javanus.com

Summary row is used to present a total sum at the bottom of the jTable.

I have developed a grid component consists from the following components: JPanel is a basic container, jScrollPaneBasic is used to display horizontal scrollbar to handle a summary table and a data table. A data table (zebraJTable1) has another scrollPabe called jScrollPaneTabel used to display vertical scrollbar.

Picture below presents the summary row from the application.

Do not hesitate to run a demo at http://www.javanus.com/AssistWeb. Here are the steps needed to display summary rows in the application:

Manual: 
1.start the demo  
2.login as a GUEST username, password is empty 
3.select Invoices in the menu and after that select the menu item Review of cash accounts (Invoices->Review of cash accounts) 
4.click Search button to display data

I was looking for a PivotTable in java(swing) for a long time. I found out three different libraries for PivotTables. Lets check out each one:

1.JIDE - http://www.jidesoft.com/products/pivot.htm

JIDE software looks amazing but it is not an open source project. At the moment I am strictly “opensource” oriented so the JIDE is not the right choice. I would be very glad if they will decided to opensource their libraries. The screenshots looks great.

2.JMAGALLANES - http://sourceforge.net/projects/jmagallanes

It is an opensource project but the project is not active at the moment. The last update is from 2006. I have written an email to the authors and I have got a reply. They have told me they are planning the next release in a few months.

3.OPENSWING - http://oswing.sourceforge.net/

It is an opensource project. The project is active. I have downloaded the opensource library and the pivotTable worked fine. After a while I found a bug (http://sourceforge.net/forum/forum.php?thread_id=3296825&forum_id=572329) but Mcarniel did his job fast and well. The bug was corrected in the next week.

Below is a picture from my application which presents the use of pivotTable.

The above screen shot is from the hotel reservation software. You are free to launch a demo from http://www.javanus.com/AssistWeb/. Below are the steps used to test a PivotTable:

1.Select “Reports->Reservations” in the menu

2.Select “Search” button

Timezone has not been kept while transfering over http.

The data are stored in the tableModel on the client side. TableModel is serialized and sent over the http to the server. The servlet on the server deserializes the data into the tableModel. TableModel is stored into the database.

My client is located in the central Europe and the server is located in the USA. The client time was Jun 06 00:00:00 CEST 2009. The data was transferred over the http and the same date on the server was Jun 05 17:00:00 CDT 2009.

Solution:

I set GMT timezone on both sides.

TimeZone tz = TimeZone.getDefault();
tz.setDefault(TimeZone.getTimeZone(”GMT”));

The client and the server date time are the same after setting default timezone: Jun 06 00:00:00 GMT 2009.

 Do not hesistate to check out a hotel reservation software using the described technology.
 

I am using a JXDatePicker component to present date fields in my application(http://www.javanus.com/AssistWeb). The application supports seven different languages at the moment. Translation is using resource bundles and it works fine. I also want to localize date fields to present date in a localized format.

It is very easy to convert a date in a paricular format in java. SimpleDateFormat is easy to use, programmer should only pass a particular date format  (dd/MM/yy or dd.MM.yyyy).

The problem arise when I want to provide a date format for a jXDatePicker component. I did not know how to set the proper format for JXDatePicker according to selected language. I just need a localized date format pattern to set the format for jXdatePicker. After a few hours I found the solution I would like to share you.

//inicialization

jXDatePickerDateField.setDate(new java.util.Date());

Solution:

Locale locale = Locale.getDefault();

String datePattern = ((SimpleDateFormat)DateFormat.getDateInstance(SimpleDateFormat.MEDIUM,locale)).toPattern();

jXDatePickerDatum.setFormats(datePattern);

This is the announcement for version 1.0 of Hotel Reservation software written in java. Application is multilanguage but it is still poorly translated at the moment. Main functionality has been translated into English and some other languages. It could be translated to other languages of course if somebody needs it. Application was originally developed in Slovenian language so you could expect to find out some fields which has not been translated yet.

I mixed different technologies in this application: swing, servlets, tomcat and mysql. The entire application is written in swing, it comunicates over http using servlets with the application server, servlets communicate over the jdbc with the database. I plan to describe particular parts of the application in more details in the following days.

You can launch a demo at http://javanus.com/AssistWeb/. The picture below presents basic steps to create your first reservation.

Application works fine as a desktop application which communicate with the database using jdbc at the moment. Please send me an email to info at javanus.com if you would like to test it a desktop version.

I would like to get your opinion on choosing an IDE to develop Java applications.

At the moment I am using Netbeans and I am very satisfied with it. I tried to get a good comparison between them with google. There are a lot of old articles about “The big Three” but I could not get a good answer because they evolve a lot in the recent time. It is time to get an up to date situation!

Here is my opinon:

JDeveloper Pro - if you would like to migrate from oracle forms to java -> use ADF (application development framework), support all phases of software development

JDeveloper Contra - it is not independent (developed by Oracle), does not have future in open source world, slow startup

Netbeans Pro - strong community, open source, independent

Netbeans Contra - bad reputation from the past, I am missing a plug-in for data modelling

Eclipse Pro - a lot of people using it, it is fast

Eclipse Contra - I think it is losing market share, no clear vision

I would be very glad to get your opinion! Do you agree or disagree with my statements? Do not hesitate to put your comment!

Do you find this post useful? Do not hesitate to leave a reply! Go to the bottom of this page.

Have you ever tried to identify zombie processes on your server? The zombie identification application is written in java and could be used on linux. It is very easy to adopt the code for other operating systems. The zombie killer has been originally written to kill zombie processes on Oracle Application Server.

Go to the end if you are only interested how to end the financial crisis…;)

Application has two parameters:

• the process name is used to find out only the specific processes. In my example the parameter value is frmweb. Parameter value frmweb is used to limit the application to check only the cpu time spent by oracle forms processes
• the cpu time used by process is used to define the maximum allowed cpu time spent by particular process

How does it works:

1. Application first get all the processes in desired format.
   1. ps -eo (to see every process with a user defined format)
   2. ps -eo user, pid, time, command (to see every process in format user, process id, time spent by process and command)
2. Application checks only the processes where the parameter value for process name match the command (parameter value is in command string)
3. Application parses the process values and check the cpu time spent by the process. Process is terminated if the cpu time spent is greater than the parameter value for cpu time.

Application could be run using crontab each 15 minutes. Example below shows how to kill oracle forms sessions which exceeds more than 1000 seconds of cpu time
0,15,30,45 * * * * /usr/java/jdk1.6.0_11/bin/java -cp . ZombieKiller frmweb 1000


import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;


/**
*
* @author http://www.javanus.com/blogs
*/

public class ZombieKiller {
public static String getUnparsedProcessList() {
InputStream in = null;
InputStream buffer = null;
Reader reader = null;
try {
//get all processes
Process p = Runtime.getRuntime().exec("ps -eo user,pid,time,command --sort stime");
in = p.getInputStream();
buffer = new BufferedInputStream(in);
reader = new InputStreamReader(buffer);
char[] charr = new char[1024];
StringBuffer strbuff = new StringBuffer();
while(true) {
int r = reader.read(charr);
if(r<=0) {
break;
}
strbuff.append(charr, 0, r);
}
return strbuff.toString();
}catch(IOException e) {
//todo - error handling
e.printStackTrace();
}
return null;
}

/**
* @param args the command line arguments
*/
public static void main(String[] args) throws IOException {
System.out.println(”Check out http://www.javanus.com/blogs && http://www.javanus.com/blog”);
if (args.length==0) {
System.out.println(”Usage: java -classpath . ZombieKiller “);
return;
}
String ls_processName = args[0];

}
}


It would be nice to end the financial crisis on the same way. I suggest to use kill -9 42 to end the economic depression. 42???

Do you find this post useful? Do not hesitate to leave a reply! Go to the bottom of this page.

I had to develop a multi language report. The report must support four languages: English, French, German and Slovenian. I decided to use Jasper reports. First I checked out the standard jasper example (”jasperreports-2.0.2\demo\samples\i18n). I have tested the example and I was very satisfied with the solution.
After that I developed my first multi language report. Below are the steps needed to achieve this functionality:
1.Create 4 properties files and use local language. In this example I will explain how to translate the word “OFFER”

i18n.properties
text.offer_number=OFFER No.:

i18n_de_DE.properties
text.offer_number=Anbieten:

i18n_fr_FR.properties
text.offer_number=Offre:

i18n_sl_SI.properties
text.offer_number=Ponudba Št:

2.Open Ireport and add a new text field
Add $R{text.ponudba_stevilka} into the expression editor

3.In the main menu select Edit->Report Properties
Select i18n tab
Put i18n into the Resource Bundle base name field

4.Put all four i18n*.properties files into the root directory!!! This MUST BE done when you try to call the report from application. In my case I have jasper reports in C:\development\MyApp\build\classes\reporti\reports and I have to put i18n file into C:\development\MyApp\build\classes.

Translation worked after that but I spend another two hours solving the problem described below.

I have a lot of problems with cp1250 fonts. Central european fonts were not displayed when i used i18n. I put a textField on the report. In the expression editor I defined the value as: $R{text.offer_number}+”Š”.
In the resource file I have defined text.offer_number=\u006F\u008A\u006E. Total expected length should be 4 characters (3characters are in i18n file and one character is concatenated).
I expected to get oŠnŠ but i get o?nŠ  (first three characters are unicode, so the problem is, that central european characters are lost during translation.

I found the solution after long hours. In http://unicode.coeurlumiere.com/ I found out that some characters are marked as “Invalid characters”. Character Š has two unicode numbers: 008A and 0160. The first one is invalid. I got the expected result when I replaced the text.offer_number=\u006F\u0160\u006E.

Do you find this post useful? Do not hesitate to leave a reply! Go to the bottom of this page.

Do you find this post useful? Do not hesitate to leave a reply! Go to the bottom of this page.

I started programming in java one year ago. I decided to convert my visual basic code to Swing. I was very unpatienced at the beginning, i did not read the swing manual, I just started to programming.

Today I will try to describe my experience with jtable and swing. In the second part I will present my grid object.

1.It is very easy to start programmic in Swing using Netbeans. It is very similar to all other RAD(Rapid application development) tools. 

2.It is very difficult to develop a more complex application in Swing on the other side. I think the basic element of every business application is a grid object. We can use jTable in Java. I was very happy, when I first saw a jTable a year ago. Ohhh, what a powerful object!!! But I got very disappointed after a few days. I realized that it is very complex to extend jTable for more serious use. And I was an absolute beginner…

3.Have anyone used PowerBuilder in the past. PB has a very powerful datagrid. I tried to develop something similar. I would like to have the following functionallity: present data in grid using SQL statement, easy editing of data…..

4.jTable is very powerful when you learn how to use rendering, cell editors, drag and drop, etc…

Ok, now it is time to move to the second part.

I have developed a grid object. It has the following features:

a) data is displayed in a grid according to sql

b) editing strarted in the next cell when user press enter or tab

c) export data to excel

d) grouping data in jtable

e) store data to database with save method

f) easy to use

Below is a picture which presents group data in a jTable.

Do you think I should start an open source project to develop this object further? Is there any other similar object with described functionalities? I am very intersting in your opinion. Please do not hesitate to answer me.

It will take me a lot of time if I would like to rewrite the object once again. At the moment it is more similar to spaghetti code. 

Ok, what is the purpose of this article? Please encourage me or give me some good arguments like :”Do not waste your time, there are thousands of similar projects….” or even better: “Do that!!! Newbies are waiting for something like this, give Swing a chance!!”

Do you find this post useful? Do not hesitate to leave a reply! Go to the bottom of this page.