JavaRanch: Java in General (intermediate)

Method names with characters like :� � � � �

Fri, 9 May 2008 14:58:59 MDT

I was doing some work with a web application, and i discovered that some method names have 'tildes'(For example: crearOperaci�n()... we talk spanish here ) .The other programmers said that the code work fine... but it doesn't feel right to me. What issue can arise with that methods? Or they are totally safe?

Reading HTML using JAVA

Fri, 9 May 2008 06:24:58 MDT

hello,
I want to display the HTML file in the TextArea using JAVA.
Java file will read the html contents and display it whole in the TextArea . No source code will be displayed only actual html contents.

thanks

TreeSet - TreeMap: What is Balenced Tree

Fri, 9 May 2008 02:32:58 MDT

I am going through the topic TreeSet and Tree Map where I found the following line:

Searching in a HashSet or HashMap can be faster than in a TreeSet or TerrMap, as hashing algorithm usually offer better performance than the search algorithms for balenced tree

My query is "What is a balenced tree?"

Order of Evaluation: i++ + ++i

Fri, 9 May 2008 00:40:57 MDT

Recently, a user on a C and C++ forum community that I am part of asked a question concerning the result of:

code:

int i = 10;
int j;
j = i++ + ++i; // or in the original: j = (i++ + ++i);

Now, in C and C++, the above code has undefined behaviour. For some reason, another user mentioned Java, and yet another user claimed that the behaviour was also undefined in Java. I disagreed and asserted that in Java, the precise evaluation order is defined.

Unfortunately, I could not remember where I read that about Java, so I decided to search to confirm what I asserted. In particular, I found out that this topic by Shivit Agarwal came up last month: Order of Evaluation ...

String array Vs String var args

Thu, 8 May 2008 23:20:57 MDT

Hi

Could anyone tell me the difference between these:

public static void main(String[] args){}

public static void main(String... args){}

Is it like that String array and String var args means the same thing?

Thanks
Krishan

File vs InputStream when getting a reference to file under the class path

Thu, 8 May 2008 14:14:56 MDT

Hi,

I have a file Sample.txt directly under my classpath. When I try to do

File file = new File("Sample.txt");
System.out.println(file.exists()) returns false;

But ClassLoader.getSystemResourceAsStream("Sample.txt") != null returns true.

Have I have done anything wrong? Please help?

Spring WebApplicationContext Question

Thu, 8 May 2008 11:46:56 MDT

Greetings everybody!

I'm writing a class that will be called via SOAP by a vendor of ours. Using Spring, I was able to get the WebApplicationContext from the HttpServletRequest in my test servlet. However, when my component is called by our vendor, it will be a SOAP call (not servlet). How can I determine the context without using a servlet, and without using HttpServletRequest? Or, can I use HttpServletRequest in classes that do not behave as servlets?

Thanks!

Thu, 8 May 2008 08:34:55 MDT

Thank for all of your advice! it was very helpful!

Michael

JCheckBox?

Thu, 8 May 2008 05:04:55 MDT

Hi
My question is: How can I add class JCheckBox into my class Frame1?
It should be only one class...Frame1
Thanks
------------------------------------------------------------
import java.awt.*;
import java.awt.event.*;
public class CheckBox{
public static void main(String[] args){
Frame frame= new Frame("Checkbox");
Checkbox check=new Checkbox("Welcome");
Checkbox check1=new Checkbox("Hello");
frame.add(check);
frame.add(check1);
frame.setLayout(new FlowLayout());
frame.setSize(300,200);
frame.setVisible(true);
frame.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
...

How to read properties file?

Thu, 8 May 2008 04:04:55 MDT

Hi all,

Can somebody tell me how to get the value of a properties file from a bean class?

i.e:- test.properties in path MyApplication/WEB-INF/test.properties

Utils.java in Path MyApplication/WEB-INF/classes/com/test/Utils.java

I want to access the test.properties file from Utils.java.

Can somebody give the code?

Thanks in advance

Kousik

How to Authenticate user before sending mail using javamail api

Thu, 8 May 2008 00:52:54 MDT

Hi everybody,
How to authenticate a user his/her credentials are correct or not,
before sending a message(mail) using javamail API.

Thanks in advance.

Help with a system call in java

Wed, 7 May 2008 22:54:55 MDT

Hey,

I am making a system call to open a particular file in ms word. I do it like this:

code:

 
Process proc = Runtime.getRuntime().exec(FilePathOfMSWORD.exe fileName);

The problem here is that I do not believe that this exe file doesn't appear in the same path on all computers...I would assume. So how can I generally make a system call that says, look for microsoft word or some flavor? I have it working for the case in which I know where the exe file.

Thanks
Michael

Problem in serial port reading

Wed, 7 May 2008 22:42:54 MDT

Hi dears,

I am doing one program which read serial port data (for bar code reader) using java application.

My program is working well and reading serial data but it is not displaying special characters.When i read through hyperterminal i can see all special characters but when see data throught the output of java program these special characters are missing...

I don't know i am doing something wrong in stream or ???

My code is

code:


[CODE]public void serialEvent(SerialPortEvent event) {
System.out.println("before serialEvent");
StringBuffer readBuffer1 = new StringBuffer();
 
switch (event.getEventType()) {

case Seri...

partial jre?

Wed, 7 May 2008 19:00:54 MDT

When making a jar file that contains a java desktop application the jre is often bundled with the application code. Seems like there should be a tool that includes only those runtime classes that are utilized by the application code. That way, the size of the jar file (and the number of bytes necessary to download the application) will be minimized.

Has anyone ever heard of such a thing?

Thanks!

Collective Intelligence in Action and Privacy

Wed, 7 May 2008 16:58:53 MDT

Satnam,

I enjoyed reading the sample chapter of your book on the Manning site. Looks like it'll be an interesting read.

Collective intelligence seems to require gathering a lot of data. Do you address privacy concerns?

Thanks for visiting us here on the JavaRanch!

Collective Intelligence in Action and Algorithms of the Intelligent Web

Wed, 7 May 2008 15:42:53 MDT

Hi Satnam,

Last time when I was visitng Manning's website I found that there are two similar titles scheduled to be published in 2008: one is your book and the other one is "Algorithms of the Intelligent Web". At first sight, these two titles seem to be very similar. What do you think? Will these two books cover the same stuff or rather complement each other?
My second question is about the content of your book. Do you focus more on the practical aspects of CI such as usage of some toolkits/frameworks or on the analysis of the math algorithms?

Thanks,
Mateusz

Add Listeners

Wed, 7 May 2008 15:42:53 MDT

Hi,
i'm using the mvc pattern for my project, and i was thinking to add the following method at the view interface , the aim is to add an Actionlistener to multiple Jcomponents.

SwingListeners(JComponent[] components, Actionlistener al)

But, i cannot obviously add an actionlistener to the single items of JComponent array. How i could do to keep just one method, without must use the overloading for JMenuItem,JButton etc etc.

Thank you.

Pooling Serial port

Wed, 7 May 2008 14:32:53 MDT

Hi friends,

I am doing one program to read the serial port.I want to do that continuously until the program stops.It should read and store the data comes into the serial port buffer....

code:


public void serialEvent(SerialPortEvent event) {
System.out.println("before serialEvent");
switch (event.getEventType()) {
case SerialPortEvent.BI:
case SerialPortEvent.OE:
case SerialPortEvent.FE:
case SerialPortEvent.PE:
case SerialPortEvent.CD:
case SerialPortEvent.CTS:
case SerialPortEvent.DSR:
case SerialPortEvent.RI:
case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
break;
case SerialPortEvent.DATA_AVAILABLE:
System.out.print...

how to disable runtime warning??

Wed, 7 May 2008 14:32:53 MDT

I have a java program that uses the built-in Transformer class to apply XSL to XML. The process of doing this is generating a "Compiler Warning" message (with details) to the console. At this time, I cannot change the XSL to get around this but at the same time, I don't want customers to see this and wonder what is wrong.

I've searched high and low for switches to "turn off" this warning both in the Xalan and Java documentation and have found none. Am I missing something??? Is there a way I can say "don't output warnings"?

I'm assuming the Transformer class is writing these messages to System.out or System.err. I also have a GUI that is redirecting this output to a TextArea window. My last resort may be to watc...

static method in abstract class

Wed, 7 May 2008 08:52:52 MDT

Friends,
I have a question that I could not solve at the moment, since my codes are long and complicated, so I made a simple case, as the codes below:

code:


/**
 *Functions used by Servers
 */ 
public abstract class ServerFunction{
 public static void printMyName(){
 //here, i want to print the class name 
 //who extends this abstact class
 //I could use the following method
 //if this is not a static method
 //System.out.println(this.getClass());
 
 System.out.println("XXXXXXXX");
 }
}
 
/**
 *Server Beta
 */ 
public class ServerBeta extends ServerFunction{...

How will you find if a binary tree is fully balanced?

Wed, 7 May 2008 08:24:52 MDT

I gave the following answer in the telephone interview:
boolean isBalanced(Tree *t,int *height)
{
if(t==NULL)
{
*height = 0;
return true;
}
int leftheight,rightheight;
boolean leftBalanced = isBalanced(t->lptr,&leftheight)
boolean rightBalanced = isBalanced(t->rptr,&rightheight)
bolean balanced = leftBalanced && rightBalanced && abs(leftheight-rightheight)<=1
*height = 1+max(leftheight,rightheight)
return balanced
}

I didn't dictate line by line but explained the above logic in words. I said the time complexity is O(n) where n is the no of nodes in the tree. But he insisted like idiot that the complexity is O(n^2) and was saying that for each subtree ...

Collective Intelligence - Mathematical Basis

Wed, 7 May 2008 08:06:52 MDT

[Caveat: I think I asked my question before to someone else's thread.]

What area(s) of mathematics contribute the most to the collective intelligence theory/algorithms?

Thanks,
Scott

date pattern for DateFormat

Wed, 7 May 2008 07:16:52 MDT

I'm working on an application that has been upgraded from Websphere 5.1 to 6.1, and everything looks fine except the showing of dates.
Including in the Websphere update is also a change in the used JDK - from 1.4 to 1.5 (or 5.0).

The dates used to be shown in the the pattern "dd-MM-yyyy", but after the upgrade, they are shown as "yyyy-MM-dd".

Can anybody tell me why this have happened?

The default Locale has been set to "da_DK".
Can anybody tell me where the "definition" of the different Locales can be found?

Thanks.

Installing Nachos with JDK

Wed, 7 May 2008 06:42:52 MDT

hello,

I am trying to install Nachos in Cygwin. My Path includes the JDK directory..and it seems to find javac ok..

When I run "nachos" from the cygwin command prompt
I get "exception in thread "main" java.lang.NoClassDefFoundError: nachos/machine/Machine....

javascript: x()
Confused

If I run nachos from the proj1 and proj2 directories...it doesn't seem to crash..

Does anyone have experience of using nachos with jdk? Why is my nachos not working from the nachos directory, but it from the project directory?

help appreciated..

Jules

How to call servlet do post method from a pojo

Wed, 7 May 2008 06:36:52 MDT

HI
i have one simple java class representing a service which should call a servlet from another server.How can i invoke that servlet and call its doPost() method?

Thanks
Raj

cloning Singleton object

Wed, 7 May 2008 02:16:51 MDT

Hi,
Can we clone Singleton object, if not why ?
Actually I am trying to clone Singleton object it is showing error, even after implementing the Cloneable interface I am getting same error.

Can anybody explain me the proper reason.

Thanks in Advance
Shashanka

Problem with hashmap

Wed, 7 May 2008 01:32:51 MDT

As I have a multiple values associated with a key ,i am adding those values to list and adding the list to the particular key.Suppose a book is taken from a library at a particular date,it can be taken anytime next 30 days.previousMonthMap contains keys and asscoiated values for last month fetched books.currentmonthmap contains this month keys and values.keys being book name and values being different date fetched.If a book is fetched it can be free for next 30 days ,n number of times.i have to calculate usage for book gone out
Video fetched in current month also have to in 30 day barrier as days between 1 and 31 is 30days.
If the book is fetched on 12th of last month,18 of last month and 5th of current month,have to calculate dif...

Collective Intelligence Book

Wed, 7 May 2008 00:14:51 MDT

Collective intelligence is defined as the capacity of human communities to evolve towards higher order complexity and harmony, through innovation mechanisms as differentiation and integration, competition and collaboration.

Does the book deal only mechanisms to better the with Web world? Does it talk about benefits like web scraping, crawling etc.

Collective intelligence in Action -- a couple of questions

Tue, 6 May 2008 21:04:51 MDT

Hi Satnam:

Do you consider or detect malicious activity?

Suppose that Im implementing a web site, based on Ci, for electing the most popular person. Everybody likes Diane but Peter hates her. Can peter alone influence the system enough to remove Diane for the first place?

Collective Intelligence - Real Time Analysis

Tue, 6 May 2008 20:56:51 MDT

Hi Satnam,

I have previously worked developing data mining applications, and one of the biggest problems we ran into is the ability to extract trends and analyze information in real-time. The data we were working with was rapidly changing (every couple of hours), so caching the data for any longer than that was not really an option. With information available in real-time from everywhere using Google, people want quick results.

Does your book discuss techniques for real time analysis? Also, do you use existing data mining frameworks (I believe I saw a weka jar in the source code, but I'm not sure their package is free anymore as it is now part of the Pentaho project)? Another issue we've had is that some of these fr...

visualizaton

Tue, 6 May 2008 18:22:50 MDT

How important is visualization for web mining tasks?

configuring service provider for jndi lookup

Tue, 6 May 2008 17:00:50 MDT

Hello looking at the code snippet here:

Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.fscontext.RefFSContextFactory");
env.put(Context.PROVIDER_URL, "file:/tmp/tutorial");
Context ctx = new InitialContext(env);

I am wondering for the env variables how do you know how to set up the service provider?

env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.fscontext.RefFSContextFactory");

how to get rid of warning: [unchecked] unchecked cast

Tue, 6 May 2008 13:00:50 MDT

Hello Folks,

I keep getting warning : [unchecked] unchecked cast for below part of code:

code:


A-
 
Map<K,V>map= (Map<K,V> ) s.readObject();
 
B-
 
IXMessage.init((IXRecordRWLock<String,IXMessage> ) rElementsCache.getNoNull("IXMessage"));
IXVariable.init((IXRecordRWLock<String,IXVariable> ) rElementsCache.getNoNull("IXVariable"));
 
where rElementsCache is of type:
IXRecord<String,IXRecord<String,? extends Object>>

How to resolve both of them?

[ May 06, 2008: Message edited by: amer seif el dine ]

Number of users a website can service !!!

Tue, 6 May 2008 10:22:49 MDT

Hi,

I want to know how many number of users can a website serve ?

Is there a Java API that lets me do so ?

Thanks in advance ...

how to make a check for index out of bound Exception

Tue, 6 May 2008 09:24:49 MDT

If have a ArrayList & i get An IndexOut Of bound Exception.
is there a way i could check/handle it .that is if this exception occurs then do this else continue.

Thanks and Regards
Madhavi.

Lower Bounded Generics

Tue, 6 May 2008 08:28:49 MDT

Hi,

On this page (http://www.javabeat.net/articles/33-generics-in-java-50-4.html), the following example is given of a lower bounded generic reference:

quote:
code:
List<? super Dog> dogs = new ArrayList<Dog>();
This declaration tells that along with Dog type, all other sub-types of Dog is also allowed. Not any of the super-type of Dog can be added including java.lang.Object. So, if we have classes like GoodDog and BadDog, both extending the Dog class, then the following statements are legal.
code:
dogs.add(new Dog());
dogs.add(new GoodDog());
dogs.add(new BadDog());
Collective Intelligence in Action - scaling

Tue, 6 May 2008 07:34:49 MDT
The Amazon description mentions real, high-use applications.

As with economics, are there thresholds (limitations) at which the techniques you describe are not applicable? What considerations should one consider before embarking on an implementation?

-Fred

Collective Intelligence in Action: Book Questions

Tue, 6 May 2008 07:28:49 MDT
Hello Satnam,

Currently I'm researching some topics on Collective Intelligence for my graduation thesis on a distributed system with Java, mainly kMeans Clustering and Independent Component Analysis, and I'm really curious about how this book explains this concepts. Do you introduce the mathematical theory or just show the "theory in action"? Are the examples based on data available on the internet (like using 3rd party web2.0/APIs to build intelligent mashups)?
Can't wait to read this book!

Thanks in advance!

Anderson
Word Count using Collections

Tue, 6 May 2008 07:26:49 MDT
Hi Friends,

Objective: To take a txt file as input and produce an output file which states which word repeated in the file how many times.

Constraints: We can not use String class for that and have to use Collectons only.

My current approach: I took the characters of the file in the ArrayList and tried to create another ArrayList which adds the first arrayList if a blank space is encountered. I planed to take the second ArrayList serch for the occurences of the word by comparing with a HashSet having all the words in it.
Here is the full code:
code:
 
package collections;
import java.io.*;
import java.util.*;
/**
 * @author Sandeep Mukherji
 *...
Method invocation done by jvm

Tue, 6 May 2008 07:22:49 MDT
Hi
I am a bit confused over the 1 point

1. Instance methods are dynamically bound except for <init> methods, private methods, and methods invoked with the super keyword. In these three special cases, instance methods are statically bound.

2. Class methods are always statically bound.

3. Instance methods invoked with an interface reference may be slower than the same methods invoked with an object reference.

Thanks in Advanced

Collective Intelligence in Action

Tue, 6 May 2008 06:48:49 MDT
Does this book assume any sort of knowledge background (other than java) or is it targeted to get people the information they need to get CI systems working in relative short order?

Thanks and welcome.

Collective Intelligence in Action

Tue, 6 May 2008 06:46:49 MDT
Satnam,

Would you be able to define "Collective Intelligence" in context and tell me how a Senior Application Developer would benefit from reading your book?

open a file pdf in unix using java

Tue, 6 May 2008 06:36:49 MDT
I have a file pdf in a path in SO UNIX and I need open this file with java code.
In windows I have used :

Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler " + fichpdf);

In unix I don't know do.
Thank you