Wednesday, December 24, 2008

Monday, November 03, 2008

Throwing this java.lang.Error can get you fired

Imagine your boss going through your server log file and he see's the Error being thrown as CoderMalfunctionError. The discussion might not start in a pleasant way but you both might end up laughing since it really has nothing to do with Coder Malfunctioning.

java.nio.charset.CoderMalfunctionError is thrown when either encoder or decoder is malfunctioning. Sun decided to call combination of encoder and decoder as Coder and hence the confusion.

Irrespective of this Error always remember that if a project fails its the Architect or Coder's fault :-).

Friday, October 17, 2008

Debugging JWS with Eclipse

After nearly 10 years, I spent considerable amount of time working on java desktop application recently. Looking at Java Web Start forums and FAQ it appears still users have issues with setting up Eclipse Remote Debugging with Java Web Start. This can be easily achieved by following three simple steps:

1. Debug Java Web Start applications locally before deploying them on your web server. i.e use javaws <<fileName>> and not javaws <<url>> and set your codebase in jnlp file to local libraries (like codebase="file:///c:/jwstest").

2. set JAVAWS_VM_ARGS environment variable to right value.
Example set JAVAWS_VM_ARGS=-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8199

Make sure you don't use "-classic".

3. Start Eclipse remote debugging targeting localhost and port set in JAVAWS_VM_ARGS (8199 in this example).

One thing that comes handy is collecting your logs from application in a log file while using Java Web Start.Tracing features for Java Web Start comes handy in this case.

Tuesday, September 23, 2008

Android Price

I saw the live webcast and tried to preorder Andriod which was supposed to be 179$ with 2 year contract. But here is what I see when I go to TMobile web site and try to buy G1:

Friday, September 19, 2008

Best PC vs Mac Parody

With all the hype around Microsoft and Apple Ads, I think this the best parody:

Monday, September 15, 2008

JPA: java.lang.IllegalArgumentException: Removing a detached

One of the common issues that I end up debugging is the following exception:

java.lang.IllegalArgumentException: Removing a detached instance

When does this occur?: While removing a record.
Why does this occur?: You are trying to delete a record which is retrieved in another transaction (probably even trying to delete a record that is stored in user HTTP session).
How to fix it?: Make sure you retrieve the record in the same transaction. Sample code for the same:

public void removeOrganization(Organization org) {
if (org.getId() != null) {
org=em.find(Organization.class, org.getId());
} else {
// your error logic.

Sunday, August 31, 2008

Low cost Multi-Touch project

Since there is too much hype of Multi-Touch products from different companies, its worth checking out Johnny Lee's cheaper version of Multi-Touch screen. I bought a LED flashlight for 18$ and ever since having fun with my WII.

Here is a introduction video from Johnny Lee:

Johnny Lee’s page has more info and is worth checking out.

Also Wiimote Whiteboard has a good Java API that worked fairly well for me (Tried only on my Mac):

Thursday, August 28, 2008

Yahoo: Nicely Done

Google and Yahoo both offer Ability to add RSS feeds to users personalized home page. While checking my personal server's access log, I noticed a nice little information that Yahoo sends with each request. It sends you data on how many users added your feed and how many times a feed has been loaded on users homepages. Here is a snippet from from yahoo and google requests from Apache access logs: - - [28/Aug/2008:13:19:43 -0700] "GET /personalfeed.rss HTTP/1.0" 304 - "-" "YahooFeedSeeker/2.0 (compatible; Mozilla 4.0; MSIE 5.5;; users 1; views 247)" - - [28/Aug/2008:13:27:11 -0700] "GET /personalfeed.rss HTTP/1.1" 200 2173 "-" "Feedfetcher-Google; (+"

Nicely done Yahoo.

Tuesday, August 26, 2008

Making Div Clickable

Here is a simple trick to make entire div clickable which is needed when you want to make a banner clickable for a site:

<div id="banner" style="cursor: pointer;" onclick="location.href='';">

The best part is inside the Div you can have other links redirecting user to a different page.

Monday, August 25, 2008

Google: Are you kidding me?

That's the related search that World No 1 Search engine could come up for Java?

Yahoo seems to be better in this case:

I guess there is still need for multiple search engines.

Wednesday, June 11, 2008

Firefox Mobile Concept Video

Forefox Mobile concept video by Aza Raskin:

Firefox Mobile Concept Video from Aza Raskin on Vimeo.

Wednesday, May 28, 2008

A Clever Hack

Once in a while you see things and think "Seems so simple, Why didn't I think of that?". This Hack by Aza Raskin belongs to that Category. He created a simple and smart way to read user browser history. In the example here, Aza is maintaining an array all the social networking sites he is aware of and checking which of those site the user has visited. How can he do that? By checking the color of link referring the Site. In his own words:

By using a cute information leak introduced by CSS. The browser colors visited links differently than non-visited links. All you have to do is load up a whole bunch of URLs for the most popular social bookmarking sites in an iframe and see which of those links are purple and which are blue. It’s not perfect (which, from a privacy perspective, is at least a little comforting) but it does get you 80% of the way there. The best/worst part is that this information leak probably won’t be plugged because it’s a fundamental feature of the browser.

Tuesday, May 13, 2008

Sunday, March 02, 2008

iPhone like Android Demo

Darren Waters of BBC interviewed Andy Rubin Google's director of mobile platforms who provided a demo of Android Phone. The phone is based on touch screen and shows features similar to Apple iPhone running on 300MHz (Compared to iPhone which is a 600MHz phone) and also running on 3G Network (3G iPhone is still in the works). Looks like iPhone killer phones may be based on Android.

I have been playing with Android API for a while now and I have to say though there are improvements to be made, Android API is superior Java API compared to any phone in market today based on JavaME.

Saturday, March 01, 2008

Go Daddy: Configure Apache HTTPd as a reverse proxy for Tomcat

Configuring Apache HTTPd as reverse proxy is one way to re-route requests to Tomcat from Apache. This post addresses how to do that for Dedicated Virtual Hosting at Doing this requires simple configuration changes as described below:

1. Find httpd.conf file (usually located at /etc/httpd/conf).
2. Make sure the following lines are not commented in the file (by default they are not commented).
LoadModule proxy_module modules/
LoadModule proxy_http_module modules/
3. Add the following lines to enable the proxy to http.conf assuming you want to enable the servlet-examples webapps that comes with Tomcat installation (better to add at the end of the file):
ProxyPass /servlets-examples http://localhost:9080/servlets-examples
ProxyPassreverse / http://localhost:9080/
4. Restart Apache (using /usr/sbin/apachectl).

Now type in your browser and you will be able to execute the Servlet samples.

Thursday, January 17, 2008

Java is everywhere

Not sure how this is missed but SUN seem to have started posting to YouTube on how Java is Everywhere. Good PR to the minimum:

Sunday, January 06, 2008

RIP Netscape Navigator

AOL has announced that its discontinuing support for Netscape Web Browser. Though it was just matter of when, somehow I still have nostalgic feelings and fond memories of Netscape. Without Netscape, Internet would not have been what it is today. Some of the contributions from Netscape are good and some are bad but when Internet history is being written Netscape would have a chapter of its own. Remember Netscape used to have "About the Internet" menu item instead of About Netscape?

Its sad that winners are out of business and losers are making Billions. When Microsoft started giving away IE free and embedded in windows it has 2 goals:
1. Destroy Netscape
2. Avoid paying to Spyglass (Spyglass's contract with Microsoft required Microsoft pay to Spyglass for using its code in IE only if Microsoft makes money on IE).
Microsoft accomplished both the goals and got sued by both Netscape and Spyglass. Both Netscape and Spyglass won in the court but are out of business today while Microsoft still makes Billions. The world is a strange place :-)

Saturday, January 05, 2008

Amazon Kindle has JVM

Amazon Kindle seems to be heavy on Java. All the applications running seems to be developed in Java. From the look of the files existing on Kindle, it appears Kindle is using CDC and CVM. If Amazon opens up Kindle, it would become a great programming device for Java Developers soon and most widely available CDC device. According to Tritschler opening up kindle API's is a future direction.

Looking at contents of Kindle has the following files indicating its CDC based implementation:

All the applications (Some of which are not made public exist as java applications based on existence of following jar files: