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当我运行使用 db40 的应用程序时，出现以下错误。

有任何想法吗？一切看起来都很好，并且Hashtable <String, db4o.Plant> l = db4o.db.getTheDatabase().getPlants();在 netbeans 中显示正常（所有方法都正确编写）。

type Exception report

message

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

org.apache.jasper.JasperException: An exception occurred processing JSP page /plante.jsp at line 37

    34: 
    35: 
    36: <%
    37: Hashtable <String, db4o.Plant> l = db4o.db.getTheDatabase().getPlants();
    38: int i = 0;
    39: 
    40: Iterator<String> iterator = l.keySet().iterator();


    Stacktrace:
        org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)


org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)

    root cause

java.lang.NullPointerException
    org.apache.jsp.plante_jsp._jspService(plante_jsp.java:89)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.
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1 回答 1

1

我的第一个猜测是 db4o.db.getTheDatabase() 返回 null。

于 2010-01-21T10:57:37.460 回答