Question

Hello I have a development version of a working productive webapp which gives me headache. When I login, I get following error, while admin.jsp is trying to display a folder structure.

    org.apache.jasper.JasperException: Exception in JSP: /admin/admin.jsp:133

130:    GenDisplay display = null;
131:    if(null==oldDisplay || true==oldDisplay.checkIsOld()) {
132:        display = new GenDisplay(oldDisplay);
133:        display.genTree(((CompanySession)ppa).getRootOrdner(), ((CompanySession)ppa).getRootType(), user.getUID(), out);
134:        ((CompanySession)ppa).setGenDisplay(display);   
135:    } else {
136:        display = oldDisplay;


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

root cause

java.lang.NullPointerException
    ppa.admin.GenDisplay.getKey(GenDisplay.java:185)
    ppa.admin.GenDisplay.isOpen(GenDisplay.java:161)
    ppa.admin.GenDisplay.genSubTree(GenDisplay.java:49)
    ppa.admin.GenDisplay.genSubTree(GenDisplay.java:57)
    ppa.admin.GenDisplay.genSubTree(GenDisplay.java:57)
    ppa.admin.GenDisplay.genSubTree(GenDisplay.java:57)
    ppa.admin.GenDisplay.genTree(GenDisplay.java:42)
    org.apache.jsp.admin.admin_jsp._jspService(admin_jsp.java:606)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

This is the admin_jsp.java around line 606 codeblock to generate the error:

GenDisplay oldDisplay = ((CompanySession)ppa).getGenDisplay();
    GenDisplay display = null;
    if(null==oldDisplay || true==oldDisplay.checkIsOld()) {
        display = new GenDisplay(oldDisplay);
        display.genTree(((CompanySession)ppa).getRootOrdner(), ((CompanySession)ppa).getRootType(), user.getUID(), out);
        ((CompanySession)ppa).setGenDisplay(display);   
    } else {
        display = oldDisplay;
    }
    //out.println(((CompanySession)ppa).getRootOrdner());
    //
    int currentOrdner = ((CompanySession)ppa).getRootOrdner();
    int currentOrdnerType = ((CompanySession)ppa).getRootType();
    if(null!=oldDisplay) {
    currentOrdner = oldDisplay.getCurrentOrdner();
    currentOrdnerType = oldDisplay.getCurrentOrdnerType();
    } else {
        display.openOrdner(((CompanySession)ppa).getRootOrdner(), ((CompanySession)ppa).getRootType());
}

So I sorted one of the variable passed to display.genTree() is null, that’s why the NullPointerException. This development is exactly copied from the working production version, why throwing an error here and not on the production version? I’m puzzled. Does anybody has idea? Thanks in advance!

p.s.: I compared java version, tomcat version, compiler version. I reestablished same settings for both tomcats. I compared mysql server versions and settings. They are almost the same versions and settings. No major release difference with the software involved. I tried newer versions of tomcat (6,7) and got different errors, so this confused me even more. I really need help, since I didn’t wrote the webapp and I am new to java.

Answer 1

The issue is not withing the generated servlet code. The NPE occurs in ppa.admin.GenDisplay.getKey(GenDisplay.java:185) a variable (null) is dereferenced, so you need to look what happens in line 185 and find out where the variable should have been set.
Tracing this back will show the difference (something like: environment variables or file system permissions) of dev and production.