java.io.IOException: No such file or directory

The following lines of code caused this issue:

File imageFile = new File("/Users/test/main/tomcat/webapps/temp/"

  + UUID.randomUUID() + ".jpg");

imageFile.createNewFile(); // Exception Caused here.

imageFileUpload.writeTo(imageFile);

Exception Logs:

DEBUG - onSubmit called
java.io.IOException: No such file or directory
at java.io.UnixFileSystem.createFileExclusively(Native Method)
at java.io.File.createNewFile(File.java:883)
at com.test.web.common.form.UpdateImageForm.onSubmit(UpdateImageForm.java:297)
at org.apache.wicket.markup.html.form.Form.delegateSubmit(Form.java:1565)
at org.apache.wicket.markup.html.form.Form.process(Form.java:958)
at org.apache.wicket.markup.html.form.Form.onFormSubmitted(Form.java:920)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.wicket.RequestListenerInterface.invoke(RequestListenerInterface.java:182)
at org.apache.wicket.request.target.component.listener.ListenerInterfaceRequestTarget.processEvents(ListenerInterfaceRequestTarget.java:73)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1250)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1329)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1436)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:486)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:319)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:680)

Dos2Unix Command

We often get issues while using the text files copied from windows/mac to unix server.
The text file from windows/mac has some special characters for tabs, carriage return or line breaks etc.You can run vi command and see that ^M  character in the file. if it exists then you need to run the dos2unix command. dos2unix command formats the text files to be usable on unix environment.

Example :  The following example formats the file myWindowsTextFile.txt copied from windows, to  myUnixTextFile.txt on unix server.
 
$dos2unix myUnixTextFile.txt < myWindowsTextFile.txt

For more details on this command please refer to its documentation:
http://linuxcommand.org/man_pages/dos2unix1.html

Apache Wicket Interview Questions

Here are some of the technical Interview questions for Apache Wicket Framework used with Java J2ee framework.

Basic Questions:

Q.1 Whats Apache Wicket?
Answer
Q.2 How does Wicket work? What are the wicket Id's?
Q.3 Does Wicket provides the features of MVC framework?
Q.4 What are the steps to create a page in wicket?
Q.5 What are wicket components?
Q.6 What are Wicket panels and how do you use them?
Q.7 How do you configure the home page?
Q.8 What is the WebApplication class?
Q.9 What is a bookmarkable page?
Q.10 Does html files contain the java statements in Apache wicket?
Q.11 How do you set the Error Page in Wicket.
Q.11 What are the deployment modes in Wicket and where they are configured.


Advance Questions.
Q.1 What is a RequestProcessor, RequestCycle, ResourceLocator in Apache Wicket?
Q.2 How can you implement ResourceLocator? What are the advantages of the same?
Q.3 How Wicket is better/different than Struts?
Q.4 How can you handle run time exceptions in wicket? Whats is the use of onRuntimeException Method in RequestCycle Class?
Q5. Explain the use of AjaxRequestTarget?
Q.6 Explain Models in Wicket and its advantages. Explain LoadableDetachable Models.
Q.7 How do you use Form Validators in Wicket? How do you create custom validators?

org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jstl/core cannot be resolved

While running a test jsp, getting following exception.

Jul 2, 2012 4:41:41 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application
    at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:51)
    at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
    at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:116)
    at org.apache.jasper.compiler.TagLibraryInfoImpl.generateTLDLocation(TagLibraryInfoImpl.java:316)
    at org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:149)
    at org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:386)
    at org.apache.jasper.compiler.Parser.parseDirective(Parser.java:450)


Following is the JSP

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c"  uri="http://java.sun.com/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<c:out value="Hello World"></c:out>
</body>
</html>

No tag "view" defined in tag library imported with prefix "f"

Exception while testing a demp jsp page.

SEVERE: Servlet.service() for servlet jsp threw exception
org.apache.jasper.JasperException: /index.jsp(10,0) No tag "view" defined in tag library imported with prefix "f"
    at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
    at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
    at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:198)
    at org.apache.jasper.compiler.Parser.parseCustomTag(Parser.java:1187)
    at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1422)
    at org.apache.jasper.compiler.Parser.parse(Parser.java:130)
    at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255)
    at org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
    at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:185)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:334)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:321)
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:592)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)

ANTLRException unexpected char: '@'

Getting Following Exception while testing a selct query in Hibernate.

DEBUG - opened session at timestamp: 13411683004
DEBUG - unable to locate HQL query plan in cache; generating (from TestContents where contentId =@pContentId and contentType =@pContentType)
DEBUG - parse() - HQL: from TestContents where contentId =@ pContentId and pContentType =@ pContentType
DEBUG - converted antlr.ANTLRException
line 1:36: unexpected char: '@'
at org.hibernate.hql.antlr.HqlBaseLexer.nextToken(HqlBaseLexer.java:278)
at antlr.TokenBuffer.fill(TokenBuffer.java:69)
at antlr.TokenBuffer.LA(TokenBuffer.java:80)
at antlr.LLkParser.LA(LLkParser.java:52)
at org.hibernate.hql.antlr.HqlBaseParser.primaryExpression(HqlBaseParser.java:874)
at org.hibernate.hql.antlr.HqlBaseParser.atom(HqlBaseParser.java:3438)
at org.hibernate.hql.antlr.HqlBaseParser.unaryExpression(HqlBaseParser.java:3216)
at org.hibernate.hql.antlr.HqlBaseParser.multiplyExpression(HqlBaseParser.java:3098)
at org.hibernate.hql.antlr.HqlBaseParser.additiveExpression(HqlBaseParser.java:2818)
at org.hibernate.hql.antlr.HqlBaseParser.concatenation(HqlBaseParser.java:570)
at org.hibernate.hql.antlr.HqlBaseParser.relationalExpression(HqlBaseParser.java:2586)
at org.hibernate.hql.antlr.HqlBaseParser.equalityExpression(HqlBaseParser.java:2449)
at org.hibernate.hql.antlr.HqlBaseParser.negatedExpression(HqlBaseParser.java:2413)
at org.hibernate.hql.antlr.HqlBaseParser.logicalAndExpression(HqlBaseParser.java:2331)
at org.hibernate.hql.antlr.HqlBaseParser.logicalOrExpression(HqlBaseParser.java:2296)
at org.hibernate.hql.antlr.HqlBaseParser.expression(HqlBaseParser.java:2082)
at org.hibernate.hql.antlr.HqlBaseParser.logicalExpression(HqlBaseParser.java:1858)
at org.hibernate.hql.antlr.HqlBaseParser.whereClause(HqlBaseParser.java:454)
at org.hibernate.hql.antlr.HqlBaseParser.queryRule(HqlBaseParser.java:708)

org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jsf/core cannot be resolved

Getting following exception while trying to run a Test Dynamic Project in Eclipse.

Jul 2, 2012 4:06:17 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jsf/core cannot be resolved in either web.xml or the jar files deployed with this application
    at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:51)
    at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
    at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:116)
    at org.apache.jasper.compiler.TagLibraryInfoImpl.generateTLDLocation(TagLibraryInfoImpl.java:316)
    at org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:149)
    at org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:386)
    at org.apache.jasper.compiler.Parser.parseDirective(Parser.java:450)
    at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1397)
    at org.apache.jasper.compiler.Parser.parse(Parser.java:130)
    at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255)
    at org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
    at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:185)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:334)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:321)
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:592)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)