无法调用PL/SQL用户定义过程

我是PL/SQL新手，我尝试定义和使用如下过程：

create or replace procedure f()
is
BEGIN
   DBMS_OUTPUT.put_line('Hello world!');
END;
/ 

BEGIN
     f();
END;
/

但是，在调用f（）时，会出现一个错误消息，并显示“对象[用户名].f无效”

---

我做错了什么？

当您创建过程时，您应该看到如下内容

Warning: Procedure created with compilation errors.

SQL> sho err
Errors for PROCEDURE MY_PROC:

LINE/COL ERROR
-------- -----------------------------------------------------------------
1/19     PLS-00103: Encountered the symbol ")" when expecting one of the
         following:
         <an identifier> <a double-quoted delimited-identifier>
         current delete exists prior

如果您键入“showererrors”或在sqldeveloper中打开该过程并编译该过程，您将得到一个错误列表。如果你这样做，你会看到

Warning: Procedure created with compilation errors.

SQL> sho err
Errors for PROCEDURE MY_PROC:

LINE/COL ERROR
-------- -----------------------------------------------------------------
1/19     PLS-00103: Encountered the symbol ")" when expecting one of the
         following:
         <an identifier> <a double-quoted delimited-identifier>
         current delete exists prior

它应该可以编译，并且可以从匿名PL/SQL块调用