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• Help understanding the Single Responsibility Principle

  - by user204588

  I'm trying to understand what a responsibility actually is so I want to use an example of something I'm currently working on. I have a app that imports product information from one system to another system. The user of the apps gets to choose various settings for which product fields in one system that want to use in the other system. So I have a class, say ProductImporter and it's responsibility is to import products. This class is large, probably too large. The methods in this class are complex and would be for example, getDescription. This method doesn't simply grab a description from the other system but sets a product description based on various settings set by the user. If I were to add a setting and a new way to get a description, this class could change. So, is that two responsibilities? Is there one that imports products and one that gets a description. It would seem this way, almost every method I have would be in it's own class and that seems like overkill. I really need a good description of this principle because it's hard for me to completely understand. I don't want needless complexity.

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• Is there a PHP library that performs MySQL Data Validation and Sanitization According to Column Type

  - by JW

  Do you know of any open source library or framework that can perform some basic validation and escaping functionality for a MySQL Db. i envisage something along the lines of: //give it something to perform the quote() quoteInto() methods $lib->setSanitizor($MyZend_DBAdaptor); //tell it structure of the table - colnames/coltypes/ etc $lib->setTableDescription($tableDescArray); //use it to validate and escape according to coltype foreach ($prospectiveData as $colName => $rawValue) if ( $lib->isValid($colName, $rawValue)) { //add it to the set clause $setValuesArray[$lib->escapeIdentifier($colName);] = $lib->getEscapedValue($colName,$rawValue); } else { throw new Exception($colName->getErrorMessage()); } etc... I have looked into - Zend_Db_Table (which knows about a table's description), and - Zend_Db_Adaptor (which knows how to escape/sanitize values depending on TYPE) but they do not automatically do any clever stuff during updates/inserts Anyone know of a good PHP library to preform this kind of validation that I could use rather than writing my own? i envisage alot of this kind of stuff: ... elseif (eregi('^INT|^INTEGER',$dataset_element_arr[col_type])) { $datatype='int'; if (eregi('unsigned',$dataset_element_arr[col_type])) { $int_max_val=4294967296; $int_min_val=0; } else { $int_max_val=2147483647; $int_min_val=-2147483648; } } (p.s I know eregi is deprecated - its just an example of laborious code)

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• How do I copy or move an NSManagedObject from one context to another?

  - by Aeonaut

  I have what I assume is a fairly standard setup, with one scratchpad MOC which is never saved (containing a bunch of objects downloaded from the web) and another permanent MOC which persists objects. When the user selects an object from scratchMOC to add to her library, I want to either 1) remove the object from scratchMOC and insert into permanentMOC, or 2) copy the object into permanentMOC. The Core Data FAQ says I can copy an object like this: NSManagedObjectID *objectID = [managedObject objectID]; NSManagedObject *copy = [context2 objectWithID:objectID]; (In this case, context2 would be permanentMOC.) However, when I do this, the copied object is faulted; the data is initially unresolved. When it does get resolved, later, all of the values are nil; none of the data (attributes or relationships) from the original managedObject are actually copied or referenced. Therefore I can't see any difference between using this objectWithID: method and just inserting an entirely new object into permanentMOC using insertNewObjectForEntityForName:. I realize I can create a new object in permanentMOC and manually copy each key-value pair from the old object, but I'm not very happy with that solution. (I have a number of different managed objects for which I have this problem, so I don't want to have to write and update copy: methods for all of them as I continue developing.) Is there a better way?

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• Advice on improving programming skills, learning capabilities?

  - by anonymous-coward1234

  Hi all, After 2,5 years of professional Java programing, I still have problems that make my job difficult and, more importantly - more times that I would like to admit - not enjoyable. I would like to ask for advice by more experienced people on ways that would help me overcome them. These are the problems I have: I do not absorb new knowledge easily. Even when I understand something, after a couple of days I easily forget even basic stuff. Other co-workers, even with the same working experience, when reading new technologies put things easily into "context", and are able to compare in "real time| similar technologies they already have used. I always try to address all the issues to whatever I am doing at one go, which results in me trying to resolve too many problems at the same time, losing completely control. I find it difficult to make my mind on a single problem that I should address first, and even when I do, and find myself throwing away code that I wrote because I started addressing the wrong issue first. As far as architecture and data modeling is concerned, I have difficulty making decisions on what objects must be created, with what hierarchy, interfaces, abstraction etc. I imagine that - to a certain degree - these things come with experience. But after 2,5 years of Java programming, I would expect myself to have come much farther that I have come, both in terms of absorption and experience. Is there a way to improve my learning speed? Any books, methods, advice is welcome.

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• wxPython, Threads, and PostEvent between modules

  - by Sam Starling

  I'm relatively new to wxPython (but not Python itself), so forgive me if I've missed something here. I'm writing a GUI application, which at a very basic level consists of "Start" and "Stop" buttons that start and stop a thread. This thread is an infinite loop, which only ends when the thread is stopped. The loop generates messages, which at the moment are just output using print. The GUI class and the infinite loop (using threading.Thread as a subclass) are held in separate files. What is the best way to get the thread to push an update to something like a TextCtrl in the GUI? I've been playing around with PostEvent and Queue, but without much luck. Here's some bare bones code, with portions removed to keep it concise: main_frame.py import wx from loop import Loop class MainFrame(wx.Frame): def __init__(self, parent, title): # Initialise and show GUI # Add two buttons, btnStart and btnStop # Bind the two buttons to the following two methods self.threads = [] def onStart(self): x = Loop() x.start() self.threads.append(x) def onStop(self): for t in self.threads: t.stop() loop.py class Loop(threading.Thread): def __init__(self): self._stop = threading.Event() def run(self): while not self._stop.isSet(): print datetime.date.today() def stop(self): self._stop.set() I did, at one point, have it working by having the classes in the same file by using wx.lib.newevent.NewEvent() along these lines. If anyone could point me in the right direction, that'd be much appreciated.

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• UIView Controller mysteriously getting deallocated

  - by Dan Ray

  I have a UINavigation scheme with a "welcome" page, a middle page, and a detail page. In the middle page, there's a segmented controller that can swap the main body of that page between a table, a calendar, and a MKMapView, each implemented with their own view controller classes. Today I implemented the MapView and its annotations and all of that. It's nice. And a detail disclosure on each callout takes you to the detail page just the same way as if you'd gotten there via the table. Lovely. I also have a right-button-bar button that pushes in a "search" view. From there you can search the data I'm navigating. When it's done filtering the data (an array of objects I'm keeping in a data singleton), it makes the table reload its data, and calls my annotation-clearer-and-builder methods on the map view, and then pops itself out, so the "middle" page (including whatever view was in the guts of it) is back on the screen. Problem is, if I go back and forth between the map and the search a couple times, any mention of the table view causes us to crash with: *** -[CALayer retain]: message sent to deallocated instance 0x710b810. (I obviously have NSZombies turned on.) I put an NSLog in the dealloc method of my table view controller. That thing's never getting called. I don't know if we're ditching it behind the scenes for memory purposes, or if I'm leaking it and can't get my hands back on it, or what. I'm sort of at a loss about where to look. Any hints?

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• NSTableView Drag and Drop not working

  - by macatomy

  Hi, I'm trying to set up very basic drag and drop for my NSTableView. The table view has a single column (with a custom cell). The column is bound to an NSArrayController, and the array controller's content array is bound to an NSArray on my controller object. The data displays fine in the table. I connected the dataSource and delegate outlets of the table view to my controller object, and then implemented these methods: - (BOOL)tableView:(NSTableView *)aTableView writeRowsWithIndexes:(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard *)pboard { NSLog(@"dragging"); return YES; } - (NSDragOperation)tableView:(NSTableView*)tv validateDrop:(id <NSDraggingInfo>)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)op { return NSDragOperationEvery; } - (BOOL)tableView:(NSTableView *)aTableView acceptDrop:(id <NSDraggingInfo>)info row:(NSInteger)row dropOperation:(NSTableViewDropOperation)operation { return YES; } I also registered the drag types in -awakeFromNib: #define MyDragType @"MyDragType" - (void)awakeFromNib { [super awakeFromNib]; [_myTable registerForDraggedTypes:[NSArray arrayWithObjects:MyDragType, nil]]; } The problem is that the -tableView:writeRowsWithIndexes:toPasteboard: method is never called. I've looked at a bunch of examples and I can't figure out anything I'm doing wrong. Could the problem be that I'm using a custom cell? Is there something I'm supposed to override in the cell subclass to enable this functionality? EDIT: Confirmed. Switching the custom cell for a regular NSTextFieldCell made dragging work. Now, how do I make drag and drop work with my custom cell?

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• Java reflection

  - by heldopslippers

  Hi people. I have a question about reflection I am trying to have some kind of eval() method. So i can call for example: eval("test('woohoo')"); Now I understand the there is no eval method in java but there is reflection. I made the following code: String s = "test"; Class cl = Class.forName("Main"); Method method = cl.getMethod(s, String.class); method.invoke(null, "woohoo"); This works perfectly (of course there is a try, catch block around this code). It runs the test method. However I want to call multiple methods who all have different parameters. I don't know what parameters these are (so not only String.class). But how is this possible? how can I get the parameter types of a method ? I know of the following method: Class[] parameterTypes = method.getParameterTypes(); But that will return the parameterTypes of the method I just selected! with the following statement: Method method = cl.getMethod(s, String.class); Any help would be appreciated !

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• How to create a magic square in PHP?

  - by TerranRich

  I'd like to try my hand at creating a Magic Square in PHP (i.e. a grid of numbers that all add up to the same value), but I really don't know where to start. I know of the many methods that create magic square, such as starting "1" at a fixed position, then moving in a specific direction with each iteration. But that doesn't create a truly randomized Magic Square, which is what I'm aiming for. I want to be able to generate an N-by-N Magic Square of N² numbers where each row and column adds up to N(N²+1)/2 (e.g. a 5x5 square where all rows/columns add up to 65 — the diagonals don't matter). Can anybody provide a starting point? I don't want anybody to do the work for me, I just need to know how to start such a project? I know of one generator, written in Java (http://www.dr-mikes-math-games-for-kids.com/how-to-make-a-magic-square.html) but the last Java experience I had was over 10 years ago before I quickly abandoned it. Therefore, I don't really understand what the code is actually doing. I did notice, however, that when you generate a new square, it shows the numbers 1-25 (for a 5x5 square), in order, before quickly generating a fresh randomized square.

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• Rails: Custom template for email "deliver_" method?

  - by neezer

  I'm building an email system that stores my different emails in the database and calls the appropriate "deliver_" method via method_missing (since I can't explicitly declare methods since they're user-generated). My problem is that my rails app still tries to render the template for whatever the generated email is, though those templates don't exist. I want to force all emails to use the same template (views/test_email.html.haml), which will be setup to draw their formatting from my database records. How can I accomplish this? I tried adding render :template => 'test_email' in the test_email method in emailer_controller with no luck. models/emailer.rb: class Emailer < ActionMailer::Base def method_missing(method, *args) # not been implemented yet logger.info "method missing was called!!" end end controller/emailer_controller.rb: class EmailerController < ApplicationController def test_email @email = Email.find(params[:id]) Emailer.send("deliver_#{@email.name}") end end views/emails/index.html.haml: %h1 Listing emails %table{ :cellspacing => 0 } %tr %th Name %th Subject - @emails.each do |email| %tr %td=h email.name %td=h email.subject %td= link_to 'Show', email %td= link_to 'Edit', edit_email_path(email) %td= link_to 'Send Test Message', :controller => 'emailer', :action => 'test_email', :params => { :id => email.id } %td= link_to 'Destroy', email, :confirm => 'Are you sure?', :method => :delete %p= link_to 'New email', new_email_path Error I'm getting with the above: Template is missing Missing template emailer/name_of_email_in_database.erb in view path app/views

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• Using multiple sockets, is non-blocking or blocking with select better?

  - by JPhi1618

  Lets say I have a server program that can accept connections from 10 (or more) different clients. The clients send data at random which is received by the server, but it is certain that at least one client will be sending data every update. The server cannot wait for information to arrive because it has other processing to do. Aside from using asynchronous sockets, I see two options: Make all sockets non-blocking. In a loop, call recv on each socket and allow it to fail with WSAEWOULDBLOCK if there is no data available and if I happen to get some data, then keep it. Leave the sockets as blocking. Add all sockets to a fd_set and call select(). If the return value is non-zero (which it will be most of the time), loop through all the sockets to find the appropriate number of readable sockets with FD_ISSET() and only call recv on the readable sockets. The first option will create a lot more calls to the recv function. The second method is a bigger pain from a programming perspective because of all the FD_SET and FD_ISSET looping. Which method (or another method) is preferred? Is avoiding the overhead on letting recv fail on a non-blocking socket worth the hassle of calling select()? I think I understand both methods and I have tried both with success, but I don't know if one way is considered better or optimal. Only knowledgeable replies please!

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• Need Advice on designing ATL inproc Server (dll) that serves as both a soure and a sink of events.

  - by Andrew

  Hi, I need to design an ATL inproc server that besides exposing methods and properties, also can fire events (source) and serve as a sink for a third party COM control that fires events. I would assume that this is a fairly common requirement. I can also foresee several "gotchas" that I would like to read up on before commencing the design. My questions/concerns are: Can someone point me to an example? Which threading model to use? Should I have a seperate COM object for the sink? Should I, and how do I, protect certain memory. For example, my server will receive data from the third party control. It will save this, and in some cases, fire an event to interested clients. The interested clients will request the data through a standard method or property. I did try to research this myself. I can find many examples of COM servers that are soures, and some that are sinks, but never both. The only post I did find was this: http://www.generation-nt.com/us/atl-control-an-event-source-sink-help-9098542.html Which strongly advocates putting the sink on a seperate COM object. Any leads, tutorials or ideas would be much appreciated. Thanks, Andrew

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• Can I have two separate projects, 1 WebForms and 1 ASP.NET MVC, to both point to the same domain?

  - by Hamman359

  Is it possible to setup two separate projects, 1 WebForms and 1 ASP.NET MVC, to both point to the same domain? i.e. both point to different pages within www.somesite.com. Here's some background on the application and why I'm asking. This is a brownfield application that is currently 2.0 WebForms and is full of WebFormy 'goodness' (i.e. ObjectDataSources, FormView controls, UpdatePanels, etc...) There are lost of other 'fun' things in the code base like 600+ Stored Procedures and 200+ line methods in the business layer code that get data from the DB via stored proc, do some processing on the data, build an HTML string using string concatenation and then return that string to the UI layer. What we are planning on doing is developing new features in MVC and slowly converting the existing features over to MVC one at a time. As part of this transition, we will also be re-writing the layers below the UI to clean up the mess there and to do things like replace the stored procedures with NHibernate and introduce an IOC container. I know that you can run WebForms and MVC side-by-side in the same project, however, because we will be making wholesale changes to the way we do many things throughout our entire development stack, I'd like the new stuff to be a completely separate project within the solution. This should help serve as very visual reminder that this is a different way of doing things than before and make it easier to remove the old code as it is no longer needed. What I don't know is, is this even possible? Can two separate project point to the same domain? Here's an quick example of what I'm thinking: www.somesite.com/orders.aspx?id=123 (Orders page from existing WebForms project) www.somesite.com/customer/987 (Customer page from new MVC project)

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• Why ClassCastException on JMS ConnectionFactory lookup in JNDI?

  - by Derek Mahar

  What might be the cause of the following ClassCastException in a standalone JMS client application when it attempts to retrieve a connection factory from the JNDI provider? Exception in thread "main" java.lang.ClassCastException: javax.naming.Reference cannot be cast to javax.jms.ConnectionFactory Here is an abbreviated version of the JMS client that includes only its start() and stop() methods. The exception occurs on the first line in method start() which attempts to retrieve the connection factory from the JNDI provider, a remote LDAP server. The JMS connection factory and destination objects are on a remote JMS server. class JmsClient { private ConnectionFactory connectionFactory; private Connection connection; private Session session; private MessageConsumer consumer; private Topic topic; public void stop() throws JMSException { consumer.close(); session.close(); connection.close(); } public void start(Context context, String connectionFactoryName, String topicName) throws NamingException, JMSException { // ClassCastException occurs when retrieving connection factory. connectionFactory = (ConnectionFactory) context.lookup(connectionFactoryName); connection = connectionFactory.createConnection("username","password"); session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); topic = (Topic) context.lookup(topicName); consumer = session.createConsumer(topic); connection.start(); } private static Context getInitialContext() throws NamingException, IOException { String filename = "context.properties"; Properties props = new Properties(); props.load(new FileInputStream(filename)); return new InitialContext(props); } }

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• In iTextSharp, can we set the vertical position of the pdfwriter?

  - by Pandincus

  Hello, I've recently started using iTextSharp to generate PDF reports from data. It works quite nicely. In one particular report, I need a section to always appear at the bottom of the page. I'm using the PdfContentByte to create a dashed line 200f from the bottom: cb.MoveTo(0f, 200f); cb.SetLineDash(8, 4, 0); cb.LineTo(doc.PageSize.Width, 200f); cb.Stroke(); Now I'd like to insert content below that line. However, (as expected) the PdfContentByte methods don't change the vertical position of the PdfWriter. New paragraphs, for example, appear earlier in the page. // appears wherever my last content was, NOT below the dashed line doc.Add(new Paragraph("test", _myFont)); Is there some way to instruct the pdfwriter that I'd like to advance the vertical position to below the dashed line now, and continue inserting content there? There is a GetVerticalPosition() method -- it'd be nice if there was a corresponding Setter :-). // Gives me the vertical position, but I can't change it var pos = writer.GetVerticalPosition(false); So, is there any way to set the writer's position by hand? Thanks!

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• Add new types to Go

  - by nevalu

  I'm trying add new types for that been managed/used as in Go core types. To create new types is anything very interesting to validate data before of send it to a non-SQL DBMS or to check data from a form. Go uses univeral constants to define them at global level: var DateType = universe.DefineType("date", universePos, &dateType{}) In this case they're defined to be called from a package like types: var Date = &dateType{} I get these errors: test.go:58: o.lit undefined (cannot refer to unexported field lit) test.go:62: *dateType is not Type missing Pos() token.Position The code is based on: http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go package main import ( "exp/eval" "fmt" // "go/token" ) // http://github.com/tav/go/blob/master/src/pkg/exp/eval/value.go type DateValue interface { eval.Value Get(*eval.Thread) string Set(*eval.Thread, string) } /* Date */ type dateV string func (v *dateV) String() string { return fmt.Sprint(*v) } func (v *dateV) Assign(t *eval.Thread, o eval.Value) { *v = dateV(o.(DateValue).Get(t)) } func (v *dateV) Get(*eval.Thread) string { return string(*v) } func (v *dateV) Set(t *eval.Thread, x string) { *v = dateV(x) } // http://github.com/tav/go/blob/master/src/pkg/exp/eval/type.go type Type interface { eval.Type // isDate returns true if this is a date type. isDate() bool } /* Common type */ type commonType struct{} // added func (commonType) isDate() bool { return false } /* Date */ type dateType struct { commonType } // * It should not be an universal constant //var universePos = token.Position{"<universe>", 0, 0, 0} // added //var DateType = universe.DefineType("date", universePos, &dateType{}) var Date = &dateType{} func (t *dateType) compat(o Type, conv bool) bool { t2, ok := o.lit().(*dateType) return ok && t == t2 } func (t *dateType) lit() Type { return t } func (t *dateType) isDate() bool { return true } func (t *dateType) String() string { return "<date>" } func (t *dateType) Zero() eval.Value { res := dateV("") return &res } /* Named types */ /* type NamedType struct { eval.NamedType Def Type }*/ type NamedType struct { // added // token.Position Name string // Underlying type. If incomplete is true, this will be nil. // If incomplete is false and this is still nil, then this is // a placeholder type representing an error. Def Type // True while this type is being defined. incomplete bool methods map[string]eval.Method } func (t *NamedType) isDate() bool { return t.Def.isDate() } /* *********************** */ func main() { print("foo") }

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• Learning Hibernate: too many connections

  - by stivlo

  I'm trying to learn Hibernate and I wrote the simplest Person Entity and I was trying to insert 2000 of them. I know I'm using deprecated methods, I will try to figure out what are the new ones later. First, here is the class Person: @Entity public class Person { private int id; private String name; @Id @GeneratedValue(strategy = GenerationType.TABLE, generator = "person") @TableGenerator(name = "person", table = "sequences", allocationSize = 1) public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } Then I wrote a small App class that insert 2000 entities with a loop: public class App { private static AnnotationConfiguration config; public static void insertPerson() { SessionFactory factory = config.buildSessionFactory(); Session session = factory.getCurrentSession(); session.beginTransaction(); Person aPerson = new Person(); aPerson.setName("John"); session.save(aPerson); session.getTransaction().commit(); } public static void main(String[] args) { config = new AnnotationConfiguration(); config.addAnnotatedClass(Person.class); config.configure("hibernate.cfg.xml"); //is the default already new SchemaExport(config).create(true, true); //print and execute for (int i = 0; i < 2000; i++) { insertPerson(); } } } What I get after a while is: Exception in thread "main" org.hibernate.exception.JDBCConnectionException: Cannot open connection Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections Now I know that probably if I put the transaction outside the loop it would work, but mine was a test to see what happens when executing multiple transactions. And since there is only one open at each time, it should work. I tried to add session.close() after the commit, but I got Exception in thread "main" org.hibernate.SessionException: Session was already closed So how to solve the problem?

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• Javascript scope chain

  - by Geromey

  Hi, I am trying to optimize my program. I think I understand the basics of closure. I am confused about the scope chain though. I know that in general you want a low scope (to access variables quickly). Say I have the following object: var my_object = (function(){ //private variables var a_private = 0; return{ //public //public variables a_public : 1, //public methods some_public : function(){ debugger; alert(this.a_public); alert(a_private); }; }; })(); My understanding is that if I am in the some_public method I can access the private variables faster than the public ones. Is this correct? My confusion comes with the scope level of this. When the code is stopped at debugger, firebug shows the public variable inside the this keyword. The this word is not inside a scope level. How fast is accessing this? Right now I am storing any this.properties as another local variable to avoid accessing it multiple times. Thanks very much!

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• Trouble parsing quotes with SAX parser (javax.xml.parsers.SAXParser)

  - by johnrock

  When using a SAX parser, parsing fails when there is a " in the node content. How can I resolve this? Do I need to convert all " characters? In other words, anytime I have a quote in a node: <node>characters in node containing "quotes"</node> That node gets butchered into multiple character arrays when the Handler is parsing it. Is this normal behaviour? Why should quotes cause such a problem? Here is the code I am using: import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpGet; import org.xml.sax.InputSource; import org.xml.sax.XMLReader; ... HttpGet httpget = new HttpGet(GATEWAY_URL + "/"+ question.getId()); httpget.setHeader("User-Agent", PayloadService.userAgent); httpget.setHeader("Content-Type", "application/xml"); HttpResponse response = PayloadService.getHttpclient().execute(httpget); HttpEntity entity = response.getEntity(); if(entity != null) { SAXParserFactory spf = SAXParserFactory.newInstance(); SAXParser sp = spf.newSAXParser(); XMLReader xr = sp.getXMLReader(); ConvoHandler convoHandler = new ConvoHandler(); xr.setContentHandler(convoHandler); xr.parse(new InputSource(entity.getContent())); entity.consumeContent(); messageList = convoHandler.getMessageList(); }

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• How does a java web project architecture look like without EJB3 ?

  - by Hendrik

  A friend and I are building a fairly complex website based on java. (PHP would have been more obvious but we chose for java because the educational aspect of this project is important to us) We have already decided to use JSF (with richfaces) for the front end and JPA for the backend and so far we have decided not to use EJB3 for the business layer. The reason we've decided not to use EJB3 is because - and please correct me if I am wrong - if we use EJB3 we can only run it on a full blown java application server like jboss and if we don't use EJB3 we can still run it on a lightweight server like tomcat. We want to keep speed and cost of our future web server in mind. So far i've worked on two JEE projects and both used the full stack with web business logic factories/persistence service entities with every layer a seperate module. Now here is my question, if you dont use EJB3 in the business logic layer. What does the layer look like? Please tell what is common practice when developing java web projects without ejb3? Do you think business logic layer can be thrown out altogether and have business logic in the backing beans? If you keep the layer, do you have all business methods static? Or do you initialize each business class as needed in the backing beans in every session as needed?

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• @Autowire strange problem

  - by Javi

  Hello, I have a strange behaviour when autowiring I have a similar code like this one, and it works @Controller public class Class1 { @Autowired private Class2 object2; ... } @Service @Transactional public class Class2{ ... } The problem is that I need that the Class2 implements an interface so I've only changed the Class2 so it's now like: @Controller public class Class1 { @Autowired private Class2 object2; ... } @Service @Transactional public class Class2 implements IServiceReference<Class3, Long>{ ... } public interface IServiceReference<T, PK extends Serializable> { public T reference(PK id); } with this code I get a org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type for Class2. It seems that @ Transitional annotation is not compatible with the interface because if I remove the @Transitional annotation or the "implements IServiceReference" the problem disapears and the bean is injected (though I need to have both in this class). It also happens if I put the annotation @Transitional in the methods instead of in the Class. I use Spring 3.0.2 if this helps. Is not compatible the interface with the transactional method? May it be a Spring bug? Thanks

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• Interface and partial classes

  - by Tomek Tarczynski

  According to rule SA1201 in StyleCop elements in class must appear in correct order. The order is following: Fields Constructors Finalizers (Destructors) Delegates Events Enums Interfaces Properties Indexers Methods Structs Classes Everything is ok, except of Interfaces part, because Interface can contain mehtods, events, properties etc... If we want to be strict about this rule then we won't have all members of Interface in one place which is often very useful. According to StyleCop help this problem can be solved by spliting class into partial classes. Example: /// <summary> /// Represents a customer of the system. /// </summary> public partial class Customer { // Contains the main functionality of the class. } /// <content> /// Implements the ICollection class. /// </content> public partial class Customer : ICollection { public int Count { get { return this.count; } } public bool IsSynchronized { get { return false; } } public object SyncRoot { get { return null; } } public void CopyTo(Array array, int index) { throw new NotImplementedException(); } } Are there any other good solutions to this problem?

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• Handling incremental Data Modeling Changes in Functional Programming

  - by Adam Gent

  Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code (functions,methods). Instead I can declarative add validation and even UI options by annotating the property (Java). In Functional Programming it seems that adding new data properties requires lots of code changes because of pattern matching and data constructors (Haskell, ML). How do I minimize this problem? This seems to be a recognized problem as Xavier Leroy states nicely on page 24 of "Objects and Classes vs. Modules" - To summarize for those that don't have a PostScript viewer it basically says FP languages are better than OOP languages for adding new behavior over data objects but OOP languages are better for adding new data objects/properties. Are there any design pattern used in FP languages to help mitigate this problem? I have read Phillip Wadler's recommendation of using Monads to help this modularity problem but I'm not sure I understand how?

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• Rewrite arrays using collections

  - by owca

  I have a task, which I was able to do with the use of simplest methods - arrays. Now I'd like to go further and redo it using some more complicated java features like collections, but I've never used anything more complicated than 2d matrix. What should I look at and how to start with it. Should Tower become a Collection ? And here's the task : We have two classes - Tower and Block. Towers are built from Blocks. Ande here's sample code for testing: Block k1=new Block("yellow",1,5,4); Block k2=new Block("blue",2,2,6); Block k3=new Block("green",3,4,2); Block k4=new Block("yellow",1,5,4); Tower tower=new Tower(); tower.add(k1,k2,k3); "Added 3 blocks." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.add(k2); "Tower already contains this block." tower.add(k4); "Added 1 block." System.out.println(tower); "block: green, base: 4cm x 3cm, thicknes: 2 cm block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" tower.delete(k1); "Deleted 1 block" tower.delete(k1); "Block not in tower" System.out.println(tower); "block: blue, base: 6cm x 2cm, thicknes: 2 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm block: yellow, base: 5cm x 4cm, thicknes: 1 cm" Let's say I will treat Tower as a collection of blocks. How to perform search for specific block among whole collection ? Or should I use other interface ?

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• Autorotation and multiple view controllers

  - by alku83

  I'm creating an iPad application which should only work in portrait and portait upsidedown modes. For performance reasons in my applicationDidFinishLaunching method I'm creating several viewControllers, and adding them to my main window as subviews. I then hide the ones I don't want to see straight away. There is no tab bar or navigation controller. My problem is that only the first viewController seems to be receiving the rotate calls. I have verified this by swapping around the order in which I add the subviews to the main window and NSLog's. Is there some way I can force all the controllers to receive the calls? Some of my views are designed to lay over the top of another view, but this behind view will not always be the same one - so it seems to make sense to have the overlay view in a separate view controller. Am I doing something fundamentally wrong, and that's why it's not behaving as I would expect? EDIT: The accepted answer for this question seems to indicate the exact problem I'm facing: http://stackoverflow.com/questions/548142/uiviewcontroller-rotate-methods

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