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• How do I call a JDialog made in one class from another class?

  - by Raptrex

  I have a class called recurring which has my JDialog that I made with the GUI editor in Netbeans. My second class is calendar, which has a button that I want to call the JDialog from the recurring class. How would I do this?

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• Is it possible to include JButton in a JTable?

  - by Benjamin Confino

  I have a JTable that stores the results of a database query, so far so good. What I want is for the last column in each table to have a clickible JButton that will open the edit screen for the object represented in that row, and that means the button will need to know the details of the first column in the table from its own row (the ID from the database). Any advice? I already tried just adding JButtons but they turned into Text when I tried to run it.

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• How to recover data from a table, and store that into list?

  - by Wilhelm

  How can I get ALL the data from a table of my DB (mySQL) using hibernate, and store the output into List of Objects? I'll use this List, to populate a JTable.

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• Casting of object for a class loaded at runtime

  - by Steven

  hi, i load a class using Class.forName(klassname,false,loader) After this i create an instance using klass.newInstance(); It returns an object type.I want to cast it to specific type(ie.Klassnamw instance).I used normal casting but it gets hung because it is not resolved during runtime.How can i cast it?Hellp

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• longest common subsequence

  - by davit-datuashvili

  i have following code public class LCS1 { public static String lcs(String a,String b) { String x; String y; int alen=a.length(); int blen=b.length(); if (alen==0 || blen==0) { return ""; } else if (a.charAt(alen-1)==b.charAt(blen-1)) { return lcs(a.substring(0,alen-1),b.substring(0,blen-1)); } else { x=lcs(a,b.substring(0,blen-1)); y=lcs(a.substring(0,alen-1),b); } return (x.length()>y.length()) ? x : y; } public static void main(String[]args){ String a="computer"; String b="houseboat"; System.out.println(lcs(a,b)); } } it should return "out" but returns nothing what is problem?

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• Pointers, links, object and reference count

  - by EugeneP

  String a = "a"; // allocate memory and write address of a memory block to a variable String b = "b"; // in a and b hold addresses b = a; // copy a address into b. // Now what? b value is completely lost and will be garbage collected //* next step a = null; // now a does not hold a valid address to any data, // still data of a object exist somewhere, yet we cannot get access to it. Correct me if there's a mistake somewhere in my reflexions. My question is: suppose anInstance object of type Instance has a property ' surname ' anInstance.getSurname() returns "MySurname". now String s = anInstance.getSurname(); anInstance = null; question is - is it true that getSurname value, namely MySurname will not be garbage collected because and only because it has active reference counter 0, and if other properties of anInstance have a zero reference counter, they'll be garbage collected?

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• Difference in Auditing and Logging?

  - by GK

  I have been coming across these two words more often but i didn't see much difference in these? I mean want to know are they used interchangeably or there are some differences in those two? Thanks.

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• Using switch and enumerations as substitute for named methods

  - by MatthewMartin

  This pattern pops up a lot. It looks like a very verbose way to move what would otherwise be separate named methods into a single method and then distinguished by a parameter. Is there any good reason to have this pattern over just having two methods Method1() and Method2() ? The real kicker is that this pattern tends to be invoked only with constants at runtime-- i.e. the arguments are all known before compiling is done. public enum Commands { Method1, Method2 } public void ClientCode() { //Always invoked with constants! Never user input. RunCommands(Commands.Method1); RunCommands(Commands.Method2); } public void RunCommands(Commands currentCommand) { switch (currentCommand) { case Commands.Method1: // Stuff happens break; case Commands.Method2: // Other stuff happens break; default: throw new ArgumentOutOfRangeException("currentCommand"); } }

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• Logback: Logging with two loggers

  - by gammay

  I would like to use slf4j+logback for two purposes in my application - log and audit. For logging, I log the normal way: static final Logger logger = LoggerFactory.getLogger(Main.class); logger.debug("-> main()"); For Audit, I create a special named logger and log to it: static final Logger logger = LoggerFactory.getLogger("AUDIT_LOGGER"); Object[] params = { new Integer(1) /* TenantID */, new Integer(10) /* UserID */, msg}; logger.info("{}|{}|{}", params); logback configuration: <logger name="AUDIT_LOGGER" level="info"> <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <pattern>%d{HH:mm:ss.SSS}|%msg%n </pattern> </encoder> </appender> </logger> <root level="all"> <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n </pattern> </encoder> </appender> </root> Problem: Messages logged through audit logger appear twice - once under the AUDIT_LOGGER and once under the root logger. 14:41:57.975 [main] DEBUG com.gammay.example.Main - - main() 14:41:57.978|1|10|welcome to main 14:41:57.978 [main] INFO AUDIT_LOGGER - 1|10|welcome to main How can I make sure audit messages appear only once under the audit logger?

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• Using exponential smoothing with NaN values

  - by Eric

  I have a sample of some kind that can create somewhat noisy output. The sample is the result of some image processing from a camera, which indicates the heading of a blob of a certain color. It is an angle from around -45° to +45°, or a NaN, which means that the blob is not actually in view. In order to combat the noisy data, I felt that exponential smoothing would do the trick. However, I'm not sure how to handle the NaN values. On the one hand, involving them in the math would result in a NaN average, which would then prevent any meaningful results. On the other hand, ignoring NaN values completely would mean that a "no-detection" scenario would never be reported. And just to complicate things, the data is also noisy in that it can get false NaN value, which ideally would be smoothed somehow to prevent random noise. Any ideas about how I could implement such an exponential smoother?

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• business object and codelist

  - by feiroox

  Hi How to design a business object? I have a library which returns me an Object which have ten lists of other different objects. I need to store it into database all. List of objects are often like: class Item { private int id; private String name; private double point; } But the name is often the same. Like basic title of the product or code. Containing from 3 characters up to 70characters. Should I make conversion for every Object to: (or something similar) class ConvertedItem { private int id; private int code; private double point; } And have a separated table of codes ( I guess around 60). Or do not bother with duplicated stuff? It's not mission critical app. What would you do in my case? thanks in advance

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• Where to put common setUp-code for differen testclasses?

  - by Benedikt

  I have several different test classes that require that certain objects are created before those tests can be run. Now I'm wondering if I should put the object initialization code into a separate helper class or superclass. Doing so would surely reduce the amount of duplicate code in my test classes but it would also make them less readable. Is there a guideline or pattern how to deal with common setUp-code for unit tests?

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• Setting up Matcher for String phrase match in file

  - by randomCoder

  Having trouble figuring out how to match a phrase string to a phrase in file stream. The file I'm dealing with contains random words such as: 3 little pigs built houses and 1 little pig went to the market etc. for many lines Using "little pig" as my pattern and matcher.find() I can locate 2 matches: "little pig" and "little pigs". However, I only want it to match "little pig". What can I do? I thought about using matcher.lookingAt() but I wouldn't know how to set a proper region when I can't rely on the file string phrases I'm matching being on separate lines.

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• Time complexity O() of isPalindrome()

  - by Aran

  I have this method, isPalindrome(), and I am trying to find the time complexity of it, and also rewrite the code more efficiently. boolean isPalindrome(String s) { boolean bP = true; for(int i=0; i<s.length(); i++) { if(s.charAt(i) != s.charAt(s.length()-i-1)) { bP = false; } } return bP; } Now I know this code checks the string's characters to see whether it is the same as the one before it and if it is then it doesn't change bP. And I think I know that the operations are s.length(), s.charAt(i) and s.charAt(s.length()-i-!)). Making the time-complexity O(N + 3), I think? This correct, if not what is it and how is that figured out. Also to make this more efficient, would it be good to store the character in temporary strings?

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• Grails query not using GORM

  - by Tihom

  What is the best way to query for something without using GORM in grails? I have query that doesn't seem to fit in the GORM model, the query has a subquery and a computed field. I posted on stackoverflow already with no response so I decided to take a different approach. I want to query for something not using GORM within a grails application. Is there an easy way to get the connection and go through the result set?

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• Keeping messages in queue in case of receiver crash

  - by John Doe

  Hi, We've a Spring JMS message listener container for receiving messages asynchronously. Using DefaultMessageListenerContainer and in sessionTransacted mode. I understand being in sessionTransacted mode means in case of an exception the message will be put back into the queue. But how can I make sure the message won't be deleted from the queue even if the receiver (which is picked the message) crashes or just the machine running it looses power? At first I thought CLIENT_ACKNOWLEDGE acknowledge mode should save me, but apparently it's not the case, Spring calls .acknowledge() no matter what. So here's my question, how can I guarantee the delivery? Using a custom MessageListenerContainer? Using a transaction manager?

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• Using HSQLDB in production environments

  - by lewap

  I want to use HSQLDB in a production environment for stroring some data in memory and for data export using files. Does anybody have experience with using hsqldb in production environments? Is hsqldb treating server resources gracefully and does it cleanup unused resources properly?

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• Hibernate/JPA DB Schema Generation Best Practices

  - by Bytecode Ninja

  I just wanted to hear the opinion of Hibernate experts about DB schema generation best practices for Hibernate/JPA based projects. Especially: What strategy to use when the project has just started? Is it recommended to let Hibernate automatically generate the schema in this phase or is it better to create the database tables manually from earliest phases of the project? Pretending that throughout the project the schema was being generated using Hibernate, is it better to disable automatic schema generation and manually create the database schema just before the system is released into production? And after the system has been released into production, what is the best practice for maintaining the entity classes and the DB schema (e.g. adding/renaming/updating columns, renaming tables, etc.)? Thanks in advance.

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• Exception durin processing XSLT transformation!

  - by Artic

  I'm usin such code to generate contents file. try { StreamResult result = new StreamResult(); TransformerFactory tf = TransformerFactory.newInstance(); for (String item: groups){ item = item.replaceAll(" ", "-").toLowerCase(); result.setOutputStream(new FileOutputStream(path+item+".html")); Templates templ = tf.newTemplates(xsltSource); Transformer transf = templ.newTransformer(); transf.clearParameters(); transf.setParameter("group", item); transf.transform(xmlSource, result); } } catch (TransformerConfigurationException e) { throw new SinkException(e.getMessage()); } catch (TransformerException e) { throw new SinkException(e.getMessage()); } But on second iteration I have an exception ERROR: javax.xml.transform.TransformerException: com.sun.org.apache.xml.internal.utils.WrappedRuntimeException: Read error Cann't understand what is the reason?

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• In JSF, how to handle repeating over a list that mutates

  - by Jon

  Hello, In a JSF page, I am iterating over a list of items provided by a session-scoped backing bean. The list needs to be kept up-to-date, so it is replaced with a fresh list every X minutes by a thread (in a thread-safe way). On my page, for each item I provide some text inputs and an "Update" button. If the list is refreshed before I hit "Update", the update does not happen (which is my problem). I happen to be using a4j:repeat, but I think this could also apply to other methods of iteration, including using dataTables. Any thoughts on how I can do this in a non-hackish way? Thanks!

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• Testing code that uses SoftReference<T>

  - by bmargulies

  To get any code with SoftReference<T> to be fully tested, one must come up with some way to test the 'yup, it's been nulled' case. One might more or less mock this by using a 'for-test' code path to force the reference to be null, but that won't manage the queue exactly as the GC does. I wonder if anyone out can share experience in setting up a repeatable, controlled, environment, in which the GC is, in fact, provoked into collecting and nulling?

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• Long running method causing race condition

  - by keeleyt83

  Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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• unable to catch org.hibernate.StaleObjectStateException while deleting record that doesn't exists in database

  - by JAB

  My application has a delete user option. Now in order to check concurrency condition I tried the following use case opened application in chrome and firefox browser. deleted user in firefox now trying to delete the same user in chrome browser I get exception org.hibernate.StaleObjectStateException .. which is right .. since I am trying to delete an object which doesn't exists. But I am not able to catch this exception try{ getHibernateTemplate().delete(userObj); } catch (StaleObjectStateException e) { e.printStackTrace(); } How do i catch this exception ??

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• Ref to map vs. map to refs vs. multiple refs

  - by mikera

  I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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• Question about factory classes

  - by devoured elysium

  Currently I have created a ABCFactory class that has a single method creating ABC objects. Now that I think of it, maybe instead of having a factory, I could just make a static method in my ABC Method. What are the pro's and con's on making this change? Will it not lead to the same? I don't foresee having other classes inherit ABC, but one never knows! Thanks

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