4.19

public static int[][] adjacency() {
    Map<String, Integer> stationIds = buildStationIdMap(); // 调用建立站点名称和对应的ID的哈希表的函数
    Connection connection = JDBCUtils.getConn();
    int[][] graph = null; // 邻接矩阵

    try {
        String sql = "SELECT Starting_Station, Terminus_Station FROM station ";

        // 从数据库中检索起始站和终点站

        Statement statement = connection.createStatement();
        ResultSet resultSet = statement.executeQuery(sql);

        int currentId = stationIds.size(); // 使用已有的ID数量作为初始ID

        // 创建邻接矩阵
        graph = new int[currentId][currentId];

        // 填充邻接矩阵
        while (resultSet.next()) {
            String startingStation = resultSet.getString("Starting_Station");
            String terminusStation = resultSet.getString("Terminus_Station");
            int startingStationId = stationIds.get(startingStation);
            int terminusStationId = stationIds.get(terminusStation);
            graph[startingStationId][terminusStationId] = 1;
            graph[terminusStationId][startingStationId] = 1;
        }

    } catch (SQLException e) {
        e.printStackTrace();
        // 在这里处理任何可能的异常...
    } finally {
        // 关闭资源
        try {
            if (connection != null) {
                connection.close();
            }
            // 关闭 statement 和 resultSet
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 返回邻接矩阵
    return graph;
}