Sourav Sourav - 1 month ago 15
Java Question

servlet: Caused by: java.lang.IllegalArgumentException: Can't convert argument: null

Here is the Error Log:



java.lang.IllegalArgumentException: Can't convert argument: null
at org.apache.tomcat.util.IntrospectionUtils.convert(IntrospectionUtils.java:889)
at org.apache.tomcat.util.digester.CallMethodRule.end(CallMethodRule.java:476)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1057)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1543)
at org.apache.catalina.startup.ContextConfig.parseWebXml(ContextConfig.java:1694)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1209)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:882)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:317)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5081)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:620)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)

Oct 04, 2015 12:53:40 AM org.apache.catalina.startup.ContextConfig parseWebXml
SEVERE: Parse error in application web.xml file at jndi:/localhost/ConfigImplicitObj/WEB-INF/web.xml
org.xml.sax.SAXParseException; systemId: jndi:/localhost/ConfigImplicitObj/WEB-INF/web.xml; lineNumber: 9; columnNumber: 18; Error at (9, 18) : Can't convert argument: null
at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2687)
at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2713)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1060)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1543)
at org.apache.catalina.startup.ContextConfig.parseWebXml(ContextConfig.java:1694)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1209)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:882)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:317)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5081)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:620)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)
Caused by: java.lang.IllegalArgumentException: Can't convert argument: null
at org.apache.tomcat.util.IntrospectionUtils.convert(IntrospectionUtils.java:889)
at org.apache.tomcat.util.digester.CallMethodRule.end(CallMethodRule.java:476)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1057)
... 36 more


Oct 04, 2015 12:53:40 AM org.apache.catalina.startup.ContextConfig parseWebXml
SEVERE: Occurred at line 9 column 18
Oct 04, 2015 12:53:40 AM org.apache.catalina.startup.ContextConfig configureStart
SEVERE: Marking this application unavailable due to previous error(s)
Oct 04, 2015 12:53:40 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Error getConfigured
Oct 04, 2015 12:53:40 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/ConfigImplicitObj] startup failed due to previous errors
Oct 04, 2015 12:53:40 AM org.apache.catalina.loader.WebappClassLoader validateJarFile
INFO: validateJarFile(C:\Users\SouRAV\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\DemoServlet\WEB-INF\lib\servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
Oct 04, 2015 12:53:40 AM org.apache.coyote.AbstractProtocolHandler start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Oct 04, 2015 12:53:40 AM org.apache.coyote.AbstractProtocolHandler start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Oct 04, 2015 12:53:40 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 1162 ms


web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>Simple</servlet-name>
<servlet-class>Simple</servlet-class>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>WelcomeServlet</servlet-name>
<servlet-class>WelcomeServlet</servlet-class>
</servlet>


<servlet-mapping>
<servlet-name>Simple</servlet-name>
<url-pattern>/go</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>WelcomeServlet</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>login.html</welcome-file>
</welcome-file-list>
</web-app>


I am just working on servlet and I am in the beginning of the project. But, It shows a error. I tried it but could not find the error.

Answer
<servlet-class>WelcomeServlet</servlet-class>.

In this provide package name also. Like this:

<servlet-class>packages.WelcomeServlet</servlet-class>