请问上java.lang.IllegalArgumentException这个错误是咋回事

java.lang.IllegalArgumentException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:42)
	at org.hibernate.tuple.entity.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:329)
	at org.hibernate.tuple.entity.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:232)
	at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:3557)
	at org.hibernate.engine.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:133)
	at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:854)
	at org.hibernate.loader.Loader.doQuery(Loader.java:729)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
	at org.hibernate.loader.Loader.doList(Loader.java:2217)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2108)
	at org.hibernate.loader.Loader.list(Loader.java:2103)
	at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:94)
	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1570)
	at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)
	at dao.PostDao.queryPostByIndex(PostDao.java:74)
	at org.apache.jsp.announce_jsp._jspService(announce_jsp.java:88)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
	at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:593)
	at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:530)
	at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:954)
	at org.apache.jsp.index_jsp._jspService(index_jsp.java:334)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at util.EncodingFilter.doFilter(EncodingFilter.java:22)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)