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  • Java Interface Usage Guidelines -- Are getters and setters in an interface bad?

    - by user68759
    What do people think of the best guidelines to use in an interface? What should and shouldn't go into an interface? I've heard people say that, as a general rule, an interface must only define behavior and not state. Does this mean that an interface shouldn't contain getters and setters? My opinion: Maybe not so for setters, but sometimes I think that getters are valid to be placed in an interface. This is merely to enforce the implementation classes to implement those getters and so to indicate that the clients are able to call those getters to check on something, for example.

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  • Grails: Problem with nested associations in criteria builder

    - by Mr.B
    I have a frustrating problem with the criteria builder. I have an application in which one user has one calendar, and a calendar has many entries. Seems straightforward enough, but when I try to get the calendar entries for a given user, I can't access the user property (MissingMethodException). Here's the code: def getEntries(User user) { def entries = Entries.createCriteria().list() { calendar { user { eq("user.id", user.id) } } } } I have even tried the following variation: def getEntries(User user) { def entries = Entries.createCriteria().list() { calendar { eq("user", user) } } } That did not raise an exception, but didn't work either. Here's the relevant parts of the domain classes: class Calendar { static belongsTo = [user: User] static hasMany = [entries: Entries] ... } class User { Calendar calendar ... } class Entry { static belongsTo = [calendar: Calendar] ... } When Googling I came across a similar problem noted in early 2008: http://jira.codehaus.org/browse/GRAILS-1412 But according to that link this issue should have been solved long ago. What am I doing wrong?

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  • Grails multiple databases

    - by srinath
    Hi, how can we write queries on 2 databases . I installed datasources plugin and domain classes are : class Organization { long id long company_id String name static mapping = { version false table 'organization_' id column : 'organizationId' company_id column : 'companyId' name column : 'name' } } class Assoc { Integer id Integer association_id Integer organization_id static mapping = { version false table 'assoc' id column : 'ASSOC_ID' association_id column : 'ASSOCIATION_ID' organization_id column : 'ORGANIZATION_ID' } } this is working : def org = Organization.list() def assoc = Assoc.list() and this is not working : def query = Organization.executeQuery("SELECT o.name as name, o.id FROM Organization o WHERE o.id IN (SELECT a.organization_id FROM Assoc a )") error : org.hibernate.hql.ast.QuerySyntaxException: Assoc is not mapped [SELECT o.name as name, o.id FROM org.com.domain.Organization o WHERE o.id IN (SELECT a.organization_id FROM AssocOrg a )] How can we connect with 2 databases using single query ? thanks in advance .

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  • Ordered many-to-many relationship in NHibernate

    - by Kristoffer
    Let's say I have two classes: Item and ItemCollection, where ItemCollection contains an ordered list of Item objects with an index, i.e. the list is ordered in a way specified by the user. Let's also say that they have a many-to-many relationship, an ItemCollection can contain many items and an Item can belong to several ItemCollections. That would, in my head, require three tables in the database. One for Item, one for ItemCollection and one for the ordered mapping. The mapping table would contain three columns: int ItemID int ItemCollectionID int ListIndex QUESTION: How would you design the ItemCollection class? Should the list of Item objects be a list, dictionary or other? What would the NHibernate mapping look like to get the ListIndex into the picture?

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  • Asp.Net Program Architecture

    - by Pino
    I've just taken on a new Asp.Net MVC application and after opening it up I find the following, [Project].Web [Project].Models [Project].BLL [Project].DAL Now, something thats become clear is that there is the data has to do a hell of a lot before it makes it to the View (DatabaseDALRepoBLLConvertToModelControllerView). The DAL is Subsonic, the repositorys in the DAL return the subsonic entities to the BLL which process them does crazy things and converts them into a Model (From the .Models) sometimes with classes that look like this public DataModel GetDataModel(EntityObject Src) { var ReturnData = new DataModel(): ReturnData.ID = Src.ID; ReturnDate.Name = Src.Name; //etc etc } Now, the question is, "Is this complete overkill"? Ok the project is of a decent size and can only get bigger but is it worth carrying on with all this? I dont want to use AutoMapper as it just seems like it makes the complication worse. Can anyone shed any light on this?

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  • Entity Framework Model with inheritance and RIA Services

    - by TimothyP
    Hi, We have an entity framework model with has some inheritance in it. The following example is not the actuall model, but just to make my point... Let's say Base class: Person Child classes: Employee, Customer The database has been generated, the DomainService has been created and we can get to the data: lstCustomers.ItemsSource = context.Persons; EntityQuery<Person> query = context.GetPeopleQuery().Take(4); context.Load(query); But how can I modify the query to only return Customers ?

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  • How to prevent HTTP 304 in Django test server

    - by Augusto Men
    I have a couple of projects in Django and alternate between one and another every now and then. All of them have a /media/ path, which is served by django.views.static.serve, and they all have a /media/css/base.css file. The problem is, whenever I run one project, the requests to base.css return an HTTP 304 (not modified), probably because the timestamp hasn't changed. But when I run the other project, the same 304 is returned, making the browser use the file cached by the previous project (and therefore, using the wrong stylesheet). Just for the record, here are the middleware classes: MIDDLEWARE_CLASSES = ( 'django.middleware.common.CommonMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.middleware.transaction.TransactionMiddleware', ) I always use the default address http://localhost:8000. Is there another solution (other than using different ports - 8001, 8002, etc.)?

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  • How can I schedule tasks in a WinForms app?

    - by Greg
    QUESTION: How can I schedule tasks in a WinForms app? That is either (a) what is the best approach / .NET classes/methods to use of (b) if there is an open source component that does this well which one would be recommended. BACKGROUND: Winforms app (.NET v3.5, C#, VS2008) I'm assuming I will run the winforms application always, and just minimise to the system tray when not in use Want a simple approach (didn't want to get into separate service running that UI winforms app talks to etc) Want to be able to let the user select how often to schedule the sync (e.g. hourly, daily - pick time, etc) Ability to at the times when the scheduler fires to run a chunk of code (assume it could be wrapped as a backgroundworker task for example) The application is always running & appears in the system tray

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  • java servlet programming errror

    - by abson
    C:\Tomcat5.5\webapps\WEB-INF\classes>javac MyServlet.java MyServlet.java:2: package javax.servlet does not exist import javax.servlet.*; ^ MyServlet.java:3: package javax.servlet.http does not exist import javax.servlet.http.*; ^ MyServlet.java:5: cannot find symbol symbol: class HttpServlet public class MyServlet extends HttpServlet ^ MyServlet.java:7: cannot find symbol symbol : class HttpServletRequest location: class MyServlet public void doGet(HttpServletRequest req, HttpServletResponse res) throws Serv letException,IOException ^ MyServlet.java:7: cannot find symbol symbol : class HttpServletResponse location: class MyServlet public void doGet(HttpServletRequest req, HttpServletResponse res) throws Serv letException,IOException ^ MyServlet.java:7: cannot find symbol symbol : class ServletException location: class MyServlet public void doGet(HttpServletRequest req, HttpServletResponse res) throws Serv letException,IOException ^ 6 errors

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  • referencing an instantiated object in another class in objective C

    - by Paul
    hi, I am working in xcode on an ipod app in objective C, and I have a field (navigationController) in one of my classes (rootViewController). How do I reference the instantiated rootViewController's navigationController from another class? For example, how would I do this if I want to reference the navigationController from the FirstViewController.m class? I seem to only be able to find references for this to reference the application delegate. If I want to reference the application delegate with FirstViewController, I just say: MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [delegate.navigationController pushViewController:childController animated:YES]; how do I do this for the rootViewController class instead of MyAppDelegate?

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  • Are xlrd and xlwt compatible?

    - by Leo
    I'm trying to create a workbook with python and I need to test the values of different cells to fill it but I'm having some troubles. I use xlrd and xlwt to create and edit the excel file. I've made a little example of my problem and I don't understand why it's not working. import xlwt import xlrd wb = xlwt.Workbook() ws = wb.add_sheet('Test') ws.write(0,0,"ah") cell = ws.cell(0,0) # AttributeError: 'Worksheet' object has no attribute 'cell' print cell.value I had taken for granted that xlrd and xlwt have shared classes which can interact with each other but it doesn't seem to be the case. How do I get the cell value of an open Worksheet object?

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  • How and where do we write try catch block to handle Exception

    - by Arpita
    We are using C# language to develope a Windows application. Our windows application consists of three layers (UI,Business and DataAccess layer). In Business Layer there are some public (business) methods through which UI communicates wilh Business layer classes. These public methods also have some private methods to implement the required functionality. There are some methods in DataAcess layer which are called from Business layer class. In this situatuion where should i wrte try-catch? a) In Business Layer Public methods b) In Busyness Layer Private methods c) In DataAccess Layer methods d) In UI methods from where Business methods are called.

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  • xpcom array can transfer in different xul files ?

    - by jin
    Now I am developing a firefox extension, can I define a global array in a js with the main xul . and I found when I use it in another js with another xul , it could not worked , so I searched the document of Firefox development. I found a common array can not be transfered between two js files with different xul files. and then I difined a xpcom mutablearray in a js: var eleList = Components.classes["@mozilla.org/array;1"] .createInstance(Components.interfaces.nsIMutableArray); but when I want to use it in another js : it still not work , why? Thank you very much!

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  • Rails 2.3.x, named_scope chaining with INNER JOIN complication

    - by randombits
    I have two hypothetical classes, Foo and Bar. Foo contains many Bars. Bar can only belong to one Foo. Ultimately the SQL query I'm trying to make happen looks like the following: SELECT * from bar INNER JOIN foo ON bar.foo_id = foo.id where bar.in_use = 0 and bar.customer_id = 1 and foo.category = 0 That query does what I need. Now I'm trying to break the problem down in Rails using chained named_scopes. First, the straight forward in_use and customer_id scopes I have set: named_scope :available, :conditions => { :in_use => 0 } named_scope :not_available, :conditions => { :in_use => 1 } named_scope :customer, lambda { |num| { :conditions => { :customer_id => num } } } Now the part I'm stuck at, is I'm trying to do something like this in my code: abar = Bar.available.customer(1).category(0) how and where do I put the category named_scope to make this work?

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  • Change Casing in WCF Service Reference

    - by Eric J.
    I'm creating a service reference to a web service written in Java. The generated classes now follow the Java casing convention used in the web service, for example class names are camelCase rather than PascalCase. Is there a way to get the desired casing from the service reference? CLARIFICATION: With WSE based services, one could modify the generated Reference.cs to provide .NET standard casing and use XmlElementAttribute to map to the Java naming presented by the external web service, like this: [System.Xml.Serialization.XmlElementAttribute("resultType", Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] [System.Runtime.Serialization.DataMember] public virtual MyResultType ResultType { ... } Not terribly maintenance-friendly without writing custom code to either generate the proxy code or modify it after it's been generated. What I'm after is one or more options to present a WCF generated client proxy to calling applications using the .NET casing conventions, achieving the same as I did previously with WSE. Hopefully with less manual effort.

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  • How to build a java applet?

    - by Stefano Borini
    Most of the tutorials around explain how to create a java applet: create a .java file with a class, compile it with javac, put the .class somewhere, add a proper tag in the html. However, I'm not able to find anything about the best practices to build and release a complex applet, made of multiple classes and with additional libraries. How is the build/release process for this case ? What is it needed to go from my java project to the final .jar to put on the web ? I'm working with pure Eclipse, no plugins.

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  • .Net Xml Serialize - XSD Definition for Multiple Namespaces

    - by MattH
    The following XML was generated by serializing .Net objects: <?xml version="1.0" encoding="utf-8"?> <Request xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://EPS.WebServices/WebServiceSchema" > <Method xmlns="http://EPS.Library/RequestSchema">PackPlacementUpdate</Method> <Type xmlns="http://EPS.Library/RequestSchema">PackPlacementUpdate</Type> </Request> I am using XSD to generate a schema. However, (I think) because there are multiple namespaces two different schema files get generated. We will be providing the XSD file externally and I'm concerned that two files will cause confusion. Without changing the namespace of the .Net classes, is there is a way I can create a single XSD schema file and not two? Thanks.

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  • SCNetworkReachability compiling error

    - by user262325
    Hello everyone I try to compile Ercia Sadun's sample codes at: http://github.com/erica/iphone-3.0-cookbook-/tree/master/C13-Networking/14-Web%20Browser/ There is error report : warning: in /Users/interdev/iphone source code/Web Browser/Classes/SystemConfiguration.framework/SystemConfiguration, missing required architecture i386 in file Undefined symbols: "_SCNetworkReachabilityScheduleWithRunLoop", referenced from: +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o "_SCNetworkReachabilityCreateWithAddress", referenced from: +[UIDevice(Reachability) hostAvailable:] in UIDevice-Reachability.o +[UIDevice(Reachability) pingReachabilityInternal] in UIDevice-Reachability.o "_SCNetworkReachabilityUnscheduleFromRunLoop", referenced from: +[UIDevice(Reachability) unscheduleReachabilityWatcher] in UIDevice-Reachability.o "_SCNetworkReachabilitySetCallback", referenced from: +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o +[UIDevice(Reachability) unscheduleReachabilityWatcher] in UIDevice-Reachability.o "_SCNetworkReachabilityGetFlags", referenced from: +[UIDevice(Reachability) hostAvailable:] in UIDevice-Reachability.o +[UIDevice(Reachability) pingReachabilityInternal] in UIDevice-Reachability.o ld: symbol(s) not found collect2: ld returned 1 exit status "_SCNetworkReachabilityScheduleWithRunLoop", referenced from: +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o "_SCNetworkReachabilityCreateWithAddress", referenced from: +[UIDevice(Reachability) hostAvailable:] in UIDevice-Reachability.o +[UIDevice(Reachability) pingReachabilityInternal] in UIDevice-Reachability.o "_SCNetworkReachabilityUnscheduleFromRunLoop", referenced from: +[UIDevice(Reachability) unscheduleReachabilityWatcher] in UIDevice-Reachability.o "_SCNetworkReachabilitySetCallback", referenced from: +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o +[UIDevice(Reachability) scheduleReachabilityWatcher:] in UIDevice-Reachability.o +[UIDevice(Reachability) unscheduleReachabilityWatcher] in UIDevice-Reachability.o "_SCNetworkReachabilityGetFlags", referenced from: +[UIDevice(Reachability) hostAvailable:] in UIDevice-Reachability.o +[UIDevice(Reachability) pingReachabilityInternal] in UIDevice-Reachability.o ld: symbol(s) not found collect2: ld returned 1 exit status Build failed (5 errors) even I add systemConfiguration.framework, it reported same error. Welcome any comment Thanks interdev

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  • How are Scala traits compiled into Java bytecode?

    - by Justin Ardini
    I have played around with Scala for a while now, and I know that traits can act as the Scala equivalent of both interfaces and abstract classes. Recently I've been wondering how exactly traits are compiled into Java bytecode. I found some short explanations that stated traits are compiled exactly like Java interfaces when possible, and interfaces with an additional class otherwise. I still don't understand, however, how Scala achieves class linearization, a feature not available in Java. Could anyone explain or provide a good source explains how traits compile to Java bytecode?

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  • Using Static methods or none static methods in Dao Class ?

    - by dankyy1
    Hi I generate Dao classes for some DB operations in this manner making methods of Dao class as static or none static is better? Using sample dao class below ,If more than one client got to use the AddSampleItem method in same time?how this may result? public class SampleDao { static DataAcessor dataAcessor public static void AddSampleItem(object[] params) { dataAcessor =new DataAcessor(); //generate query here string query="..." dataAcessor.ExecuteQery(query); dataAcessor.Close(); } public static void UpdateSampleItem(object[] params) { dataAcessor =new DataAcessor(); //generate query here string query="..." dataAcessor.ExecuteQery(query); dataAcessor.Close(); } }

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  • In a distributed environment, how can I configure log4j to log to different files for each JVM insta

    - by Renan Mozone
    My application runs on IBM WebSphere 6.1 Network Deployment. The application have several JSP files and Java classes. Today each host have only one JVM instance but my intention is to start another instance on each host. How can I configure log4j to log to different files for each JVM instance in the same host? I thought of using variable substitution on log4j XML configuration file but it only works with system properties. So, it is safe and recommended to set a custom system property just to store the JVM name? Anyone knows another strategy to achieve this in a 'elegant' way?

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  • Can't transfer list<T> to web service?

    - by iTayb
    I have the same classes on my server and on my web service. I have the following WebMethod: [WebMethod] public int CreateOrder(List<Purchase> p, string username) { o.Add(new Order(p,username)); return o.Count; } However the following code, run at server: protected void CartRepeater_ItemCommand(object source, RepeaterCommandEventArgs e) { List<Purchase> l = ((List<Purchase>)Session["Cart"]); if (e.CommandName == "Order") { localhost.ValidateService WS = new localhost.ValidateService(); WS.CreateOrder(l, Session["username"].ToString()); } } gives the following error: Argument '1': cannot convert from 'System.Collections.Generic.List<Purchase>' to 'localhost.Purchase[]'. How can I transfer the list<Purchase> object to the web service? Thank you very much.

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  • LinkedList cannot be serialised?

    - by iTayb
    Here are my classes: http://pastebin.com/3dc5Vb1t When I try to run BookStore b = new BookStore(); b.LoadFromXML(Server.MapPath("list.xml")); Label1.Text = b.ToString(); I get the following error: You must implement a default accessor on System.Collections.Generic.LinkedList`1[[Book, App_Code.cxsacizw, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]] because it inherits from ICollection. The error source is XmlSerializer s = new XmlSerializer(typeof(BookStore)); When I tried to look for a solution on google, I found it that LinkedList has some problems with serialization. How can I deal with it? Thank you very much.

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  • Java EE 6 - ordering Servlet Request Listeners

    - by Walter White
    Hi all, I finally updated to Java EE 6 (web profile) and would like to control the ordering of my servlet request listeners. I did that before through the XML ordering by listing the listeners in a particular order. Now, I have placed the @WebListener annotation on the classes which are listeners and am trying to figure out how to order the listeners such that they work properly. One must run before another one, otherwise, it won't have the information it needs and won't work. Also, it doesn't seem my listeners are actually being invoked even though they're marked with @WebListener. I am running embedded glassfish 3.0. Another question that is somewhat related - ServletRequestListeners in Java EE 6 by default are still synchronous meaning they're hit first, then servlet filters, right? ServletRequestListeners are not asynchronous where they merely get notified of an event without interrupting the execution? Walter

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  • Datacontracts property getter running twice

    - by user321426
    I have a set of data contracts that act as wrappers to base classes that we wish to expose. A quick example is: [DataMember] public List<decimal> Points { get { return sourceObject.ListPoints(); } private set{} } We have some other properties that we have to massage the data first (we are converting object graphs and need to guard against circular references). The issue that we are seeing is that this getter will fire twice, once within the service operation, then again during serialization. This is causing two problems: We manually add to collections, since this is running twice the collections are filled with dupes. If an exception is thrown during the second run, it happens outside of the try/catch in the operation, and does not throw a fault. The service throws a cryptic timeout message, and the only way to see the error is via WCF trace logs.

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