一连接数据库就显示基础错误 'java.lang.NumberFormatException: For input string: "3306:"

public class DButils {
private static Connection connection = null ;
private static String drivname ="com.mysql.jdbc.Driver";
private static String username = "root";
private static String password = "123123";
private static String url= "jdbc:mysql://localhost:3306:/sys";

public static Connection getConnection() {
    if (connection == null) {
        try {
            Class.forName(drivname);
            connection = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }
    return connection;
}

}

jdbc:mysql://localhost:3306:/sys
多了一个冒号

换成
private static String url= "jdbc:mysql://localhost:3306/sys";

url: jdbc:mysql://localhost:3306/book
所以是/sys之前多了冒号
private static String url= "jdbc:mysql://localhost:3306:/sys";

NumberFormatException数字转换异常, For input string: "3306:"输入字符串3306:, :冒号肯定转不了数字

参考格式如下
jdbc:oracle:thin:@localhost:1993:dbnms

jdbc:mysql://ip:3306/database

jdbc:clickhouse://ip:9000

jdbc:hive2://ip:10000/default

jdbc:postgresql://ip:5432/database