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  • J2EE and alternatives

    - by Ilya K
    Hello, I am J2SE developer but I have rich web-background (php, perl/cgi and so on) and now I am starting new project. It will have web interface, spaghetti business logic, relational database as storage and connections to other services. I do it from the scratch. My colleagues told me to use spring, spring security and struts. I look briefly at J2EE spec and found that it covers almost all aspects of enterprise application. I asked my colleagues why do they need spring and struts, but looks like they use technologies simply because they are familiar with them and not familiar with classic J2EE stack. So, my question is: what is bad about J2EE? Why do I need spring if there are JNDI lookups? It will take a day or two to create fake InitialContext for unit-tests. And that is all: I stand with out of external tools like spring. Why do I need spring-security if there is a security built in Servlets spec? I can map any request to any servlet using web.xml, no struts.xml is needed. I can use servlet-filters instead of struts interceptors. There is RMI, so I do not need spring-remote. And so on.. Why should I bother my self with all that fancy stuff if there is J2EE? I really want to find situation when J2EE is not enough. Do you have any? Thanks!

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  • Why is NULL/0 an illegal memory location for an object?

    - by aioobe
    I understand the purpose of the NULL constant in C/C++, and I understand that it needs to be represented some way internally. My question is: Is there some fundamental reason why the 0-address would be an invalid memory-location for an object in C/C++? Or are we in theory "wasting" one byte of memory due to this reservation?

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  • Maven easyb plugin java heap space settings?

    - by vinnu
    Hi, I attempted to change my heap size for maven easyb plugin http://www.easyb.org/maven-easyb-plugin/. In my easyb test I added standard code to print the heap size using the code Runtime.getFreeMemory() and Runtime.getTotalMemory(). I tried setting the MAVEN_OPTS=-Xmx1024m -Xms1024m and also set the maven opts in Maven surefire plugin. Now when I run the same class from the Junit I can see the getTotalMemory() displaying a number close 1Gig but the when the same classes are invoked from easyb plugin they do not reflect the memory size. Shouldn't there be a way of passing JVM opts to maven easyb plugin when it runs these easyb tests? At the very minimum it should atleast pick up the MAVEN_OPTS settings from the environment. Has someone bumped into problems like this? (A search on this group's archive does not reveal much)

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  • Java Thread - Synchronization issue

    - by Yatendra Goel
    From Sun's tutorial: Synchronized methods enable a simple strategy for preventing thread interference and memory consistency errors: if an object is visible to more than one thread, all reads or writes to that object's variables are done through synchronized methods. (An important exception: final fields, which cannot be modified after the object is constructed, can be safely read through non-synchronized methods, once the object is constructed) This strategy is effective, but can present problems with liveness, as we'll see later in this lesson. Q1. Is the above statements mean that if an object of a class is going to be shared among multiple threads, then all instance methods of that class (except getters of final fields) should be made synchronized, since instance methods process instance variables?

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  • afterTransactionCompletion not working

    - by Attilah
    I created an hibernate interceptor : public class MyInterceptor extends EmptyInterceptor { private boolean isCanal=false; public boolean onSave(Object entity, Serializable arg1, Object[] arg2, String[] arg3, Type[] arg4) throws CallbackException { for(int i=0;i<100;i++){ System.out.println("Inside MyInterceptor(onSave) : "+entity.toString()); } if(entity instanceof Canal){ isCanal=true; } return false; } public void afterTransactionCompletion(Transaction tx){ if(tx.wasCommitted()&&(isCanal)){ for(int i=0;i<100;i++){ System.out.println("Inside MyInterceptor(afterTransactionCompletion) : Canal was saved to DB."); } } } but the method afterTransactionCompletion doesn't get executed after a transaction is commited. I've tried all the ways I know of but I can't make it work. What's more surprising is that the onSave method works fine. Help ! Could this be due to this bug ? : http://opensource.atlassian.com/projects/hibernate/browse/HHH-1956 How can I circumvent this bug if it's the cause ?

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  • Authenticating a SOAP service in Java (password security)

    - by user1686448
    I am writing an application, in Java, which needs to log in to a remote SOAP service (JIRA) prior to calling methods on that service. I have looked at examples of how to do this, for example http://www.j-tricks.com/1/post/2010/8/jira-soap-client.html, however I am concerned that I need to put the password in memory at some point. I've read that I should store the password as a char[] but still, I'm concerned about storing the password in the clear at all. How should I store the password used by my client to log into the SOAP service? And how should I read it and pass it to JIRA?

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  • Reference variable to an object instantiated/initialized in another class in Java

    - by Alex
    The reason I'm asking is because I'm getting NullPointerException. I now this is very easy but I'm pretty new programming and find this a bit confusing. So say I have initialized an object in a class and want to access that same object from another class. Like now for instance I'm working on a small Chess game, in my model Game class I have an instance of Board, an object. Board, in turn, has an array of Squares. Square[][]. Game has board, board has Square[][]. Now if I want to access the Square[][] through the object board (in Game) of type Board. Do I just declare a variable with the same name and type or do I have to initialize it again? Board board OR Board board = new Board(); Note, I have already initialized board in the class Game so if I do it again, won't they be two totally different Board objects?

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  • Intercommunication between Java Chat Servers

    - by Pravingate
    I have a application in which I am using socket programming , having this(image) scenario. Where number of clients will try to connect Broadcast server. Now here I am managing load through LVS(Load balancer). so as a example shown in image, suppose 200 clients will wish to login for broadcast they will be distributed as 100 users on server 1 and another 100 users on server 2.clients will get connected to servers using TCP connection. Now I am maintaining user information on server side in arraylist which will be stored in heap memory,Now the problem is if client wish to broadcast to all logged in users, but that particular client is logged in server 1. and so client will not be able to broadcast another 100 users from server 2. Because both ther servers are unaware about each others state. please suggest to solve this scenario by whatever means you want.

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  • Filter---after setting attribute--->Servlet---after getting and setting the attribute---->Jsp How do I do this?

    - by Y.E.P
    This is what I want to do : A servlet is called.Before a servlet is called , the request is intercepted by a filter. Filter gets some details out from the request,sets them as an attribute and the forwards it to a servlet via chain.doFilter(request,response). Request finally reaches the servlet. Servlet gets the attribute set by the filter before and sets a new attribute by another name. Then it forwards it to some jsp page where the page gets the attribute and processes it. How do I do this ? I know how to write a filter and a servlet but how do I forward it to a jsp page from the servlet or is there any other way to achieve this ?

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  • Reference to an instance method of a particular object

    - by Andrey
    In the following code, if i try to pass method reference using the class name, works. But passing the reference variable compiler gives an error, i do not understand why? public class User { private String name; public User(String name) { this.name = name; } public void printName() { System.out.println(name); } } public class Main { public static void main(String[] args) { User u1 = new User("AAA"); User u2 = new User("BBB"); User u3 = new User("ZZZ"); List<User> userList = Arrays.asList(u1, u2, u3); userList.forEach(User::printName); // works userList.forEach(u1::printName); // compile error } } Thanks,

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  • Why is 1942/4/3 00:00:00 an illegal date in java.util.Calendar?

    - by Aleksi
    Is there something special in the date 3rd of April 1942? For some reason the the hour of day 0 (12:00 am) is illegal for this specific date. The date is accepted when a lenient calendar is used but the hour of day is incremented to 1 (1:00 am). Relevant code java.util.Calendar calendar = java.util.Calendar.getInstance(); calendar.clear(); calendar.setLenient(false); calendar.set(1942, 3, 3, 0, 0, 0); calendar.getTimeInMillis(); Exception java.lang.IllegalArgumentException: HOUR_OF_DAY at java.util.GregorianCalendar.computeTime(Unknown Source) at java.util.Calendar.updateTime(Unknown Source) at java.util.Calendar.getTimeInMillis(Unknown Source) I'd really prefer is the dates were not lenient as I don't want to accept impossible dates.

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  • In MVC framworks (such as Ruby on Rails), do usually Model spell as singular and controller and view

    - by Jian Lin
    I usually see Ruby on Rails books using script/generate model Story name:string link:string which is a singular Story, while when it is controller script/generate controller Stories index then the Story now is Stories, which is plural. Is this a standard on Ruby on Rails? Is it true in other MVC frameworks too, like CakePHP, Symfony, Django, or TurboGears? I see that in the book Rails Space, the controller is also called User, which is the same as the model name, and it is the only exception I see.

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  • Long primitive or AtomicLong for a counter?

    - by Rich
    Hi I have a need for a counter of type long with the following requirements/facts: Incrementing the counter should take as little time as possible. The counter will only be written to by one thread. Reading from the counter will be done in another thread. The counter will be incremented regularly (as much as a few thousand times per second), but will only be read once every five seconds. Precise accuracy isn't essential, only a rough idea of the size of the counter is good enough. The counter is never cleared, decremented. Based upon these requirements, how would you choose to implement your counter? As a simple long, as a volatile long or using an AtomicLong? Why? At the moment I have a volatile long but was wondering whether another approach would be better. I am also incrementing my long by doing ++counter as opposed to counter++. Is this really any more efficient (as I have been led to believe elsewhere) because there is no assignment being done? Thanks in advance Rich

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  • EJB3.1 logout doesn't work

    - by Kevin
    Hello, I've got a problem with the authentication features of EJB3.1: With this code in a Servlet v3: log.info(""+request.getUserPrincipal()); log.info(""+request.getAuthType()); log.info("===^==="); request.logout() ; log.info(""+request.getUserPrincipal()); log.info(""+request.getAuthType()); request.authenticate(response) ; log.info("===v==="); log.info(""+request.getUserPrincipal()); log.info(""+request.getAuthType()); I would always expect to see the Username/login windows, because of the logout() function. Instead, it seems to be a 'cache' mechanism which repopulate the credential and cancel my logout ... Admin BASIC ===^=== null null ===v=== Admin BASIC is it a problem with my firefox, or something I'm missing in the Servlet code? Thanks

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  • How to maintain GridPane's fixed-size after adding elemnts dynamically

    - by Eviatar G.
    I need to create board game that can be dynamically change. Its size can be 5x5, 6x6, 7x7 or 8x8. I am jusing JavaFX with NetBeans and Scene builder for the GUI. When the user choose board size greater than 5x5 this is what happens: This is the template on the scene builder before adding cells dynamically: To every cell in the GridPane I am adding StackPane + label of the cell number: @FXML GridPane boardGame; public void CreateBoard() { int boardSize = m_Engine.GetBoard().GetBoardSize(); int num = boardSize * boardSize; int maxColumns = m_Engine.GetNumOfCols(); int maxRows = m_Engine.GetNumOfRows(); for(int row = 0; row < maxRows ; row++) { for(int col = maxColumns - 1; col >= 0 ; col--) { StackPane stackPane = new StackPane(); stackPane.setPrefSize(150.0, 200.0); stackPane.getChildren().add(new Label(String.valueOf(num))); boardGame.add(stackPane, col, row); num--; } } boardGame.setGridLinesVisible(true); boardGame.autosize(); } The problem is the stack panes's size on the GridPane are getting smaller. I tried to set them equal minimum and maximum size but it didn't help they are still getting smaller. I searched on the web but didn't realy find same problem as mine. The only similar problem to mine was found here: Dynamically add elements to a fixed-size GridPane in JavaFX But his suggestion is to use TilePane and I need to use GridPane because this is a board game and it more easier to use GridPane when I need to do tasks such as getting to cell on row = 1 and column = 2 for example. EDIT: I removed the GridPane from the FXML and created it manually on the Controller but now it print a blank board: @FXML GridPane boardGame; public void CreateBoard() { int boardSize = m_Engine.GetBoard().GetBoardSize(); int num = boardSize * boardSize; int maxColumns = m_Engine.GetNumOfCols(); int maxRows = m_Engine.GetNumOfRows(); boardGame = new GridPane(); boardGame.setAlignment(Pos.CENTER); Collection<StackPane> stackPanes = new ArrayList<StackPane>(); for(int row = 0; row < maxRows ; row++) { for(int col = maxColumns - 1; col >= 0 ; col--) { StackPane stackPane = new StackPane(); stackPane.setPrefSize(150.0, 200.0); stackPane.getChildren().add(new Label(String.valueOf(num))); boardGame.add(stackPane, col, row); stackPanes.add(stackPane); num--; } } this.buildGridPane(boardSize); boardGame.setGridLinesVisible(true); boardGame.autosize(); boardGamePane.getChildren().addAll(stackPanes); } public void buildGridPane(int i_NumOfRowsAndColumns) { RowConstraints rowConstraint; ColumnConstraints columnConstraint; for(int index = 0 ; index < i_NumOfRowsAndColumns; index++) { rowConstraint = new RowConstraints(3, Control.USE_COMPUTED_SIZE, Double.POSITIVE_INFINITY, Priority.ALWAYS, VPos.CENTER, true); boardGame.getRowConstraints().add(rowConstraint); columnConstraint = new ColumnConstraints(3, Control.USE_COMPUTED_SIZE, Double.POSITIVE_INFINITY, Priority.ALWAYS, HPos.CENTER, true); boardGame.getColumnConstraints().add(columnConstraint); } }

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  • JAAS : on Callback ( Interesting based on HTTP headers )

    - by VJS
    I am using NameCallback and PasswordCallback for username and password.For username and password, popup comes on browser and when i enter username ans password, JAAS authenticates my request. On the wireshark, I have seen that 401 Unauthorized message (WWW-Authenticate header)comes and when i enter username/password HTTP request with credentials generate ( with Authorization header) and goes to server. My requirement : I don't want pop up to come.My application on other server having username / password, so once it received 401 then based on some logic it will generate HTTP request with Authorization header / credentials and sent it back. FLow : User - Other Server - My Tomcat5.5 Here on Other Server, nobody is available to enter username/password manually.Application is deployed and it will only generate HTTP request with credential and sent it back to tomcat. Can we have any other callback which behave like this.Need your help.Please provide me feedback as well related to approach.

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  • How do I make an object a property of a model in Ruby on Rails?

    - by iTake
    I have this in my schema: create_table "robots_matches", :force => true do |t| t.integer "robot_id" t.integer "match_id" and I think I want to be able to load a robot and match from within my robots_match model so I can do something like this: robots_match.find(:id).get_robot().Name My attempt in the robots_matches model was this: def get_robot Robot.find(this.id) end I am super new to rails, so feel free to correct my architectural decision here.

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  • how to get all 'username' from my model 'MyUser' on google-app-engine ..

    - by zjm1126
    my model is : class MyUser(db.Model): user = db.UserProperty() password = db.StringProperty(default=UNUSABLE_PASSWORD) email = db.StringProperty() nickname = db.StringProperty(indexed=False) and my method which want to get all username is : s=[] a=MyUser.all().fetch(10000) for i in a: s.append(i.username) and the error is : AttributeError: 'MyUser' object has no attribute 'username' so how can i get all 'username', which is the simplest way . thanks

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