cols + current[1]});
                }
            }
        }
        return new ArrayList<>(); // open列表为空，无法找到路径
    }

    public AStar(int[][] grid, int[] start, int[] end) { // 构造函数
        this.grid = grid;
        this.rows = grid.length;
        this.cols = grid[0].length;
        this.start = start;
        this.end = end;
    }
}

调用示例：

public class Main {
    public static void main(String[] args) {
        int[][] grid = {{0, 0, 0, 0, 0},
                        {0, 0, 1, 0, 0},
                        {0, 0, 1, 0, 0},
                        {0, 0, 1, 0, 0},
                        {0, 0, 0, 0, 0}}; // 网格
        int[] start = {0, 0}; // 起点坐标
        int[] end = {4, 4}; // 终点坐标
        AStar aStar = new AStar(grid, start, end);
        List<int[]> path = aStar.findPath();
        for (int[] node : path) {
            System.out.println(node[0] + "," + node[1]); // 打印路径节点坐标
        }
    }
}