cannot find symbol找不到符号？netBeans里面提示错误什么意思？
 我的连数据库的Bean的public class ExecuteDB extends ConnectDB{}这句话有错  可是在JBuilder里面没有提示错误
这是什么意思？

这是我调试的时候出现的错误 调试后 之前的cannot find symbol错误没了 而且没有红色下滑曲线提示错误   


HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP

An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:65: 找不到符号
符号： 方法 setuserName(java.lang.String)
位置： 类 bbs.User
    User.setuserName(sUserName);
            ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:66: 找不到符号
符号： 方法 setuserPassword(java.lang.String)
位置： 类 bbs.User
    User.setuserPassword(sUserPassword);
            ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:75: 找不到符号
符号： 方法 getuserName()
位置： 类 bbs.User
        session.setattribute("userName",User.getuserName());
                                                    ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:76: 找不到符号
符号： 方法 getuserID()
位置： 类 bbs.User
        session.setattribute("userID",User.getuserID());
                                                  ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:77: 找不到符号
符号： 方法 getrole()
位置： 类 bbs.User
        session.setattribute("role",User.getrole());
                                                ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:80: 找不到符号
符号： 方法 getrole()
位置： 类 bbs.User
        if(User.getrole().equals("0"))
                       ^
6 错误



    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    (MonitorFilter.java:368)


root cause

org.apache.jasper.JasperException: Unable to compile class for JSP

An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:65: 找不到符号
符号： 方法 setuserName(java.lang.String)
位置： 类 bbs.User
    User.setuserName(sUserName);
            ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:66: 找不到符号
符号： 方法 setuserPassword(java.lang.String)
位置： 类 bbs.User
    User.setuserPassword(sUserPassword);
            ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:75: 找不到符号
符号： 方法 getuserName()
位置： 类 bbs.User
        session.setattribute("userName",User.getuserName());
                                                    ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:76: 找不到符号
符号： 方法 getuserID()
位置： 类 bbs.User
        session.setattribute("userID",User.getuserID());
                                                  ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:77: 找不到符号
符号： 方法 getrole()
位置： 类 bbs.User
        session.setattribute("role",User.getrole());
                                                ^


An error occurred at line: 9 in the jsp file: /user_login.jsp
Generated servlet error:
C:\Documents and Settings\cs\.netbeans\5.5\apache-tomcat-5.5.17_base\work\Catalina\localhost\BBS\org\apache\jsp\user_005flogin_jsp.java:80: 找不到符号
符号： 方法 getrole()
位置： 类 bbs.User
        if(User.getrole().equals("0"))
                       ^
6 错误