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  • How can you write a function that accepts multiple types?

    - by matthy
    I have a function that should work on int[] and on String[] now i have made the same function with a int parameter and an String parameter however if it has to go this way its a bit copy paste work and doesn't look very organized is there a way to solve this and put these 4 functions in 2? static public void print(String s) { System.out.println(s); } static public void print(int s) { System.out.println(s); } static public void printArray(String[] s) { for (int i=0; i<s.length; i++) print(s[i]); } static public void printArray(int[] s) { for (int i=0; i<s.length; i++) print(s[i]); } Thanks Matthy

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  • Problem in using C# generics with method overloading

    - by Siva Chandran
    I am trying to call an overloaded method based on the generic type. I've been doing this in C++ without any pain. But I really don't understand why am not able to do this in C# with generics. Can anybody help me how can I achieve this in C# with generics? class Test<T> { public T Val; public void Do(T val) { Val = val; MainClass.Print(Val); } } class MainClass { public static void Print(UInt16 val) { Console.WriteLine("UInt16: " + val.ToString()); } public static void Print(UInt32 val) { Console.WriteLine("UInt32: " + val.ToString()); } public static void Print(UInt64 val) { Console.WriteLine("UInt64: " + val.ToString()); } public static void Main (string[] args) { Test<UInt16> test = new Test<UInt16>(); test.Do(); } }

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  • Best practice for storage and retrieval of error messages.

    - by ferrari fan
    What is a best practice for storing user messages in a configuration file and then retrieving them for certain events throughout an application? I was thinking of having 1 single configuration file with entries such as REQUIRED_FIELD = {0} is a required field INVALID_FORMAT = The format for {0} is {1} etc. and then calling them from a class that would be something like this public class UIMessages { public static final String REQUIRED_FIELD = "REQUIRED_FIELD"; public static final String INVALID_FORMAT = "INVALID_FORMAT"; static { // load configuration file into a "Properties" object } public static String getMessage(String messageKey) { // return properties.getProperty(messageKey); } } Is this the right way to approach this problem or is there some de-facto standard already in place?

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  • Cannot set g:checkbox to off for a child on one-to-many relationship

    - by icon911
    Got a weird issue with g:checkbox not being saved when its switched from on to off for a child in one-to-many relationship. For example: class Parent { Boolean enabled static hasMany = [children: Child] static constraints = { enabled(blank: true, nullable: true) } } class Child { Boolean enabled static belongsTo = [parent: Parent] static constraints = { enabled(blank: true, nullable: true) } } Posting to Parent controller true/false values will work for Parent: <g:checkBox name="enabled" value="${parentInstance?.enabled}"/> However, not for Child! When posting to Parent controller I can only go from false to true, trying to change from true to false again will not work: <g:each in="${parentInstance.children}" status="i" var="child"> <g:checkBox name="child[${i}].enabled" value="${child?.enabled}" /> </g:each> That seems to be a bug. Any ideas? Thanks.

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  • Issue with deserialization in .Net

    - by Punit Singhi
    I have a class called Test which has four public properties and one of them is static. the problem is after deserialization the static property contains null value. i have debugged the code and found that at server side it contains the value which is a collection , but at client side it becomes null after deserialization. i know static members doesn't serialize and deserialize so obviously it shud contain the value.

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  • How to model interentity membership in entity-component architecture?

    - by croxis
    I'm falling in love with simple grace of entity-component design, although I still have issues breaking from MVC and OOP practices. Some of my game entities have membership relationships with each other (ex: a player is a member of a city, a city is a member of a nation), and I am unsure on the best way to implement it. My initial reaction is to have a a MemberOfCity component that points to the appropriate city component, but components are suppose to have no references to each other. My other option is to have a System do it, but that would require the system to persist data outside of a component. Is there a clean way to do this in an entity-component design, or am I trying to use a hammer on a screw and should use a hybrid/another approach?

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  • Can it be done in a more elegant way with the Swing Timer?

    - by Roman
    Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer? import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; public class CountdownNew { static JLabel label; // Method which defines the appearance of the window. public static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. public static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); counter.start(); } }); } }

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  • Confusion about inheritance

    - by Samuel Adam
    I know I might get downvoted for this, but I'm really curious. I was taught that inheritance is a very powerful polymorphism tool, but I can't seem to use it well in real cases. So far, I can only use inheritance when the base class is an abstract class. Examples : If we're talking about Product and Inventory, I quickly assumed that a Product is an Inventory because a Product must be inventorized as well. But a problem occured when user wanted to sell their Inventory item. It just doesn't seem to be right to change an Inventory object to it's subtype (Product), it's almost like trying to convert a parent to it's child. Another case is Customer and Member. It is logical (at least for me) to think that a Member is a Customer with some more privileges. Same problem occurred when user wanted to upgrade an existing Customer to become a Member. A very trivial case is the Employee case. Where Manager, Clerk, etc can be derived from Employee. Still, the same upgrading issue. I tried to use composition instead for some cases, but I really wanted to know if I'm missing something for inheritance solution here. My composition solution for those cases : Create a reference of Inventory inside a Product. Here I'm making an assumption about that Product and Inventory is talking in a different context. While Product is in the context of sales (price, volume, discount, etc), Inventory is in the context of physical management (stock, movement, etc). Make a reference of Membership instead inside Customer class instead of previous inheritance solution. Therefor upgrading a Customer is only about instantiating the Customer's Membership property. This example is keep being taught in basic programming classes, but I think it's more proper to have those Manager, Clerk, etc derived from an abstract Role class and make it a property in Employee. I found it difficult to find an example of a concrete class deriving from another concrete class. Is there any inheritance solution in which I can solve those cases? Being new in this OOP thing, I really really need a guidance. Thanks!

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  • Namespaces and deserialization issue

    - by CaffGeek
    UPDATE: You can run the code at the end of this to recreate and see the error I am having and hopefully solve it! UPDATE2: It's not the removal of the xmlns="" that's the issue... as you can remove it from the initial xml string. The problem is with the [XmlType(TypeName = "Systems")] somehow causing it to be added... UPDATE3: Turns out the problem is in here, I need to set the TypeName based on what is in the existing, XmlTypeAttribute if it already exists on the class.... xmlAttributes.XmlType = new XmlTypeAttribute { Namespace = "" }; I get the following XML as a string from a webservice <Systems xmlns=""> <System id="1"> <sys_name>ALL</sys_name> </System> <System id="2"> <sys_name>asdfasdf</sys_name> </System> <System id="3"> <sys_name>fasdfasf</sys_name> </System> <System id="4"> <sys_name>asdfasdfasdf</sys_name> </System> </Systems> I then execute this, to convert it to an object result = XElement.Parse(xmlResult.OuterXml).Deserialize<AwayRequestSystems>(); Strangely though, in the Deserialize method, while the RemoveAllNamespaces works and returns the xml without the namespace I get the error <Systems xmlns=''> was not expected. in the catch when return (T) serializer.Deserialize(reader); executes! Why is it doing this? The xmlns is GONE!!! EXECUTABLE CODE! (Just put it in a test project) using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; using System.Xml; using System.Xml.Linq; using Microsoft.VisualStudio.TestTools.UnitTesting; using System.Xml.Serialization; namespace DeserializationTest { [TestClass] public class UnitTest1 { public TestContext TestContext { get; set; } [TestMethod] public void RemoveXmlnsFromSystems() { var xml = XElement.Parse(@"<Systems xmlns=""""> <System id=""1""> <sys_name>ALL</sys_name> </System> <System id=""2""> <sys_name>ePO</sys_name> </System> <System id=""3""> <sys_name>iEFT</sys_name> </System> <System id=""4""> <sys_name>Away Requests</sys_name> </System> <System id=""5""> <sys_name>RP3</sys_name> </System> </Systems>"); var systems = xml.Deserialize<AwayRequestSystems>(); Assert.IsInstanceOfType(systems, typeof(AwayRequestSystems)); var xmlnsFree = xml.RemoveAllNamespaces(); var str = xmlnsFree.ToString(); Debug.WriteLine(str); Assert.AreNotEqual("Error", xmlnsFree.Name.ToString(), "Serialization Error"); Assert.IsFalse(str.Contains("xmlns"), "Xmlns still exists"); } } [XmlType(TypeName = "Systems")] public class AwayRequestSystems : List<AwayRequestSystem> { } [XmlType(TypeName = "System")] public class AwayRequestSystem { [XmlAttribute("id")] public int ID { get; set; } [XmlElement("sys_name")] public string Name { get; set; } } public static class XmlSerializerFactory { private static Dictionary<Type, XmlSerializer> _serializers = new Dictionary<Type, XmlSerializer>(); public static void ResetCache() { _serializers = new Dictionary<Type, XmlSerializer>(); } public static XmlSerializer GetSerializerFor(Type typeOfT) { if (!_serializers.ContainsKey(typeOfT)) { var xmlAttributes = new XmlAttributes(); var xmlAttributeOverrides = new XmlAttributeOverrides(); Debug.WriteLine(string.Format("XmlSerializerFactory.GetSerializerFor(typeof({0}));", typeOfT)); xmlAttributes.XmlType = new XmlTypeAttribute { Namespace = "" }; xmlAttributes.Xmlns = false; var types = new List<Type> { typeOfT, typeOfT.BaseType }; foreach (var property in typeOfT.GetProperties()) { types.Add(property.PropertyType); } types.RemoveAll(t => t.ToString().StartsWith("System.")); foreach (var type in types) { if (xmlAttributeOverrides[type] == null) xmlAttributeOverrides.Add(type, xmlAttributes); } var newSerializer = new XmlSerializer(typeOfT, xmlAttributeOverrides); //var newSerializer = new XmlSerializer(typeOfT, xmlAttributeOverrides, types.ToArray(), new XmlRootAttribute(), string.Empty); //var newSerializer = new XmlSerializer(typeOfT, string.Empty); _serializers.Add(typeOfT, newSerializer); } return _serializers[typeOfT]; } } public static class XElementExtensions { public static XElement RemoveAllNamespaces(this XElement source) { if (source.HasAttributes) source.Attributes().Where(a => a.Name.LocalName.Equals("xmlns")).Remove(); return source.HasElements ? new XElement(source.Name.LocalName, source.Attributes()/*.Where(a => !a.Name.LocalName.Equals("xmlns"))*/, source.Elements().Select(el => RemoveAllNamespaces(el)) ) : new XElement(source.Name.LocalName) { Value = source.Value }; } } public static class SerializationExtensions { public static XElement Serialize(this object source) { try { var serializer = XmlSerializerFactory.GetSerializerFor(source.GetType()); var xdoc = new XDocument(); using (var writer = xdoc.CreateWriter()) { serializer.Serialize(writer, source, new XmlSerializerNamespaces(new[] { new XmlQualifiedName("", "") })); } var result = (xdoc.Document != null) ? xdoc.Document.Root : new XElement("Error", "Document Missing"); return result.RemoveAllNamespaces(); } catch (Exception x) { return new XElement("Error", x.ToString()); } } public static T Deserialize<T>(this XElement source) where T : class { //try //{ var serializer = XmlSerializerFactory.GetSerializerFor(typeof(T)); var cleanxml = source.RemoveAllNamespaces(); var reader = cleanxml.CreateReader(); return (T)serializer.Deserialize(reader); //} //catch (Exception x) //{ // return null; //} } } }

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  • accessing widgets inside a GWT element

    - by flyingcrab
    I want to access the text elements inside this textbox in GWT from the main method (where I call it like this) DialogBox aBox = newCandidatePop.buildNewElecPopup(); aBox.center(); aBox.getWidget(); MiscUiTools.newCandidateHandler(aBox.firstName, aBox.surName); in newCandidateHandler i want to attach a click handler to the two text boxes However, the above doesnt quite work - I cant get access to the aBox.firstName elements because they are static methods -- I am wondering what is best practice, how would you code something like this up? static TextBox firstName = new TextBox(); static TextBox surName = new TextBox(); static DialogBox box; // public newCandidatePop() { // box = buildNewElecPopup(); // } static public DialogBox buildNewElecPopup() { DialogBox box = new DialogBox(); box.setAutoHideEnabled(true); box.setText("Add a New Candidate"); box.setAnimationEnabled(true); box.setGlassEnabled(true); Grid dialogGrid = new Grid(2, 3); dialogGrid.setPixelSize(250 , 125); dialogGrid.setCellPadding(10); dialogGrid.setWidget(0, 0, new HTML("<strong>First Name</strong>")); dialogGrid.setWidget(0, 1, firstName); dialogGrid.setWidget(1, 0, new HTML("<strong>Surname</strong>")); dialogGrid.setWidget(1, 1, surName); box.add(dialogGrid); return box; }

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  • Managing accounts on a private website for a real-life community

    - by Smudge
    Hey Pro Webmasters, I'm looking at setting-up a walled-in website for a real-life community of people, and I was wondering if anyone has any experience with managing member accounts for this kind of thing. Some conditions that must be met: This community has a set list of real-life members, each of whom would be eligible for one account on the website. We don't expect or require that they all sign-up. It is purely opt-in, but we anticipate that many of them would be interested in the services we are setting up. Some of the community members emails are known, but some of them have fallen off the grid over the years, so ideally there would be a way for them to get back in touch with us through the public-facing side of the site. (And we'd want to manually verify the identity of anyone who does so). Their names are known, and for similar projects in the past we have assigned usernames derived from their real-life names. This time, however, we are open to other approaches, such as letting them specify their own username or getting rid of usernames entirely. The specific web technology we will use (e.g. Drupal, Joomla, etc) is not really our concern right now -- I am more interested in how this can be approached in the abstract. Our database already includes the full member roster, so we can email many of them generated links to a page where they can create an account. (And internally we can require that these accounts be paired with a known member). Should we have them specify their own usernames, or are we fine letting them use their registered email address to log-in? Are there any paradigms for walled-in community portals that help address security issues if, for example, one of their email accounts is compromised? We don't anticipate attempted break-ins being much of a threat, because nothing about this community is high-profile, but we do want to address security concerns. In addition, we want to make the sign-up process as painless for the members as possible, especially given the fact that we can't just make sign-ups open to anyone. I'm interested to hear your thoughts and suggestions! Thanks!

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  • conflict with php zend libs and c++ libs(ctime) to build extension for php [migrated]

    - by user69800
    Im going to build an extension for PHP 5.3.x everything is OK when I build without vc++ lib. error C2039: 'clock_t' : is not a member of '`global namespace'' error C2873: 'clock_t' : symbol cannot be used in a using-declaration error C2039: 'asctime' : is not a member of '`global namespace'' error C2873: 'asctime' : symbol cannot be used in a using-declaration and... I include just and got this error. I know this problem is from my include header file in properties that required from PHP zend engine, But I do not know how solve this problem. thanks

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  • How `is_base_of` works?

    - by Alexey Malistov
    Why the following code works? typedef char (&yes)[1]; typedef char (&no)[2]; template <typename B, typename D> struct Host { operator B*() const; operator D*(); }; template <typename B, typename D> struct is_base_of { template <typename T> static yes check(D*, T); static no check(B*, int); static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes); }; //Test sample class Base {}; class Derived : private Base {}; //Exspression is true. int test[is_base_of<Base,Derived>::value && !is_base_of<Derived,Base>::value]; Note that B is private base. Note that operator B*() is const. How does this work? Why this works? Why static yes check(D*, T); is better than static yes check(B*, int); ?

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  • How to set text above and below a JButton icon?

    - by mre
    I want to set text above and below a JButton's icon. At the moment, in order to achieve this, I override the layout manager and use three JLabel instances (i.e. 2 for text and 1 for the icon). But this seems like a dirty solution. Is there a more direct way of doing this? Note -I'm not looking for a multi-line solution, I'm looking for a multi-label solution. Although this article refers to it as a multi-line solution, it actually seems to refer to a multi-label solution. EXAMPLE import java.awt.Component; import java.awt.FlowLayout; import javax.swing.BoxLayout; import javax.swing.Icon; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; import javax.swing.UIManager; public final class JButtonDemo { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable(){ @Override public void run() { createAndShowGUI(); } }); } private static void createAndShowGUI(){ final JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLayout(new FlowLayout()); frame.add(new JMultiLabelButton()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } private static final class JMultiLabelButton extends JButton { private static final long serialVersionUID = 7650993517602360268L; public JMultiLabelButton() { super(); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); add(new JCenterLabel("Top Label")); add(new JCenterLabel(UIManager.getIcon("OptionPane.informationIcon"))); add(new JCenterLabel("Bottom Label")); } } private static final class JCenterLabel extends JLabel { private static final long serialVersionUID = 5502066664726732298L; public JCenterLabel(final String s) { super(s); setAlignmentX(Component.CENTER_ALIGNMENT); } public JCenterLabel(final Icon i) { super(i); setAlignmentX(Component.CENTER_ALIGNMENT); } } }

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  • How to make safe frequent DataSource switches for AbstractRoutingDataSource?

    - by serg555
    I implemented Dynamic DataSource Routing for Spring+Hibernate according to this article. I have several databases with same structure and I need to select which db will run each specific query. Everything works fine on localhost, but I am worrying about how this will hold up in real web site environment. They are using some static context holder to determine which datasource to use: public class CustomerContextHolder { private static final ThreadLocal<CustomerType> contextHolder = new ThreadLocal<CustomerType>(); public static void setCustomerType(CustomerType customerType) { Assert.notNull(customerType, "customerType cannot be null"); contextHolder.set(customerType); } public static CustomerType getCustomerType() { return (CustomerType) contextHolder.get(); } public static void clearCustomerType() { contextHolder.remove(); } } It is wrapped inside some ThreadLocal container, but what exactly does that mean? What will happen when two web requests call this piece of code in parallel: CustomerContextHolder.setCustomerType(CustomerType.GOLD); //<another user will switch customer type here to CustomerType.SILVER in another request> List<Item> goldItems = catalog.getItems(); Is every web request wrapped into its own thread in Spring MVC? Will CustomerContextHolder.setCustomerType() changes be visible to other web users? My controllers have synchronizeOnSession=true. How to make sure that nobody else will switch datasource until I run required query for current user? Thanks.

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  • My first c# app and first null object exception

    - by Fresheyeball
    Total noob here. This is my first c# attempt, its a console application that simulates a drinking game called 'Left Right Center'. In the console I receive the following: CONSOLE Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 C# using System; namespace LeftRightCenter { class Player { //fields private int _quarters = 4; public int Quarters { get{ return _quarters; } set{ _quarters += value; } } public Player (string name) { } } class Dice { Random random = new Random(); public int Roll () { random = new Random (); int diceSide; diceSide = random.Next (0, 6); diceSide = (diceSide > 2) ? 3 : diceSide; return diceSide; } } class MainClass { static int activePlayer = 0; static int theCup = 0; static Player[] thePlayers = { new Player ("Jessica"), new Player ("Isaac"), new Player ("Ed"), new Player ("Bella"), new Player ("Elisa"), new Player ("Fake RedHead"), new Player ("Linda"), new Player ("MJ"), new Player ("Irene"), new Player("Devin") }; static Dice[] theDice = new Dice[2]; private static void MoveQuarter (int direction) { int numberOfPlayers = thePlayers.Length - 1; switch (direction) { case 0: thePlayers [activePlayer].Quarters = -1; theCup++; break; case 1: thePlayers [activePlayer].Quarters = -1; int leftPlayer = (activePlayer == 0) ? numberOfPlayers : activePlayer - 1; thePlayers [leftPlayer].Quarters = +1; break; case 2: thePlayers [activePlayer].Quarters = -1; int rightPlayer = (activePlayer == numberOfPlayers) ? 0 : activePlayer + 1; thePlayers [rightPlayer].Quarters = +1; break; } } public static void Main (string[] args) { int cupEndPoint = thePlayers.Length * 4 - 1; while (theCup < cupEndPoint) { foreach (Dice rattle in theDice) { if (thePlayers [activePlayer].Quarters > 0) { MoveQuarter (rattle.Roll ()); // this line seems to be the problem } } Console.WriteLine ("{0} Quarters In the Cup", theCup); } } } } I have no idea what the problem is or why, and my googling have proven more use confusing than helpful.

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  • Magi squares, recursive

    - by user310827
    Hi, my problem is, I'm trying to permute all posibilities for 3x3 square and check if the combination is magic. I've added a tweak with (n%3==0) if statement that if the sum of numbers in row differs from 15 it breaks the creation of other two lines... but it doesn't work, any suggestions, I call the function with Permute(1). public static class Global { //int[] j = new int[6]; public static int[] a= {0,0,0,0,0,0,0,0,0}; public static int[] b= {0,0,0,0,0,0,0,0,0}; public static int count = 0; } public static void Permute(int n) { int tmp=n-1; for (int i=0;i<9;i++){ if (Global.b[i]==0 ) { Global.b[i]=1; Global.a[n-1]=i+1; if ((n % 3) == 0) { if (Global.a[0+tmp]+Global.a[1+tmp]+Global.a[2+tmp] == 15) { if (n<9) { Permute(n+1); } else { isMagic(Global.a); } } else break; } else { Permute(n+1); } Global.b[i]=0; } } }

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  • Efficient representation of Hierarchies in Hibernate.

    - by Alison G
    I'm having some trouble representing an object hierarchy in Hibernate. I've searched around, and haven't managed to find any examples doing this or similar - you have my apologies if this is a common question. I have two types which I'd like to persist using Hibernate: Groups and Items. * Groups are identified uniquely by a combination of their name and their parent. * The groups are arranged in a number of trees, such that every Group has zero or one parent Group. * Each Item can be a member of zero or more Groups. Ideally, I'd like a bi-directional relationship allowing me to get: * all Groups that an Item is a member of * all Items that are a member of a particular Group or its descendants. I also need to be able to traverse the Group tree from the top in order to display it on the UI. The basic object structure would ideally look like this: class Group { ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { ... } /** @return all direct children of this group */ Set<Group> getChildren() { ... } ... } class Item { ... /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { ... } ... } Originally, I had just made a simple bi-directional many-to-many relationship between Items and Groups, such that fetching all items in a group hierarchy required recursion down the tree, and fetching groups for an Item was a simple getter, i.e.: class Group { ... private Set<Item> items; private Set<Group> children; ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { Set<Item> allItems = new HashSet<Item>(); allItems.addAll(this.items); for(Group child : this.getChildren()) { allItems.addAll(child.getAllItems()); } return allItems; } /** @return all direct children of this group */ Set<Group> getChildren() { return this.children; } ... } class Item { ... private Set<Group> groups; /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { return this.groups; } ... } However, this resulted in multiple database requests to fetch the Items in a Group with many descendants, or for retrieving the entire Group tree to display in the UI. This seems very inefficient, especially with deeper, larger group trees. Is there a better or standard way of representing this relationship in Hibernate? Am I doing anything obviously wrong or stupid? My only other thought so far was this: Replace the group's id, parent and name fields with a unique "path" String which specifies the whole ancestry of a group, e.g.: /rootGroup /rootGroup/aChild /rootGroup/aChild/aGrandChild The join table between Groups and Items would then contain group_path and item_id. This immediately solves the two issues I was suffering previously: 1. The entire group hierarchy can be fetched from the database in a single query and reconstructed in-memory. 2. To retrieve all Items in a group or its descendants, we can select from group_item where group_path='N' or group_path like 'N/%' However, this seems to defeat the point of using Hibernate. All thoughts welcome!

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  • When should I open and close a connection to SQL Server

    - by Martin
    I have a simple static class with a few methods in it. Each of those methods open a SqlConnection, query the database and close the connection. This way, I am sure that I always close the connection to the database, but on the other hand, I don't like to always open and close connection. Below is an example of what my methods look like. public static void AddSomething(string something) { using (SqlConnection connection = new SqlConnection("...")) { connection.Open(); // ... connection.Close(); } } Considering that the methods are inside a static class, should I have a static member containing a single SqlConnection? How and when should I drop it? What are the best practices?

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  • Can a CWinApp be placed in a DLL?

    - by jmucchiello
    I'm updating some legacy apps to Visual Studio 10 and am in linker hell. All of these DLLs derive classes from CWinApp and use AfxGetApp() to get access to the object. When I link the DLLs I get unresolved externals that look like global static objects that would get pulled in by a normal app's main(): Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CException::classCException" (?classCException@CException@@2UCRuntimeClass@@B) Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CFrameWnd::classCFrameWnd" (?classCFrameWnd@CFrameWnd@@2UCRuntimeClass@@B) Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static class CRect const CFrameWnd::rectDefault" (?rectDefault@CFrameWnd@@2VCRect@@B) My current combination of ignore default libraries and additional libraries (the method you can easily google to find the answer to linker hell) is: msvcprtd.lib,mfc100d.lib,mfcs100d.lib,libcmtd.lib When I add nafxcwd.lib (the mfc library), these three external symbols resolve but I end up with a bunch of other duplicate symbols (requiring the use of /FORCE:MULTIPLE) and in end __argc and __argv become unresolved. So the basic question is: Can you link a DLL containing a CWinApp in VS10? How do you setup the linker to do it?

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  • java gui changing picture causes heapspace error

    - by pie154
    I have a java programme than when a button is clicked it updates the image on screen to the according image. this will work for the first 15 or so clicks then it causes a java heapspace error. I think it is because of the way I am updating the jpanel that contains the bufferedimage but not sure what the reason is. My code to get make the JPanel contain the new image is, public class extraScreenPanel { static JPanel screenPanel = new JPanel(new BorderLayout()); public static JPanel extraScreenPanel(int dispNum) { JLabel label = new JLabel("" + dispNum + ""); label.setPreferredSize(new Dimension(800, 600)); //label.setUI( new VerticalLabelUI(true) ); label.setVerticalAlignment( SwingConstants.TOP ); screenPanel = imgDisp(dispNum); label.setForeground(Color.white); label.setFont(new Font("Serif", Font.BOLD, 200)); screenPanel.add(label, BorderLayout.PAGE_END ); return screenPanel; } public static JPanel imgDisp(int picNum) { /* String url[] = new String[5000]; String part1; url[0] = "C:/PiPhotoPic/pic16.jpg"; for(Integer i=1;i<5000;i++){ if(i<10){part1 = "C:/temp/new0000000";} else if(i<100){part1 = "C:/temp/new000000";} else if(i<1000){part1 = "C:/temp/new00000";} else {part1 = "C:/temp/new00000";} String num = Integer.toString(i); url[i]= part1 + num + ".jpg"; } if(picNum<0){picNum=0;} String ref = url[picNum];*/ //this code is just to get specific ref for image location BufferedImage loadImg = loadImage(ref); JImagePanel panel = new JImagePanel(loadImg, 0, 0); panel.setPreferredSize(new Dimension(800, 600)); return panel; } public static class JImagePanel extends JPanel{ private BufferedImage image; int x, y; public JImagePanel(BufferedImage image, int x, int y) { super(); this.image = image; this.x = x; this.y = y; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); g.drawImage(image, x, y, null); } } public static BufferedImage loadImage(String ref) { BufferedImage bimg = null; try { bimg = javax.imageio.ImageIO.read(new File(ref)); } catch (Exception e) { e.printStackTrace(); } BufferedImage bimg2 = resize(bimg,800,600); return bimg2; } public static BufferedImage resize(BufferedImage img, int newW, int newH) { int w = img.getWidth(); int h = img.getHeight(); BufferedImage dimg = dimg = new BufferedImage(newW, newH, img.getType()); Graphics2D g = dimg.createGraphics(); g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR); g.drawImage(img, 0, 0, newW, newH, 0, 0, w, h, null); g.dispose(); return dimg; } } And the code that updates my gui is, it works by removing the panel from its containg panel and then readding it to it. picPanel = imgDisp.imgDisp(num); repaintPicPanel(); public static void repaintPicPanel() { picPanel.removeAll(); menuPanel.remove(picPanel);; menuPanel.add(picPanel, BorderLayout.LINE_START); }

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  • Replacing SUMIFS in Excel 2003

    - by yc
    So, I need to find an Excel 2003 substitute for =SUMIFS, which is only 2007+ (apparently). The formula is used to generate this summary data table, from a list of revenue, where each revenue line has the field type (static, email or outreach) and the field fund (ABC, QRS and XYZ). type fund total count average static ABC $12,390.88 171 $72.46 email ABC $6,051.32 65 $93.10 outreach ABC $8,835.00 138 $64.02 static QRS $12,925.44 79 $163.61 email QRS $9,305.44 99 $93.99 outreach QRS $1,799.00 49 $36.71 static XYZ $4,912.20 36 $136.45 email XYZ $75.00 2 $37.50 outreach XYZ $0.00 0 #DIV/0! This is the formula `=SUMIFS('revenue'!G:G,'revenue'!AH:AH,Sheet2!A2,'revenue'!AI:AI,Sheet2!B2)` Where G is a dollar amount, and AH and AI are matching the type or fund column. How do i get this to work in Excel 2003?

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  • Is There A Security Risk With Users That Are Also Groups?

    - by Rob P.
    I know a little about users and groups; in the past I might have had a group like 'DBAS' or 'ADMINS' and I'd add individual users to each group... But I was surprised to learn I could add users to other users - as if they were groups. For example if my /etc/group contained the following: user1:x:12501: user2:x:12502:user1 admin:x:123:user2,jim,bob Since user2 is a member of the admin group, and user1 is a member of user2 - is user1 effectively an admin? If the admin group is in the sudoers file, can user1 use it as well? I've tried to simulate this and I haven't been able to do so as user1...but I'm not sure it's impossible. EDIT: SORRY - updated error in question.

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  • Recursive Maze in Java

    - by Api
    I have written a short Java code for solving a simple maze problem to go from S to G. I do not understand where the problem is going wrong. import java.util.Scanner; public class tester { static char [][] grid={ {'.','.'}, {'.','.'}, {'S','G'}, }; static int a=2; static int b=2; static boolean findpath(int x, int y) { if((x > grid.length-1) || (y > grid[0].length-1) || (x < 0 || y < 0)) { return false; } else if(x==a && y==b){ return true; } else if (findpath(x,y-1) == true){ return true; } else if (findpath(x+1,y) == true){ return true; } else if (findpath(x,y+1) == true) { return true; } else if (findpath(x-1,y) == true){ return true; } return false; } public static void main(String[] args){ boolean result=findpath(2,0); System.out.print(result); } } I am giving the starting position directly and goal is defined in a & b. Do help.

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