Lowyat.NET: Latest topics by purple07

use of GPL software

purple07 — Thu, 25 Sep 2008 16:14:03 +0800

hi, i found got many open source software are licensed under GPL, but i just wonder whether we can use GPL software to develop commercial software?

i tried to read the research of GPL, but seem it is not clearly stated about this case or i misread it...all i know is if we modify GPL software, we must give our source code too...

how about if we develop our own software with GPL software?

Need help for postgresql

purple07 — Sun, 21 Sep 2008 17:36:41 +0800

currently, i try to configure postgresql in my pc, but face some problems here.
i did install postgresql successfully for a few time in my pc, but due to want to test and more understand it, i uninstalled it for further testing. now, i fail to install it as an error message keep pop up...

i have attached the captured picture here.

my application's database

purple07 — Tue, 16 Sep 2008 21:07:12 +0800

hi, i'm using HSQLDB as my java application database. but, it only able to support about 30k of my application record. the more records will make it fail.
from the hsqldb guide, it shouldn't be support only so little record.

so, i just wonder whether is my java code problem, i.e. the way i code utilize most of the memory, causing not enough memory for my database?(hsqldb is run based on the hardware memory)

FYI, in my application there are 3 main panels, each time the particular panel is called, then i'll code that so my resultset will get the new set of recordset like:

rs = stm.executeQuery("SELECT * FROM mytbl ORDER BY id");

so, rs will keep refresh it's recordset. i just want to know will this keep taking new memory
space for rs?

Apostrophe in insert record

purple07 — Sat, 30 Aug 2008 20:31:25 +0800

i tried to add a new record with apostrophe(') in a string e.g "It's Java" but it keep throw SQLException, can I know what's the problem? A string with apostrophe can't be added? but, when i edit the record with adding an apostrophe, it's allowed.

JTextArea problem

purple07 — Sat, 30 Aug 2008 15:31:44 +0800

how can i code my JTextArea that will has a specified length of width and when the entry come to the end of the component, it'll directly wrap to the next line?

Need help for Java sorter

purple07 — Sat, 30 Aug 2008 11:46:41 +0800

hi, i have set a sorter to my JTable to filter out the records. this is my line of code

sorter.setRowFilter(RowFilter.regexFilter(filterText.getText().toLowerCase(), selectOption));

where the user entry will get from filterText, but i faced a problem here...
let's say my JTable contains a row that is "Java is powerful", when user enter "java is powerful", it's fail to filter out for the lower case issue...

so, how can i solve this problem to make it the filter is trace only the character but ignore the upper or lower case?

Will compiled Java class file affected by virus

purple07 — Thu, 28 Aug 2008 12:17:16 +0800

hi, i have suspected my pc being infected virus...
and currently i'm developing a Java application, so i just wonder if my pc being infected virus, will my compiled class file being infected too?

Java Interface Problem

purple07 — Sun, 17 Aug 2008 22:05:09 +0800

hi, i'm currently face a big problem with my interface...

as my string data is very long, and being retrieved and displayed in my interface-JTextField, JTable, JList...
those interface(component) will be horizontally extended, causing the user unable to see those interface at the most left and right part...even when the user click the maximize button, the things can't be seen as a whole too...

Maximize JFrame

purple07 — Sat, 16 Aug 2008 22:25:01 +0800

how can i open my JFrame as maximize state? i tried this

CODE

this.setExtendedState(this.getExtendedState() | this.MAXIMIZED_BOTH);

but, it take no effect! can anyone please tell me what's the problem here? thanks!

Unique number to identify each pc

purple07 — Sat, 09 Aug 2008 11:05:12 +0800

hi, my friend did told me that each hardware will got a unique number to identify it, can i know what's that? what's the number attached with? processor? hardisk?

Java JTree

purple07 — Mon, 04 Aug 2008 22:58:56 +0800

i would like to create a JTree with TreeModel, but how can i make it as several root that will represent all the drives that available?

.java.bak

purple07 — Mon, 28 Jul 2008 00:01:53 +0800

hi, recently i found there are some .java.bak file being automatically created in my folder that contains all my .java and compiled .class file...

what are these file type? even though i try to delete all of them, i found a few created again(i didn't compile and run my java application in this case, these .java.bak just appear themselves...)

CREATE TABLE AS command

purple07 — Sat, 26 Jul 2008 12:03:24 +0800

hi, i would like to create a new table based on an existing table...

the following is my code, but it fail to create the new table, can anyone here please point out my mistake? thanks!

String qr = "CREATE TABLE joined_tbl AS (SELECT * FROM mytbl)";

try{
int i = connectcn.update(qr); //update is my custom create table function in
//another class

}catch(SQLException e3){

System.out.println("ERROR: Fail to create the joined table!");
e3.printStackTrace();
return;
}

this is the error:

java.sql.SQLException: Unexpected token AS, requires ( in statement [CREATE TABL
E joined_tbl AS]

Remove TableModel set to a JTable

purple07 — Wed, 23 Jul 2008 16:16:46 +0800

I have created a JTable and use setModel() to set a TableModel for it. but, i face problem to refresh the table. so, what i need now is to remove the entire TableModel set to it, and use setModel() once again to assign new records for it. can anyone please tell me how to remove TableModel in this case? i searched through the API, seem not found such method...what i found is fireTableDataChanged(), but not sure is it what i need and don't know how to use it too...so, hope someone can help me! thanks!

Method to get total elements in JList

purple07 — Mon, 21 Jul 2008 19:35:47 +0800

hi, can anyone here please tell me, the method that allows me to get the last element's index of a JList? in this case, i can't use getLastIndex() which requires the ListSelectionEvent...

thanks!

Why this code fail

purple07 — Mon, 14 Jul 2008 14:58:21 +0800

i'm trying to open file with the following code. however, it's fail. can anyone here kindly point out my mistake? thanks in advance!

CODE

private Desktop desktop;
private Desktop.Action action = Desktop.Action.OPEN;

public void openFile(){

String fileStr = "C:/myfile.ppt";
File file = new File(fileStr);

try {

desktop.open(file);

} catch (IOException e) {

System.out.println("ERROR:Fail to open file");
}
}

this's the error:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

How to filter chinese character

purple07 — Fri, 11 Jul 2008 14:20:45 +0800

I have displayed my database data into a JTable, and using a JTextField to do the table filter. so far, it's work. but, when my data is in chinese character, the filter fail. so, how can i filter my table when data is in chinese character?

What is <> meant here?

purple07 — Tue, 24 Jun 2008 15:48:11 +0800

for this line of code:

final TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(model);

there is <> symbol, can anyone here please tell me that what this line of code meant as i'm not understand what <> meant here. thanks!

Can Java do this

purple07 — Mon, 16 Jun 2008 16:55:45 +0800

let say i have several power point files, can java copy all slides of those files, then creating a new power point file by inserting all those slides?

What's Wrong with this code

purple07 — Wed, 11 Jun 2008 17:44:55 +0800

hi, can anyone point out for me what's wrong with the following code? thanks!

CODE

try{
String test = "My_Dir/Test/Test.jpg";

java.net.URL imgURL = MyClass.class.getResource(test);
Image img = Toolkit.getDefaultToolkit().getImage(imgURL);
setIconImage(img);

}catch(NullPointerException e){
System.out.println("ERROR:Fail to display icon");
return;
}

if String test = "Test.jpg", then no error occur...but why?