BeanUtils.populate throwing NullPointerException in struts after migrating to Tomcat7

Question

I am migrating a Struts 1 application from Tomcat 6 to Tomcat 7. most of the application is working fine but at a point while a form submit the following error is occurring.

javax.servlet.ServletException: BeanUtils.populate
    org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1254)
    org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:254)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

root cause

java.lang.NullPointerException
    org.apache.commons.beanutils.PropertyUtilsBean.getIndexedProperty(PropertyUtilsBean.java:543)
    org.apache.commons.beanutils.PropertyUtilsBean.getIndexedProperty(PropertyUtilsBean.java:446)
    org.apache.commons.beanutils.PropertyUtilsBean.getNestedProperty(PropertyUtilsBean.java:806)
    org.apache.commons.beanutils.PropertyUtilsBean.getProperty(PropertyUtilsBean.java:884)
    org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:894)
    org.apache.commons.beanutils.BeanUtilsBean.populate(BeanUtilsBean.java:821)
    org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:431)
    org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1252)
    org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:254)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.55 logs.

Does any one have an idea why this is occurring?

The full stack trace is

java.lang.NullPointerException
    at org.apache.commons.beanutils.PropertyUtilsBean.getIndexedProperty(PropertyUtilsBean.java:543)
    at org.apache.commons.beanutils.PropertyUtilsBean.getIndexedProperty(PropertyUtilsBean.java:446)
    at org.apache.commons.beanutils.PropertyUtilsBean.getNestedProperty(PropertyUtilsBean.java:806)
    at org.apache.commons.beanutils.PropertyUtilsBean.getProperty(PropertyUtilsBean.java:884)
    at org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:894)
    at org.apache.commons.beanutils.BeanUtilsBean.populate(BeanUtilsBean.java:821)
    at org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:431)
    at org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1252)
    at org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:254)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:610)
    at com.homedepot.ta.aa.catalina.realm.THDFormAuthenticator.invoke(Unknown Source)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at com.homedepot.ta.aa.dao.catalina.THDDAOValve.invoke(Unknown Source)
    at com.homedepot.ta.aa.catalina.realm.THDSingleSignOn.invoke(Unknown Source)
    at com.homedepot.ta.aa.catalina.valves.HDAccessLogValve.invoke(Unknown Source)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

This is occurring even before it is going to the particular class. the application is working as expected in tomcat 6.

Answer 1

Our team at work ran into this issue migrating from Websphere 7 to Webshpere 8. The issue was that they were using two setters using the same name, but took a int parameter for one and an Integer parameter in another.

The solution was to remove one of the setters.

I am unsure if this is the reason, but I think the null pointer is because the size of the collection is larger than the number of actual methods that gets resolved through reflection. Two setters having the same name, with the same parameter datatype(essentially because the int gets boxed to Integer when they get the methods via reflection) would cause an off by one error when they try to iterate over the list of setters.