Something About J

Shutdown Hook and Eclipse

2009-08-20T18:17:00.000+08:00

If you would like to get shutdown hook to execute on a process launched from Eclipse, by clicking the red stop button, it won't be called. Here is the reported Eclipse bug, which is opened since 2003-05-23, and the Resolution is WONTFIX. :)

How to Add/Deploy WAR file into Eclipse Tomcat Server

2009-07-28T17:35:00.005+08:00

In some scenario, you wish to deploy a default web application into Eclipse Tomcat which is not part of your project, you may just add the war file into the below directory:

%your_workspace%\.metadata\.plugins\org.eclipse.wst.server.core\tmpX\webapps

where tmpX could be tmp0, tmp1 etc

Why My Java Program Shows Wrong Timestamp?

2009-03-11T15:29:00.002+08:00

It may due to you set up time zone wrongly if you are in Solaris or Unix machine. For the below example, if you use GMT[+/-] format instead of City or a valid timzone name, you will got wrong timestamp. Refer to my previous post about how to set TZ correctly.

fwsst36 scadm$ echo $TZ;date;date -u;java DateUtils
CST6CDT
Tue Mar 10 03:53:35 CDT 2009
Tue Mar 10 08:53:35 GMT 2009
Tue Mar 10 03:53:35 CDT 2009

fwsst36 scadm$ echo $TZ;date;date -u;java DateUtils
Asia/Jakarta
Tue Mar 10 15:54:05 WIT 2009
Tue Mar 10 08:54:05 GMT 2009
Tue Mar 10 15:54:05 WIT 2009

fwsst36 scadm$ echo $TZ;date;date -u;java DateUtils
GMT-7
Tue Mar 10 15:54:26 GMT 2009
Tue Mar 10 08:54:26 GMT 2009
Tue Mar 10 01:54:26 GMT-07:00 2009
(This is wrong)

How To Set Time Zone (TZ) Correctly in a Unix/Solaris System?

2009-03-11T15:14:00.004+08:00

First, check your environ manual:

> man -s5 environ
...
TZ

Timezone information. The contents of this environment
variable are used by the functions ctime(3C),
localtime(3C), strftime(3C), and mktime(3C) to override
the default timezone. The value of TZ has one of the two
formats (spaces inserted for clarity):

:characters

or

std offset dst offset, rule

If TZ is of the first format (that is, if the first
character is a colon (:)), or if TZ is not of the second
format, then TZ designates a path to a timezone database
file relative to /usr/share/lib/zoneinfo/, ignoring a
leading colon if one exists.
...

Second, check is your city is under /usr/share/lib/zoneinfo.

csdbld03: zoneinfo> find . -name Kuala_Lumpur
./Asia/Kuala_Lumpur

Third, update TZ at your /etc/TIMEZONE. Example TZ=Asia/Kuala_Lumpur.

Avoid to use GMT[+/-] format as it is obsolete.

> cat /usr/share/lib/zoneinfo/src/README
...
The following files have been removed from the release:

/usr/share/lib/zoneinfo/GMT-12
/usr/share/lib/zoneinfo/GMT-11
/usr/share/lib/zoneinfo/GMT-10
/usr/share/lib/zoneinfo/GMT-9
/usr/share/lib/zoneinfo/GMT-8
/usr/share/lib/zoneinfo/GMT-7
/usr/share/lib/zoneinfo/GMT-6
/usr/share/lib/zoneinfo/GMT-5
/usr/share/lib/zoneinfo/GMT-4
/usr/share/lib/zoneinfo/GMT-3
/usr/share/lib/zoneinfo/GMT-2
/usr/share/lib/zoneinfo/GMT-1
/usr/share/lib/zoneinfo/GMT+1
/usr/share/lib/zoneinfo/GMT+2
/usr/share/lib/zoneinfo/GMT+3
/usr/share/lib/zoneinfo/GMT+4
/usr/share/lib/zoneinfo/GMT+5
/usr/share/lib/zoneinfo/GMT+6
/usr/share/lib/zoneinfo/GMT+7
/usr/share/lib/zoneinfo/GMT+8
/usr/share/lib/zoneinfo/GMT+9
/usr/share/lib/zoneinfo/GMT+10
/usr/share/lib/zoneinfo/GMT+11
/usr/share/lib/zoneinfo/GMT+12
/usr/share/lib/zoneinfo/GMT+13
...

How to solve error "Informix -567: Cannot write sorted rows"?

2009-02-23T16:45:00.002+08:00

Try to get the related ISAM error (Follow this for JDBC). If it is "2: No such file or directory", look for your DBSPACETEMP or PSORT_DBTEMP value (via onstat -g env or onstat -c). Ensure the folder points by DBSPACETEMP or PSORT_DBTEMP exists.

How To Check Is Your Informix Server Shutdown Gracefully?

2008-11-03T15:53:00.003+08:00

Compare the first set of Informix log:

20:28:34 Checkpoint Completed: duration was 1 seconds.
20:28:34 Checkpoint loguniq 1, logpos 0xd40018, timestamp: 0xf638
20:28:34 Maximum server connections 1
20:28:35 IBM Informix Dynamic Server Stopped.
20:28:36 IBM Informix Dynamic Server Started.

Sat Oct 11 20:28:36 2008

20:28:36 Event alarms enabled. ALARMPROG = '/usr/informix/etc/log_full.sh'
20:28:36 Booting Language from module <>
20:28:36 Loading Module
20:28:36 Booting Language from module <>
20:28:36 Loading Module
20:28:41 DR: DRAUTO is 0 (Off)
20:28:41 IBM Informix Dynamic Server Version 10.00.UC7 Software Serial Number AAA#B000000
20:28:43 IBM Informix Dynamic Server Initialized -- Shared Memory Initialized.

20:28:43 Physical Recovery Started at Page (1:2283).
20:28:43 Physical Recovery Complete: 0 Pages Examined, 0 Pages Restored.
20:28:43 Logical Recovery Started.
20:28:43 10 recovery worker threads will be started.
20:28:46 Logical Recovery has reached the transaction cleanup phase.
20:28:46 Logical Recovery Complete.
0 Committed, 0 Rolled Back, 0 Open, 0 Bad Locks

20:28:46 Dataskip is now OFF for all dbspaces
20:28:47 Checkpoint Completed: duration was 0 seconds.
20:28:47 Checkpoint loguniq 1, logpos 0xd41018, timestamp: 0xf648

20:28:47 Maximum server connections 0
20:28:47 On-Line Mode

and second set of log:

19:11:22 Maximum server connections 39
19:16:22 Fuzzy Checkpoint Completed: duration was 0 seconds, 4 buffers not flushed.
19:16:22 Checkpoint loguniq 5, logpos 0x2c63080, timestamp: 0x4958f6

19:16:22 Maximum server connections 39
No stopped message listed. The engine did not shutdown cleanly.
19:23:37 IBM Informix Dynamic Server Started.

Tue Oct 21 19:23:39 2008

19:23:39 Event alarms enabled. ALARMPROG = '/usr/informix/etc/log_full.sh'
19:23:40 Booting Language from module <>
19:23:40 Loading Module
19:23:40 Booting Language from module <>
19:23:40 Loading Module
19:23:56 DR: DRAUTO is 0 (Off)
19:23:56 IBM Informix Dynamic Server Version 10.00.UC7 Software Serial Number AAA#B000000
19:23:59 IBM Informix Dynamic Server Initialized -- Shared Memory Initialized.

19:23:59 Physical Recovery Started at Page (1:4321).
19:23:59 Physical Recovery Complete: 0 Pages Examined, 0 Pages Restored.
19:23:59 Logical Recovery Started.
19:23:59 10 recovery worker threads will be started.
19:24:02 Logical Recovery has reached the transaction cleanup phase.
19:24:02 Logical Recovery Complete.
21 Committed, 0 Rolled Back, 0 Open, 0 Bad Locks

19:24:04 Dataskip is now OFF for all dbspaces
19:24:04 (11) connection rejected - no calls allowed for sqlexec
19:24:04 listener-thread: err = -27002: oserr = 0: errstr = : No connections are allowed in quiescent mode.

19:24:04 (13) connection rejected - no calls allowed for sqlexec
19:24:04 listener-thread: err = -27002: oserr = 0: errstr = : No connections are allowed in quiescent mode.

19:24:05 Checkpoint Completed: duration was 1 seconds.
19:24:05 Checkpoint loguniq 5, logpos 0x2c69018, timestamp: 0x4959d3

19:24:05 Maximum server connections 0
19:24:05 On-Line Mode

The first one came right to online mode in 11 seconds. If you look at the log you will see the engine was stopped right before restarting it. When the engine is stopped, all transactions are cleaned up. They are either rolled back or committed and the physical log is also cleared out. If you look at the second startup, there was no clean shutdown, This was due to someone killing the oninit process or perhaps the OS getting rebooted. Regardless the engine was still performing work. When the engine was restarted, it discovered that there were open transactions that needed to be dealt with . This explains the additional time it took to come online. The 27002 errors were due to users trying to connect before the engine was ready for them. The engine is working as designed.

How to enable Informix ISAM/RSAM error in JDBC?

2008-07-29T11:52:00.004+08:00

You will not able to get Informix RSAM / ISAM error with normal SQLException. ISAM error is important to find the real database problem. For example, if an SQLCODE message says that a table cannot be created, the RSAM message states the reason, which might be insufficient disk space. You need to get the nested/chained exception via SQLException.getNextException(). Code example is at Java Developers Almanac.

When you should give up on Facebook?

2008-02-15T09:53:00.003+08:00

You should give up on Facebook when you getting some 8,000 requests per day like Bill Gates. Bill Gates has stopped using it because he was inundated with friend requests, so stop to add him as friend. Yesterday I was still able to check his friends as View Friends link was there (It is good to know who he has added). He has friends about 120 something count. However, he just disable it recently. Maybe is good I should cache it yesterday. :)

How to refer/get info for a Klocwork code problems, security vulnerabilities category easily?

2007-11-07T19:10:00.000+08:00

If you run Klocwork in Eclipse, you can click the Help button (Question button) in InForce Error Details view/window (right upper corner by default). By doing this, you do not need to refer to separate Klocwork manual pdf file.

Famous Java Concurrent Library Memory Leak Bug

2007-09-18T14:10:00.000+08:00

The famous Java concurrent library memory leak bug: 6460501 Synchronizer timed acquire still leaks memory is fixed and backported to 1.5.0_12 and 1.6.0_02. You should upgrade your Java version if you use Java concurrent library. The test code now does not show OOME on iteration.

D:\>java -showversion -Xmx16m -esa -ea Leak6
java version "1.6.0_02"Java(TM) SE Runtime Environment (build 1.6.0_02-b05)Java HotSpot(TM) Client VM (build 1.6.0_02-b05, mixed mode, sharing)

Free: 4996912
Memory used: 70104
D:\>

Google Reader Search and Google Gear

2007-09-16T16:37:00.000+08:00

If you are unable to find/user search text box under Google Reader in Firefox, you can disable Google Gear plugin/extension (Tools -> Add-ons -> Google Gear -> Disable) and restart your Firefox. You do not need to uninstall Google Gear. No problem is reported for IE 7.

Eclipse and Klocwork Developer Plugin

2007-09-13T13:57:00.000+08:00

If you ever see the below error when you try to run Klocwork InForce for Eclipse plugin (version 7.0) in Windows environment,

Cannot load profile file: unknown protocol: c
Error:InforceJava: Exiting with error: Error during loading checkers xml file: unknown protocol: c
Error: cannot parse error report.
OR
Cannot load profile file: unknown protocol: d
Error:InforceJava: Exiting with error: Error during loading checkers xml file: unknown protocol: d
Error: cannot parse error report.
etc

try to move your Eclipse directory to root (C:\ or D:\) instead of subdirectory (C:\Program Files, D:\Program Files etc). It should solve the problem.

iPhone™ idea in 15 years ago?

2007-09-09T08:02:00.000+08:00

I have just uploaded a video from James Gosling's blog to Youtube. It shows Sun has a similar finger touch sensitive UI project in year 1992.

Note: I did not contact James Gosling about posting this video to Youtube. The original video is in mpeg format with file size 141MB and it took me awhile to watch the full video. Before I upload to Youtube, I have to convert it to another format to make it smaller than 100MB file size (Youtube set file size limit to 100MB). I believe this is a good video to be shared and James Gosling is busy to do this. Hope father of Java does not mind to let us know some history about this project easier (in streaming video).

How To Solve "management agent is not enabled" Problem for JConsole

2007-07-20T20:43:00.000+08:00

JConsole from JDK 6 supports dynamic attach capability, this means it is able to attach any running Java application which does not need to start with -Dcom.sun.management.jmxremote option. However, you may not able to attach a running Java process because of "The management agent is not enabled on this process" error. To solve this, just create a new temporary directory (e.g. C:\tmp) and points your TMP environment to there. (Control Panel -> System -> Advanced -> Environment Variables). Restart your Java application and now your JConsole should be able to attach it now. For more troubleshooting tip, you may read Daniel Fuchs Blogs and Sun Forum.

Google Guice Links and Resources

2007-06-13T08:42:00.000+08:00

Here are some useful links and resources for Google Guice, besides its official site where you can find its Javadocs, user's guide etc:

Official slides in pdf 01
Official slides in pdf 02
Youtube video in Google Developer Day Beijing, using slide 01
Presentation video in OSS Speaker Series Google Video, using slide 02
Blog article from Software Engineering - Best Practices

JUnit 4.3 and Primitive Array

2007-04-12T21:00:00.000+08:00

Finally, the below simple primitive array test case has passed with JUnit 4.3

int[] intArr00 = {1};
int[] intArr01 = {1};
assertArrayEquals(intArr00, intArr01);

If you use Eclipse IDE, you need not upgrade the internal JUnit jar, just include the JUnit 4.3 jar in your build path and remove the default JUnit jar (Eclipse 3.2 come with 4.1 JUnit jar)

Java Profiler and Java/JDK 6/1.6

2007-03-18T07:46:00.000+08:00

In many cases, if your Java profiler (mine is IBM Rational Purify 7 for Windows) does not work as before after your upgrade your Java version to 6 and throws the below error

FATAL ERROR: JVMPI, an experimental interface, is no longer supported.
Please use the supported interface: the JVM Tool Interface (JVM TI).

This is because in JDK 6, Virtual Machine Tool Interface (JVM TI) has replaced Java Virtual Machine Profiler Interface (JVMPI) and the Java Virtual Machine Debug Interface (JVMDI). See Sun official note at here. The workaround is to install JRE/JDK 5 and set your Java environment (JAVA_HOME) and path (use java -version to check which java version your are using) before bringing up your Java application with your Java profiler.

Return Auto Increment field from Informix Database

2007-03-03T12:10:00.000+08:00

If you would like to get auto increment field in database after an INSERT statement, you may use Statement.getGeneratedKeys(), which returns an ResultSet in JDK 1.4 and above. You may need to check do your JDBC driver and database support it through DatabaseMetaData.supportsGetGeneratedKeys() method. For Informix Dynamic Server (IDS) it is only supported by its JDBC 3.00 driver and IDS 10 and later.

My production database is IDS version 9.4. Thus I can't use Statement.getGeneratedKeys(), and have to use vendor based solution: IfmxStatement.getSerial() which return int (Read here for more). Note that the return type of offical JDBC interface is ResultSet and IDS specific is int.

If your driver and/or database does not support both of the above, you can try this solution: Add a timestamp column with a unique index . Before you insert a new record, set its
timestamp to now. After inserting you can select the record by its timestamp and find out its
autogenerated key. If you like, you could then update the record by setting the timestamp to null. (suggestion by DrLaszloJamf in Sun Forum)

Working Way To Test Primitive Array

2007-02-04T19:31:00.000+08:00

I have tried Andres's EZMorph. By using his ArrayAssertions, the below simple test case finally passed successfully.

@Test
public void intArr() {
int[] intArr00 = {1};
int[] intArr01 = {1};
ArrayAssertions.assertEquals(intArr00, intArr01);
}

I have tested with my another test case that involves int array of 6 elements and it passed a well. If your test class only contains primitive array, you can just replace your import class import static org.testng.Assert.*; with import static net.sf.ezmorph.test.ArrayAssertions.*; without changing piece of your code.

TestNG and JUnit Have The Same Bug in Primitive Array

2007-02-04T17:59:00.000+08:00

In my previous post about incorrect result for JUnit against primitive array type. I run the same test case with TestNG, it seems like it has the same wrong result as JUnit:

Test case:

@Test
public void intArr() {
int[] intArr00 = {1};
int[] intArr01 = {1};
assertEquals(intArr00, intArr01);
}

Test result:

FAILED: intArr
java.lang.AssertionError: expected:<[I@127734f> but was:<[I@1037c71>
at SimpleTest.intArr(SimpleTest.java:18)

Andres Almiray suggested to try ArrayAssertions from EZMorph.

Insert Current Class Name to Logger Without Hassle

2007-01-27T12:08:00.000+08:00

In Creating Loggers DRY-ly by Dr. Heinz M. Kabutz, he mentioned typical copy-paste and (forgot to) modify error when creating a static logger variable, which cause logging is incorrect (wrong class name) and thereby confusing. He suggested 2 ways, first is to leave the static logger undefined, and initialize it in an initializer block. The other is to create a LoggerFactory that uses the method call stack (Throwable.getStackTrace()[1]) to determine from where it is being called. It saves works, and does not have few limitations as the first way. Sounds good, if you do not mind it is actually a trick, and a little bit overhead.

IMHO, if you have a good IDE, and you do not want to use the above ways, you may manipulate your IDE auto-completion template/shortcut, if possible. In Eclipse, Window --> Preferences --> Java --> Editor --> Templates, create a new template with the below name qlogger, and patterns:

private static final Logger logger = Logger.getLogger(${primary_type_name}.class.getName());
${cursor}

Now, everytime for a new class that need to create logger variable, just type qlogger, then Ctrl+Space. The ${primary_type_name} will be replaced by the current file name. Of course, it won't work for other classes that exists in the same file that is not public, and it does not look like an advanced professional tip, but it works. :)

JUnit 4 and NetBeans IDE 5.0

2007-01-20T22:50:00.000+08:00

According to article Notes about Integrating JUnit4 into NetBeans in netbeans.org, the author said the JUnit output window for a test method with name howTheAddGoes had an empty name and not howTheAddGoes. I believe it is because the embedded Ant in NetBeans 5.0 still does not support JUnit 4. In my first post, I faced the same problem (the test case name is unknown) but it is resolved after I have upgraded Ant to 1.7. If you are a NetBeans user, let me know if this problem is resolved in NetBeans 5.5 (or its beta 6)?

Some Useful JUnit 4 Links

2007-01-20T10:01:00.000+08:00

Here are some useful JUnit 4 links/resources:

Basic:
JUnit 4.0 cheat sheet/reference card in pdf format by Codign Software.
JUnit Cookbook
- official and short JUnit 4 cookbook.
JUnit 4.0 in 10 minutes by Gunjan Doshi
- A simple and quite comprehensive tutorial
JUnit Reloaded in Jave.net by Ralf Stuckert
- read this if you have experience in JUnit 3.8.x.

Intermediate:
JUnit 4 and Java SE 5: Better Testing by Design in JavaOne, by Kent Beck and Alberto Savoia
- for both new and experienced JUnit user. (Note: Sun SDN login needed)
JUnit 4 Extension
- added few new annotations like @Prerequisite (ignore tests based on conditions), @Category (filter and sort tests based on a Category) etc
Jump into JUnit 4 in IBM developerWorks, by Andrew Glover (Updated 09 Mar 07)
- To understand the major changes to JUnit 4, as well as being familiar with features such as exception testing, parametric testing, and the new flexible fixture model. (IBM Id login is required)

Here is my del.icio.us for the above links.

Common:
Unit Testing Recommended Best Practices in pdf by Codign Software.
- common for all unit test.

Beware Of JUnit's assertEquals for Primitive Array

2007-01-12T18:58:00.000+08:00

If you run the below JUnit test case

int[] intArr00 = {1};
int[] intArr01 = {1};
assertEquals(intArr00, intArr01);

It looks simple, and should pass. However, it will throw AssertionFailedError. Why? It is because the compiler calls assertEquals(Object expected, Object actual) as array of primitive type is an Object. Since we do not overwrite the Object.equals(Object obj) method, so you are actually running:

public boolean equals(Object obj) {
return (this == obj);
}

intArr00 and intArr01 are two different references, thus it returns false. I have a method to return array of int, but now, I can't create a test case with official JUnit library. Hope I have time to look at some extension library of JUnit.

Some Useful Tips After You Removed Blogger NavBar

2007-01-11T23:18:00.000+08:00

As in my previous post about how to remove NavBar (navigation bar) in new Blogger/Blogspot, you will not see the bar anymore, as well as some useful link like New Post and Customize. To eliminate this problem, you can create a bookmark/favorite with URL as below

http://www2.blogger.com/post-create.g?blogID=xxxxxxx (for New Post)
http://www2.blogger.com/customize-template.g?blogID=xxxxxxx (for Customize)

Replace xxxxxxx with your real blog id.

A better way is,

Go to blogger.com
Log in to your blogger account
Drag & drop "New Post" to your Bookmarks Toolbar (Firefox) / Links (IE). How?
Do the same for other link if you wish

Note: Each blog has different blog id even is under a same login/username.