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Sean Zhang

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Recent posts by Sean Zhang

Dear Hobson, Hannes, and Cole,

I am new to Natural Language Processing (NLP). Before I read your book, can you please answer a question? I have used the ANTLR tool develop a software; do you know what's the difference between ANTLR and NLP? Thank you for your time!

Best,

Sean
I today took the Oracle 1Z0-810 Exam (Upgrade Java SE 7 to Java SE 8 OCP Programmer) with a score of 96.

My boss wanted to release the code of a scientific software I developed. B/c of this, I self-studied the new features of Java 8, including but not limited to lambda expressions, functional programming and (parallel) streams, and have incorporated these new features into the software development. That's my motivation to take the Java 8 Exam.

It took me three months to thoroughly digest the following two books: i) OCP Java SE 8 Programmer II Exam Guide (Exam 1Z0-809), and ii) OCP: Oracle Certified Professional Java SE 8 Programmer II Study Guide: Exam 1Z0-809.
9 months ago
Dear Kathy, Bert, and Elisabeth,

I've postponed taking 1Z0-810, because I want to read your guide book. Now that you have published this book, I can now schedule my 1Z0-810 exam. Thank you.

BTW, I read your wonderful book of exam guide for 803 and 804.

Lin
Dear Bert,

Thank you for your quick reply. Your bible book "OCA/OCP Java SE 7 Programmer I & II Study Guide" helped me a lot to pass the exams of 803 and 804 in 2015. I would say you are a great educator and writer. You know what, I still keep a copy of this book in my office as reference book. (I am now an informatics programmer.)

Can you please tell me when you will publish your book "OCP Java SE 8 Programmer II Exam Guide (Exams 1Z0-809)"? I hope very soon!

Best,

Sean
Dear Kathy and Bert,

When I used your bible book "OCA/OCP Java SE 7 Programmer I & II Study Guide" to prepare for Exams 1Z0-803 & 1Z0-804 in 2015, I really hoped your book "OCA/OCP Java SE 7 Programmer I & II Practice Exams (Exams 1Z0-803 & 1Z0-804)" was already published by that time.

But until now this book of "OCA/OCP Java SE 7 Programmer I & II Practice Exams" has not yet been published. Can you please tell me whether you will continue this book project, especially for Java 8? Thank you for your time.

Sean

Welcome Kathy and Bert! Looking forward to your book of OCP Java SE 8.
Dear Kathy and Bert,

Welcome this new book. I look forward to your book of OCP Java SE 8.
I am using <s:radio> today:

Following Struts doc, I have the following code in my jsp:


NetBeans is not happy with my code and marks the whole list component in red. But it allows me to run the program. The three radio buttons are displayed, but the first button is not pre-selected, as we want. In other words, is not working.

Now following mkyong, I change my code as follows:


This time, everything is working perfected: the three radio buttons are displayed and the first button is pre-selected. But even that, NetBeans is not happy either in that it marks the whole list component in red. Do you know why?
2 years ago
I found the problem of my code. I misspelled one field in Event.java. After changing the name of this field, List<Event> isn't null any more, but my select dropdown list stills runs wrong. So my strategy of populating the select list is incorrect. I now have figured out how to do it. If you are interested in it, let me know.
2 years ago
I am working on a project using Struts2 and Hibernate. After employees successfully log on, they will be brought to a new page displaying an event list. This list will be a dropdown select list. I have successfully written and tested my code for logon part, but when I add the second jsp page with <s:select> tag, they show me the following exception:

message tag 'select', field 'list', name 'yourEvent': The requested list key 'events' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: tag 'select', field 'list', name 'yourEvent': The requested list key 'events' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:555)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:164)
org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)

The following is my MemberScreen.jsp with <s:select> tag inside:



The following is my action code:



The following is my code for the Event Entity



The following is my Hibernate data processing code;



The following code is my struts.xml:



The following is hibernate config:



For completeness, I also post my logon.jsp and its action codes here:











Can any Struts2 expert tell me what's wrong is my code so that I cannot populate data from database into my select dropdown list in MemberScreen.jsp? Thank you for your time and help.
2 years ago
Can anyone recommend good books on R programming? Thanks.
2 years ago
Has anyone used PostgreSQL? Can you please recommend good books on PostgreSQL database? Thanks.
Dear All,

I'm happy to tell you that I passed my 047 exam this afternoon w my score of 77. Although the score is not high, but given that I only spent 9 days on preparing this exam, this result is acceptable to me. I started to read Steve O'Hearn's book from last Tue, which took me one whole week. Then yesterday morning, I went to Oracle website to learn the other new things not covered in Steve O'Hearn's book, like pivot and unpivot clause, analytical functions, and pattern matching. I, yesterday afternoon, then did the mock exam contained in the CD of Steve O'Hearn's book. That's the whole process of my preparation for 047. I'd say the following loudly to future exam-takers:

i) Since the 2nd edition of Steve O'Hearn's book has not come up, you should browse SQL reference manual for the new exam topics not covered in the current edition. I'd say there were around 10 questions not covered in Steve O'Hearn's book.

ii) Don't be misguided! The mock exam in the CD of Steve O'Hearn's book has only 67 questions, but the actual exam has 75 questions. Actually I had 2 questions unanswered in my exam b/c of running out of time.

ii) Even you have prepare very carefully for this exam, don't be surprised to find very bizarre questions which should be appearing in the more advanced SQL performance tuning exam.

iii) Be ready to see quite a few questions asking you to "Choose all that apply", instead of those telling you to choose how many correct answers. I had at least 5 questions like this in my 047 exam. I didn't see such question formats in my Java programmer OCP exam, and because of it, I'd say 047 exam is harder than 804 (Java OCP) exam. And yes my 804 score (83) is higher than 047.

Good luck for future 047 exam-takers!

Best,

S.
I think I have written very clearly. But I will say it one more time.

By using ajax, a jsp page (named a.jsp) can display another jsp page (named b.jsp) inside it. Now when clicking a button inside b.jsp, if there is some error, I ask the servlet to let me stay in the current page, which is a.jsp including the b.jsp inside it. Do you know how to do it?
3 years ago