Jan 26, 2010

Show/Hide and Disable Click of Radio Buttons in JQuery

Here is a nice code snippet that can help you really while you work with radio buttons and jquery!

When you have a group of radio buttons, you might want to hide all of them when one is selected and submitted.

Here is the code that can hide the radio buttons for you: (assuming that the name of the radio button that you give to all of them is "answers")


Yet another interesting code snippet that might help you while you work with radio buttons is as given below:

There are times when you feel like disabling the click of the radio button based on certain conditions. Following code helps you in disabling the click on the radio button when the radios are actually hidden and the corresponding texts are visible. (name of the radio buttons is given as "radios")

<br />$('input[name="radios"]').each(function() {<br />$(this).click(function(){ <br />// test if radio is hidden<br />if ( $(this).is(':hidden') ) { <br /> return false;<br /> } else {<br /> return true;<br /> }<br />});<br />});<br />

How to Resolve java.lang.NoSuchMethodError: javax.persistence.Persistence.getPersistenceUtil()Ljavax/persistence/PersistenceUtil?

I had a chance to have a look the new features of Spring 3.0 today. The validation and formatting that is implemented as a part of JSR-303 implementation seems to be very exciting and interesting. Of course, it made me feel that we are moving towards codeless web based applications sooner or later!

I was very much curious to do a proof-of-concept application for this implementation. So I downloaded the Spring3.0 jars and made use of Hibernate Validator 4.0.2 GA version and validation-api-1.0.0 GA version.I had been using java 1.5

After removing all the old jars and even after implementing everything whatever was required, I was stuck with the following error

java.lang.NoSuchMethodError: javax.persistence.Persistence.getPersistenceUtil()Ljavax/persistence/PersistenceUtil

Please find the stack trace below:

<br />SEVERE: Servlet.service() for servlet springapp threw exception<br />java.lang.NoSuchMethodError: javax.persistence.Persistence.getPersistenceUtil()Ljavax/persistence/PersistenceUtil;<br /> at org.hibernate.validator.engine.resolver.JPATraversableResolver.isReachable(JPATraversableResolver.java:33)<br /> at org.hibernate.validator.engine.resolver.DefaultTraversableResolver.isReachable(DefaultTraversableResolver.java:95)<br /> at org.hibernate.validator.engine.resolver.SingleThreadCachedTraversableResolver.isReachable(SingleThreadCachedTraversableResolver.java:47)<br /> at org.hibernate.validator.engine.ValidatorImpl.isValidationRequired(ValidatorImpl.java:761)<br /> at org.hibernate.validator.engine.ValidatorImpl.validateConstraint(ValidatorImpl.java:331)<br /> at org.hibernate.validator.engine.ValidatorImpl.validateConstraintsForRedefinedDefaultGroup(ValidatorImpl.java:278)<br /> at org.hibernate.validator.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:260)<br /> at org.hibernate.validator.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:213)<br /> at org.hibernate.validator.engine.ValidatorImpl.validate(ValidatorImpl.java:119)<br /> at org.springframework.validation.beanvalidation.SpringValidatorAdapter.validate(SpringValidatorAdapter.java:74)<br /> at org.springframework.validation.DataBinder.validate(DataBinder.java:684)<br /> at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:746)<br /> at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:296)<br /> at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:163)<br /> at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:414)<br /> at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:402)<br /> at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)<br /> at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)<br /> at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)<br /> at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)<br /> at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)<br /> at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)<br /> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)<br /> at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)<br /> at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)<br /> at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)<br /> at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)<br /> at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)<br /> at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)<br /> at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)<br /> at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)<br /> at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)<br /> at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)<br /> at java.lang.Thread.run(Thread.java:595)<br />

It was almost 6-8 hours, I kept trying to do away with this problem since a colleague of mine seemed to get away with it in java 1.5. The following were the pointers that I understood as a result of my research googling the Internet!
  • The org.springframework.validation.beanvalidation.LocalValidatorFactoryBean while calling the SpringValidatorAdapter's validate(), invokes the Hibernate validator's ValidatorImpl.validate() method.
  • The hibernate validoator 4.0.2 GA version has a very strong dependency on JDK6 which contains the Persistence class with javax.persistence.Persistence.getPersistenceUtil()
So,I finally upgraded my machine to Java 6. It was just a miracle. Everything started working without problems and errors disappeared!!!

Jan 5, 2010

Resource Out of Sync With the File System in Eclipse: How To fix?

If you come across the error 'Resource out of sync with the file system' while working with eclipse, you can fix it within a minute. Get to know the root cause and you can fix it within minutes.

Root cause of 'Resource out of sync with the file system'

It is likely that you would have edited the file from outside eclipse environment and hence when you try to access the file from eclipse after this, you would get this problem.

Solution for 'Resource out of sync with the file system'

  1. Right click on the file from within eclipse.
  2. Click Refresh
  3. Now try to open the file in eclipse again.
  4. Error  is gone!
  5. You can got Windows. Point to Preferences. Click on General. Go to Workspace and check the box ' Refresh Automatically' as shown in the figure below. The problem 'Resource out of sync with the file system' would never pop in again!

(function($){ }) JQuery : What It Really Is?

Today I happen to use the code snippet

(function($){ })(jQuery);

But, for around an hour, I was wondering as to what the above function really does? what is the use of wrapping functions like


inside the above?

After a bit of research, I understood what it really does and that is awesome. This post further gives you a heads up on what

(function($){ })(jQuery);

is in detail.

The $ in

(function($){ })(jQuery);

can be considered to be prototype reference outside the function call. This $ becomes a jquery reference inside the function. as a result, even if this $ variable or function is being used by any other javascript library, this reference overwrites all and proves to be a nice jquery reference well within the function.

Generally you can expect to see all JQuery plug-ins to be written inside this function where $ is being passed as a parameter. Before we take a look at jQuery plug-ins, consider the code snippet below:

var userDefinedFunction = function ($) { 
  //your code here
userDefinedFunction (jQuery);

is equivalent to

(function ($) { 
    //your code here

Having discussed this, let me give you ahead up on writing customized plug-ins. Just follow the steps below and your customized JQuery plug-in is ready!

  1. Let us consider that we write a plugin by name sample.
  2. You have to have a file jquery.sample.js
  3. Within the file we can have methods for the plug-in. For this, you need to extend the JQuery object as follows:
  4. (function($){  
    $.fn.sample = function() {});
  5. You can now access this function using the below code in your html file:
  6. <script language="javascript" type="text/javascript">
                $('#<form name>').sample();
  7. Default settings for this plug-in is created by using the code

    $.fn.sample = function(options) 
    {var defaults = {inputVal: 1, trueVal : 'true', falseVal : 'false',submitButton : '#submit'}
    var pluginOptions = $.extend(defaults, options);

  8. If ever you intend to call this function with new values which are different from the default values, use the following snippet and get it done!
  9. <script language="javascript" type="text/javascript">
                $('#<form name>').sample({inputVal:2, trueVal:'yes',falseVal:'no', submitButton:'#ClickMe');
  10. As such, this was a nice learning and a great heads up on JQuery plug-ins!But, there are much more interesting tips to come! Stay tuned!