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  • Hibernate: Check if object exists/changed

    - by swalkner
    Assuming I have an object Person with long id String firstName String lastName String address Then I'm generating a Person-object somewhere in my application. Now I'd like to check if the person exists in the database (= firstname/lastname-combination is in the database). If not = insert it. If yes, check, if the address is the same. If not = update the address. Of course, I can do some requests (first, try to load object with firstname/lastname), then (if existing), compare the address. But isn't there a simpler, cleaner approach? If got several different classes and do not like to have so many queries. I'd like to use annotations as if to say: firstname/lastname = they're the primary key. Check for them if the object exists. address is the parameter you have to compare if it stayed the same or not. Does Hibernate/JPA (or another framework) support something like that? pseude-code: if (database.containsObject(person)) { //containing according to compound keys if (database.containsChangedObject(person)) { database.updateObject(person); } } else { database.insertObject(person); }

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  • Finding key Solr performance metrics

    - by Mike Malloy
    To improve performance of Solr find your slowest searches, monitor query results, cache hit rate and cache size, document cache and filter cache; find problems with Solr update handlers by tracking index operations and document operations. There is a tool from New Relic which may help. http://www.newrelic.com/solr.html

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  • Replacing ORM schema without dropping the entire data

    - by Udi
    Hey, I'm using OpenJPA as a JPA provider. Is there a way in which I can recreate the database tables (When an entity changes) without dropping the entire data? When an entity changes, I drop and create every table in the store, and obviously lose the data within. Is there a tool or product to keep the data somehow? Thanks, Udi

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  • Setting a value into a object using reflection

    - by marionmaiden
    Hello I have an object that has a lot of attributes, each one with it's getter and setter. Each attribute has a non primitive type, that I don't know at runtime. For example, what I have is this: public class a{ private typeA attr1; private typeB attr2; public typeA getAttr1(){ return attr1; } public typeB getAttr2(){ return attr2; } public void setAttr1(typeA at){ attr1 = at; } public void setAttr2(typeB at){ attr2 = at; } } public class typeA{ public typeA(){ // doesn't matter } } public class typeB{ public typeB(){ // doesn't matter } } So, using reflection, I obtained the setter method for an attribute. Setting a value in the standard way is something like this: a test = new a(); a.setAttr1(new typeA()); But how can I do this using reflection? I already got the setAttr1() method using reflection, but I don't know how to create a new typeA object to be inserted in the setter.

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  • How can user change the jre parameter values after the exe is generated in Launch4j?

    - by Wing C. Chen
    Is it possible to change the jre parameter values after the exe file is generated through Launch4j? The ideal scenario is like this: The default parameter values are applied when the program is started. However, when the user wants to change some jre parameter values, he goes to a .ini file, MyProgram.ini for example, changes the values there, and the new values will be applied next time the program is started. I think eclipse uses the same way for its memory and some other parameter settings.

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  • How to get equivalent of ResultSetMetaData without ResultSet

    - by javanix
    Hey Guys - I need to resolve a bunch of column names to column indexes (so as to use some of the nice ResultSetMetaData methods). However, the only way that I know how to get a ResultSetMetaData object is by calling getMetaData() on some ResultSet. The problem I have with that is that grabbing a ResultSet takes up uneccesary resources in my mind - I don't really need to query the data in the table, I just want some information about the table. Does anyone know of any way to get a RSMD object without getting a ResultSet (from a potentially huge table) first? Thanks!

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  • do I need to close an audio Clip?

    - by Michael
    have an application that processes real-time data and is supposed to beep when a certain event occurs. The triggering event can occur multiple times per second, and if the beep is already playing when another event triggers the code is just supposed to ignore it (as opposed to interrupting the current beep and starting a new one). Here is the basic code: Clip clickClip public void prepareProcess() { super.prepareProcess(); clickClip = null; try { clipFile = new File("C:/WINDOWS/Media/CHIMES.wav"); ais = AudioSystem.getAudioInputStream(clipFile); clickClip = AudioSystem.getClip(); clickClip.open(ais); fileIsLoaded = true; } catch (Exception ex) { clickClip = null; fileIsLoaded = false; } } public void playSound() { if (fileIsLoaded) { if ((clickClip==null) || (!clickClip.isRunning())) { try { clickClip.setFramePosition(0); clickClip.start(); } catch (Exception ex) { System.out.println("Cannot play click noise"); ex.printStackTrace(); } } } The prepareProcess method gets run once in the beginning, and the playSound method is called every time a triggering event occurs. My question is: do I need to close the clickClip object? I know I could add an actionListener to monitor for a Stop event, but since the event occurs so frequently I'm worried the extra processing is going to slow down the real-time data collection. The code seems to run fine, but my worry is memory leaks. The code above is based on an example I found while searching the net, but the example used an actionListener to close the Clip specifically "to eliminate memory leaks that would occur when the stop method wasn't implemented". My program is intended to run for hours so any memory leaks I have will cause problems. I'll be honest: I have no idea how to verify whether or not I've got a problem. I'm using Netbeans, and running the memory profiler just gave me a huge list of things that I don't know how to read. This is supposed to be the simple part of the program, and I'm spending hours on it. Any help would be greatly appreciated! Michael

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  • Why does "request.getUserPrincipal().getName()" sometimes return a blank string?

    - by Marcus
    Has somebody an idea, why the getName method of the requests getUserPrincipal Method sometimes provides an empty String? Most of the time it returns the correct user name but not every time. This behaviour does occur randonmly. I can start the application, run the command and it works. The next time I start the application and run the command (exactly the same way as before!) it does not work... Any ideas?

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  • Strange behaviour with GregorianCalendar

    - by Spark
    I just encountered a strange behaviour with the GregorianCalendar class, and I was wondering if I really was doing something bad. This only appends when the initialization date's month has an actualMaximum bigger than the month I'm going to set the calendar to. Here is the example code : // today is 2010/05/31 GregorianCalendar cal = new GregorianCalendar(); cal.set(Calendar.YEAR, 2010); cal.set(Calendar.MONTH, 1); // FEBRUARY cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH)); cal.set(Calendar.HOUR_OF_DAY, cal.getActualMaximum(Calendar.HOUR_OF_DAY)); cal.set(Calendar.MINUTE, cal.getActualMaximum(Calendar.MINUTE)); cal.set(Calendar.SECOND, cal.getActualMaximum(Calendar.SECOND)); cal.set(Calendar.MILLISECOND, cal.getActualMaximum(Calendar.MILLISECOND)); return cal.getTime(); // => 2010/03/03, wtf I know the problem is caused by the fact that the calendar initialization date is a 31 day month ( may ), which mess with the month set to february (28 days). The fix is easy ( just set day_of_month to 1 before setting year and month ), but I was wondering is this really was the wanted behaviour. Any thoughts ?

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  • struts2 validate

    - by teehoo
    In Struts2 you can change the method used for execution for an action by changing the method attribute in the following line: <action name="registerVal" class="cz.vutbr.fit.pishotel.model.action.Register" method="execute"> Is it possible to change the validation method used as well, or is the validate method name hardcoded.

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  • IDE support for Spring framework; Are they worth using?

    - by Zwei Steinen
    I'm using Intellij IDEA for IDE, and I like it a lot. However, it does not have any special "Spring support" (plug-ins/tools). My next project uses Spring (which I'm not very familiar with), and I'm wondering whether I should consider changing my IDE from early on; e.g. to SpringSource eclipse/Intellij IDEA Professional. Do you guys have any experience with these IDE-built-in Spring support? Is it worth using?

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  • How can I disable all images for an JFace menu but leave them enabled in the toolbar

    - by David
    If I create a set of actions to be used in a JFace application and I assign images to those actions, those images show up in both the toolbar (where I want them) and in the menus (where I don't want them). Other than supplying two completely separate sets of actions (which eliminates part of the point of actions in the first place), how can I arrange to have those images displayed ONLY in the toolbar, and have the menus display only text?

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  • JPA is not good enough

    - by Cristiano Sanchez
    Working in a medium size project during last 4 months - we are using JPA and Spring - I'm quite sure that JPA is not powerfull for projects that requires more than CRUD screen... Query interface is poor, Hibernate doesn't respect JPA spec all the time and lot of times I need to use hibernate classes, annotations and config. What do you guys think about JPA? Is it not good enough?

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  • problem with JMF !

    - by Razan
    Hi.. I have windows vista OS.. I Installed JMF to work with it.. but it seems I'm having some conflicts between Sound and JMF.. because after I installed JMF my projects that use Sound.. midi.. sequences.. are giving exceptions that they don't have some sound classes and so.. and when I removed JMF every thing went OK !! so what I'm gonna do?

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  • Netty options for real-time distribution of small messages to a large number of clients?

    - by user439407
    I am designing a (near) real-time Netty server to distribute a large number of very small messages to a large number of clients across the internet. In internal, go as fast as you can testing, I found that I could do 10k clients no sweat, but now that we are trying to go across the internet, where the latency, bandwidth etc varies pretty wildly we are running into the dreaded outOfMemory issues, even with 2 gigs of RAM. I have tried various workarounds(setting the socket stack sizes smaller, setting high and low water marks, cancelling things that are too old), and they help a little, but they seem to only help a little bit. What would some good ways to optimize Netty for sending large #s of small messages without significant delays? Also, the bulk of the message only consists of one kind of message that I don't particularly care if it doesn't arrive. I would use UDP but because we don't control the client, thats not really a possibility. Is it possible to set a separate timeout solely for this kind of message without affecting the other messages? Any insight you could offer would be greatly appreciated.

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  • How can i underline a text in JDK5, NOT JDK6

    - by Serkan Kasapbasi
    when i search internet i have found a way to underline font like this, Font f=jLabel1.getFont(); Map<TextAttribute,Object> map = new Hashtable<TextAttribute,Object>(); map.put(TextAttribute.UNDERLINE,TextAttribute.UNDERLINE_ON); f=f.deriveFont(map); jLabel1.setFont(f); it works well on jdk6, however it doesnt work on jdk5, and it doesnt warn about anything. first, how can i get same effect on jdk5? second, why is there a TextAttribute.UNDERLINE constant, if it doesnt work?

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  • commons-exec: Executing a program on the system PATH?

    - by Stefan Kendall
    I'm trying to execute a program (convert from ImageMagick, to be specific) whose parent folder exists on the path. Ergo, when I run convert from the command line, it runs the command. The following, however, fails: String command = "convert" CommandLine commandLine = CommandLine.parse(command); commandLine.addArgument(...) ... int exitValue = executor.execute(commandLine); If I specify the full path of the convert executable (C:\Program files\...) then this code works. If I don't do this, I get an exception thrown with exit value 4. How do I get commons-exec to recognize the system path?

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