最后运行报错：Word无法转化成OfficeAble类型

D:\IdeaProjects>javac Word.java

D:\IdeaProjects>javac OfficeBetter.java

D:\IdeaProjects>java OfficeBetter Word
java.lang.ClassCastException: Word cannot be cast to OfficeAble
        at OfficeBetter.main(OfficeBetter.java:7)