Posts by ~s.o.s~

The first piece of advice; catch stuff only if you plan on handling it. And by handling I don't mean printing stuff on the console and carrying on your merry way. One logical use case can be a retry-logic. If you plan on trying to connect to a host with a retry-counter, you would normally catch the connection exception, increase the failure count and try again.

Also, make sure you always close resources in the finally block since that's the only block which is guaranteed to be executed. So either you end up having try catch for each close method call or end up skipping closing a few resources. Since closing resources is a pretty repetitive task, a lot of folks end up using utility classes like the one posted below:

class Utils {

    private static final Logger log = Logger.getLogger(Utils.class.getName());

    /**
     * Close a list of AutoCloseable objects quietly. Works for pretty much all types of resources. But works only with
     * Java 1.7+
     * 
     * @param closeables
     */
    public static void closeQuietly(AutoCloseable... closeables) {
        for (final AutoCloseable resource : closeables) {
            try {
                if (resource != null)
                    resource.close();
            } catch (final Exception e) {
                log.log(Level.WARNING, "Exception when closing resource", e);
            }
        }
    }

    /**
     * Close a bunch of Closeable objects silently; doesn't work for DB resources like ResultSet, Connection etc.
     * 
     * @param closeables
     */
    public static void closeQuietly(Closeable... closeables) {
        for (final Closeable resource : closeables) {
            try {
                if (resource != null)
                    resource.close();
            } …

Looks like a nifty feature Dani. Hopefully this can also motivate the posters to at least read the similar threads rather than jumping the gun and saying "me too" when the answer is right in front of them. :/

Let's start with why option 3 doesn't work. Generic types in Java are not covariant i.e. List<Integer> is not a List<Number>. Consider the following example:

List<Integer> list = Arrays.asList(1);
List<Number> numList = list; // doesn't work actually but assume it does
numList.add(Double.valueOf(1.0)); // Double is a Number
Integer i = list.get(1); // KABOOM!!

This above explanation forms the basis of the problem persented here. You just can't pass around GenericDemo instances of different parametric types and expect them to operate seemlessly with your API.

Since things can get complicated pretty quickly with the class definition you posted, let's create a new trivial minimal example to reproduce your problem:

class Hose<E extends Number> {
    // assume constructor

    public E doStuff(E e, Number e2) {
        return e2; // doesn't work
    }
}

What's the problem here? Isn't E a type which "extends" or is always equal to or a sub-type of Number. Well, the problem comes up with you try to use the result of doStuff method. Here is one usage:

Hose<Integer> h = new Hose<Integer>(1); // E now is Integer
Integer i = h.doStuff(2, 2.0); // BOOM! I'm expecting Integer but go 2.0

To get around this, here is what we can do:

public <T extends Number> T doStuff(E e, T e2) {
    return e2;
}

Now, since the compiler knows that the return type T is something which is a Number but can be any sub-type, you are able to do something …

I would personally recommend an editor which supports Markdown to ensure what I'm typing is a valid markdown construct/document. There are different ways of going about this. You can either compose your posts in the editor offered by StackOverflow which has excellent support for Markdown. Or you can just use this on-line markdown editor which works fairly well.

I guess with To Love Ru out, theres no better time but the [present]!

Unfortunately, the To Love Ru Darkness episodes aired have some sort of stupid censorship (light beams) which makes viewing not so much fun (constant visual interruptions). Plus there is no ATX broadcast for this which implies no "normal" episode before the BD comes out. This is the reason why I have put TLRD is on hold till the BD's come out.

but kind of heady if you try to follow the merchant explanations

I thought the explanations in Spice and Wolf were the hardest to follow until I came across Horizon in the middle of nowhere. Oh, and while we are at it, bonus points for following the background narration of The Tatami Galaxy without pausing the video. That anime has pretty much the "fastest" narration I have ever seen though that's just one of the points that makes it a good/unique anime. :)

These days I find myself having trouble keeping up with everything

Maybe you need more coffee? ;)

Oh, and I've been reading Baby Steps recently

Sports plus Romance. Reminds me a bit of Cross Game which was an exceptional adaptation. If it's anything like that, I'm sold. That said, Baby Steps has got super ratings on the manga sites. Must be interesting...

BTW, a lot of good animes are out today (K, Btooom, To Love Ru). Yay!

You might want to have a look at this site

Or AnimeCalendar. I guess there was a time when AniDB was the de-facto site for sifting through anime but given the introduction of MyAnimeList and its old interface, I'm not sure. Maybe it's just me. :)

Haha, I guess I can give them a try too. Since they are your recommendation, they better be good. ;0

Also I'm surprised that you are content with just two good shows when the entire season looks like a jackpot. :P

Can you try the steps mentioned in this post and let us know if it helps?

Howdy folks,

Fall 2012 season has started airing! The final draft for the series to be aired can be found at the Neregate blog.

I'll be absolutely watching the following series:

• Bakuman 3 (Awesome romance, slice of life)
• Jormungand: Perfect Order (Prequel rocked; reminds me a bit of Black Lagoon)
• To Love Ru Trouble: Darkness (Good harem IMO)

The following look promising so I'll definitely try them out:

• Code Breaker
• K [This one was a pain to search for on MAL, trust me...]
• Little Busters
• Psycho Pass
• Robotics; Notes
• Btooom!
• Zetsu No Tempest

All in all, I think this season has to offer a lot of "looking good" anime. Let's see how it actually turns out.

So, what's caught your fancy? Don't be afraid of speaking up; I swear I won't call you an otaku. ;)

isn't there any way that you can know who is down-voting or up-voting your posts ? if yes, then how can i know that ? thanks ;)

No, there is no way by which a Daniweb member can know who is down/up voting his/her posts.

may be this feature can be added. ;)

Not happening unfortunately. In a distant past, the only way to show appreciation/disdain towards a post was "add reputation" feature which publicly showed the name of the person adding/deducting your reputation. As you can imagine, it resulted in up/down rep flame wars between individuals and groups. In short, it was quite a mess. Plus some folks are not comfortable with their name being showed when they like/dislike a post and prefer to remain anonymous. The public nature of the system drastically reduced the voting/rep activity on the site.

The current system is an attempt to get around those peculiar situations. If you want to publicly express your like/dislike, just use the add/remove reputation feature. If you wish to remain anonymous, use the up/down voting feature. Of course we are open to complaints wherein a given member is continuously down-voted on all his posts by a single member or is a target of an auto down-voting script.

or if there is one then where to find it ?

Adding to Davey's answer, the technical reason is that if you use a "textarea", the browser pretty much automatically fills in the spell checker's role for you. Unfortunately if you'll notice, the Daniweb answer box is implemented as a div instead of a textarea resulting in no support from the browser. I'm really hoping Daniweb revamps the current answer area to use a textarea instead of a div. :)

Hate to say this but this really isn't a minor project anymore with a desktop GUI front end which needs to simulate a forum view and having a server as a central authority. :)

Anyways, if it needs to be a simple college project, there isn't a lot of variation here. The GUI needs to be in stock Swing. In terms of server, there are three options:

• Raw socket; will surely be a pain since you need to write the entire infrastructure right from receiving requests, saving stuff in database and sending across response
• RMI; a bit involved to set up but will expose your server code as a simple service which can be called using simple Java style method invocation
• JBoss remoting; third-party RMI like features but is a bit more easier to set up

I would personally go with RMI unless you have a restriction of not using any abstraction and doing it via raw sockets.

I'm assuming this class isn't part of the "System FRONT".jar? Anyways, this means you are missing a dependency. Stock JAR files can't have other JAR files inside them as dependencies. You'll have to search for the JAR file containing the given class net/packNetSystem and invoke your JAR as:

java -cp "System FRONT.jar":packnet.jar your.main.class

Here your.main.class is the entry point or the main class of the System FRONT.jar which is automatically invoked in case you use the -jar switch. Here I'm assuming you already know the main class which resides in your System FRONT.jar.

class Movie():

This defines an old style class. A better way would be to have:

class Movie(object):
  pass

This is suggested because old style classes don't play well with type and other new Python constructs. E.g.

>>> class A(): pass
...
>>> type(A())
<type 'instance'>  <--- not good enough
>>> class A(object): pass
...
>>> type(A())
<class '__main__.A'> <---- now we are talking

Lists don't have indexes

Actually, they do. From the official tutorial:

Like string indices, list indices start at 0, and lists can be sliced, concatenated and so on:

A forum software is almost always a server-side web application which runs on a servlet container (Tomcat, Jetty) and is powered by a view technology like raw JSP's or JSF. As far as suggestions go, it really depends since the web-development landscape is pretty much saturated with a lot of technologies. One way would be to go the raw JSP route which is a bit painful/verbose and is as primitive as it gets (Servlets are not really a view technology).

If you are doing it for fun/learning, then going the JSP way would teach you a lot of things. If you are doing it with the intent of making it big with your software, using a framework is pretty much a requirement to shorten the time-to-market. There are three big/famous ones which come to mind:

• Vaadin
• Spring MVC
• Play

Like any other technology out there, you'll have to play with a bunch of frameworks to understand which one is a perfect fit for you. Unfortunately, there is no easy way out and picking up a forum software as your first software is a tough nut to crack IMHO especially if you are new to Java. Good luck.

Does that JAR file really have a space in between "System" and "FRONT". If yes, I guess you'll need to enclose the entire thing in quotes. Something like: java -jar "System FRONT.jar".

For some reason your app can't find the aspectjweaver.jar file. Are you sure you have that file in your runtime classpath? If you can find it, open up the JAR file and make sure you have the org/aspectj/lang/Signature file in it.

so like admins are working on daniweb, is this a full time job for them ? I mean is it their part time job or complete full time work ?

It depends. I'm one of the admins who isn't strictly employed by Daniweb/Dani. I contribute to Daniweb in my free time just like the other moderators here.

Davey and Deceptikon are employed by Dani for being a staff writer and Daniweb developer respectively though I can't comment on the "full time" part.

secondly, like sanjay is indian, so is he working from india ?

Yes, I "contribute" from India.

So they all work sitting in on place ? strange !

"Come together" as in bring together as a group of tight knit people who contribute to/work towards the betterment of Daniweb. We don't actually sit or "work" from a single place.

That really shouldn't be happening. For the time being, go to the profile page and check the 'disable ads' checkbox. See if that makes a difference. Hopefully Dani will pick up this bug report when she is online.

Maybe the reason for the threads dating back 2 weeks is because people feel intimidated when looking in the section, and possibly feel like their question wont be answered.

Well, in that case, splitting that forum in other sub-forums will only make it worse. We now have three sub-forums with threads dating back 4 weeks on the front page.

Thats really how I feel when I go into it(which is why I havent posted in there yet).

Well, for a sub-forum/category to thrive, there has to be balanced activity i.e. a group of people who can respond to queries and a group of people who have queries. Looking at the Java and the C++ forums, you can clearly see that there is a lot of activity in terms of questions and a lot of feedback given by old-timers. IMO unless a balance of these two entities is established, it is difficult to get a decent activity in any forum. It's quite possible that the Mobile Development forum might be lacking both right now. Or maybe what you say is indeed correct in which case we might need a bit more feedback from others to confirm it.

Nitin, I don't think it's reasonable to coax someone to reply to threads they aren't interested in. Further coaxing/requesting would just make them lose interest in replying to any of your threads. Let's just respect each other's preferences, shall we?

What would you think about having the Mobile Section split up?

IMO Daniweb currently has a lot of categories/sub-divisions right now. I mean look at the number of forums and sub-forums. This is one of the reason why tagging was introduced and everyone is pretty much encouraged to use tagging to improve post/thread visibility (though I agree it isn't followed a lot many times).

Secondly, the front page of Mobile development still shows threads 2 weeks back. This is pretty low activity to warrant 3 new forums. We normally tend to split forums if we find a lot of activity and in case it is a lot of effort to identify the programming language/technology used by just looking at the thread. For e.g. splitting C/C++ forum into separate forums.

If you will have a go through the archives of this "Daniweb Feedback Section", you'll come across a lot of threads with similar suggestions and responses from admins/moderators as to why new forums are generally not added.

Good list though I feel the section "not good enough" is confusing IMO. You put "C++ Primer Plus" in there and then go out to say that it might be a good fit if the OP has some prior programming experience.

I can think of two books to add on to the above list:

• Programming: Principles and Practice using C++ which I think is good enough for beginner/intermediate C++ programmers. One word of caution though; the author uses an external lib for demonstrating the examples in the book. It is assumed that the beginner has someone whom he/she can catch and get all the setup done. Setting up a new library/headers in Visual Studio is not a beginner if you know what I'm talking about :)
• API Design for C++ Not exactly a book just about API design but also contains bits and pieces of generic C++ wisdom. Obviously an intermdediate/advanced level book. Teaches you why you should put in more thought before attempting to write an API, the implications of all the code you write etc.

Nice work folks! Also one more thing which bugs me: any way you can refresh the page after marking forums as read? The lack of prominent visual feedback sometimes makes me want to double check. Not frightfully necessary, just something I miss from the vBulletin days.

The name has changed; you can now find the new button at the bottom left on the screen just below the last post. Here is a screenie showing it. Also, just for the record, only the "thread creator" or the moderator/admin team can mark threads as solved. It seems that you posted the question using your facebook login and now want to mark it as solved by using your old Daniweb ID. I'm not sure if that's possible but Dani should be able to clarify on this given that facebook login was recently added.

Also mods rely on the "flag bad post" reports by regulars to keep the forum clean so as long as any "regular" flags off-topic posts, it would be a big help and should make the life of moderators easier.

Also, to kickstart the thread, it will be a good idea to "mimic" the one in the Python forum and let the regulars decide the direction which the thread should take.

I have replied to James in the mod section and I'll reply here again. I'm favour of a new sticky thread as long as it stays on-topic and doesn't become a dumping ground for "plz halp me" posts. Someone will also need to ensure that "reponses" to the challenges/projects are not posted in the same thread so as to clutter it. It's a difficult task (e.g. take a look at the number of deleted posts in the current Java forum sticky) but if the Java forum members can pull it off, it would be a nice addition to the forum. That being said, I approve of the idea and would be more than happy if James lead the initiative.

Mel, it seems like the book isn't free; it costs around $20 with a sample chapter one available for preview.

The problem is that I need to know that file name to later discard it.

Two solutions:

• If you really need to discard it as soon as the operation/request is done, make sure you pass around the file name "across" the layers of your code (probably wrapped up in some request object). Plus, temporary file is just like any other file; it has a name and other attributes.
• If the files are small and if you can affrod to cleanup all the files later on i.e. after the JVM/server terminates gracefully, invoke the deleteOnExit method on that file object which will ensure that the files are physically deleted when the JVM exits. Another alternative would be to cleanup the temp area by a batch job/script when the server is restarted.

I DO though use a temp file called temp.txt (literally) which is sometimes when I try to access it with more than one user at a time, it spits out a error because it cant be found.

That's not good; using a common file name which can be used by multiple threads is not a good idea. The java.io.File class has a method for creating a random named temporary file. Use that if all you want to do is access the file just for a single request.

Exactly. My code tries to access the database continually which is were the main problem is.

Accessing the database continuously isn't the problem. If you have used the stock JDBC code, it should just work. Make sure you use transactions if you want a certain sequence of steps to be atomic. Reading through the JDBC official tutorials should be a good start in case you don't know about them.

What other information do you need? Ill try to give it to you.

I don't need any other information. Unless you post specific exception stack traces of specific parts of the code which you are stuck with, there isn't much I can help with.

Hashing always happens at the binary level i.e. with bytes and not text. Hashing a .class file is in no way different that hashing a .avi file. If you'll notice in my original snippet, I hash the underlying bytes of the line read and not the line itself.

That being said, what kind of directions do you need? Hashing a .class file is as simple as running it through the code I posted but instead using a FileInputStream (since we want to read raw bytes) though I really see no use for this sort of stuff. If you need protection, use the JAR signer mentioned by James. Or a very simple utility like Proguard which provides the first line of defense by obfuscating the jar file.

The problem is that once the member is taken to an "old" thread via the "related article" link, the reply box doesn't show "how" old the original question is. It is kind of given that new members will think that it is OK to respond to the thread. For e.g. one of the articles I navigated to, which was solved 8 years back just shows me "this thread has been solved".

I don't think that is enough to stop newbies from resurrecting old stuff. I think a bit more detail like "This thread is XX years old; if you want to ask a new question pertaining to this topic, please create a new thread" with the "create a new thread" part linked to "create a new article" URL.

@kovidd: I have received your PM which brings this scammer to light. Unfortunately, you didn't include the member profile link or member name for me to take appropriate action. If possible, please include the same in your report PM's so that we can take prompt action. :)

These functions are called one-way hashes (as opposed to encryption-decryption which are often confused with hashing). There are multiple solutions to your problem. If you are reading the entire file in-memory as a single string, the simplest solution would be to just call hashCode method on that string. This is a pretty rudimentary solution which might raise some eyebrows though.

If you need real one-way hash algorithms, there are many out there, ranging from simple MD5 to SHA and others. MessageDigest class is your friend. A sample code which I found in the wild from here:

import java.security.MessageDigest;

reader = null; // buffered/file reader
MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
while ((line = reader.readLine()) != null) {  
  messageDigest.update(line.getBytes());
}
final String encryptedString = new String(messageDigest.digest());

BTW, what exactly are you trying to hash here? The source code in plain text or the .class files?

+ character has a special meaning when it comes to HTTP POST contents/URL etc. It is decoded to a "space". If you want a literal "plus" sign, you need to encode to something the server side encoder understands. This is where the URLEncoder class comes in. Make sure all the values on the RHS of your equal signs are url encoded with proper encoding.

Something like:

String mail = URLEncoder.encode("a+b@gmail.com", "UTF-8");
String pwd = URLEncoder.encode("yourpassword", "UTF-8");
String action = URLEncoder.encode("Login", "UTF-8");
// now create a POST data string out of these variables and submit them

Without specifics, it's kind of hard to suggest what you should try out. As already mentioned, web services implemented on the Java platform are by default multithread ready. You should try to investigate the errors you get and dig out the underlying problem.

And like I mentioned, I also deal with file systems (writing/reading/etc files/folders) so yes, those are 2 shared resources I use which may cause problems.

Just to be clear here, using the FileSystem doesn't cause any problems. As long as the different threads are writing to different files, the OS takes care of the concurrency. The problem comes when two or more users try to access the same resource. If your code is simply writing to a file which has a unique name for each user request, you should be good to go.

It is not a servlet. It uses the Axis2 framework

AFAIK, Axis2 uses servlet specification under the hood for serving the content i.e. it runs on a servlet container like Tomcat, Jetty etc. Aren't you using one of these for hosting your web service?

Come to think of it, what makes you say that the current service is one thread / one user? As always, you just have to make sure you are properly handling the shared resources (databases, file systems etc.) and the concurrency can be easily taken care by the framework.

That's really great news, good luck with the interviews!

Not enough details. When you say web service, what does your current service do? "Official" web services fall under two categories: SOAP and REST with SOAP IMO being the more complicated one. These typically run in a web container which automatically helps you take advantage of the servlet specification and implementation (which is also used by web applications). As a starting point look at Resteasy and Restlet frameworks.

Some general advice. Don't use StringTokenizer; the Javadocs clearly state that it's a legacy class. Use the split method of the String class instead. Never catch exceptions only to print out something. Make sure you either propagate them, log them to a file/console or at least print the stack trace. The cast to String on line 62 is unnecessary. Calling matches on the String object compiles the passed in pattern for each iteration. If your regex doesn't change, consider creating/compiling a pattern just once and reusing it for different strings.

Regarding your problem, it seems you need to match words which have a c followed by e in a case insensitive manner. The trick is to use character classes i.e. use the pattern as .*[Cc].*[Ee].*. But use of wildcards at the start of string triggers a lot of backtracking so your pattern can be simply reduced to [Cc].*[Ee] along with using the find method of the Matcher class instead of matches. The difference between those two methods is explained here.

Whoops, my bad, totally missed that part. I read a post somewhere claiming that Java with jBlas takes a the same amount of time as R for the given test case; I guess it was for a specific use case. I would totally recommend hitting the jBlas mailing list since they might be able to suggest something out of their own experiences. If you already have and the reply was not satisfactory, maybe try to max out the performance by branching out computations to different threads and then merging them (if it's possible).

AFAIK, writing number crunching algorithms in pure Java never was a viable solution. Scientific Java applications typically use third party libraries tuned towards doing fast math operations. Though I haven't personally worked with it, take a look at JBlas. R performs better because I think it is a language specifically tuned for statistical computing.

Looks good. What is the exact error you are getting (complete trace)? Also, are you sure you don't have multiple Java versions installed? Which JVM does the Eclipse refer to? What does java -version show?

Important details are missing from your post. Which OS (Win 7 64 or 32 bit)? Which Java version (32 or 64 bit JVM; try doing java -version at the command line)?

If you are using a 32 bit JVM, you need to install 32 bit SWT. Likewise, for convinience, make sure everything is 64 bit (i.e. Java and SWT) in case your OS is 64 bit.

Your situation sounds a bit similar to what I've been through in the past so I'll try to put my 2 cents here. The wall of text presented below assumes that you want to land up in a good company and become a better programmer, not just the former.

Is it better to learn a maximum langage syntax, so im not limited to php, c and java or i better go deeper in 1 langage so i really get good at it and apply only on that langage, so far i really like Java?

Programming is not just about knowing the syntax; it's more about implementing your "logical problem solving" constructs. Let's say you want to write a method which returns a toString implementation of an array. No matter what the language, the core concept of this little exercise remains the same. Sure, you have to know Java to write it in Java, but if your only strength is the "syntax", then you would find yourself struggling with code even though you know Java. Try not to take on more than 3 langauges when starting out because it might turn out real confusing with your language expertise kind of "spread out".

nearly the same question as 1, but about the field of interest. should i take 1 field of expertise and develop my knowledge on that, exemple: its been 9 months, that i work around communication and the asterisk platform, going deeper in communication is good or …

can i private msg you for carreer tips

If you have career questions related to Java, I think creating a new topic in this forum might help you get more responses given we have a healthy population of professional Java developers here with varying backgrounds.

The actual differences can be found here. And yes, Glassfish as an application container provides many more features when compared to a servlet container like Tomcat.

Also, depending on the complexity of your application to be ported, you should look into other lightweight alternatives like the Spring stack in case you are looking for migrating an enterprise or simple web app.

No, it's not a security issue. The code doesn't behave as expected because the way HTTP protocol works.

@bloodblender:

HTTP protocol deals with resources, not files. Plus, it defines VERBS as part of its specification. When you issue a file read request, what happens under the hood is that the code sends across a "GET" HTTP request which returns the resource present at the location http://blah/something.txt which in this case is a text file. If you need to update the resource, you'll have to satisfy two conditions:

• Issue a POST HTTP request with the contents of the file as the payload
• Make sure the server code supports the POST request and knows that it has to update the "text" file

What exactly is this server running? Apache HTTP server? How are you currently uploading the modified files to the server? Can't you do the same with your code?

I couldn't find it. Turns out it wasn't included in my jdk.

If you are using JDK 1.5+, the visualvm binary should be present in the bin directory; not sure why it isn't in your case.

Does et load a .class file per instance or per class?

.class files are loaded once per classloader. Unless you have a web application, in normal cases, all .class files will be loaded only once. But once you start loading around thousand classes with each having a dependency of their own, it doesn't take time for memory consumed to build up.