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• WSDL AXIS Arrays

  - by SKS

  I am trying to create wsdl definition for the below soap response, < reasonCode Required="TRUE" < ValidCodeRR< /ValidCode < ValidCodeRB< /ValidCode < ValidCodeRT< /ValidCode < ValidCodeAR< /ValidCode < /reasonCode Below is the wsdl definition I have, < xsd:complexType < xsd:sequence < xsd:element name="ValidCode" type="xsd:string" minOccurs="0" maxOccurs="20" / < /xsd:sequence < xsd:attribute name="Required" type="xsd:string" / < /xsd:complexType < /xsd:element I am using Axis 1 to generate the webservices client and for the above wsdl definition, the tool generates the reasonCode as a string array like below. private java.lang.String[] reasonCode It ignores the attribute required. Does anyone know how to write wsdl defintion, such that axis creates reasonCode as an element with an attribute "required". Any help on this would be greatly appreciated. Thanks, SK

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• Broken console in Maven project using Netbeans

  - by Maciek Sawicki

  Hi, I have strange problem with my Neatens+Maven installation. This is the shortest code to reproduce the problem: public class App { public static void main( String[] args ) { // Create a scanner to read from keyboard Scanner scanner = new Scanner (System.in); Scanner s= new Scanner(System.in); String param= s.next(); System.out.println(param); } } When I'm running it as Maven Project inside Netbeans console seems to be broken. It just ignores my input. It's look like infinitive loop in System.out.println(param);. However this project works fine when it's compiled as "Java Aplication" project. It also works O.K. if I build and run it from cmd. System info: Os: Vista IDE: Netbeans 6.8 Maven: apache-maven-2.2.1 //edit Built program (using mavean from Netbeans) works fine. I just can't test it using Net beans. And I think I forgot to ask the question ;). So of course my first question is: how can I fix this problem? And second is: Is it any workaround for this? For example configuring Netbeans to run external commend line app instead of using built in console.

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• Google app engine: Poor Performance with JDO + Datastore

  - by Bosh

  I have a simple data model that includes USERS: store basic information (key, name, phone # etc) RELATIONS: describe, e.g. a friendship between two users (supplying a relationship_type + two user keys) I'm getting very poor performance, for instance, if I try to print the first names of all of a user's friends. Say the user has 500 friends: I can fetch the list of friend user_ids very easily in a single query. But then, to pull out first names, I have to do 500 back-and-forth trips to the Datastore, each of which seems to take on the order of 30 ms. If this were SQL, I'd just do a JOIN and get the answer out fast. I understand there are rudimentary facilities for performing joins across un-owned relations in a relaxed implementation of JDO (as described at http://gae-java-persistence.blogspot.com) but they sound experimental and non-standard (e.g. my code won't work in any other JDO implementation). Is this really my best bet? Otherwise, how do people extract satisfactory performance from JDO/Datastore in this kind of (very common) situation? -Bosh

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• Approach for fixing NoClassDefFoundError?

  - by DJC

  I'm seeing this question is getting asked a lot in many different contexts. Perhaps we can set some strategies for locating and fixing it? I'm noobish myself so all I can contribute are horror stories and questions, sorry... It seems this is thrown when a class is visible at compile time but not at run time... how can this happen? In my case I am developing an app that uses the Google APIs, in Eclipse, for the Android platform. I've configured the Project Properties / Java Build Path / Libraries to include the gdata .jars and all is well. When I execute in the emulator I get a force close and the logcat shows a NoClassDefFoundError on a simple new ContactsService("myApp"); I've also tried a new CalendarService("myApp") with the same results. Is it possible or desirable to statically bind at compile time to avoid the problem? How could dynamic binding of an add-on library work in the mobile environment anyway? Either it has to be bound into my .apk or else I need to "install" it? ... hmmm. Advice much appreciated.

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• Set size of JTable in JScrollPane and in JPanel with the size of the JFrame

  - by user1761818

  I want the table with the same width as the frame and also when I resize the frame the table need to be resized too. I think setSize() of JTable doesn't work correctly. Can you help me? import java.awt.Color; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.SwingUtilities; public class Main extends JFrame { public Main() { setSize(400, 600); String[] columnNames = {"A", "B", "C"}; Object[][] data = { {"Moni", "adsad", 2}, {"Jhon", "ewrewr", 4}, {"Max", "zxczxc", 6} }; JTable table = new JTable(data, columnNames); JScrollPane tableSP = new JScrollPane(table); int A = this.getWidth(); int B = this.getHeight(); table.setSize(A, B); JPanel tablePanel = new JPanel(); tablePanel.add(tableSP); tablePanel.setBackground(Color.red); add(tablePanel); setTitle("Marks"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { Main ex = new Main(); ex.setVisible(true); } }); } }

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• Using maven to distribute a swing application that can have each dependency individually tracked

  - by tms

  I'm moving my project to Maven and eventually OSGi. I currently distribute the project is a large Zip file with all the dependencies. Although my projects code is only 20% of the total package I have to redistribute all the dependency. With smaller independent modules this may be even less. Looking here on stack overflow it seems that to keep my current plan the maven-assembly-plugin should do the trick. I was considering having a base installer that would look at a XML manifest, then collect all the libraries that needed to be updated. This would mean that libraries that change occasionally would be downloaded less often. This also makes since for something like OSGi plugins (which could have independent release schedules). In essence I want my software to look and manage individual libraries, and download on demand (based on the manifest). I was wondering if there is a "maven way" of generating this Manifest and publishing all the libraries to a website? I believe the deploy life-cycle would do the second step. As an alternative, is there a OpenSource Java library that does this type of deployment? I don't want to embed Maven or something larger with the distributed code. The application is not for coders, the simpler the better, and the smaller the installer the better.

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• Custom Swing component: questions on approach

  - by phatmanace

  Hi Folks, I'm trying to build a new java swing component, I realise that I might be able to find one that does what I need on the web, but this is partly an exercise for me to learn ow to do this. I want to build a swing component that represents a Gantt chart. it would be good (though not essential for people to be able to interact with it (e.g slide the the tasks around to adjust timings) it feels like the best approach for this is to subclass JComponent, and override PaintComponent() to 'draw a picture' of what the chart should look like, as opposed to doing something like trying to jam everything into a custom JTable. I've read a couple of books on the subject, and also looked at a few examples (most notably things like JXGraph) - but I'm curious about a few things When do I have to switch to using UI delegates, and when can I stick to just fiddling around in paintcomponent() to render what I want? if I want other swing components as sub-elements of my component (e.g I wanted a text box on my gantt chart) can I no longer use paintComponent()? can I arbitrarily position them within my Gantt chart, or do I have to use a normal swing layout manager many thanks in advance. -Ace

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• How to disable scaling in JFreeChart?

  - by Alex Arnon

  Hi All, We're using JFreeChart to build an engine to display graphs. This is a web service that runs on Tomcat + Java 1.5.0, and renders charts to PNGs and JPEGs (using ChartUtilities.writeChartAs{PNG,JPEG}() ). We've run into a problem where JFreeChart seems to scale everything inside the Plot area, but only by a few pixels. The result is that the graph looks inconsistent, e.g.: Minor ticks are sometimes stretched horizontally, so that they seem to be two pixels wide instead of one. We use a small image in the top-right of the plot area as a watermark. This is stretched by one pixel horizontally and vertically somewhere near (but not exactly) its middle. Background grid lines seem to appear on sub-pixel boundaries. I have not found a way to create an accurately dotted grid line. We have tried both 1.0.9 and 1.0.13, with exactly the same results (except for the minor ticks, which were not available in the older version). Also, rendering the image to a Frame instead of JPEG/PNG produced an identical result. Help is greatly appreciated, in advance :)

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• What's the vbs code to schedule a task every time Windows starts up?

  - by Wing C. Chen

  I would like to know how to write up the vbs code to schedule a windows task to start a .exe program every time the Windows starts up. I found the following code online: strComputer = "." Set objWMIService = GetObject("winmgmts:" _ & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2") Set objNewJob = objWMIService.Get("Win32_ScheduledJob") errJobCreated = objNewJob.Create _ ("Notepad.exe", "********123000.000000-420", _ True , 1 OR 4 OR 16, , , JobID) Wscript.Echo errJobCreated But it only tells me how to schedule the task every on some specific days and hours. I thought of creating a windows service. However the following is the story why I must look for an alternative to it. I created a windows service with RunAsService for my java program wrapped with Janel. The Service worked fine when I first installed and started it. However, after restarting my windows xp, a dialog window poped out saying that my janel generated .exe file has crashed, with my RunAsService service kept on going. The service worked fine when I terminated the service and restarted it again manually. Nevertheless, the same crash happens over and over again every time I restart my Windows.

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• Logic for family tree program

  - by david robers

  Hi All, I am creating a family tree program in Java, or at least trying to. I have developed several classes: Person - getters and setter for name gender age etc FamilyMember - extends Person getters and setters for setting arents and children Family - which consists of multiple family members and methods for adding removing members FamilyTree which is the main class for setting relationships. I have two main problems: 1) I need to set the relationships between people. Currently I am doing: FamilyMember A, FamilyMember B B.setMother(A); A.setChild(B); The example above is for setting a mother child relationship. This seems very clunky. Its getting very long winded to implement all relationships. Any ideas on how to implement multiple relationships in a less prodcedural way? 2) I have to be able to display the family tree. How can I do this? Are there any custom classes out there to make life easier? Thanks for your time...

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• Third party multipart request in playframework

  - by Brian

  I'm making an application to post photos to yfrog and twitpic and I am having a little trouble figuring out how to set the parameters. Here is my code: public static Result index() { HttpClient httpclient = new DefaultHttpClient(); WSRequestHolder holder = WS.url("http://api.twitpic.com/2/upload.json"); holder.setHeader("Authorization", ""); return async(holder.post("").map(new Function<WS.Response, Result>() { public Result apply(WS.Response response) { return ok(response.getBody()); } })); } Now, I don't expect this to actually get an ok response from the server, as I am just testing the responses that I get back from the server, and that is one that says I need to provide the api key. I figured as much, but I'm not sure of the syntax for providing that parameter, as I need to also give the name of the file and the file. I tried setting holder.post("key=somekey"), with the hope that I would get a different error message (like the key you provided is invalid) but I just get the same error. I'm assuming that I probably need to send it in the for of a multipart request, but I am not very experienced with this kind of request and can't find any play documentation on how to create a multipart request, other than in an html form. Any suggestions and help will be much appreciated. And fyi, I do know that there are yfrog and twitpic java classes to handle this kind of stuff, but I want to do it myself, more so for learning how to do this kind of stuff. Thanks in advance!

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• Scala newbie vproducer/consumer attempt running out of memory

  - by Nick

  I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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• Problem in inferring instances that have integer cardinality constraint

  - by Mikae Combarado

  Hello, I have created an RDF/OWL file using Protege 4.1 alpha. I also created a defined class in Protege called CheapPhone. This class has a restriction which is shown below : (hasPrice some integer[< 350]) Whenever, a price of a phone is below 350, it is inferred as CheapPhone. There is no problem for inferring this in Protege 4.1 alpha. However, I cannot infer this using Jena. I also created a defined class called SmartPhone. This class also has a restriction which is shown below : (has3G value true) and (hasInternet value true) Whenever, a phone has 3G and Internet, it is inferred as SmartPhone. In this situation, there is no problem inferring this in both Protege and Jena. I have started to think that there is a problem in default inference engine of Jena. The code that I use in Java is below : Reasoner reasoner = ReasonerRegistry.getOWLReasoner(); reasoner = reasoner.bindSchema(ontModel); OntModelSpec ontModelSpec = OntModelSpec.OWL_MEM_MINI_RULE_INF; ontModelSpec.setReasoner(reasoner); // Create ontology model with reasoner support // ontModel was created and read before, so I don't share the code in order // not to create garbage here OntModel model = ModelFactory.createOntologyModel(ontModelSpec, ontModel); OntClass sPhone = model.getOntClass(ns + "SmartPhone"); ExtendedIterator s = sPhone.listInstances(); while(s.hasNext()) { OntResource mp = (OntResource)s.next(); System.out.println(mp.getURI()); } This code works perfectly and returns me the instances, but when I change the code below and make it appropriate for CheapPhone, it doesn't return anything. OntClass sPhone = model.getOntClass(ns + "CheapPhone"); Am I doing something wrong ?

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• JUnit test failing - complaining of missing data that was just inserted

  - by Collin Peters

  I have an extremely odd problem in my JUnit tests that I just can't seem to nail down. I have a multi-module java webapp project with a fairly standard structure (DAO's, service clasess, etc...). Within this project I have a 'core' project which contains some abstracted setup code which inserts a test user along with the necessary items for a user (in this case an 'enterprise', so a user must belong to an enterprise and this is enforced at the database level) Fairly simple so far... but here is where the strangeness begins some tests fail to run and throw a database exception where it complains that a user cannot be inserted because an enterprise does not exist. But it just created the enterprise in the preceding line of code! And there was no errors in the insertion of the enterprise. Stranger yet, if this test class is run by itself everything works fine. It is only when the test is run as part of the project that it fails! And the exact same abstracted code was run by 10+ tests before the one that fails! f I have been banging my head against a wall with this for days and haven't really made any progress. I'm not even sure what information to offer up to help diagnose this. Using JUnit 4.4, Spring 2.5.6, iBatis 2.3.0, Postgresql 8.3 Switching to org.springframework.jdbc.datasource.DriverManagerDataSource from org.apache.commons.dbcp.BasicDataSource changed the problem. Using DriverManagerDataSource the tests work for the first time, but now all of a sudden a lot of data isn't rolled back in the database! It leaves everything behind. All with no errors Tests fail when run via Eclipse & Maven Please ask for any info which may help me solve my problem!

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• make a thread which recieves values from other threads

  - by farteaga88

  This program in Java creates a list of 15 numbers and creates 3 threads to search for the maximum in a given interval. I want to create another thread that takes those 3 numbers and get the maximum. but i don't know how to get those values in the other thread. public class apple implements Runnable{ String name; int time, number, first, last, maximum; int[] array = {12, 32, 54 ,64, 656, 756, 765 ,43, 34, 54,5 ,45 ,6 , 5, 65}; public apple(String s, int f, int l){ name = s; first = f; last = l; maximum = array[0]; } public void run(){ try{ for(int i = first; i < last; i++ ) { if(maximum < array[i]) { maximum = array[i]; } } System.out.println("Thread"+ name + "maximum = " + maximum); }catch(Exception e){} } public static void main(String[] args){ Thread t1 = new Thread(new apple("1 ", 0, 5)); Thread t2 = new Thread(new apple("2 ", 5, 10 )); Thread t3 = new Thread(new apple("3 ", 10, 15)); try{ t1.start(); t2.start(); t3.start(); }catch(Exception e){} } }

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• How do I add mouseClicked event to a swing table?

  - by Ayelet

  Hi, I am a new, terribly green user of Swing. I managed to create a table class using examples from java.sun tutorials, and I managed to load data dynamically into it. I want to be able to react to a click on a row by displaying a dialog box. How do I add the event Handler that will identify the selected row number? The main function code: public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { try { MainWindow window = new MainWindow(); window.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. createAndShowGUI(); //... and: private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("Data Table"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up data of the content pane. TableClass mainTable = new TableClass(fh.getColNames(), fh.getTableContent()); mainTable.setOpaque(true); frame.setContentPane(mainTable); //Display the window. frame.pack(); frame.setVisible(true); } Thank you

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• getting java.lang.OutOfMemoryError exception while running a Midlet (using netbeans)

  - by Jeeka

  I am writing a Midlet(using Netbeans) which reads a file containing exactly 2400 lines (each line being 32 characters long) and (extract a part of each line) puts them in an array. I am doing the same for 11 such files( all files have exactly 2400 lines).The Midlet runs fine for reading 6 files and putting them in 6 arrays. However, the Midlet stops while doing it for the 7th file throwing the following exception: TRACE: , startApp threw an Exception java.lang.OutOfMemoryError (stack trace incomplete) java.lang.OutOfMemoryError (stack trace incomplete) I have tried the modifying the netbeans.conf file to increase the heap memory ( as suggested by many forums and blogs) but nothing works for me. Here are the parameters that i had modified in the netbeans.conf file: -J-Xss2m -J-Xms1024m -J-Xmx1024m -J-XX:PermSize=1024m -J-XX:MaxPermSize=1536m -J-XX:+UseConcMarkSweepGC -J-XX:+CMSClassUnloadingEnabled -J-XX:+CMSPermGenSweepingEnabled Can anyone please help me to get me out of this ! I badly need this to be sorted out ASAP ! Thanks in advance !

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• How well does Scala Perform Comapred to Java?

  - by Teja Kantamneni

  The Question actually says it all. The reason behind this question is I am about to start a small side project and want to do it in Scala. I am learning scala for the past one month and now I am comfortable working with it. The scala compiler itself is pretty slow (unless you use fsc). So how well does it perform on JVM? I previously worked on groovy and I had seen sometimes over performed than java. My Question is how well scala perform on JVM compared to Java. I know scala has some very good features(FP, dynamic lang, statically typed...) but end of the day we need the performance...

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• Framework or design pattern for mailing all users of a webapp

  - by Todd Owen

  My app takes care of user registration (with the option to receive email announcements), and can easily handle the actual template-based rendering of email for a given user. JavaMail provides the mail transport layer. But how should I design the application layer between the business objects (e.g. User) and the mail transport? The straightforward approach would be a simple, synchronous loop: iterate through the users, queue the emails, and be done with it. "Queue" might mean sending them straight to the MTA (mail server), or to an in-memory queue to be consumed by another thread. However, I also plan to implement features like throttling the rate of emails, processing bounced emails (NDRs), and maintaining status across application restarts. My intuition is that a good design would decouple this from both the business layer and the mail transport layer as much as possible. I wondered if others had solved this problem before, but after much searching I haven't found any Java libraries which seem to fit this problem. Standalone mail apps such as James or list servers are too large in scope; packages like Spring's MailSender or Commons Email are too small in scope (being basically drop-in replacements for JavaMail). For other languages I haven't found anything appropriate either. I'm curious about how other developers have gone about adding bulk mailing to their applications.

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• Remotely connecting two non-local computers with sockets

  - by Velizar Hristov

  This question seems like something very obvious to ask, and yet I spent more than an hour trying to find an answer. First I host and wait for someone to connect. Then, from another instance of the application, I try to connect with a socket - for the constructor, I use InetAddress, port. The port is always right, and everything works if I use "localhost" for the address. However, if I type my IP, I get an IOException. I even sent the application to someone else, gave him my IP, and it didn't work. The aim of the application is to connect two computers. It's in Java. Here is the relevant code. Server: ServerSocket serverSocket = new ServerSocket(port); Socket clientSocket = serverSocket.accept(); Client: InetAddress a = InetAddress.getByName(ip); Socket s = new Socket(a, port); I don't get past that. Obviously, the values of int port and String ip are taken from text fields. Edit: the purpose of my application is to connect two non-local computers.

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• How to Connect to a web service (SSL enabled and proxy interface)

  - by blgnklc

  There is a web service running on tomcat on a server. It is built on Java Servlet. It is listening others to call itself on a SSL enabled http port. so its web service adreess looks like: https://172.29.12.12/axis/services/XYZClient?wsdl On the other hand I want to connect the web service above from a windows application which is built on .NET frame work. Finally, when I want to connect the web service from my computer; I get some specific erros; Firstly I get; Proxy authentication error; then I added some new line to my code; Dim cr As System.Net.NetworkCredential = New System.Net.NetworkCredential("xname", "xsurname", "xdomainname") Dim myProxy As New WebProxy("http://mar.xxxyyy.com", True) myProxy.Credentials = cr Secondly, after this modifications It says that bad request. I did not get over this error. Moreover I did try to connect the web server on the same computer. I copied my executable program to the computer where the web service runs. The error was like; The underlying connection was closed: Could not establish trust relationship for SSL/TLS secure channel PS: When I try to connect to web service by using Internet Explorer; I see firstly some warnings about accepting an unknown certificate and I click take me to web service an I get there clearly. I want to know what are the basic elements to connect a web service, could you please tell me the requirements that I have to use on my windows project. regards bk

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• Error creating Google Calendar

  - by Don

  Hi, I'm trying to use the Google Calendar Java API to create a secondary calendar for a Google apps user. The relevant code is: // Initialise the API client CalendarService googleCalendar = new GCalendarService("canimo.ca"); googleCalendar.setUserCredentials("[email protected]", "secret"); // Create the calendar CalendarEntry cal = new CalendarEntry(); cal.title = new PlainTextConstruct(user.email); cal.summary = new PlainTextConstruct("Collection calendar"); cal.timeZone = new TimeZoneProperty("America/Montreal"); cal.hidden = HiddenProperty.FALSE; googleCalendar.insert(CALENDAR_URL, calendar); The call to insert() above results in com.google.gdata.util.ServiceException: Internal Server Error and no calendar is created. If I try and perform the same operation through the Google calendar website, it also fails with the error message: We could not save changes. Please try again in a few minutes. An obvious conclusion is that there's some problem on Google's side, but this has been going on for several days now. Strangely, if I create a new user, everything works fine for a while. I can create calendars via the website, and download them via the API. But as soon as I try and create a new calendar using the API, I get the exception above, and thereafter can't create new calendars using either the website or the API. Thanks, Don

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• array of structures, or structure of arrays?

  - by Jason S

  Hmmm. I have a table which is an array of structures I need to store in Java. The naive don't-worry-about-memory approach says do this: public class Record { final private int field1; final private int field2; final private long field3; /* constructor & accessors here */ } List<Record> records = new ArrayList<Record>(); If I end up using a large number ( 106 ) of records, where individual records are accessed occasionally, one at a time, how would I figure out how the preceding approach (an ArrayList) would compare with an optimized approach for storage costs: public class OptimizedRecordStore { final private int[] field1; final private int[] field2; final private long[] field3; Record getRecord(int i) { return new Record(field1[i],field2[i],field3[i]); } /* constructor and other accessors & methods */ } edit: assume the # of records is something that is changed infrequently or never I'm probably not going to use the OptimizedRecordStore approach, but I want to understand the storage cost issue so I can make that decision with confidence. obviously if I add/change the # of records in the OptimizedRecordStore approach above, I either have to replace the whole object with a new one, or remove the "final" keyword. kd304 brings up a good point that was in the back of my mind. In other situations similar to this, I need column access on the records, e.g. if field1 and field2 are "time" and "position", and it's important for me to get those values as an array for use with MATLAB, so I can graph/analyze them efficiently.

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• To use the 'I' prefix for interfaces or not to

  - by ng

  That is the question? So how big a sin is it not to use this convention when developing a c# project? This convention is widely used in the .NET class library. However, I am not a fan to say the least, not just for asthetic reasons but I don't think it makes any contribution. For example is IPSec an interface of PSec? Is IIOPConnection An interface of IOPConnection, I usually go to the definition to find out anyway. So would not using this convention cause confusion? Are there any c# projects or libraries of note that drop this convention? Do any c# projects that mix conventions, as unfortunately Apache Wicket does? The Java class libraries have existed without this for many years, I don't feel I have ever struggled to read code without it. Also, should the interface not be the most primitive description? I mean IList<T> as an interface for List<T> in c#, is it not better to have List<T> and LinkedList<T> or ArrayList<T> or even CopyOnWriteArrayList<T>? The classes describe the implementation? I think I get more information here, than I do from List<T> in c#.

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• What is an efficient strategy for multiple threads posting jobs and waiting for response from a single thread?

  - by jakewins

  In java, what is an efficient solution to the following problem: I have multiple threads (10-20 or so) generating jobs ("Job Creators"), and a single thread capable of performing them ("The worker"). Once a job creator has posted a job, it should wait for the job to finish, yielding no result other than "it's done", before it keeps going. For sending the jobs to the worker thread, I think a ring buffer or similar standard fan-in setup would perhaps be a good approach? But for a Job Creator to find out that her job has been done, I'm not so sure.. The job creators could sleep, and the worker interrupt them when done.. Or each job creator could have an atomic boolean that it checks, and that the worker sets. I dunno, neither of those feel very nice. I'd like to do it with as few (none, if possible) locks as absolutely possible. So to be clear: What I'm looking for is speed, not necessarily simplicity. Does anyone have any suggestions? Links to reading about concurrency strategies would also be very welcome!

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