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  • What are the downsides to using dependency injection?

    - by kerry
    I recently came across an interesting question on stack overflow with some interesting reponses.  I like this post for three reasons. First, I am a big fan of dependency injection, it forces you to decouple your code, create cohesive interfaces, and should result in testable classes. Second, the author took the approach I usually do when trying to evaluate a technique or technology; suspend personal feelings and try to find some compelling arguments against it. Third, it proved that it is very difficult to come up with a compelling argument against dependency injection. What are the downsides to using dependency injection?

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  • Libgdx Box2d createfixture crashes vm intermittently

    - by user45021
    I have a hard to debug problem. I have a Box2D game which creates a wheeled vehicle. I want the vehicle body to reflect when it goes from moving left to moving right. to do this i set a flag in a changelistener on a button and then in update method i destroy and recreate the body facing the other way. it works fine most of the time but if i flip the vehicle several times quickly JVM crashes. no errors nothing in log. i added system.out.prints and the errors occur in the routine that instantiates the new body and before anything gets deleted/removed so i don't think the UI is trying to access null pointers. and if it was it should throw an error. M the crash seems to be at createFixture statements. but the work most of the first time. I tried debugging but the error doesn't happen much when the flips are slow. in any case createFixture drops fairly quickly into jni. Is this a Box2D bug? Is GC the issue? From Mission Control I see the GC is collecting on a period of ooh maybe 5s and flipping slower than that mostly works. how do i debug this? i am win7 64bit with 64bit at and jdk7 64bit. libgdx-0.9.9 and sometimes libgdx-nightly-20140215.

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  • Naming methods that do the same thing but return different types

    - by Konstantin Ð.
    Let's assume that I'm extending a graphical file chooser class (JFileChooser). This class has methods which display the file chooser dialog and return a status signature in the form of an int: APPROVE_OPTION if the user selects a file and hits Open /Save, CANCEL_OPTION if the user hits Cancel, and ERROR_OPTION if something goes wrong. These methods are called showDialog(). I find this cumbersome, so I decide to make another method that returns a File object: in the case of APPROVE_OPTION, it returns the file selected by the user; otherwise, it returns null. This is where I run into a problem: would it be okay for me to keep the showDialog() name, even though methods with that name — and a different return type — already exist? To top it off, my method takes an additional parameter: a File which denotes in which directory the file chooser should start. My question to you: Is it okay to call a method the same name as a superclass method if they return different types? Or would that be confusing to API users? (If so, what other name could I use?) Alternatively, should I keep the name and change the return type so it matches that of the other methods? public int showDialog(Component parent, String approveButtonText) // Superclass method public File showDialog(Component parent, File location) // My method

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  • Improvements to Joshua Bloch's Builder Design Pattern?

    - by Jason Fotinatos
    Back in 2007, I read an article about Joshua Blochs take on the "builder pattern" and how it could be modified to improve the overuse of constructors and setters, especially when an object has a large number of properties, most of which are optional. A brief summary of this design pattern is articled here [http://rwhansen.blogspot.com/2007/07/theres-builder-pattern-that-joshua.html]. I liked the idea, and have been using it since. The problem with it, while it is very clean and nice to use from the client perspective, implementing it can be a pain in the bum! There are so many different places in the object where a single property is reference, and thus creating the object, and adding a new property takes a lot of time. So...I had an idea. First, an example object in Joshua Bloch's style: Josh Bloch Style: public class OptionsJoshBlochStyle { private final String option1; private final int option2; // ...other options here <<<< public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private String option1; private int option2; // other options here <<<<< public Builder option1(String option1) { this.option1 = option1; return this; } public Builder option2(int option2) { this.option2 = option2; return this; } public OptionsJoshBlochStyle build() { return new OptionsJoshBlochStyle(this); } } private OptionsJoshBlochStyle(Builder builder) { this.option1 = builder.option1; this.option2 = builder.option2; // other options here <<<<<< } public static void main(String[] args) { OptionsJoshBlochStyle optionsVariation1 = new OptionsJoshBlochStyle.Builder().option1("firefox").option2(1).build(); OptionsJoshBlochStyle optionsVariation2 = new OptionsJoshBlochStyle.Builder().option1("chrome").option2(2).build(); } } Now my "improved" version: public class Options { // note that these are not final private String option1; private int option2; // ...other options here public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private final Options options = new Options(); public Builder option1(String option1) { this.options.option1 = option1; return this; } public Builder option2(int option2) { this.options.option2 = option2; return this; } public Options build() { return options; } } private Options() { } public static void main(String[] args) { Options optionsVariation1 = new Options.Builder().option1("firefox").option2(1).build(); Options optionsVariation2 = new Options.Builder().option1("chrome").option2(2).build(); } } As you can see in my "improved version", there are 2 less places in which we need to add code about any addition properties (or options, in this case)! The only negative that I can see is that the instance variables of the outer class are not able to be final. But, the class is still immutable without this. Is there really any downside to this improvement in maintainability? There has to be a reason which he repeated the properties within the nested class that I'm not seeing?

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  • Moving sprites on a graph in libGDX

    - by nosferat
    In my game I'd like to move sprites on a fixed path. Until this point I was trying to stick with the tools already provided by libGDX, like the Tiled map renderer classes so I'm looking for a solution nearly as convenient as that, e.g. I'd like to avoid creating the adjacency matrix by hand. Tiled has the functionality to add objects to the map but I'm not sure if I can use it for this purpose. Any idea?

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  • Poor mobile performance when running from Eclipse

    - by Yajirobe_LOL
    So after weeks of thinking my rendering code was bad, I accidentally discovered the following: Running my game on a Nexus S From Eclipse (Debug as - Android application): 12fps From the device while still attached to USB (getting log info in Eclipse still): 24fps From the device while not attached via USB: 56fps I was wondering if anyone else has issues like this? I mean, the problem really isn't a problem since the final release build will likely have good performance, but for the time being I don't want to have to keep (un)plugging my device in and out when testing code all day long. Is there some remedy for this or does anyone have any input/advice? Thanks.

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  • how do you manage application performance reviews

    - by CoolBeans
    I have been trying to figure out ways to effectively do performance reviews before an install happens for all releases done by our team. Do you usually make this a part of code review process or do you handle it as a separate review task? FYI - we do not have a dedicated performance testing team. It is up to the developers to make sure the app performs well. The apps I am referring to are web applications.

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  • how to develop a common pool of functions?

    - by user975234
    I need to develop an application which runs on the web as well as on mobile platform. I want to make something like a directory where i hold my common functions in respect to web and mobile platform. This is the diagram which describes what i exactly want: I just want to know how do i implement this thing? If you can help me with the technical details that would be great! P.S: I am new to web app and stuff!

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  • Spring Roo Database Reverse Engineer with Oracle

    - by kerry
    So you are trying to reverse engineer an Oracle database with roo? Unfortunately, due to licensing restrictions with the Oracle JDBC Drivers, this is a little difficult. There are a few blog posts and forum threads that address the problem but I figured I would post what worked for me here. First, you need to download the appropriate Oracle Drivers from Oracle. The required login, stringent password requirements, nosy registration form, and general system instability made this a pretty painful step for me. I’d also like to say that companies that have password requirements that don’t allow symbols (or any other non-standard requirement) have a special place in my heart. Having to recover my password every time I go to your site virtually guarantees I will only go there when I absolutely have to (not often). Anyways, once you have it downloaded you need to install is with maven: mvn install:install-file -Dfile=~/Downloads/ojdbc6.jar -DgroupId=com.oracle -DartifactId=ojdbc6 -Dversion=11.2.0.3 -Dpackaging=jar -DgeneratePom=true Here comes the fun part. You need to create an osgi wrapper for the driver to install it in roo. Otherwise, roo cannot see the driver. Create a new folder and put the contents of the oracle roo addon pom gist I created. Now build it with maven. You may want to change some of the artifact ids and dependencies for your particular situation. mvn package No open a roo shell and execute the following command: osgi install --url file:///Users/me/my-osgi-project/target/the-jar-it-built.jar Now run (in roo): jpa setup --provider HIBERNATE --database ORACLE dependency remove --groupId com.oracle --artifactId ojdbc14 --version 10.2.0.2 dependency add --groupId com.oracle --artifactId ojdbc6 --version 11.2.0.3 database properties set --key database.driverClassName --value oracle.jdbc.OracleDriver database properties set --key database.url --value jdbc:oracle:thin:@%YOUR_CONNECTION_INFO% database properties set --key database.username --value %YOUR_USERNAME% database properties set --key database.password --value %YOUR_PASSWORD% database reverse engineer --schema %YOUR_SCHEMA% --package ~.domain If you have any package loading exceptions when running the reverse engineer command you can uninstall the osgi bundle, set the package to optional in the osgi pom in the IncludedPackages tag (javax.some.package.*;resolution:=optional) rebuild, then reinstall in roo.

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  • Is there any reason to use "plain old data" classes?

    - by Michael
    In legacy code I occasionally see classes that are nothing but wrappers for data. something like: class Bottle { int height; int diameter; Cap capType; getters/setters, maybe a constructor } My understanding of OO is that classes are structures for data and the methods of operating on that data. This seems to preclude objects of this type. To me they are nothing more than structs and kind of defeat the purpose of OO. I don't think it's necessarily evil, though it may be a code smell. Is there a case where such objects would be necessary? If this is used often, does it make the design suspect?

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  • Slick2D, Nifty GUI listeners problem

    - by Patokun
    I'm trying to get Nifty GUI to work with Slick2D. So far everything is going great, except that I can't seem to figure out how to properly interact with the GUI. I'm trying the example in the nifty manual http://sourceforge.n....0.pdf/download but it doesn't seem to entirely work. The Element controller is being called for bind(...), init(...) and onStartScreen() as it should, as I can see their println output, but the next() method isn't being called when I click on the GUI element that I assigned the controller to, nor the screen controller as no output from println is shown. What's weird is, that the player is moving, so the mouse input is working. It's supposed to be called when I click the mouse button on it from the in the XML. Here is my code: My Element controller: public class ElementController implements Controller { private Element element; @Override public void bind(Nifty nifty, Screen screen, Element element, Properties parameter, Attributes controlDefinitionAttributes) { this.element = element; System.out.println("bind() called for element: " + element); } @Override public void init(Properties parameter, Attributes controlDefinitionAttributes) { System.out.println("init() called for element: " + element); } @Override public void onStartScreen() { System.out.println("onStartScreen() alled for element: " + element); } @Override public void onFocus(boolean getFocus) { System.out.println("onFocus() called for element: " + element + ", with: " + getFocus); } @Override public boolean inputEvent(NiftyInputEvent inputEvent) { return false; } public void next() { System.out.println("next() clicked for element: " + element); } } MyScreenController: class MyScreenController implements ScreenController { public void bind(Nifty nifty, Screen screen) {} public void onEndScreen() {} public void onStartScreen() {} public void next() { System.out.println("next() called from MyScreenController"); } } And my XML file: <?xml version="1.0" encoding="UTF-8"?> <nifty xmlns="http://nifty-gui.sourceforge.net/nifty-1.3.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://niftygui.sourceforge.net/nifty-1.3.xsd http://nifty-gui.sourceforge.net/nifty-1.3.xsd"> <screen id="start" controller="predaN00b.theThing.V0004.MyScreenController"> <layer childLayout="center" controller="predaN00b.theThing.V0004.ElementController"> <panel width="100px" height="100px" childLayout="vertical" backgroundColor="#ff0f"> <text font="aurulent-sans-16.fnt" color="#ffff" text="Hello World!"> <interact onClick="next()" /> </text> </panel> </layer> </screen> </nifty> My main class, in case it's needed: public class MainGameState extends BasicGame { public Nifty nifty; public MainGame() { super("Test"); } public void init(GameContainer container, StateBasedGame game) throws SlickException { nifty = new Nifty(new SlickRenderDevice(container), new NullSoundDevice(), new PlainSlickInputSystem(), new AccurateTimeProvider()); nifty.addXml("/xml/MainState.xml"); nifty.gotoScreen("start"); } public void update(GameContainer container, StateBasedGame game, int delta) throws SlickException { nifty.update(); } public void render(GameContainer container, StateBasedGame game, Graphics graphics) throws SlickException { nifty.render(false); } public static void main(String[] args) throws SlickException { AppGameContainer app = new AppGameContainer(new MainGame()); app.setAlwaysRender(true); app.setDisplayMode( 1260 , 720, false); //window size app.start(); } }

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  • How to teach Exception Handling for New Programmers?

    - by Kanini
    How do you go about teaching Exception Handling to Programmers. All other things are taught easily - Data Structures, ASP.NET, WinForms, WPF, WCF - you name it, everything can be taught easily. With Exception Handling, teaching them try-catch-finally is just the syntactic nature of Exception Handling. What should be taught however is - What part of your code do you put in the try block? What do you do in the catch block? Let me illustrate it with an example. You are working on a Windows Forms Project (a small utility) and you have designed it as below with 3 different projects. UILayer BusinessLayer DataLayer If an Exception (let us say of loading an XDocument throws an exception) is raised at DataLayer (the UILayer calls BusinessLayer which in turns calls the DataLayer), do you just do the following //In DataLayer try { XDocument xd_XmlDocument = XDocument.Load("systems.xml"); } catch(Exception ex) { throw ex; } which gets thrown again in the BusinessLayer and which is caught in UILayer where I write it to the log file? Is this how you go about Exception Handling?

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  • Architecture design with MyBatis mappers

    - by Wolf
    I am creating rest web service for providing data. I am using Spring MVC for handling rest requests, and MyBatis for data access. Application should be designed in the way that it should be easy to change the data access implementation (for example to hibernate or something else) and it has to be fast (so I am trying to avoid unnecessary overcomplication of design). Now my question is about the general design of layers. I would normally use DAO interface and then different implementations for different data access strategies, but MyBatis uses interfaces to access the data. So I can think of 2 possible models but I am not sure which one is better or if there is any other nice way: Controller layer - uses Service layer interfaces services are then implemented for each data access stretegy - for example for mybatis: service implementation uses Mapper classes to access data and do whatever it needs to do with them and sends them to controller layer Controller layer - uses Service layer - service layer uses DAO interfaces DAOs are then implemented for each data access strategy - for example for mybatis: DAO class uses mapper interface to access data and sends them to service layer, service layer then do whatever it needs to do with them and sends them to controller layer I prefer the first strategy as it seems to be less complicated, but then I would have to write all of the service code for another data access again. What do you think? Thank You

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  • Sphere-Sphere intersection and Circle-Sphere intersection

    - by cagirici
    I have code for circle-circle intersection. But I need to expand it to 3-D. How do I calculate: Radius and center of the intersection circle of two spheres Points of the intersection of a sphere and a circle? Given two spheres (sc0,sr0) and (sc1,sr1), I need to calculate a circle of intersection whose center is ci and whose radius is ri. Moreover, given a sphere (sc0,sr0) and a circle (cc0, cr0), I need to calulate the two intersection points (pi0, pi1) I have checked this link and this link, but I could not understand the logic behind them and how to code them. I tried ProGAL library for sphere-sphere-sphere intersection, but the resulting coordinates are rounded. I need precise results.

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  • Steady zoom on center in LWJGL (Modelview)

    - by l5p4ngl312
    I am having a problem in LWJGL with zooming in and out. I am using glScaled(zoom, zoom, 1) before glTranslated. There are 2 problems: 1. The rate of zoom speeds up a lot when zooming out (lower zoom value). 2. It zooms in on the bottom left corner of the screen rather than the center. Eventually, I would like to have the zoom focused on the mouse position. I have tried to fix these problems by make it glScaled(zoom^12, zoom^12, 1) so that the greater the zoom value, the faster it will zoom in order to balance out the faster zoom at lower zoom values. To compensate for the zoom focused on the bottom left, I have tried to subtract (zoom+1)^10 + 2^10 from the X and Y of each sprite. This results in a curved zoom path, first to the left and then to the right. It is a 2D game.

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  • Silverlight and .NET 4 tools

    - by Fabrice Marguerie
    I've just added two new attributes to SharpToolbox.com: Built for Silverlight and Built for .NET 4. There are already more than 30 tools tagged as offering support for Silverlight, and 20 tools for .NET 4.You can search for tools, libraries and add-ins with these attributes using the search page. PS: if you have submitted tools, be patient, I have a lot to process...

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  • When modeling a virtual circuit board, what is the best design pattern to check for cycles?

    - by Wallace Brown
    To make it simple assume you have only AND and OR gates. Each has two inputs and one output. The output of two inputs can be used as an input for the next gate For example: A AND B - E C AND D - F E OR F - G Assuming an arbitrary number of gates, we want to check if the circuit ever connects back into itself at an earlier state? For example: E AND F - A This should be illegal since it creates an endless cycle. What design pattern would best be able to check for these cycles?

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  • Make a controller a superclass in MVC design pattern

    - by Nikola
    I am really confused how to handle this. I have: model.Outsider model.SubContractor (which extends Outsider) Basically, Outsider would mean Supplier, but SubContractor is not a Supplier itself so I had to divide it somehow. I used to have model.Outsider (super class of the two bellow) model.Supplier model.SubContractor But Supplier didn't have any unique fields so I have removed it (Was this correct?) So, continuing, I have db layer which has: db.DBOutsider db.DBSubContractor (which again extends the top one) And I have no place to put my Supplier methods. I can do that in DBOutsider, but then DBSubContractor (which extends DBOutsider) would get unnecessary methods. Do I create a DBSupplier even though there is no such class in the model layer? Then again, going to controller layer. It is the same situation as db layer. I have OutsiderController and SubContractorController (which extends the first one) (is this correct in first place? to have an extended controller?). But I have no place to put the methods which are concerned with Supplier and if I put them in the OutsiderController the SubContractorController would recieve unneccessary methods. At the moment I am going for the extra DBSupplier and SupplierController classes, but I have no idea if this is the correct way. Basically what perplexes me is the "empty" Supplier. Since it is supposed to be an Outsider but has no extra methods or fields, should there be an empty class?

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  • Apache Commons PropertiesConfiguration escapes characters on Save [migrated]

    - by Anuvrat
    I am using the commons-configuration from apache commons library. I have a properties file which has properties like: blog_loc=http://my.blog.com blog_name="my blog name" I open the properties file, change the blog_name property and save the file. The following are the lines of code I use: PropertiesConfiguration propertyFile = new PropertiesConfiguration(propertyFileName); propertyFile.setProperty(blog_name, "blog name"); propertyFile.save(propertyFileName + ".out"); Unfortunately, in the output file certain characters get escaped as follows: blog_loc=http:\/\/my.blog.com blog_name=\"blog name\" Is there any way of preventing escaping of the above characters?

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  • Project Coin: JSR 334 has a Proposed Final Draft

    - by darcy
    Reaching nearly the last phase of the JCP process, JSR 334 now has a proposed final draft. There have been only a few refinements to the specification since public review: Incorporated language changes into JLS proper. Forbid combining diamond and explicit type arguments to a generic constructor. Removed unusual protocol around Throwable.addSuppressed(null) and added a new constructor to Throwable to allow suppression to be disabled. Added disclaimers that OutOfMemoryError, NullPointerException, and ArithmeticException objects created by the JVM may have suppression disabled. Added thread safely requirements to Throwable.addSuppressed and Throwable.getSuppressed. Next up is the final approval ballot; almost there!

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  • Packing jar files into library jar files

    - by Hillel
    Firstly, this question is not about packing a simple jar file (e.g. lwjgl) into a runnable jar file. I know how to do this using JarSplice. So if I have a game which uses JInput, I will pack my game jar and jinput.jar using JarSplice and enter the natives in the process. The problem arises when I want to create a custom library that uses JInput, and then pack that into my games. See, the whole idea of writing a game library is that I don't ever have to even copy code like the wrapper I wrote for JInput Controller, and I always have a definitive version inside a library jar. Basically what I wanna do is create a jar file of my library, pack jinput.jar into it using JarSplice, possibly with the natives as well, and then when I want to export a jar of my game, I either export it automatically through Eclipse with the library jar, or, if that doesn't work, use JarSplice. I've tried several solutions, and nothing works. When I try to pack the game jar and the library jar using JarSplice, I get an error saying that there's either duplicate .project or .classpath. When I try to export my game through Eclipse with the library jar, it won't run (which is to be expected), but then, if I try to attach the natives with JarSplice, it doesn't give me any errors but the jar doesn't run. I'm not expecting anyone to solve this, but if anyone has an idea, something that will allow me to never look at the Gamepad code ever again, that would be awesome. I don't care if I have to package my library jar using JarSplice 5 times, and then do the same with the game jar, as long as it works. Otherwise I'll just have to copy the Gamepad class into every project alongside the library jar. :(

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  • Design Pattern Advice for Bluetooth App for Android

    - by Aimee Jones
    I’m looking for some advice on which patterns would apply to some of my work. I’m planning on doing a project as part of my college work and I need a bit of help. My main project is to make a basic Android bluetooth tracking system where the fixed locations of bluetooth dongles are mapped onto a map of a building. So my android app will regularly scan for nearby dongles and triangulate its location based on signal strength. The dongles location would be saved to a database along with their mac addresses to differentiate between them. The android phones location will then be sent to a server. This information will be used to show the phone’s location on a map of the building, or map of a route taken, on a website. My side project is to choose a suitable design pattern that could be implemented in this main project. I’m still a bit new to design patterns and am finding it hard to get my head around ones that may be suitable. I’ve heard maybe some that are aimed at web applications for the server side of things may be appropriate. My research so far is leading me to the following: Navigation Strategy Pattern Observer Pattern Command Pattern News Design Pattern Any advice would be a great help! Thanks

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  • How to make this game loop deterministic

    - by Lanaru
    I am using the following game loop for my pacman clone: long prevTime = System.currentTimeMillis(); while (running) { long curTime = System.currentTimeMillis(); float frameTime = (curTime - prevTime) / 1000f; prevTime = curTime; while (frameTime > 0.0f) { final float deltaTime = Math.min(frameTime, TIME_STEP); update(deltaTime); frameTime -= deltaTime; } repaint(); } The thing is, I don't always get the same ghost movement every time I run the game (their logic is deterministic), so it must be the game loop. I imagine it's due to the final float deltaTime = Math.min(frameTime, TIME_STEP); line. What's the best way of modifying this to perform the exact same way every time I run it? Also, any further improvements I can make?

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  • Builder Pattern: When to fail?

    - by skiwi
    When implementing the Builder Pattern, I often find myself confused with when to let building fail and I even manage to take different stands on the matter every few days. First some explanation: With failing early I mean that building an object should fail as soon as an invalid parameter is passed in. So inside the SomeObjectBuilder. With failing late I mean that building an object only can fail on the build() call that implicitely calls a constructor of the object to be built. Then some arguments: In favor of failing late: A builder class should be no more than a class that simply holds values. Moreover, it leads to less code duplication. In favor of failing early: A general approach in software programming is that you want to detect issues as early as possible and therefore the most logical place to check would be in the builder class' constructor, 'setters' and ultimately in the build method. What is the general concensus about this?

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