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  • What is the best practice for adding persistence to an MVC model?

    - by etheros
    I'm in the process of implementing an ultra-light MVC framework in PHP. It seems to be a common opinion that the loading of data from a database, file etc. should be independent of the Model, and I agree. What I'm unsure of is the best way to link this "data layer" into MVC. Datastore interacts with Model //controller public function update() { $model = $this->loadModel('foo'); $data = $this->loadDataStore('foo', $model); $data->loadBar(9); //loads data and populates Model $model->setBar('bar'); $data->save(); //reads data from Model and saves } Controller mediates between Model and Datastore Seems a bit verbose and requires the model to know that a datastore exists. //controller public function update() { $model = $this->loadModel('foo'); $data = $this->loadDataStore('foo'); $model->setDataStore($data); $model->getDataStore->loadBar(9); //loads data and populates Model $model->setBar('bar'); $model->getDataStore->save(); //reads data from Model and saves } Datastore extends Model What happens if we want to save a Model extending a database datastore to a flatfile datastore? //controller public function update() { $model = $this->loadHybrid('foo'); //get_class == Datastore_Database $model->loadBar(9); //loads data and populates $model->setBar('bar'); $model->save(); //saves } Model extends datastore This allows for Model portability, but it seems wrong to extend like this. Further, the datastore cannot make use of any of the Model's methods. //controller extends model public function update() { $model = $this->loadHybrid('foo'); //get_class == Model $model->loadBar(9); //loads data and populates $model->setBar('bar'); $model->save(); //saves } EDIT: Model communicates with DAO //model public function __construct($dao) { $this->dao = $dao; } //model public function setBar($bar) { //a bunch of business logic goes here $this->dao->setBar($bar); } //controller public function update() { $model = $this->loadModel('foo'); $model->setBar('baz'); $model->save(); } Any input on the "best" option - or alternative - is most appreciated.

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  • Java EE Website Planning Questions

    - by Tom Tresansky
    I'm a .NET programming who is soon moving to the Java EE world. I have plenty of experience with .NET web technologies, web services, WebForms and MVC. I am also very familiar with the Java language, and have written a few servlets and modified a couple of JSP pages, but I haven't touched EE yet. I'd like to set up a public website using Java EE so I can familiarize myself with whats current. I'm thinking just a technology playground at this point with no particular purpose in mind. What Java technologies are the current hotness for this sort of thing? (For example, if someone asked me what I'd recommend learning to set up a new .NET site, I'd say use ASP MVC instead of WebForms and recommend LINQ-to-SQL as a quick, simple and widely used ORM.) So, what I'd like to know is: Is there a recommended technology for the presentation layer? Is JSP considered a good approach, or is there anything cleaner/newer/more widespread? Is Hibernate still widely used for persistence? Is it obsolete? Is there anything better out there? (I've worked with NHibernate some, so I wouldn't be starting from scratch.) Is cheap Java EE web hosting available? What should I know being a .NET web developer moving to the Java world?

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  • Do you think Scala will be the dominant JVM langauge, ie be the next Java? [on hold]

    - by user1037729
    From what I've read about Scala do far I think it has some nice features but I do not think it should be "the next Java". It might however end up being the next Java (due to fashion rather than fact) but lets not hope it does not... To me adds a lot of complexity over Java which is a simple and scalable language. Scala Pattern matching allows you to perform some type/value checking in a more concise way, this is possible in Java, Scala's pattern matching has a limit to it, you cannot continuously match deeper and deeper down the object graph, so why not just stick to Java and use decent invariants? Scala provides tuples, easy enough to make in Java, create a static factory method and it all reads nicely too. Scala provides mixins, why not just use composition? I believe Scala implicit's are bad, they can lead to code becoming complex and hard to maintain, explicitness is good. Scala provides closures, well they will be in Java 8 too. Scala has lazy keyword for lazy instantiation, this is easy enough to do in Java by calling a getter which creates the instance when needed, no hidden magic here. Scala can be used with AKKA, well so can Java, there is an Java AKKA implementation. Scala offers addition functional features but these can all be created in Java, there are many frameworks with have implemented functional features in Java. All in all Scala seems to offer is addition complexity and thats it...

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  • Why isn't garbage collection being activated in my code? [migrated]

    - by Netmoon
    I have a foreach statement in my code, where each iteration calculates huge amounts of data and goes to the next iteration. I run this code, but when I read the log, I see there's a memory leak error. PHP.net says when this happens, using gc_enabled() is a good way to handle this. I've added these lines to last line of the foreach block: echo "Check GC enabled : " . gc_enabled(); echo "Number of affected cycles : " . gc_collect_cycles(); And this is the output: Check GC enabled : 1 Number of affected cycles : 0 Why do cycles exist, but the affected cycles is 0?

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  • What should the memory configuration be?

    - by AngryHacker
    We have a server (ProLiant DL585 G1 by HP), which hosts Windows 2003 x64 R2 with SQL Server 2005 x64 and a host of other apps. It currently has 6GB of RAM. We are currently very memory constrained and it's clear that we need to get more memory. 8GB will probably do the trick, however, we are not sure as to what memory configuration will give us the biggest performance buck. Currently all 8 memory slots are filled (4 slots have 1GB chip, while the other 4 slots have 512MB chips). Should we throw the 512MB sticks away and just replace them all with 1GB sticks? If we decided to go with a higher memory configuration (e.g. 10GB or 12GB or 16GB), is it advisable to keep all the sticks of the same size or it does not matter? I was once told that interleaved memory requires (for better performance) that memory should be in multiples (e.g. 2 or 4 or 8 or 16, etc...). I am not even sure that the server has an interleaved configuration (and don't know how to find out), but is this true? Thanks.

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  • Is Akka a good solution for a concurrent pipeline/workflow problem?

    - by herpylderp
    Disclaimer: I am brand new to Akka and the concept of Actors/Event-Driven Architectures in general. I have to implement a fairly complex problem where users can configure a "concurrent pipeline": Pipeline: consists of 1+ Stages; all Stages execute sequentially Stage: consists of 1+ Tasks; all Tasks execute in parallel Task: essentially a Java Runnable As you can see above, a Task is a Runnable that does some unit of work. Tasks are organized into Stages, which execute their Tasks in parallel. Stages are organized into the Pipeline, which executes its Stages sequentially. Hence if a user specifies the following Pipeline: CrossTheRoadSafelyPipeline Stage 1: Look Left Task 1: Turn your head to the left and look for cars Task 2: Listen for cars Stage 2: Look right Task 1: Turn your head to the right and look for cars Task 2: Listen for cars Then, Stage 1 will execute, and then Stage 2 will execute. However, while each Stage is executing, it's individual Tasks are executing in parallel/at the same time. In reality Pipelines will become very complicated, and with hundreds of Stages, dozens of Tasks per Stage (again, executing at the same time). To implement this Pipeline I can only think of several solutions: ESB/Apache Camel Guava Event Bus Java 5 Concurrency Actors/Akka Camel doesn't seem right because its core competency is integration not synchrony and orchestration across worker threads. Guava is great, but this doesn't really feel like a subscriber/publisher-type of problem. And Java 5 Concurrency (ExecutorService, etc.) just feels too low-level and painful. So I ask: is Akka a strong candidate for this type of problem? If so, how? If not, then why, and what is a good candidate?

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  • is Java free for mobile development?

    - by exTrace101
    Q1. I would like to know if it's free for a developer (I mean, if I have to pay no royalties to Sun/Oracle) to develop (Android) mobile apps in Java? After reading this snippet about use of Java field, I'm getting the impression that Java is not free for mobile development, is that right? .."General Purpose Desktop Computers and Servers" means computers, including desktop and laptop computers, or servers, used for general computing functions under end user control (such as but not specifically limited to email, general purpose Internet browsing, and office suite productivity tools). The use of Software in systems and solutions that provide dedicated functionality (other than as mentioned above) or designed for use in embedded or function-specific software applications, for example but not limited to: Software embedded in or bundled with industrial control systems, wireless mobile telephones, wireless handheld devices, netbooks, kiosks, TV/STB, Blu-ray Disc devices, telematics and network control switching equipment, printers and storage management systems, and other related systems are excluded from this definition and not licensed under this Agreement... and from http://www.excelsiorjet.com/embedded/ Notice : The Java SE Embedded technology license currently prohibits the use of Java SE in cell phones. Q2. how come these plethora of Android Java developers aren't paying Sun/Oracle a dime?

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  • MMGR Questions, code use and thread-saftey

    - by chadb
    1) Is MMGR thread safe? 2) I was hoping someone could help me understand some code. I am looking at something where a macro is used, but I don't understand the macro. I know it contains a function call and an if check, however, the function is a void function. How does wrapping "(m_setOwner (FILE,_LINE_,FUNCTION),false)" ever change return types? #define someMacro (m_setOwner(__FILE__,__LINE__,__FUNCTION__),false) ? NULL : new ... void m_setOwner(const char *file, const unsigned int line, const char *func); 3) What is the point of the reservoir? 4) On line 770 ("void *operator new(size_t reportedSize)" there is the line "// ANSI says: allocation requests of 0 bytes will still return a valid value" Who/what is ANSI in this context? Do they mean the standards? 5) This is more of C++ standards, but where does "reportedSize" come from for "void *operator new(size_t reportedSize)"? 6) Is this the code that is actually doing the allocation needed? "au-actualAddress = malloc(au-actualSize);"

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  • JSP Model 2 Architecture and Dependency Injection

    - by Robert
    If I'm writing a web application that uses the model 2 architecture, is it possible to use the Google Guice framework (or really any IoC container)? The reason I ask this question is because everything I've researched about DI, IoC, et cetera always uses Spring, Hibernate or some other framework/container in their examples. I'm just using Java classes, controllers, and JSP's to build this application and I can't find any good documentation about the subject.

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  • EXC_BAD_ACCESS when simply casting a pointer in Obj-C

    - by AlexChilcott
    Hi all, Frequent visitor but first post here on StackOverflow, I'm hoping that you guys might be able to help me out with this. I'm fairly new to Obj-C and XCode, and I'm faced with this really... weird... problem. Googling hasn't turned up anything whatsoever. Basically, I get an EXC_BAD_ACCESS signal on a line that doesn't do any dereferencing or anything like that that I can see. Wondering if you guys have any idea where to look for this. I've found a work around, but no idea why this works... The line the broken version barfs out on is the line: LevelEntity *le = entity; where I get my bad access signal. Here goes: THIS VERSION WORKS NSArray *contacts = [self.body getContacts]; for (PhysicsContact *contact in contacts) { PhysicsBody *otherBody; if (contact.bodyA == self.body) { otherBody = contact.bodyB; } if (contact.bodyB == self.body) { otherBody = contact.bodyA; } id entity = [otherBody userData]; if (entity != nil) { LevelEntity *le = entity; CGPoint point = [contact contactPointOnBody:otherBody]; } } THIS VERSION DOESNT WORK NSArray *contacts = [self.body getContacts]; for (NSUInteger i = 0; i < [contacts count]; i++) { PhysicsContact *contact = [contacts objectAtIndex:i]; PhysicsBody *otherBody; if (contact.bodyA == self.body) { otherBody = contact.bodyB; } if (contact.bodyB == self.body) { otherBody = contact.bodyA; } id entity = [otherBody userData]; if (entity != nil) { LevelEntity *le = entity; CGPoint point = [contact contactPointOnBody:otherBody]; } } Here, the only difference between the two examples is the way I enumerate through my array. In the first version (which works) I use for (... in ...), where as in the second I use for (...; ...; ...). As far as I can see, these should be the same. This is seriously weirding me out. Anyone have any similar experience or idea whats going on here? Would be really great :) Cheers, Alex

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  • Trouble installing Java

    - by BRKsays
    I am running Ubuntu 12.04 LTS. I wanted to install Java and so I downloaded the 32-bit self extracting .bin file from http://www.java.com and tried to install it according to their instruction. First I made the file an executable one. Then created /usr/java/. After that I have to run this command: ./jre-7u<version>-linux-i586.bin. But I'm stuck here. My Java version is Java 6 u32. When I enter the command it says "no such file or directory". What to do? Please help. Also I'm trying to install 32-bit Java on my 64-bit Precise. Could that possibly be the problem? I tried to follow second answer by Jonas Christensen. I tried to open it, it says file is an unknown type. I tried the terminal command: ./jre-6u31-linux-i586.bin. But it gave this: Unpacking... Checksumming... Extracting... ./jre-6u32-linux-i586.bin: 86: ./jre-6u32-linux-i586.bin: ./install.sfx.5736: not found Failed to extract the files. Please refer to the Troubleshooting section of the Installation Instructions on the download page for more information.

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  • Installed Memory (RAM): 8GB (4GB Useable)

    - by Mike Bannister
    I have 4X 2GB RAM sticks installed, Windows 7 Ultimate x64 shows "Installed Memory (RAM): 8GB (4GB Useable)" in the system information. The motherboard says it supports up to 16GB of memory. I had Windows XP x64 and I'm pretty sure it was able to use all 8Gigs of memory. I've just formatted and am not burning through 4GB for sure. *The BIOS only show 4096MB while booting. I was only able to find one option relating to memory mapping and it took it from 4Gigs to 3 and change. CPU-Z shows all 4 sticks as 2048MB I went in to msconfig and checked the limits, they are not set. I tried resetting the CPU and RAM sticks 3 times, the CPU has no pins to be bent (flat contacts, I5) I rearranged all the RAM. I have separate video memory from the system memory. I have a 64 bit OS (I am 100% certain) Hardware: Memory: Four Corsair XMS3 TW3X4G1333C9AG Motherboard: Asus P7P55D Pro CPU: Intel Core i5-760 BX80605I5760 Graphics: Two ZOTAC ZT-50401-10L GeForce GTX 550 Ti If anyone has new ideas or knows the exact setting in the bios, it would be greatly appreciated.

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  • Java vs. C# - Productivity perspective

    - by Edin Dazdarevic
    If you have a number of years experience in working with JAVA and a number of years experience in working with C# and .NET, I would value your opinion on software development productivity differences between these two environments. One of our customers is considering to technically replace their existing software solution. As the replacement will require approx. 10 - 15 man years work, a choice for JAVA or .NET, based on productivity differences between the them, may significantly influence the investment required and time-to-market. Would you be able to provide us, based on your honest and expert opinion, an indication of software development productivity differences between JAVA and C#/.NET? I would prefer to receive an answer as follows: My experience is based on X years experience working with JAVA and X years experience working with C#/.NET. JAVA is X% more productive then C#.NET or C#/.NET is X% more productive than JAVA if you take the the following into account . . . . . . . Thanks

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  • Java: immutability, overuse of stack -- better data structure?

    - by HH
    I overused hashSets but it was slow, then changed to Stacks, speed boost-up. Poly's reply uses Collections.emptyList() as immutable list, cutting out excess null-checkers. No Collections.emptyStack(). Combining the words stack and immutability, from the last experiences, gets "immutable stack" (probably not related to functional prog). Java Api 5 for list interface shows that Stack is an implementing class for list and arraylist, here. The java.coccurrent pkg does not have any immutable Stack data structure. The first hinted of misusing stack. The lack of immutabily in the last and poly's book recommendation leads way to list. Something very primitive, fast, no extra layers, with methods like emptyThing(). Overuse of stack and where I use it DataFile.java: public Stack<DataFile> files; FileObject.java: public Stack<String> printViews = new Stack<String>(); FileObject.java:// private static Stack<Object> getFormat(File f){return (new Format(f)).getFormat();} Format.java: private Stack<Object> getLine(File[] fs,String s){return wF;} Format.java: private Stack<Object> getFormat(){return format;} Positions.java: public static Stack<Integer[]> getPrintPoss(String s,File f,Integer maxViewPerF) Positions.java: Stack<File> possPrint = new Stack<File>(); Positions.java: Stack<Integer> positions=new Stack<Integer>(); Record.java: private String getFormatLine(Stack<Object> st) Record.java: Stack<String> lines=new Stack<String>(); SearchToUser.java: public static final Stack<File> allFiles = findf.getFs(); SearchToUser.java: public static final Stack<File> allDirs = findf.getDs(); SearchToUser.java: private Stack<Integer[]> positionsPrint=new Stack<Integer[]>(); SearchToUser.java: public Stack<String> getSearchResults(String s, Integer countPerFile, Integer resCount) SearchToUser.java: Stack<File> filesToS=Fs2Word.getFs2W(s,50); SearchToUser.java: Stack<String> rs=new Stack<String>(); View.java: public Stack<Integer[]> poss = new Stack<Integer[4]>(); View.java: public static Stack<String> getPrintViewsFileWise(String s,Object[] df,Integer maxViewsPerF) View.java: Stack<String> substrings = new Stack<String>(); View.java: private Stack<String> printViews=new Stack<String>(); View.java: MatchView(Stack<Integer> pss,File f,Integer maxViews) View.java: Stack<String> formatFile; View.java: private Stack<Search> files; View.java: private Stack<File> matchingFiles; View.java: private Stack<String> matchViews; View.java: private Stack<String> searchMatches; View.java: private Stack<String> getSearchResults(Integer numbResults) Easier with List: AllDirs and AllFs, now looping with push, but list has more pow. methods such as addAll [OLD] From Stack to some immutable data structure How to get immutable Stack data structure? Can I box it with list? Should I switch my current implementatios from stacks to Lists to get immutable? Which immutable data structure is Very fast with about similar exec time as Stack? No immutability to Stack with Final import java.io.*; import java.util.*; public class TestStack{ public static void main(String[] args) { final Stack<Integer> test = new Stack<Integer>(); Stack<Integer> test2 = new Stack<Integer>(); test.push(37707); test2.push(80437707); //WHY is there not an error to remove an elment // from FINAL stack? System.out.println(test.pop()); System.out.println(test2.pop()); } }

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  • can a OOM be caused by not finding enough contiguous memory?

    - by raticulin
    I start some java code with -Xmx1024m, and at some point I get an hprof due to OOM. The hprof shows just 320mb, and give me a stack trace: at java.util.Arrays.copyOfRange([CII)[C (Arrays.java:3209) at java.lang.String.<init>([CII)V (String.java:215) at java.lang.StringBuilder.toString()Ljava/lang/String; (StringBuilder.java:430) ... This comes from a large string I am copying. I remember reading somewhere (cannot find where) what happened is these cases is: process still has not consumed 1gb of memory, is way below even if heap still below 1gb, it needs some amount of memory, and for copyOfRange() it has to be continuous memory, so even if it is not over the limit yet, it cannot find a large enough piece of memory on the host, it fails with an OOM. I have tried to look for doc on this (copyOfRange() needs a block of continuous memory), but could not find any. The other possible culprit would be not enough permgen memory. Can someone confirm or refute the continuous memory hypothesis? Any pointer to some doc would help too.

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  • how to force operating system to give java more memory?

    - by Denny
    Hello, I've got problem with java jar files and memory. I use netbeans 6.7 to develop an application and this application need more memory to run because it converts another files. Whenever this application convert a 6-10 mb file, it'll crash. So I set netbeans VM Options : -Xms32m -Xmx256m and the application can convert 6-10mb files with no problem. I Clean and Build the project so it can make a jar file of my application. I run the jar on my computer and use jconsole to monitor the memory. The maximum memory to use by the application shows 256 mb. But whenever I move it to some other computers, it shows 65-66 mb on jconsole and the application will crash when convert 6-10 mb files. So I need to use command prompt : java -jar -Xmx256m myjar.jar to execute the jar with maximum memory Why it can be happen, in my computer the maximum memory shows 256 mb but on another computer 65-66 mb? Can I force another computer to give extra maximum memory to my application? Thank you for your answer. I'm sorry for my inadequate English. If you all find my question is hard to understand, please let me know. Best Regards Denny ps: fyi the computer i used to develop the application have 2gb ram, on the other computers i tested have 1-2 gb ram.

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  • Why is my program getting slower and slower ?

    - by RedWolf
    I'm using the program to send data from database to the Excel file . It works fine at the beginning and then becomes more and more slowly,finally it run out of the memory and the following error ocurrs: "java.lang.OutOfMemoryError: Java heap space...". The problem can be resolved by adding the jvm heap sapce.But the question is that it spends too much time to run out the program. After several minutes,it finished a loop with 4 seconds which can be finished with 0.5 seconds at the beginning . I can't found a solution to make it always run in a certain speed. Is it my code problem? Any clues on this? Here is the code: public void addAnswerRow(List<FinalUsers> finalUsersList,WritableWorkbook book){ if (finalUsersList.size() >0 ) { try { WritableSheet sheet = book.createSheet("Answer", 0); int colCount = 0; sheet.addCell(new Label(colCount++,0,"Number")); sheet.addCell(new Label(colCount++,0,"SchoolNumber")); sheet.addCell(new Label(colCount++,0,"District")); sheet.addCell(new Label(colCount++,0,"SchoolName")); sheet.setColumnView(1, 15); sheet.setColumnView(3, 25); List<Elements> elementsList = this.elementsManager.getObjectElementsByEduTypeAndQuestionnaireType(finalUsersList.get(0).getEducationType().getId(), this.getQuestionnaireByFinalUsersType(finalUsersList.get(0).getFinalUsersType().getId())); Collections.sort(elementsList, new Comparator<Elements>(){ public int compare(Elements o1, Elements o2) { for(int i=0; i< ( o1.getItemNO().length()>o2.getItemNO().length()? o2.getItemNO().length(): o1.getItemNO().length());i++){ if (CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && !CommonFun.isNumberic(o2.getItemNO().substring(0, o2.getItemNO().length()>3? 4: o2.getItemNO().length()-1))){ return 1; } if (!CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && CommonFun.isNumberic(o2.getItemNO().substring(0,o2.getItemNO().length()>3? 4:o2.getItemNO().length()-1))){ return -1; } if ( o1.getItemNO().charAt(i)!=o2.getItemNO().charAt(i) ){ return o1.getItemNO().charAt(i)-o2.getItemNO().charAt(i); } } return o1.getItemNO().length()> o2.getItemNO().length()? 1:-1; }}); for (Elements elements : elementsList){ sheet.addCell(new Label(colCount++,0,this.getTitlePre(finalUsersList.get(0).getFinalUsersType().getId(), finalUsersList.get(0).getEducationType().getId())+elements.getItemNO()+elements.getItem().getStem())); } int sheetRowCount =1; int sheetColCount =0; for(FinalUsers finalUsers : finalUsersList){ sheetColCount =0; sheet.addCell(new Label(sheetColCount++,sheetRowCount,String.valueOf(sheetRowCount))); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getSchoolNumber())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getDistrict().getDistrictNumber().toString().trim())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getName())); List<AnswerLog> answerLogList = this.answerLogManager.getAnswerLogByFinalUsers(finalUsers.getId()); Map<String,String> answerMap = new HashMap<String,String>(); for(AnswerLog answerLog :answerLogList ){ if (answerLog.getOptionsId() != null) { answerMap.put(answerLog.getElement().getItemNO(), this.getOptionsAnswer(answerLog.getOptionsId())); }else if (answerLog.getBlanks()!= null){ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getBlanks()); }else{ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getSubjectiveItemContent()); } } for (Elements elements : elementsList){ sheet.addCell(new Label(sheetColCount++,sheetRowCount,null==answerMap.get(elements.getItemNO())?"0":answerMap.get(elements.getItemNO()))); } sheetRowCount++; } book.write(); book.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (RowsExceededException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (WriteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

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  • Does the Java Memory Model (JSR-133) imply that entering a monitor flushes the CPU data cache(s)?

    - by Durandal
    There is something that bugs me with the Java memory model (if i even understand everything correctly). If there are two threads A and B, there are no guarantees that B will ever see a value written by A, unless both A and B synchronize on the same monitor. For any system architecture that guarantees cache coherency between threads, there is no problem. But if the architecture does not support cache coherency in hardware, this essentially means that whenever a thread enters a monitor, all memory changes made before must be commited to main memory, and the cache must be invalidated. And it needs to be the entire data cache, not just a few lines, since the monitor has no information which variables in memory it guards. But that would surely impact performance of any application that needs to synchronize frequently (especially things like job queues with short running jobs). So can Java work reasonably well on architectures without hardware cache-coherency? If not, why doesn't the memory model make stronger guarantees about visibility? Wouldn't it be more efficient if the language would require information what is guarded by a monitor? As i see it the memory model gives us the worst of both worlds, the absolute need to synchronize, even if cache coherency is guaranteed in hardware, and on the other hand bad performance on incoherent architectures (full cache flushes). So shouldn't it be more strict (require information what is guarded by a monitor) or more lose and restrict potential platforms to cache-coherent architectures? As it is now, it doesn't make too much sense to me. Can somebody clear up why this specific memory model was choosen? EDIT: My use of strict and lose was a bad choice in retrospect. I used "strict" for the case where less guarantees are made and "lose" for the opposite. To avoid confusion, its probably better to speak in terms of stronger or weaker guarantees.

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  • Problem launch Java on Debian: "error while loading shared libraries: libjli.so"

    - by aetaur
    I'm trying to launch Java: $ java -version java: error while loading shared libraries: libjli.so: cannot open shared object file: No such file or directory $ ldd /usr/lib/jvm/java-6-openjdk/jre/bin/java linux-gate.so.1 => (0xb779f000) libz.so.1 => /usr/lib/libz.so.1 (0xb7780000) libpthread.so.0 => /lib/i686/cmov/libpthread.so.0 (0xb7767000) libjli.so => /usr/lib/jvm/java-6-openjdk/jre/bin/../lib/i386/jli/libjli.so (0xb7762000) libdl.so.2 => /lib/i686/cmov/libdl.so.2 (0xb775e000) libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb7603000) /lib/ld-linux.so.2 (0xb77a0000 $ ls /usr/lib/jvm/java-6-openjdk/jre/bin/../lib/i386/jli/ libjli.so However Java does work under root: $ sudo java -version java version "1.6.0_18" OpenJDK Runtime Environment (IcedTea6 1.8.7) (6b18-1.8.7-2~lenny1) OpenJDK Client VM (build 14.0-b16, mixed mode, sharing) How can I launch Java as a regular user without errors?

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  • Wrong java -version being reported

    - by Malachi
    I am running Windows 7 Professional x64 and have the following Java versions installed: x64 C:\Program Files\Java jdk1.6.0_24 jdk1.7.0_04 jdk1.7.0_07 jre6 jre7 x86 C:\Program Files (x86)\Java jre1.6.0_07 jre6 jre7 in my environment variables I have my PATH containing C:\Program Files\Java\jdk1.6.0_24\bin and JAVA_HOME set to C:\Program Files\Java\jdk1.6.0_24\bin However running java -version reports java version "1.7.0_07" Java(TM) SE Runtime Environment (build 1.7.0_07-b10) Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode) How is this the case when there is no reference to this version of Java in my Environment variables. Any help on this issue would be great as I am trying to run Apache ANT using Java 1.6.

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  • java.io.EOFException while writing and reading froma servlet

    - by mithun1538
    Hello everyone, I have the following code on the applet side: URL servlet = new URL(appletCodeBase, "FormsServlet?form=requestRoom"); URLConnection con = servlet.openConnection(); con.setDoOutput(true); con.setDoInput(true); con.setUseCaches(false); con.setRequestProperty("Content-Type", "application/octet-stream"); ObjectOutputStream out = new ObjectOutputStream(con.getOutputStream()); out.writeObject(user);//user is an object of a serializable class out.flush(); out.close(); ObjectInputStream in = new ObjectInputStream(con.getInputStream()); status = (String)in.readObject(); in.close(); if("success".equals("status")) { JOptionPane.showMessageDialog(rootPane, "Request submitted successfully."); } else { JOptionPane.showMessageDialog(rootPane, "ERROR! Request cannot be made at this time"); } In the servlet side I recieve the code as follows: form = request.getParameter("form"); if("requestRoom".equals(form)) { String fullName, eID, reason; UserRequestingRoom user; try { in = new ObjectInputStream(request.getInputStream()); user = (UserRequestingRoom)in.readObject(); fullName = user.getFullName(); eID = user.getEID(); reason = user.getReason(); Class.forName("com.mysql.jdbc.Driver"); Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/chat_applet","root",""); PreparedStatement statement = con.prepareStatement("INSERT INTO REQCONFROOM VALUES(\"" + fullName + "\",\"" + eID + "\",\"" + reason + "\")"); statement.execute(); out = new ObjectOutputStream(response.getOutputStream()); out.writeObject("success"); out.flush(); } catch (Exception e) { e.printStackTrace(); out = new ObjectOutputStream(response.getOutputStream()); out.writeObject("fail"); out.flush(); } } When I click on the button that calls the code in the applet side, I get the following error: java.io.EOFException at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source) at java.io.ObjectInputStream$BlockDataInputStream.readShort(Unknown Source) at java.io.ObjectInputStream.readStreamHeader(Unknown Source) at java.io.ObjectInputStream.<init>(Unknown Source) at com.org.RequestRoomForm.requestActionPerformed(RequestRoomForm.java:151) **//Line 151 is "ObjectInputStream in..." line in the applet code** at com.org.RequestRoomForm.access$000(RequestRoomForm.java:7) at com.org.RequestRoomForm$1.actionPerformed(RequestRoomForm.java:62) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Window.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source) Why am I getting this error? I have flushed when I output, I have closed the connections also, yet I get the error. Any reason for this?

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  • Class Not found exception in JApplet.

    - by Nitesh Panchal
    Hello, I created a simple Applet using JApplet and everything seems to work fine but as soon i create an object of my userdefined class named ChatUser in my applet, i get this error :- SEVERE: java.lang.ClassNotFoundException: applet.ChatUser at com.sun.enterprise.loader.ASURLClassLoader.findClassData(ASURLClassLoader.java:713) at com.sun.enterprise.loader.ASURLClassLoader.findClass(ASURLClassLoader.java:626) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:604) at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:43) Any idea what can be wrong? It only happens when i create an object of any user defined class. Do i need to set some security settings or something? Please help :(

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  • Quickie Guide Getting Java Embedded Running on Raspberry Pi

    - by hinkmond
    Gary C. and I did a Bay Area Java User Group presentation of how to get Java Embedded running on a RPi. See: here. But, if you want the Quickie Guide on how to get Java up and running on the RPi, then follow these steps (which I'm doing right now as we speak, since I got my RPi in the mail on Monday. Woo-hoo!!!). So, follow along at home as I do the same steps here on my board... 1. Download the Win32DiskImager if you are on Windows, or use dd on a Linux PC: https://launchpad.net/win32-image-writer/0.6/0.6/+download/win32diskimager-binary.zip 2. Download the RPi Debian Wheezy image from here: http://files.velocix.com/c1410/images/debian/7/2012-08-08-wheezy-armel/2012-08-08-wheezy-armel.zip 3. Insert a blank 4GB SD Card into your Windows or Linux PC. 4. Use either Win32DiskImager or Linux dd to burn the unzipped image from #2 to the SD Card. 5. Insert the SD Card into your RPi. Connect an Ethernet cable to your RPi to your network. Connect the RPi Power Adapter. 6. The RPi will boot onto your network. Find its IP address using Windows Wireshark or Linux: sudo tcpdump -vv -ieth0 port 67 and port 68 7. ssh to your RPi: ssh <ip_addr_rpi> -l pi <Password: "raspberry"> 8. Download Java SE Embedded: http://www.oracle.com/technetwork/java/embedded/downloads/javase/index.html NOTE: First click accept, then choose the first bundle in the list: ARMv6/7 Linux - Headless EABI, VFP, SoftFP ABI, Little Endian - ejre-7u6-fcs-b24-linux-arm-vfp-client_headless-10_aug_2012.tar.gz 9. scp the bundle from #8 to your RPi: scp <ejre-bundle> pi@<ip_addr_rpi> 10. mkdir /usr/local, untar the bundle from #9 and rename (move) the ejre1.7.0_06 directory to /usr/local/java That's it! You are ready to roll with Java Embedded on your RPi. Hinkmond

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  • Four New Java Champions

    - by Tori Wieldt
    Four luminaries in the Java community have been selected as new Java Champions. The are Agnes Crepet, Lars Vogel, Yara Senger and Martijn Verburg. They were selected for their technical knowledge, leadership, inspiration, and tireless work for the community. Here is how they rock the Java world: Agnes Crepet Agnes Crepet (France) is a passionate technologist with over 11 years of software engineering experience, especially in the Java technologies, as a Developer, Architect, Consultant and Trainer. She has been using Java since 1999, implementing multiple kinds of applications (from 20 days to 10000 men days) for different business fields (banking, retail, and pharmacy). Currently she is a Java EE Architect for a French pharmaceutical company, the homeopathy world leader. She is also the co-founder, with other passionate Java developers, of a software company named Ninja Squad, dedicated to Software Craftsmanship. Agnes is the leader of two Java User Groups (JUG), the Lyon JUG Duchess France and the founder of the Mix-IT Conferenceand theCast-IT Podcast, two projects about Java and Agile Development. She speaks at Java and JUG conferences around the world and regularly writes articles about the Java Ecosystem for the French print Developer magazine Programmez! and for the Duchess Blog. Follow Agnes @agnes_crepet. Lars Vogel Lars Vogel (Germany) is the founder and CEO of the vogella GmbH and works as Java, Eclipse and Android consultant, trainer and book author. He is a regular speaker at international conferences, such as EclipseCon, Devoxx, Droidcon and O'Reilly's Android Open. With more than one million visitors per month, his website vogella.com is one of the central sources for Java, Eclipse and Android programming information. Lars is committer in the Eclipse project and received in 2010 the "Eclipse Top Contributor Award" and 2012 the "Eclipse Top Newcomer Evangelist Award." Follow Lars on Twitter @vogella. Yara Senger Yara Senger (Brazil) has been a tireless Java activist in Brazil for many years. She is President of SouJava and she is an alternate representative of the group on the JCP Executive Committee. Yara has led SouJava in many initiatives, from technical events to social activities. She is co-founder and director of GlobalCode, which trains developers throughout Brazil.  Last year, she was recipient of the Duke Choice's Award, for the JHome embedded environment.  Yara is also an active speaker, giving presentations in many countries, including JavaOne SF, JavaOne Latin Ameria, JavaOne India, JFokus, and JUGs throughout Brazil. Yara is editor of InfoQ Brasil and also frequently posts at http://blog.globalcode.com.br/search/label/Yara. Follow Yara @YaraSenger. Martijn Verburg Martijn Verburg (UK) is the CTO of jClarity (a Java/JVM performance cloud tooling start-up) and has over 12 years experience as a Java/JVM technology professional and OSS mentor in a variety of organisations from start-ups to large enterprises. He is the co-leader of the London Java Community (~2800 developers) and leads the global effort for the Java User Group "Adopt a JSR" and "Adopt OpenJDK" programmes. These programmes encourage day to day Java developer involvement with OpenJDK, Java standards (JSRs), an important relationship for keeping the Java ecosystem relevant to the 9 million Java developers out there today. As a leading expert on technical team optimisation, his talks and presentations are in high demand by major conferences (JavaOne, Devoxx, OSCON, QCon) where you'll often find him challenging the industry status quo via his alter ego "The Diabolical Developer." You can read more in the OTN ariticle "Challenging the Diabolical Developer: A Conversation with JavaOne Rock Star Martijn Verburg." Follow Martijn @karianna. The Java Champions are an exclusive group of passionate Java technology and community leaders who are community-nominated and selected under a project sponsored by Oracle. Java Champions get the opportunity to provide feedback, ideas, and direction that will help Oracle grow the Java Platform. Congratulations to these new Java Champions!

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