Its description says it’s an iterator but it certainly is NOT a true iterator.

For example:

Let me know what you expect the code below to return.

var myVars = ['foo1', 'foo2', 'foo3'];

function containsValue(myValue, myCollection) {
	jQuery.each(myCollection, function(i, val) {
		if(val == myValue) {
			return true;
		}
	});
	return false;
}

$(document).ready(function() {
	console.log(containsValue('foo2', myVars));
});

Before I know better, I’d expect it to return true. Since myCollection DOES CONTAIN the value ‘foo2′. However the function containsValue WILL ALWAYS RETURN FALSE. That’s because when you return out of jQuery.each, it simply exits out of jQuery.each but not the containing function. In fact, whether you do anything in the callback function at all, jQuery.each ALWAYS RETURNS the collection you pass in.

e.g.

var returnedVar = jQuery.each(myVars, function(i, val) {});
console.log(returnedVar === myVars); // evaluates to true

In my opinion, jQuery.each acts more like a closure than an iterator. Sure you may use it as an iterator as long as you not returning anything. If you are just changing behaviors or collecting information, it will mimic an iterator. But you need to know, it really is not an iterator.

Personally I’m going to start to use Javascript’s native for..in statement instead of jQuery.each for Javascript collection variables. There is also an argument that jQuery.each may never perform faster than the native support for an iterator. Therefore below I will rewrite the function above using for..in.

function containsValueWithFor(myValue, myCollection) {
	for (index in myCollection) {
		if(myCollection[index] == myValue) {
			return true;
		}
	}
	return false;
}

console.log(containsValueWithFor('foo2', myVars)); // true

var myMap = {'lala':'foo1', '2':'foo2', 'b':'foo3'};

console.log(containsValueWithFor('foo2', myMap)); // true as well for an object/map

—>Example code<—

Benefits to you and the company from attending this event:
Keep up to date regarding the current technologies and development in the Java community.

Information that your co-workers / the company should be aware of:
Functional programming is making a big splash on the JVM. We really should come out of the traditional OO & imperative programming mindset and start think of solving programming challenges in a multi-paradigm fashion. We should upgrade from CVS to Git

Information that you learned that may have negative impacts to the company:
None

Would recommend this event / company presenting to someone else? Why?
Yes. The presenters have great knowledge about their topics. They always make me think harder and different about what I am doing at work.

Additional Comments or Suggestions:
I greatly enjoyed learning more about Scala, akka and functional programming thinking. The multi-paradigm session by Ted Neward opened my eyes. I took logic & functional programming courses in college and was super impressed by how concise and powerful those languages can be used to solve particular issues. Now many frameworks on the JVM prove that as Java programmers (who are innately OO & imperative), we may fully utilize the power of programming languages of other paradigms. This motivates me to explore a newer realm of programming.

I learned a lot from the Seven wastes of software development session e.g. communication is 38% tone, 7% words & 55% body languages. Therefore we should avoid plain emails for especially business rules discussion; converse with a coworker face to face is a much more effective way of communication. I think I don’t always do well in this area. Perhaps programmers are generally shy and introverted. I need to learn to open up more.

I also loved the Spock session although I feel Spock as a framework is yet completely mature for prime time. The fact it doesn’t have a version 1.x release somewhat speaks for this. (And it’s not yet in maven central repository.) I love its various features. But it’s still under heavy development phase as its community is actively adding more features to the framework. If we start using it now, we may need to upgrade our code dramatically later to get its full effects e.g. the @Unroll feature is going to change soon. However, I’m super excited to revisit it in a few months or so to see where it’s at. The fact that it’s a test framework great for both state testing & interaction testing (mocking) is awesome! It sounds like the mocking part of it is yet as mature as other mocking frameworks e.g. Mockito. For example, it doesn’t support partial mock/spy. This does not make me want to switch from Mockito to use it.

I will also use many of the new features of Groovy I learned since I just started using Groovy for testing. The SQL class Groovy has is extremely powerful and gave me many ideas as how I can utilize it to make testing more dynamic and more maintenance free.

It’s sad but better late than never.

The truth is, in my opinion, the fact that javascript test frameworks do not yet maturely work with many of the continuous integration software deters programmers from using them. What’s the point of unit testing if they don’t automatically get run? Based on my research, JSUnit is the only one that integrates with ANT innately. But JSUnit is more of an abandomware now so people are looking for alternatives.

QUnit + CI topics

• jQuery tests under CI
• Syn instead of Selenium?
• QUnit and automated browser tools

>> Run my test suite <<

QUnit simple example:

HTML:

<!DOCTYPE html>
<html>
<head>
	<title>Test Suite</title>
	<script src="http://code.jquery.com/jquery-latest.js"></script>
	<link rel="stylesheet" href="http://code.jquery.com/qunit/git/qunit.css" type="text/css" media="screen" />
	<script type="text/javascript" src="http://code.jquery.com/qunit/git/qunit.js"></script>
	<!-- Your source files go here -->
	<script type="text/javascript" src="functions.js"></script>

	<!-- Your tests files go here -->
	<script type="text/javascript" src="isEvenTest.js"></script>
	<script type="text/javascript" src="startsWithTest.js"></script>

</head>
<body>
	<h1 id="qunit-header">QUnit example</h1>
	<h2 id="qunit-banner"></h2>
	<div id="qunit-testrunner-toolbar"></div>
	<h2 id="qunit-userAgent"></h2>
	<ol id="qunit-tests"></ol>

	<!-- Any HTML you may require for your tests to work properly -->
	<div id="qunit-fixture">test markup, will be hidden</div>
</body>
</html>

Source javascript file:

function isEven(val) {
	return val % 2 === 0;
}

function startsWith(data, startsWithStr) {
	data = jQuery.trim(data);
	startsWithStr = jQuery.trim(startsWithStr);
	if(data) {
		return data.toUpperCase().lastIndexOf(startsWithStr.toUpperCase(), 0) === 0;
	} else if(data === startsWithStr) {
		return true;
	} else {
		return false;
	}
}

Sample test file:

$(document).ready(function(){

	module("startsWithTest");

	test('startsWith', function() { 
		ok(startsWith("ll-925", "ll-"), 'Starts with ll-'); 
		ok(!startsWith("ll-925", "xl-"), 'Does not start with xl-'); 
		ok(!startsWith("", "xx-"), 'Does not start with xx-'); 
		ok(startsWith(" xx-sdgj ", "xx-"), 'Trimming test: starts with xx-'); 
		ok(startsWith(" xx-sdgj", " xx- "), 'Trimming test 2: starts with xx-'); 
		ok(startsWith("", " "), 'Empty string starts with empty string'); 
		ok(startsWith("Mn-u59", "mN-"), 'Non case sensitive test'); 
//		raises(startsWith(foo, " "), 'Undefined test 1');  // undefined is obviously not considered a normal exception
	}) 

});

>> git repo for the source <<

Additional resources:

• QUnit tutorials
• API documentation

Background:

I needed a year variable for some work on a jsp page. It’s not always defined. I know for our routable datasource, a default year is required in order for it to work. I wanted to use the same default year but I only want the variable to be defined once and used in both places.

So I looked into SPEL.

It seems like the correct solution for the problem.

My original idea:

As it turns out, SPEL does not yet support embedded variables. SPEL, you must improve yourself!

My workaround:

I do not love it but it accomplishes my goal of not defining it more than one place.

Define the variable in a properties file e.g. application.properties
defaultYear=2011

Then use placeholder instead of SPEL notation to include it in spring.

Syntax grrr syntax:

Sadly some of my time was to learn the fact you CANNOT put a space between # and { in SPEL. For example, # {bean.property} will NOT work, but #{bean.property} will. It seems obvious afterwards but the error message you get just DOES NOT help you come to that conclusion.

Moral of the story:

SPEL is very handy but it’s yet perfect. Do keep that in mind as an alternative solution when dealing with Spring. If you use annotation, you can do @Value(“#{bean.property}”). Refer documentation for more info.

However, the twist I need is to have the main batch application thread die as soon as either queue monitoring thread dies.

I’ve been searching for a graceful way to handle such a concurrency need in Java. Thank you to Gary Myers, I’ve got a great start on it.

The basic idea is to pass a java blocking queue to both of the threads and if either thread fails, do blockingQueue.offer to indicate so. Then in the main thread, it will check for the blocking queue’s result. blockingQueue.take() blocks/waits for it to return and then continues the execution of the main thread.

Things I learned that made today AMAZING!

• Put repositories in the pom.xml instead of settings.xml for maven to look through multiple repositories
• Use SynchronousQueue to ensure only 1 element at a time may exist in the queue
• Use daemon to make sure the JVM will die even if there is a thread running
• You can EMBED ActiveMQ using spring so you don’t have install it at all

Below is a simple concurrency example that demonstrates the idea from Gary Myers.

Worker:

public class Worker implements Runnable {
   private BlockingQueue<String> finishedQueue;
   private String result;
   private long sleepTime;
   
   public Worker(BlockingQueue<String> finishedQueue, String result, long sleepTime) {
      this.finishedQueue=finishedQueue;
      this.result=result;
      this.sleepTime=sleepTime;
   }
   
   public void run() {
      try {
         TimeUnit.SECONDS.sleep(sleepTime);
         finishedQueue.offer(result); //you have to use offer to get this queue to work.  It will throw an exception if there is something in the queue.
      } catch(InterruptedException e) {
         e.printStackTrace();
      }
   }
}

DaemonThreadFactory:

public class DaemonThreadFactory implements ThreadFactory {
   private AtomicInteger counter;
   
   public DaemonThreadFactory() {
      this.counter=new AtomicInteger(0);
   }
   
   public Thread newThread(Runnable r) {
      Thread thread=new Thread(r);
      
      //if you wanted you can make this class generic by having the constructor take arguments that can be used to configure the following
      thread.setDaemon(true); //need it to be daemon so the JVM will die even if there is a thread running
      thread.setName("Daemon Thread: " + counter.incrementAndGet()); //you don't have to give it a name, but I always do.
      
      return thread;
   }
}

Test the threads in a simple example:

public class Main {
   public static void main(String[] args) throws InterruptedException {
      ExecutorService service=Executors.newFixedThreadPool(2, new DaemonThreadFactory());
      SynchronousQueue<String> queue=new SynchronousQueue<String>(); //this queue can hold 1 element at a time, so basically the first thread to finish will be the one to successfully put the element in the queue
      //create the runnables before hand so that extra time isn't spent instantiating the runnables at submission time.
      Runnable runnable1=new Worker(queue, "Runnable 1", 4);
      Runnable runnable2=new Worker(queue, "Runnable 2", 3);
      
      service.execute(runnable1);
      service.execute(runnable2);
      
      System.out.println("before queue");
      System.out.println(queue.take());
      System.out.println("after queue");
      
      service.shutdown(); 
   }
}

I will not go into the details of the code I added for queue monitoring as they are a lot more involved.

The coolest thing I learned about ActiveMQ is how you can embed it using the following spring configuration:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:jms="http://www.springframework.org/schema/jms"
       xmlns:amq="http://activemq.apache.org/schema/core"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       				http://www.springframework.org/schema/jms http://www.springframework.org/schema/context/spring-jms-3.0.xsd
					http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
 
    <!--  Embedded ActiveMQ Broker -->
    <amq:broker id="broker" useJmx="false" persistent="true">
        <amq:transportConnectors>
            <amq:transportConnector uri="tcp://localhost:0" />
        </amq:transportConnectors>
    </amq:broker>

    <!--  ActiveMQ Destination  -->
    <amq:queue id="destination" physicalName="com.threads.example.queue" />

    <!-- JMS ConnectionFactory to use, configuring the embedded broker using XML -->
    <amq:connectionFactory id="jmsFactory" brokerURL="vm://localhost" />

    <!-- JMS Producer Configuration -->
    <bean id="jmsProducerConnectionFactory" 
          class="org.springframework.jms.connection.SingleConnectionFactory"
          depends-on="broker"
          p:targetConnectionFactory-ref="jmsFactory" />

    <bean id="jmsTemplate" class="org.springframework.jms.core.JmsTemplate"
          p:connectionFactory-ref="jmsProducerConnectionFactory"
          p:defaultDestination-ref="destination" />
</beans>

If running in Eclipse…

• Install m2eclipse plugin if you have not
• Import -> Maven -> Existing Maven Projects
• Select the MultipleQueueMonitors folder
• Add src, resources, properties as source folders
• Change the jre to whatever you want to use

The following error may occur in Eclipse

Caused by: org.xml.sax.SAXParseException: cvc-complex-type.2.4.c:
The matching wildcard is strict, but no declaration can be found for element 'amq:broker'. 

To fix it, you must associate the ActiveMQ XSD URL with the schema.

Go to XML->XML Catalog in Preferences, and add a User Specified Entry.

Location: http://activemq.apache.org/schema/core/activemq-core-5.3.0.xsd
Key Type: Namespace Name
Key: http://activemq.apache.org/schema/core

Then add a second one:

Location: http://activemq.apache.org/schema/core/activemq-core-5.3.0.xsd
Key Type: Schema Location
Key: http://activemq.apache.org/schema/core/activemq-core.xsd

Hit OK.

For more info, visit this stackoverflow thread.

>>>Check out or download the source from my github account if you are interested<<<

I searched around for solutions.

The one that SORTA worked for me is below from here.

• cd .metadata/.plugins
• mv org.eclipse.core.resources org.eclipse.core.resources.bak
• Start eclipse. (It should show an error message or an empty workspace because no project is found.)
• Close all open editors tabs.
• Exit eclipse.
• rm -rf org.eclipse.core.resources (Delete the newly created directory.)
• mv org.eclipse.core.resources.bak/ org.eclipse.core.resources (Restore the original directory.)
• Start eclipse and start working.

However, just doing that did not exactly solve my problem. I ended up going to the .metainfo/.plugins/org.eclipse.core.resources/.project directory and started deleting random project and trial on error. I finally found the project that was the culprit and fixed my issue.

Another suggestion by a coworker that has worked before if Eclipse freezes at startup is:

• cd workspace\.metadata\.plugins\org.eclipse.ui.workbench
• Make backup of workbench.xml
• Edit workbench.xmlfile and remove all <editor> tags.

After I installed the m2eclipse plugin on Eclipse 3.6, I keep getting the following warning on the console:

The Maven Integration requires that Eclipse be running in a JDK, beacuase a number of Maven core plugins are using jars from the JDK.

Please make sure the -vm options in eclipse.ini is pointing to a JDK and verify that Installed JREs are also using JDK installs.

The solution that worked for me is changing the shortcut properties for eclipse e.g.

C:\JAVA\eclipse\eclipse.exe -vm "C:\Program Files\Java\jdk1.6.0_25\bin\javaw.exe"

I couldn’t get the eclipse.ini updates to work for some stupid reason.

import static org.junit.Assert.*;

I’ve figured it out for a while but I’ve been noticing it conflicting with my save action -> organize imports setting.

I finally got fed up and decided to investigate a bit further today.

Below are screenshots of Eclipse version 3.6.

• Preferences -> Java -> Editor -> Content Assit -> Favorites all of the paths you wish to import statically e.g. org.junit.Assert.*
  
• Then if you have Preferences -> Java -> Editor -> Save Actions -> Organize imports selected
  

  Make sure you update Preferences -> Java -> Code Style -> Orangize Imports to have Number of static imports needed for .* (e.g. ‘java.lang.Math.*) to 1.
  

  This way when you save your java files in Eclipse, it will not change your org.junit.Assert.* import to org.junit.Assert.assertTrue import. Otherwise it will require you to import again if you wish to use another method like assertFalse which in my opinion is annoying.