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  • Is inheritance bad nowadays?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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  • Null reference but it's not?

    - by Clint Davis
    This is related to my previous question but it is a different problem. I have two classes: Server and Database. Public Class Server Private _name As String Public Property Name() As String Get Return _name End Get Set(ByVal value As String) _name = value End Set End Property Private _databases As List(Of Database) Public Property Databases() As List(Of Database) Get Return _databases End Get Set(ByVal value As List(Of Database)) _databases = value End Set End Property Public Sub LoadTables() Dim db As New Database(Me) db.Name = "test" Databases.Add(db) End Sub End Class Public Class Database Private _server As Server Private _name As String Public Property Name() As String Get Return _name End Get Set(ByVal value As String) _name = value End Set End Property Public Property Server() As Server Get Return _server End Get Set(ByVal value As Server) _server = value End Set End Property Public Sub New(ByVal ser As Server) Server = ser End Sub End Class Fairly simple. I use like this: Dim s As New Server s.Name = "Test" s.LoadTables() The problem is in the LoadTables in the Server class. When it hits Databases.Add(db) it gives me a NullReference error (Object reference not set). I don't understand how it is getting that, all the objects are set. Any ideas? Thanks.

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  • Twitter Bootstrap: how to put unknown number of span* within a row-fluid?

    - by StackOverflowNewbie
    Assume I have the following nesting: <div class="cointainer-fluid"> <div class="row-fluid"> <div class="span3"> <!-- left sidebar here --> </div> <div class="span9"> <!-- main content here --> </div> </div> </div> I'd like to put an unknown number of <div class="span3"></div> in the main content area. (Each of the span3 is suppose to contain a product photo, name, price, etc.) Of course, my aim is that be responsive. So, I might display 20 products, which I'd like to possibly display 5 products per "row" on a wide screen, then 4 products per "row" on a slightly less wide screen, then 3, then 2, then 1. For example (each X represents a product): Wide Screen row 1: X X X X X row 2: X X X X X row 3: X X X X X row 4: X X X X X Less Wide Screen row 1: X X X X row 2: X X X X row 3: X X X X row 4: X X X X row 5: X X X X Even Less Wide Screen row 1: X X X row 2: X X X row 3: X X X row 4: X X X row 5: X X X row 6: X X X row 7: X X It seems like I need to do nested rows. However, if I do that, then I'll only be able to fit a certain amount of products in each nested row. That'll cause problems as the screen width decreases, for example (each X represents a product): Wide Screen row 1: X X X X X row 2: X X X X X row 3: X X X X X Less Wide Screen row 1: X X X X X row 2: X X X X X row 3: X X X X X How do I do what I want to do in Twitter Bootstrap?

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  • Is there a way to get the current UIEvent being handled?

    - by not-
    I'm working in a class that is a delegate of another class; this other class is in a third-party library that I'd like to avoid changing if at all possible. The original class is handling a -touchesEnded event, and is delegating responsibility to me, but it doesn't pass the UIEvent itself to me. Is there a way to get a handle to the current event in progress? It's a double-tap handler, and all that is passed to me is the view being touched, and the point at which the touch occurred. I want to know exactly how many touches are involved in the event. Thanks! randy

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  • get premitive , complex, ArrayEnumerable types

    - by john
    i have a separate class for each of my database entities and when i create an object of my class to reference the properties of a class it returns a circular reference which contains properties of other entities too that are related via FK ... to remove the circular reference i want to first make a copy of the object through "context proxy object" copy and then get the primitive, complex, arrayEnumerable types of that object and strip off these types from the object and then the object get returned by web service....

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  • Trying to create C++/CLI assembly for use in .NET

    - by Bad Man
    I'm trying to bring a C++ library into C#, so naturally I am trying to make a C++/CLI project. In visual studio I created a new project (Visual C++ project, class library). I then tried to make a test class out of the pre-generated "Class1" namespace Test { public ref class TestIt { public: void DoWork() { System::Console::WriteLine("sup"); } // TODO: Add your methods for this class here. }; } So I compile in and go to the build folder.... hrmm no .dll wetf?? There's a .dll.intermediate.manifest file, but no .dll. So wut I did wrong?

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  • What else I must do allow my method to handle any type of objects

    - by NewHelpNeeder
    So to allow any type object I must use generics in my code. I have rewrote this method to do so, but then when I create an object, for example Milk, it won't let me pass it to my method. Ether there's something wrong with my generic revision, or Milk object I created is not good. How should I pass my object correctly and add it to linked list? This is a method that causes error when I insert an item: public void insertFirst(T dd) // insert at front of list { Link newLink = new Link(dd); // make new link if( isEmpty() ) // if empty list, last = newLink; // newLink <-- last else first.previous = newLink; // newLink <-- old first newLink.next = first; // newLink --> old first first = newLink; // first --> newLink } This is my class I try to insert into linked list: class Milk { String brand; double size; double price; Milk(String a, double b, double c) { brand = a; size = b; price = c; } } This is test method to insert the data: public static void main(String[] args) { // make a new list DoublyLinkedList theList = new DoublyLinkedList(); // this causes: // The method insertFirst(Comparable) in the type DoublyLinkedList is not applicable for the arguments (Milk) theList.insertFirst(new Milk("brand", 1, 2)); // insert at front theList.displayForward(); // display list forward theList.displayBackward(); // display list backward } // end main() } // end class DoublyLinkedApp Declarations: class Link<T extends Comparable<T>> {} class DoublyLinkedList<T extends Comparable<T>> {}

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  • ruby confusing -- local variable or instance_method ?

    - by boblu
    I have the following program. module C def self.included(base) base.extend(ClassMethods) end module ClassMethods def test_for class_eval <<-DEFINECLASSMETHODS def self.my_method(param_a) puts "SELF is: #{self.inspect}" puts param_a puts "#{param_a}" end DEFINECLASSMETHODS end end end class A include C end class B < A test_for end when I run B.new.my_method("aaa"), I got this error NameError: undefined local variable or method `param_a' for B:Class I am quite confused. I define param_a as a local variable in class method my_method, puts param_a runs good, and will output the "aaa". however, puts "#{param_a}" output that error. why? Can anyone explain this?

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  • Joining tables with composite keys in a legacy system in hibernate

    - by Steve N
    Hi, I'm currently trying to create a pair of Hibernate annotated classes to load (read only) from a pair of tables in a legacy system. The legacy system uses a consistent (if somewhat dated) approach to keying tables. The tables I'm attempting to map are as follows: Customer CustomerAddress -------------------------- ---------------------------- customerNumber:string (pk) customerNumber:string (pk_1) name:string sequenceNumber:int (pk_2) street:string postalCode:string I've approached this by creating a CustomerAddress class like this: @Entity @Table(name="CustomerAddress") @IdClass(CustomerAddressKey.class) public class CustomerAddress { @Id @AttributeOverrides({ @AttributeOverride(name = "customerNumber", column = @Column(name="customerNumber")), @AttributeOverride(name = "sequenceNumber", column = @Column(name="sequenceNumber")) }) private String customerNumber; private int sequenceNumber; private String name; private String postalCode; ... } Where the CustomerAddressKey class is a simple Serializable object with the two key fields. The Customer object is then defined as: @Entity @Table(name = "Customer") public class Customer { private String customerNumber; private List<CustomerAddress> addresses = new ArrayList<CustomerAddress>(); private String name; ... } So, my question is: how do I express the OneToMany relationship on the Customer table?

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  • Why do we need a private constructor?

    - by isthatacode
    if a class has a private constructor then it cant be instantiated. so, if i dont want my class to be instantiated and still use it, then i can make it static. what is the use of a private constructor ? Also its used in singleton class, except that, is there any othe use ? (Note : The reason i am excuding the singleton case above is because I dont understand why do we need a singleton at all ? when there is a static class availble. You may not answer for my this confusion in the question. )

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  • Easiest way to submit data via PHP?

    - by Abijah
    I'm new to PHP, and have spent 10 hours trying to figure this problem out. The goal is to take all data entered into this order form, and send it to my email via PHP. I have 2 questions: 1. I can get PHP to send data from a single menu item (example: Mexican Tortas), but how do I get PHP to send data from multiple items (example: Mexican Tortas, Fish Sandwich and Hamburger)? 2. How do I tell PHP to not send data from menu items that don't have the "How Many?" or "Customize It?" text fields filled out? If you could provide a super simple example (or a link to a learning resource) I would really appreciate it. Thank you, Abijah PHP <?php if(isset($_POST['submit'])) { $to = "[email protected]"; $subject = "New Order"; $name_field = $_POST['name']; $phone_field = $_POST['phone']; $item = $_POST['item']; $quantity = $_POST['quantity']; $customize = $_POST['customize']; } $body = "Name: $name_field\nPhone: $phone_field\n\nItem: $item\nQuantity: $quantity\nCustomize: $customize"; echo "Data has been submitted to $to!"; mail($to, $subject, $body); ?> HTML <form action="neworder.php" method="POST"> <div class ="item"> <img style="float:left; margin-right:15px; border:1px Solid #000; width:200px; height:155px;" src="images/mexicantortas.jpg"> <h1>Mexican Torta - $8.50</h1> <input name="item" type="hidden" value="Mexican Torta"/> <h2>How Many? <font color="#999999">Ex: 1, 2, 3...?</font></h2> <input name="quantity" type="text"/> <h3>Customize It? <font color="#999999">Ex: No Lettuce, Extra Cheese...</font></h3> <textarea name="customize"/></textarea> </div><!-- ITEM_LEFT --> <div class ="item"> <img style="float:left; margin-right:15px; border:1px Solid #000; width:200px; height:155px;" src="images/fishsandwich.jpg"> <h1>Fish Sandwich - $8.50</h1> <input name="item" type="hidden" value="Fish Sandwich"/> <h2>How Many? <font color="#999999">Ex: 1, 2, 3...?</font></h2> <input name="quantity" type="text"/> <h3>Customize It? <font color="#999999">Ex: No Lettuce, Extra Cheese...</font></h3> <textarea name="customize"/></textarea> </div><!-- ITEM_LEFT --> <div class ="item"> <img style="float:left; margin-right:15px; border:1px Solid #000; width:200px; height:155px;" src="images/hamburgers.jpg"> <h1>Hamburger w/ Fries - $7.00</h1> <input name="item" type="hidden" value="Fish Sandwich"/> <h2>How Many? <font color="#999999">Ex: 1, 2, 3...?</font></h2> <input name="quantity" type="text"/> <h3>Customize It? <font color="#999999">Ex: No Lettuce, Extra Cheese...</font></h3> <textarea name="customize"/></textarea> </div><!-- ITEM_LEFT --> <div class="horizontal_form"> <div class="form"> <h2>Place Your Order Now: <font size="3"><font color="#037B41">Fill in the form below, and we'll call you when your food is ready to be picked up...</font></font></h2> <p class="name"> <input type="text" name="name" id="name" style="text-align:center;" onClick="this.value='';" value="Enter your name"/> </p> <p class="phone"> <input type="text" name="phone" id="phone" style="text-align:center;" onClick="this.value='';" value="Enter your phone #"/> </p> <p class="submit"> <input type="submit" value="Place Order" name="submit"/> </p> </div><!-- FORM --> </div><!-- HORIZONTAL_FORM --> </form>

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  • css displaying divs inside a Tr fine in FireFox, but IE increases the width of the row...

    - by Ronedog
    I'm having some difficulty figuring out what is going on and how to fix it. I have some divs that contain some icons that are causing a width problem when displaying tabular data. If I remove the div's that contain the icons, the row width ends up the way I want it (See the firefox example below). Here's the view in Firefox which is what I want (notice the positioning of the icons circled in red, which is aligned on the same y coordinate, or thereabouts): Here's the view in IE7 (Notice what happens to the icons and the width of the grey line, which is the table row): Here's the HTML: <table> <tbody> <tr> <td> <span>stuff 1</span> <span>stuff 2</span> <div class="prop_edit"><img class="img_height14" src="edit.jpg"></div> <div class="prop_archive"><img class="img_height14" src="archive.jpg"></div> <div class="prop_delete"><img class="img_height14" src="delete.jpg"></div> <div style="display:none;"> <div>Links Here</div> </div> </td> </tr> </tbody> Heres the CSS: .prop_edit{ float:right; position: relative; top: 0px; right:50px; } .prop_archive{ float:right; position: relative; top: 0px; right:10px; } .prop_delete{ float:right; position: relative; top: 0px; right: -30px; } .img_height14{ height:14px; vertical-align:top; position:relative; } I've tried a bunch of different css things, but really am just hacking away hoping to figure something out. Anyone got some tips that could help me? Thanks in advance.

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  • Why does the check for an interface fail?

    - by chobo
    I have a class that implements an interface. In another area of the code I check if that class instance contains that interface, but it doesn't work. The check to see if the class contains the interface always fails (false) when it should be true. Below is a simple representation of what I am trying to accomplish. Example public interface IModel { bool validate(); } public class SomeModel : IModel { public SomeModel { } public bool Validate() { return true; } } // Dummy method public void Run() { SomeModel model = new SomeModel(); if (model is IModel) { string message = "It worked"; } else { string message = "It failed"; } }

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  • Rails: bi-directional has_many :through relationship

    - by Chris
    I have three models in a Rails application: Game represents an instance of a game being played. Player represents an instance of a participant in a game. User represents a registered person who can participate in games. Each Game can have many Players, and each User can have many Players (a single person can participate in multiple games at once); but each Player is in precisely one Game, and represents precisely one User. Hence, my relationships are as follows at present. class Game has_many :players end class User has_many :players end class Player belongs_to :game belongs_to :user end ... where naturally the players table has game_id and user_id columns, but games and users have no foreign keys. I would also like to represent the fact that each Game has many Users playing in it; and each User has many Games in which they are playing. How do I do this? Is it enough to add class Game has_many :users, :through => :players end class User has_many :games, :through => :players end

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  • How to mock static member variables

    - by pkrish
    I have a class ClassToTest which has a dependency on ClassToMock. public class ClassToMock { private static final String MEMBER_1 = FileReader.readMemeber1(); protected void someMethod() { ... } } The unit test case for ClassToTest. public class ClassToTestTest { private ClassToMock _mock; @Before public void setUp() throws Exception { _mock = mock(ClassToMock.class) } } When mock is called in the setUp() method, FileReader.readMemeber1(); is executed. Is there a way to avoid this? I think one way is to initialize the MEMBER_1 inside a method. Any other alternatives? Thanks!

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  • c# How to implement a collection of generics

    - by Amy
    I have a worker class that does stuff with a collection of objects. I need each of those objects to have two properties, one has an unknown type and one has to be a number. I wanted to use an interface so that I could have multiple item classes that allowed for other properties but were forced to have the PropA and PropB that the worker class requires. This is the code I have so far, which seemed to be OK until I tried to use it. A list of MyItem is not allowed to be passed as a list of IItem even though MyItem implements IItem. This is where I got confused. Also, if possible, it would be great if when instantiating the worker class I don't need to pass in the T, instead it would know what T is based on the type of PropA. Can someone help get me sorted out? Thanks! public interface IItem<T> { T PropA { get; set; } decimal PropB { get; set; } } public class MyItem : IItem<string> { public string PropA { get; set; } public decimal PropB { get; set; } } public class WorkerClass<T> { private List<T> _list; public WorkerClass(IEnumerable<IItem<T>> items) { doStuff(items); } public T ReturnAnItem() { return _list[0]; } private void doStuff(IEnumerable<IItem<T>> items) { foreach (IItem<T> item in items) { _list.Add(item.PropA); } } } public void usage() { IEnumerable<MyItem> list= GetItems(); var worker = new WorkerClass<string>(list);//Not Allowed }

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  • Ruby Metaprogramming

    - by Veerendra Manikonda
    I am having a method which returns the price of a given symbol and i am writing a test for that method. This is my test def setup @asset = NetAssetValue.new end def test_retrieve_price_for_symbol_YHOO assert_equal(33.987, @asset.retrieve_price_for_a_symbol('YHOO')) end def test_retrive_price_for_YHOO def self.retrieve_price_for_a_symbol(symbol) 33.77 end assert_equal(33.97, @asset.retrieve_price_for_a_symbol('YHOO')) end This is my method. def retrieve_price_for_a_symbol(symbol) symbol_price = { "YHOO" => 33.987, "UPS" => 35.345, "T" => 80.90 } raise Exception if(symbol_price[symbol].nil?) symbol_price[symbol] end I am trying to mock the retrieve_price_for_a_symbol method by writing same method in test class but when i call it, the call is happening to method in main class not in the test class. How do I add that method to meta class from test and how do i call it? Please help.

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  • Error : The Type Initializer of Daemon.Global threw an exception in c#

    - by srk
    I am using the below class file, where some variables are declared to use in the entire application. Now I used that variable BlockLogOut in another class file to make the value true. I just put this below line and getting error in it.. TypeInitializationException Global.BlockLogOut = True; The weird thing is, it was working fine for many months and i am getting this error now on the above line. Of course i was modifying some other stuffs in the application, but surely not this class file. What would have been the problem? namespace Daemon { class Global { public static bool BlockLogOut = false; } }

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  • How can i access the value of the moving slider in a jquery variable

    - by user1673591
    html <h1>HTML Slider Test</h1> <div class="slider" data-max="10"></div> <p>Your slider has a value of <span class="slider-value"></span></p> <div class="slider" data-max="100"></div> <p>Your slider has a value of <span class="slider-value"></span></p> jquery $(".slider").each(function() { $(this).slider({ value : 1, min : 1, max : $(this).data('max'), step : 1, slide : function (event, ui) { var a= $(this).next().find('span.slider-value').html(ui.value); } }); }); I want the value of the moving slider in a jquery variable

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  • jQuery 1.5.1 vs 1.4.4 weirdness

    - by zobgib
    I have been getting some weird errors when I upgrade jQuery from 1.4.4 to 1.5.1. Maybe you guys can explain what I need to change or why the new version is not working. In 1.4.4 I have the following code <div class="navlink home" data-link="home"> <span class="top">Home</span> </div> <div id="index-03"> </div> <div class="navlink resume" data-link="resume"> <span class="top">Resume</span> </div> <div id="index-05"> </div> <div id="index-06"> </div> <div class="navlink portfolio" data-link="portfolio"> <span class="bottom">Portfolio</span> </div> JS: $(".navlink").hover( function () { $(this).delay(100).animate({backgroundPosition: "-100% 0"}, 400); $(this).find("span").css("textDecoration","underline"); }, function () { $(this).queue("fx", []); $(this).animate({backgroundPosition: "0% 0%"}, 400); $(this).find("span").css("textDecoration","none"); } ); Which works just fine. but when I switch jQuery versions by changing this line in my header from <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script> to <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js"></script> The above code quits animating and the background image just disappears. Here is a jsFiddle that shows what's happening just change the jQuery version on the side between 1.4.4 and 1.5.1 http://jsfiddle.net/fUXZ4/ -- 1.4.4 http://jsfiddle.net/3APCd/ -- 1.5.1 Here is a video of exactly what is happening to me: http://img.zobgib.com/2011-03-07_1905.swf

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  • c++ template and its element type

    - by David
    This is my template matrix class: template<typename T> class Matrix { public: .... Matrix<T> operator / (const T &num); } However, in my Pixel class, I didn't define the Pixel/Pixel operator at all! Why in this case, the compiler still compiles?

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  • jQuery: Hide/Display tabs (and its corresponding content) with check boxes

    - by Ricardo
    Hello, Well, this must be very simple to do for most of you, but I have no idea how to accomplish this. I have a set of tabs and on top of the tabs is a set of checkboxes ; each checkbox 'corresponds' to a tab. What I need is to be able to activate/deactivate each checkbox and have its corresponding tab (and the tab's content) hide/display. Here's my HTML: <div class="show-results-from"> <ul> <li>See results from:</li> <li> <label> <input type="checkbox" name="a" id="a"> Products &amp; Services <span>(16)</span></label> </li> <li> <label> <input type="checkbox" name="b" id="b"> Publications <span>(9)</span></label> </li> <li> <label> <input type="checkbox" name="c" id="c"> Other <span>(150)</span></label> </li> </ul> </div> <ul class="tabs"> <li><span rel="tabs1" class="defaulttab">Products &amp; Services</span></li> <li><span rel="tabs2">Publications</span></li> <li><span rel="tabs3">Other</span></li> </ul> <div class="tab-content" id="tabs1">content</div> <div class="tab-content" id="tabs2">content</div> <div class="tab-content" id="tabs3">content</div> Any help with this is greatly appreciated.

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  • C++: Is there a way to limit access to certain methods to certain classes without exposing other pri

    - by dadads
    I have a class with a protected method Zig::punt() and I only want it to be accessible to the class "Avocado". In C++, you'll normally do this using the "friend Avocado" specifier, but this will cause all of the other variables to become accessible to "Avocado" class; I don't want this because this breaks encapsulation. Is what I want impossible, or does there already exist an obscure trick out there that I can use to achieve what I want? Or possibly alternative class design patterns that'll achieve the same thing? Thanks in advance for any ideas!

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  • How can I map a String to a function in Java?

    - by Bears will eat you
    Currently, I have a bunch of Java classes that implement a Processor interface, meaning they all have a processRequest(String key) method. The idea is that each class has a few (say, <10) member Strings, and each of those maps to a method in that class via the processRequest method, like so: class FooProcessor implements Processor { String key1 = "abc"; String key2 = "def"; String key3 = "ghi"; // and so on... String processRequest(String key) { String toReturn = null; if (key1.equals(key)) toReturn = method1(); else if (key2.equals(key)) toReturn = method2(); else if (key3.equals(key)) toReturn = method3(); // and so on... return toReturn; } String method1() { // do stuff } String method2() { // do other stuff } String method3() { // do other other stuff } // and so on... } You get the idea. This was working fine for me, but now I need a runtime-accessible mapping from key to function; not every function actually returns a String (some return void) and I need to dynamically access the return type (using reflection) of each function in each class that there's a key for. I already have a manager that knows about all the keys, but not the mapping from key to function. My first instinct was to replace this mapping using if-else statements with a Map<String, Function>, like I could do in Javascript. But, Java doesn't support first-class functions so I'm out of luck there. I could probably dig up a third-party library that lets me work with first-class functions, but I haven't seen any yet, and I doubt that I need an entire new library. I also thought of putting these String keys into an array and using reflection to invoke the methods by name, but I see two downsides to this method: My keys would have to be named the same as the method - or be named in a particular, consistent way so that it's easy to map them to the method name. This seems WAY slower than the if-else statements I have right now. Efficiency is something of a concern because these methods will tend to get called pretty frequently, and I want to minimize unnecessary overhead. TL; DR: I'm looking for a clean, minimal-overhead way to map a String to some sort of a Function object that I can invoke and call (something like) getReturnType() on. I don't especially mind using a 3rd-party library if it really fits my needs. I also don't mind using reflection, though I would strongly prefer to avoid using reflection every single time I do a method lookup - maybe using some caching strategy that combines the Map with reflection. Thoughts on a good way to get what I want? Cheers!

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