Java Q&A

Combobox change combobox which adds text in textArea

danger_dave — Wed, 28 Dec 2011 06:31:01 -0500

Hi, I have been scratching my head for a couple of hours wondering why my Japplet isnt working. The problem is, the second time I select the first combobox, the second combobox does not update its content and hangs. I am not sure where its looping to and have tried to trace it out. The code is as follows.

public class brake extends JApplet implements ActionListener {

JComboBox state, traintype;
Container c;

String[] sNSW = { "Select", "Titan", "HMT" };
String[] sVIC = { "Select", "Nokia", "Sony" };

TextArea display = new TextArea(10, 80);
String str;

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Problem with back button

satish_ravula — Fri, 16 Dec 2011 05:09:32 -0500

Your Application logoutSampleJSP3 working fine. But am facing small problem.

When i am login in to the application then i am getting home page. OK this is fine. But my problem is in home page am clicking back button then it will

show again login page without logout. So please solve this problem as soon as possible.

Thanks,
satish.

Enterprise Java

Database data doesn't fill into JTable

neocorp — Tue, 13 Dec 2011 02:09:07 -0500

I've been working on this code for couple of days. My procedure on the database works fine but it doesn't fill into the table. I'm going through the code again and again but I can't find what's wrong... The error I get is: JavaNullPointerException and the line involving is the piece of code that returns notes.length. Here's a piece of my code:
private Object[][] notes = null; setUpStatusColumn(noteTable, noteTable.getColumnModel().getColumn(2));


protected JTable createTable(GradesModel gradesModel) {

        return new JTable(gradesModel);

    } 

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Core Java



read inputstream works in office, not at home
senderj — Sun, 11 Dec 2011 22:26:59 -0500
I use NetBeans both at work and at home, v7.0.1. Recently, I developed a small program using HttpURLConnection to read web page and process the contents. It works fine in my office, but not at home! In the office, the whole html code is listed. At home, it stopped in the middle with socket reset or freeze forever. After many testing, I summarize my finding here:
With higher chance (but not always) of success:

1. use read(byteArray, offset, length)

2. use byteArray size = inputStream length

3. write the byteArray to file immediately

4. small inputStream size (e.g web page small) 

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Character.reverseBytes error!
stratosb — Thu, 01 Dec 2011 10:53:19 -0500
Hello,

I have written some code to encrypt the contents of a textfile by using the method Character.reverseBytes as shown below:


    try {

        reader = new BufferedReader(new FileReader(file));

        writer = new BufferedWriter(new FileWriter(outfile));

        String text = "";

        // repeat until all lines are read

        while ((text = reader.readLine()) != null) {

            String reverseText = "";

            for (int i=0; i 

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Core Java



How to manage a dbms with multimedia content in java - jdbc(client /server)
arunrajp — Mon, 07 Nov 2011 09:54:46 -0500
I am an old timer from the 90s so java7 is a bit of a shock to me as ima an SCJP for java 2 platform from 2000.
Please suggest the best way to manage a multimedia databse containg (*.jpg and *.au) files in a DBMS or RDBMS using JDBC for both client(Standalone java application) and server side(Servlets).
Enterprise Java



How do I access the POI Jakarta?
yjs1210 — Wed, 21 Sep 2011 15:16:57 -0400
Hi, I'm trying to write a program that needs to access excel
I've never worked with POI Jakarta before and I do not know how to import correctly
I downloaded poi-src3.8beta file and unzipped it and it spits out a folder.
what do i do with this?
I tried to import using statements

import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import org.apache.poi.hssf.usermodel.HSSFSheet;

import org.apache.poi.hssf.usermodel.HSSFRow;

import org.apache.poi.hssf.usermodel.HSSFCell;
but none of them seem to work. 
how do i address this issue?
Core Java



Newbie System.out.println
eclipse007 — Mon, 20 Jun 2011 09:10:25 -0400
Hi guys,
I’m Nick I’ve just joined the forum. Just wanted to say hello. I am pretty new to Java but have been teaching myself using books and the eclipse IDE. I know quite a lot about the syntax now and can write some pretty simple classes. I think I also understand classes, interfaces, inheritance and so on pretty well so think I’m well on my way. 
The thing I’m wondering is what the ‘out’ refers in: system.out.println(“something”) 
Usually you will have:

SomeClass.someMethod()

or

SomeClass.someMethod().someSubMethod().someSubMethod() etc… 

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Core Java



JavaOne 2011
t3chno — Tue, 19 Apr 2011 03:05:52 -0400
My development team is largely Java based. I am aware of Devoxx and would hope to attend next year, but what are the other conferences that would be useful for my requirements?
Mobile Java



how to insert system.out.println into each and every method of every class in a java project
dmvsatyakumar — Mon, 11 Apr 2011 01:35:16 -0400
I have a set of class and doesnt have a debugger to debug the application. Hence i want to insert SOP into each and every method so that it will be easier for me to trace the code flow for any activity.
Core Java



JUSB
adeel809 — Wed, 06 Apr 2011 11:51:40 -0400
please give me all step to run or install jusb api on ubuntu
Tools and Methods



JMS Custom message ordering
abhishekchouhan — Fri, 01 Apr 2011 06:54:19 -0400
JMS Question:- Is there any way to change the messages order in JMSQUEUE based on custom rule/policy/strategy? Other then FIFO..
Enterprise Java



QCon or Javaone ????
lisaantony06 — Thu, 24 Mar 2011 05:04:55 -0400
My company allows me to visit one international work related (I'm Java/JEE Developer/Technical Lead interested in polyglot programming) conference each year. I've visited Javapolis (devox) in the past.

For this year I'm looking for a conference which is less technology but a bit more methodology focussed... possible like Oracle Develop or QCon or Javaone What would you recommend?
Tools and Methods



Java challenge!
FirePhoenix — Mon, 07 Mar 2011 05:08:30 -0500
Hi all,
I have been given the following challenge:

-------------------------------------------------------------------------

Write a Base64 encoder/decoder in Java for me in two ways:
1) Using an existing Base64 library routine

2) From scratch, using string/character/byte manipulation.
I'd like a unix-style command line program (with the obvious issue that it's actually running via Java, but I'll not worry about that detail), and I'd like it to take the following parameters:
-v = display version

-? = display some help on how to use the program
-e = encode

-d = decode 

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new to programming
eddie79 — Tue, 01 Mar 2011 15:15:40 -0500
hello board. i am new here with 0% knowledge of programming but i am eager to learn. i have been doing research and trying to find a book that will fit my need. I want to start making simple games for Android. i have an idea for a game but requires the game to talk and you have to repeat to get to the next level. it's a learning game. what links or videos i can research on to make this happen?
Mobile Java



Cannot get TransferHandler to work in Swing
pbpersson — Sun, 30 Jan 2011 13:00:25 -0500
I have created a Swing application and I'm trying to configure Drag and Drop support for a JTextArea.  There are two capabilities I need for this object, I want it to accept text pasted into it from the clipboard and I also want to accept files dropped onto the object, grab the file name and then send that to another routine which will open the file, read the contents, and perform some work.
However, I cannot even get past first base on this.  I have created a class of transferhandler as follows:


class FileDropHandler extends TransferHandler { 

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Does garbage collection occurs in PERM Area of Java Heap ?
javabuddy — Fri, 21 Jan 2011 22:43:22 -0500
Hi Guys,
I am a relative new member in this forum , My name is Javin Paul and I am Java programmer. I have question related to garbage collection in Java 
Does garbage collection occurs in PERM Area of Java Heap ?
As per my knowledge PERM area is used to store meta data about classes, methods , variable etc also String Pool created in PERM area of heap so I believe  garbage collection does not occur in this place but just wanted to know what do you guys think of it ?
Thanks

Javin
Core Java



Help developing a Java App that requires Image reader capabilities
srikkan — Wed, 10 Nov 2010 02:49:11 -0500
Hi All,
I am planning to develop an application which does the following.
Problem description:- In my college I see a lot of postings on the notice board regarding various Tech events,distinguished lectures and others. We need to note down the info in a diary ( or may be store it as an appointment in the mobile phone) since there are no remainders for those notices.
Solution:- 

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Mobile Java



Automated File Transfer Tool with Java APIs
vShridharv — Mon, 13 Sep 2010 00:07:34 -0400
Hi,
Are there any automated file transfer tools available in the market which provide Java APIs? We are using JDK 1.4. 
I wanted to know if there are any such tools available so that they can be integrated into our application code.
Thanks,

Shridhar
Tools and Methods



How to extract Context-params from web.xml into POJOs?
indianapple89 — Sat, 04 Sep 2010 17:27:58 -0400
I have information regarding the DB connection params stored in the web.xml file. I am connecting to the DB from a POJO (used as the DAO). Is there a way to extract the context-params from the web.xml file in the POJO?
Enterprise Java



Java's TimeZone and Calendar classes not working correctly for me
kiwiyogurt — Fri, 03 Sep 2010 15:53:51 -0400
So, I was given some data in UTC time, and needed to convert it to Pacific Standard Time (well, technically Pacific Daylight Time now.)  I did this like so:
		//given in UTC - this needs to be converted to local time

		GregorianCalendar current = new GregorianCalendar(TimeZone.getTimeZone("UTC"));

		current.set(year, monthInt, day, hour, min, sec);

		//convert from UTC to PST

		cal = new GregorianCalendar(TimeZone.getTimeZone("America/Los_Angeles"));

		cal.setTimeInMillis(current.getTimeInMillis());
		//reset the fields - have changed now that timezone has changed 

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Connecting to MySQL 4.1 over the a LAN
iranga — Wed, 01 Sep 2010 04:03:08 -0400
HI,
I've installed mysql 4.1 to windows XP pc and my java swing application running in another windows xp machine.So I need to connect Mysql Database to  my swing application...Its already working correctly when I installed mysql in my local pc and write a code as bellow.
public class DB {

private static  Connection con;

public static Connection connect()throws Exception{

    Class.forName("com.mysql.jdbc.Driver").newInstance();

    String url="jdbc:mysql://localhost:3306/ecal";

    con=DriverManager.getConnection(url,"root","sa");

    return con;

}

} 

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Tools and Methods



Bean Scripting Framework Question
nklea01 — Thu, 29 Jul 2010 05:50:49 -0400
Hello,
Can someone who knows about Jakarta BSF project help me on this :
I am trying to run a jython script from java. Ive created a BSFManager and i can execute the script with its "exec" method. However i have modified the script to accept arguments (sys.argv[1]). How can i pass arguments from within BSFManager and how can i capture its output? I think there is a method "apply" which does this but i don't understand how to use it.
I want to pass to my script a String argument and get back a String result
Thanks
Community Discussion



core java
rohitsi — Wed, 07 Jul 2010 10:23:45 -0400
Can you tell any bad example of Inheritance?
Core Java



About Random class
praneeta — Tue, 06 Jul 2010 02:05:26 -0400
I want to know that the java Random class is based on the Monte Carlo algorithm and if not implementation about this algorithm using java.
Core Java