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  • Getting all inner classes by reflection

    - by Roman
    I have the following problem. I have this pretty class and now I want to get all the classes that extend that class (inner classes ) and fill 'classList' with it. ( in an automatic way of course ) public abstract class CompoundReference { private static List<Class<? extends CompoundReference>> classList = new ArrayList<Class<? extends CompoundReference>>(); @CompoundKey(gsType = User.class, dbType = UserDetailsMappings.class) public static class CUser extends CompoundReference { } @CompoundKey(gsType = Catalog.class, dbType = CatalogDetailsMappings.class) public static class CCatalog extends CompoundReference { } @CompoundKey(gsType = Product.class, dbType = ProductDetailsMappings.class) public static class CProduct extends CompoundReference { } @CompoundKey(gsType = Category.class) public static class CCategory extends CompoundReference { } @CompoundKey(gsType = Poll.class, dbType = PollDetailsMappings.class) public static class CPoll extends CompoundReference { } // much mroe inner classes Some manual solution would be just to main such a static block , that is something that I dont want to do. static { classList.addAll(Arrays.asList(CUser.class, CCatalog.class, CProduct.class, CCategory.class, CPoll.class, CComment.class, CWebPage.class, CReview.class, CPost.class, CMessage.class, CStory.class,CPicture.class)); }

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  • Core Data: Detecting the type and casting it

    - by Tim Sullivan
    I have set up a Core Data model that includes an entity, Item with a 1-M relationship with the abstract entity Place, so that an item has many places. There are several entities with the parent set to Place. I want to set up several UI elements depending on the descendent place types. I have a loop that looks something like this: for (Place *place in item.places) { } ... but I'm not sure how to detect what type the place is, and how to cast it to the proper type so that I can access its properties. Thanks for any help!

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  • How to filter/sort/rank object model nodes?

    - by BCS
    I have some kind of object model and I need to filter and sort it's nodes for some kind of property. What kinds of automated systems exist to generate and select properties of the object model that correlate to what I want? (I'm intentionally being abstract and non-specific) I'm thinking of a system that works kind of like spam filters or supervised classification systems in that given an example data set it identifies rules that find nodes of interest. However I'm looking for a more general system in that it shouldn't require any design time information about the object model. It should work equality well as a spam filter on e-mail, a bug finder on a code base, an interest filter in a newsgroup or bot accounts finder on a social networking site. As long as it can explore the object model via reflection and be given a set of "interesting" nodes, it should be able to find rules that will find more nodes like them.

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  • How to step into the world of J2EE?

    - by Michael Lai
    I am new to J2ee. I have experience in Java core, JSP,Servlet, XML, HTML, What should i learn to step into the world of J2EE? Framework(Spring, Hibernate, Struts)? But the framework is too abstract for me.I saw lots of job post which requires frameworks, some jobs require EJB,JPA. I do not where to start. Any experts can give me hints on that? I found the tutorial of J2EE 5 published by ORACLE is not easy to understand. Too much jargon....

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  • EntityFramework 4.0: can you return different types depending on data in the database?

    - by user200341
    I have a Media table in the database. I also have an IMedia interface. I have two different media types that implements the same interface: 1) AudioMedia 2) PictureMedia What I wonder here, is if I can use EntityFramework (I'm using an EDMX file but I have my models in a separate library, with automatic code generation turned off), and depending on the data in the database, select what type to get (AutioMedia or PictureMedia). Since they are both implementing the same interface (could be changed to an abstract class if needed I suppose), I'm thinking that somewhere along the way you could specify what class it should be. I should perhaps point out that I have a class that inherits from ObjectContext to access the objects. Perhaps there is something that that can be done?

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  • Create object of unknown class (two inherited classes)

    - by Paul
    I've got the following classes: class A { void commonFunction() = 0; } class Aa: public A { //Some stuff... } class Ab: public A { //Some stuff... } Depending on user input I want to create an object of either Aa or Ab. My imidiate thought was this: A object; if (/*Test*/) { Aa object; } else { Ab object; } But the compiler gives me: error: cannot declare variable ‘object’ to be of abstract type ‘A’ because the following virtual functions are pure within ‘A’: //The functions... Is there a good way to solve this?

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  • .NET CF 2.0: Stream implements IDisposable ... kind of?

    - by mvanbem
    I've run into something odd in a .NET CF 2.0 project for Pocket PC 2003 (Visual Studio 2005). I was dealing with a System.IO.Stream object and found that the IDE wouldn't auto-complete the Dispose() method. I typed it in manually and received: 'System.IO.Stream.Dispose(bool)' is inaccessible due to its protection level The error is referring to the protected Dispose(bool) method. Dispose() is either private or not present. Question 1: How is this possible? Stream implements IDisposable: public abstract class Stream : MarshalByRefObject, IDisposable ... and IDisposable requires a Dispose() method: public interface IDisposable { void Dispose(); } I know the compiler won't let me get away with that in my code. Question 2: Will I cause problems by working around and disposing my streams directly? IDisposable idisp = someStream; idisp.Dispose(); The implicit cast is accepted by the compiler.

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  • Fastest method for SQL Server inserts, updates, selects

    - by Ian
    I use SPs and this isn't an SP vs code-behind "Build your SQL command" question. I'm looking for a high-throughput method for a backend app that handles many small transactions. I use SQLDataReader for most of the returns since forward only works in most cases for me. I've seen it done many ways, and used most of them myself. Methods that define and accept the stored procedure parameters as parameters themselves and build using cmd.Parameters.Add (with or without specifying the DB value type and/or length) Assembling your SP params and their values into an array or hashtable, then passing to a more abstract method that parses the collection and then runs cmd.Parameters.Add Classes that represent tables, initializing the class upon need, setting the public properties that represent the table fields, and calling methods like Save, Load, etc I'm sure there are others I've seen but can't think of at the moment as well. I'm open to all suggestions.

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  • EF4 (CPT5) ForeignKeyAttribute in base class - Assert Failure entityType != null

    - by Anthony Johnston
    Getting an error when trying to set a ForeignKeyAttribute in a base class class User{} abstract class FruitBase{ [ForeignKey("CreateById")] public User CreateBy{ get; set; } public int CreateById{ get; set; } } class Banana{} class DataContext : DbContext{ DbSet<Banana> Bananas{ get; set; } } If I move the FruitBase code into the banana, all is well, but I don't want to, as there will be many many fruit and I want to remain relatively DRY if I can Is this a know issue that will be fixed by March? Does anyone know a work around?

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  • Calling inheriting class methods via interface.

    - by Stacey
    Given the scenario... interface IBase{ void Process(int value); } abstract class Base : IBase { public virtual void Process(int value){ throw new NotImplementedException(); } } class Implemented: Base, IBase { public void Process(int value) { // .. some code here.. } } I'm trying to write a loop similar to the following. foreach( Base b in CollectionOfImplemented ) { b.Process( // something will go here // ); } Trying this, it keeps calling Base.Process, instead of Implemented.Process; but the type in the collection is Implemented, not Base. Boxing it seems to work, but I was hoping to see if I could find a more intelligent approach to it, since the Collection will contain other types of objects that also inherit from Base.

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  • Reflection alternative for switch on enum in order to select namespace/class

    - by Am
    Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks. I will give my 2 cents of why I want to change this. There several people writing harvesters, I want them to focus only on building more harvesters, without ever needing to update the enum, or at worst, update only the enum.

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  • Why don't hardware failures show up at the programming language level?

    - by Julian Cienfuegos
    I am wondering if anyone can give my a good answer, or at least point me in the direction of a good reference to the following question: How come I have never heard of a computer breaking in a very fundamental way? How come when I declare x to be a double it stays as a double? How come there is never a short circuit that robs it of some bytes and makes it an integer? Why do we have faith that when we initialize x to 10, there will never be a power surge that will cause it to become 11, or something similar? I think I need a better understanding of memory. Thanks, and please don't bash me over the head for such a simple/abstract question.

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  • Design classes/interface to support methods returning different types

    - by Nayn
    Hi, I have classes as below. public interface ITest <T> { public T MethodHere(); } public class test1 implements ITest<String> { String MethodHere(){ return "Bla"; } } public class test2 implements ITest<Integer> { Integer MethodHere(){ return Integer.valueOf(2); } } public class ITestFactory { public static ITest getInstance(int type) { if(type == 1) return new test1(); else if(type == 2) return new test2(); } } There is a warning in the factory class that ITest is used as raw type. What modification should I do to get rid of it? Thanks Nayn

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  • How can I remove the numeration of some titles in LaTeX?

    - by Tae
    Hi: I'm writing my degree project report using the article class and I want a structure like this: Abstract Introduction 1. What 2. Where 3. Etc. I was searching and I found that using \setcounter{secnumdepth}{-1} the complete numeration is eliminated. And if I use * these sections don't appear in the table of content. So what can I do? Can this be done without installing packages (like memoir)?

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  • Just how much do I want to make virtual?

    - by Alex
    I am writing an abstract superclass where literally every method is going to be overridden. There is some default functionality I could implement, but most of the time it's enough to leave the implementation to the subclass writer. Since just about every method is going to be overwritten, how much should I make virtual and how much should I just leave as regular methods? In the current incarnation, everything is virtual, but I still haven't let this loose to anyone to use, so the design is flexible. What advantages/disadvantages are there to virtual functions? Links to good reading material about this would be appreciated.

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  • Dispatching generic tasks in WCF or .Net Remoting

    - by Eric
    Hello all, I've been researching for a couple days on and off, and have yet to figure out the best way to achieve the following goal. I would like to define either an interface or abstract class in C# which has an associated Run method, similar to the Java runnable interface. The goal would be to have a shared queue which contains a list of these objects. Then individual clients would be able to derive their own concrete runnable classes and add them to the queue hosted by the server. Clients would also be able to pop these runnable objects off the queue and execute them arbitrarily. This seems like it should be feasible in a VM based language without needing to place any of the concrete implementations in a shared assembly, but I have thus far had no luck finding a working example of such a system. Does anyone know how this might be achieved?

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  • Working with sets of rows in (My)SQL and comparing values

    - by Pep.
    Hello, I am trying to figure out the SQL for doing some relatively simple operations on sets of records in a table but I am stuck. Consider a table with multiple rows per item, all identified by a common key. For example: serial model color XX1 A blue XX2 A blue XX3 A green XX5 B red XX6 B blue XX1 B blue What I would for example want to do is: Assuming that all model A rows must have the same color, find the rows which dont. (for example, XX3 is green). Assuming that a given serial number can only point to a single type of model, find out the rows which that does not occur (for example XX1 points both to A and B) These are all simple logically things to do. To abstract it, I want to know how to group things by using a single key (or combination of keys) and then compare the values of those records. Should I use a join on the same table? should i use some sort of array or similar? thanks for your help

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  • C++ template restrictions

    - by pingvinus
    I wondering is there any way to set restrictions on template class? Specify that every type substituted in template must have specific ancestor (realize some interface). template < class B > //and every B must be a child of abstract C class A { public: B * obj; int f() { return B::x + this->obj->f(); } }; Like = in haskell func :: (Ord a, Show b) => a -> b -> c

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  • what to use in place of std::map::emplace?

    - by kfmfe04
    For containers such as std::map< std::string, std::unique_ptr< Foo >>, it looks like emplace() has yet to be implemented in stdc++ as of gcc 4.7.2. Unfortunately, I can't store Foo directly by value as it is an abstract super-class. As a simple, but inefficient, place-holder, I've just been using std::map< std::string, Foo* > in conjunction with a std::vector< std::unique_ptr< Foo >> for garbage collection. Do you have a interim solution that is more efficient and more easily replaced once emplace() is available?

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  • Configuring jdbc-pool (tomcat 7)

    - by john
    i'm having some problems with tomcat 7 for configuring jdbc-pool : i`ve tried to follow this example: http://www.tomcatexpert.com/blog/2010/04/01/configuring-jdbc-pool-high-concurrency so i have: conf/server.xml <GlobalNamingResources> <Resource type="javax.sql.DataSource" name="jdbc/DB" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/mydb" username="user" password="password" /> </GlobalNamingResources> conf/context.xml <Context> <ResourceLink type="javax.sql.DataSource" name="jdbc/LocalDB" global="jdbc/DB" /> <Context> and when i try to do this: Context initContext = new InitialContext(); Context envContext = (Context)initContext.lookup("java:/comp/env"); DataSource datasource = (DataSource)envContext.lookup("jdbc/LocalDB"); Connection con = datasource.getConnection(); i keep getting this error: javax.naming.NameNotFoundException: Name jdbc is not bound in this Context at org.apache.naming.NamingContext.lookup(NamingContext.java:803) at org.apache.naming.NamingContext.lookup(NamingContext.java:159) pls help tnx

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  • can I get .class from generic type argument?

    - by Mike S
    I have the following class: public abstract class MyClass<T extends Object> { protected T createNewFromData(Reader reader){ GSON.fromJSON(reader,T.class); // T.class isn't allowed :( } } How do I pass a Class<T instance into there? Is there some wierd and wacky work around? Is there a way to get a Class<T reference other than from a pre-instantiated Object of type T? It won't let me do this either: T t = new T(); Class<T> klass = t.class; ANSWER BELOW Thanks to the accepted answer, here is the solution: Type type = new TypeToken<T>(){}.getType(); return gson.fromJson(reader, type);

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  • I want to make a wrapped acces type for certain internals of one of classes and I have some performa

    - by Alex
    I am writing an abstract matrix class (and some concrete subclasses) for use on very differing hardwares/architectures, etc. and I want to write a row and column type that provides a transparent reference to the rows and columns of the matrix. However, I want to tune for performance, so I'd like this class to be essentially a compiler construct. In other words, I'm willing to sacrifice some dev time to making the overhead of these classes as small as possible. I assume all (small) methods would want to be virtual? Keep the structure small? Any other suggestions?

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  • Problem with fetching table to array

    - by jasmine
    I have writed this function: function news_array() { $sql = "SELECT * FROM content WHERE home=1"; $query = mysql_query($sql); $i = 0; while($row = mysql_fetch_array($query)){ $row_array[$i] = array( TITLE => $row['title'], ABSTRACTT => $row['abstract'], BODY => $row['body'], ID => $row['conID'] ); $i++; } return $row_array; } When using this function like this: <?php $row_array = news_array(); for($i = 0 ; $i < count($row_array) ; $i++){ echo $row_array[$i][TITLE]; } ?> There no output in html. What is wrong in my function? Thanks in advance

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  • Tied up with injection implemented with setter functions

    - by puudeli
    Hi, I'm trying to use Scala as part of an existing Java application and now I run into an issue with dependencies injected with a setter method (no DI frameworks in this part of code). How is this handled in a Scala way? In Scala both val and var require to be initialized when declared but I can't do that, since the Java setters inject objects that implement a certain interface and interfaces are abstract and can not be instantiated. class ScalaLogic { var service // How to initialize? def setService (srv: OutputService) = { service = srv } Is there a way to initialize the var service so that I can later assign a dependency into it? It should be lexically scoped to be visible in the whole class.

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  • Java inheritance question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = method-call();` // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void some-method(LIst<A> a) However, when I do: C c = new C(). c. some-method(b) I get an error that some-method is not applicable for the argument List, instead it's expecting to get List. Is there a good way to fix this problem? Many thanks!

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