public class HelloJava{                                                                           public static void main（String[]args){                                                           System.out.println("Hello Java");                                                       }                                                                                       }                                              保存在记事本中，以。java为文件保存类型，然后在控制台中输入cd\    javac HelloJava。java            显示‘javac’不是内部或外部命令，也不是可运行的程序或批处理文件。                    怎么破？？？