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  • Should I use multiple column primary keys or add a new colum?

    - by Covar
    My current database design makes use of a multiple column primary key to use existing data (that would be unique anyway) instead of creating an additional column assigning each entry an arbitrary key. I know that this is allowed, but was wondering if this is a practice that I might want to use cautiously and possibly avoid (much like goto in C). So what are some of the disadvantages I might see in this approach or reasons I might want a single column key?

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  • How many tiers should my models have in a DB driven web app?

    - by Hanno Fietz
    In my experience, the "Model" in MVC is often not really a single layer. I would regularly have "backend" models and "frontend" models, where the backend ones would have properties that I want to hide from the UI code, and the frontend ones have derived or composite properties which are more meaningful in the context of the UI. Recently, I have started to introduce a third layer in between when database normalization created tables that did not really match the conceptual domain objects anymore. In those projects I have model classes that are equivalent with the DB structure, these become components of objects that represent the domain model, and finally these are filtered and amended for displaying information to the user. Are there patterns or guidelines for how, when and why to organize the data model across application layers?

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  • Almost working 2D Collisions

    - by TheGag96
    I'm terribly sorry I'm asking this question YET AGAIN, but I can almost guarantee that this will be the last time I'll have to ask. I'm currently on the verge of FINALLY getting these collisions to work for my game, made with libGDX in Java. My collisions use the same method as (and are basically copied and modified code from) the XNA Platformer example (here) where the direction of the collision is based on the rectangle where two objects are overlapping. The collisions themselves almost work perfectly, but for some reason, holding down/up and left and colliding with the floor/ceiling while doing so doesn't seem to work well. I'm not at all sure why. Instead of vaguely giving my problem and snippets of code, I've decided to instead provide a binary and the source of the game I have so far so you can see for yourself what my problem is. Link. (Note: make sure you unzip everything into a folder somewhere or it will not work) You'll find the collision code in the method workingCollisions() in Link.java. Please excuse the messy code and terrible graphics as this whole thing is in pre-pre-alpha. If anyone is kind enough and helps me out here, you are the best person ever. I'm completely desperate; I've been trying this on and off for months and I just can't get it to work. I cannot thank you enough.

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  • Is acoustic fingerprinting too broad for one audio file only?

    - by IBG
    We were looking for some topics related to audio analysis and found acoustic fingerprinting. As it is, it seems like the most famous application for it is for identification of music. Enter our manager, who requested us to research and possible find an algorithm or existing code that we can use for this very simple approach (like it's easy, source codes don't show up like mushrooms): Always-on app for listening Compare the audio patterns to a single audio file (assume sound is a simple beep) If beep is detected, send notification to server With a flow this simple, do you think acoustic fingerprinting is a broad approach to use? Should we stop and take another approach? Where to best start? We haven't started anything yet (on the development side) on this regard, so I want to get other opinion if this is pursuit is worth it or moot.

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  • What is the term that means "keeping the arguments for different API calls as similar as possible"?

    - by larson4
    There is a word which I can never remember... it expresses a design goal that API calls (or functions or methods or whatever) should be as similar as reasonably possible in their argument patterns. It may also extend to naming as well. In other words, all other things being equal, it is probably bad to have these three functions: deleteUser(email) petRemove(petId,species) destroyPlanet(planetName,starName) if instead you could have deleteUser(userId) deletePet(petId) deletePlanet(planetId) What is the word for this concept? I keep thinking it's "orthogonal" but it definitely isn't. Its a very important concept, and to me it's one of the biggest things that makes some APIs a joy to work with (because once you learn a few things you can pretty much use everything without looking at doco), and others a pain (because every function is done inconsistently).

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  • Server-side Architecture for Online Game

    - by Draiken
    basically I have a game client that has communicate with a server for almost every action it takes, the game is in Java (using LWJGL) and right now I will start making the server. The base of the game is normally one client communicating with the server alone, but I will require later on for several clients to work together for some functionalities. I've already read how authentication server should be sepparated and I intend on doing it. The problem is I am completely inexperienced in this kind of server-side programming, all I've ever programmed were JSF web applications. I imagine I'll do socket connections for pretty much every game communication since HTML is very slow, but I still don't really know where to start on my server. I would appreciate reading material or guidelines on where to start, what architecture should the game server have and maybe some suggestions on frameworks that could help me getting the client-server communication. I've looked into JNAG but I have no experience with this kind of thing, so I can't really tell if it is a solid and good messaging layer. Any help is appreciated... Thanks ! EDIT: Just a little more information about the game. It is intended to be a very complex game with several functionalities, making some functionalities a "program" inside the program. It is not an usual game, like FPS or RPG but I intend on having a lot of users using these many different "programs" inside the game. If I wasn't clear enough, I'd really appreciate people that have already developed games with java client/server architecture, how they communicated, any frameworks, apis, messaging systems, etc. It is not a question of lack of knowledge of language, more a question for advice, so I don't end up creating something that works, but in the later stages will have to be rewriten for any kind of limiting reason. PS: sorry if my english is not perfect...

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  • How can I improve my skills while working on actual projects, in the absence of more experienced developers?

    - by LolCoder
    I'm the lead developer at a small company, working with C# and ASP.Net. Our team is small, 2-3 people, without much experience in development and design. I don't have the opportunity to learn from more senior developers, there is no one in my team to guide me and help me choose the best approaches, as I take care most of the projects myself. How can I improve my software development skills while working on actual projects, in the absence of more experienced developers?

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  • Attaching new animations onto skeleton via props, a good idea?

    - by Cardin
    I'm thinking of coding a game with an idea of mine. I've coded 2D games before, but I'm new to 3D programming, so I'd like to ask if this idea of mine is feasible or out of my depth. I'm making a game where there are many different characters for the player to choose from (JRPG style). So to save time, I have an idea of creating many different varied characters using a completely naked body mesh and animation skeleton, standardised across all characters. For example, by placing different hair, boots, armor props on the character mesh, new characters can be formed. Kinda like playing dress-up with a barbie doll. I'm thinking this can be done by having a bone on the prop that I can programmically attach to the main mesh. Also, I plan to have some props add new animations to the base skeleton, so equipping some particular props would give it new attack, damage, idle animations. This is because I can't expect the character to have the same swinging animation if he had a big sword or an axe. I think this might be possible if the prop has its own instance of the animation skeleton with just only the new animations, and parenting the base body mesh to this new skeleton. So all the base body mesh has are just the basic animations, other animations come from the props. My concerns are, 1) the props might not attach to the mesh properly and jitter a lot, 2) since prop and body are animated differently, the props and base mesh will cause visual artefacts, like the naked thighs showing through the pants when the character walks, 3) a custom pipeline have to be developed to export skeletons without mesh, and also to attach the base body mesh to a new skeleton during runtime in the game. So my question: are these features considered 'easy' to code? Or am I trying to do something few have ever succeeded with on their own? It feels like all these can be done given enough time and I know I definitely have to do a bit of bone matrix calculations, but I really don't want to drag out the development timeline unnecessarily from coding mathematically intense things or analyzing how to parse 3D export formats. I'm currently only at the Game Design stage, so if these features aren't a good idea, I can simply change the design of the game. (Unrelated to question) I could always, as last resort, have the characters have predetermined outfit and weapon selections so as to animate everything manually.

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  • How do I start working as a programmer - what do I need?

    - by giorgo
    Hello, i am currently learning Java and PHP as I have some projects from university, which require me to apply both languages. Specifically, a Java GUI application, connecting to a MySQL database and a web application that will be implemented in PHP/MySQL. I have started learning the MVC pattern, Struts, Spring and I am also learning PHP with zend. My first question is: How can I find employment as a programmer/software engineer? The reason I ask is because I have sent my CV into many companys, but all of them stated that I required work experience. I really need some guidance on how to improve my career opportunites. At present, I work on my own and haven't worked in collaboration with anyone on a particular project. I'm assuming most people create projects and submit them along with their CVs. My second question is: Everyone has to make a start from somewhere, but what if this somewhere doesn't come? What do I need to do to create the circumstances where I can easily progress forward? Thanks

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  • Interaction of a GUI-based App and Windows Service

    - by psubsee2003
    I am working on personal project that will be designed to help manage my media library, specifically recordings created by Windows Media Center. So I am going to have the following parts to this application: A Windows Service that monitors the recording folder. Once a new recording is completed that meets specific criteria, it will call several 3rd party CLI Applications to remove the commercials and re-encode the video into a more hard-drive friendly format. A controller GUI to be able to modify settings of the service, specifically add new shows to watch for, and to modify parameters for the CLI Applications A standalone (GUI-based) desktop application that can perform many of the same functions as the windows service, expect manually on specific files instead of automatically based on specific criteria. (It should be mentioned that I have limited experience with an application of this complexity, and I have absolutely zero experience with Windows Services) Since the 1st and 3rd bullet share similar functionality, my design plan is to pull the common functionality into a separate library shared by both parts applications, but these 2 components do not need to interact otherwise. The 2nd and 3rd bullets seem to share some common functionality, both will have a GUI, both will have to help define similar parameters (one to send to the service and the other to send directly to the CLI applications), so I can see some advantage to combining them into the same application. On the other hand, the standalone application (bullet #3) really does not need to interact with the service at all, except for possibly sharing a few common default parameters that can easily be put into an XML in a common location, so it seems to make more sense to just keep everything separate. The controller GUI (2nd bullet) is where I am stuck at the moment. Do I just roll this functionality (allow for user interaction with the service to update settings and criteria) into the standalone application? Or would it be a better design decision to keep them separate? Specifically, I'm worried about adding the complexity of communicating with the Windows Service to the standalone application when it doesn't need it. Is WCF the right approach to allow the controller GUI to interact with the Windows Service? Or is there a better alternative? At the moment, I don't envision a need for a significant amount of interaction, maybe just adding a new task once in a while and occasionally tweaking a parameter, but when something is changed, I do expect the windows service to immediately use the new settings.

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  • How to Install WebLogic 12c ZIP on Linux

    - by Bruno.Borges
    I knew that WebLogic had this small ZIP distribution, of only 184M, but what I didn't know was that it is so easy to install it on Linux machines, specially for development purposes, that I thought I had to blog about it. You may want to check this blog, where I found the missing part on this how to, but I'm blogging this again because I wanted to put it in a simpler way, straight to the point. And if you are looking for a how to for Mac, check Arun Gupta's post.  So, here's the step-by-step: 1 - Download the ZIP distribution (don't worry if your system is x86_64)Don't forget to accept the OTN Free Developer License Agreement! 2 - Choose where to install your WebLogic server and your domain, and set as your MW_HOME environment variableI will use /opt/middleware/weblogic for this how to export MW_HOME=/opt/middleware/weblogicMake sure this path exists in your system. 'mydomains' will be used to keep your WebLogic domain. mkdir -p $MW_HOME/mydomain 3 - If you don't have your JAVA_HOME environment variable still configured, do it. Point it to where your JDK is installed. export JAVA_HOME=/usr/lib/jvm/default-java 4 - Unzip the downloaded file into MW_HOME unzip wls1211_dev.zip -d $MW_HOME 5 - Go to that directory and run configure.sh cd $MW_HOME ./configure.sh 6 - Call the setEnvs.sh script . $MW_HOME/wlserver/server/bin/setWLSEnv.sh7 - Create your development domain. It will ask you for username and password. I like to use weblogic / welcome1cd $MW_HOME/mydomain $JAVA_HOME/bin/java $JAVA_OPTIONS -Xmx1024m \ -Dweblogic.management.allowPasswordEcho=true weblogic.Server8 - Start WebLogic and access its web console(sh startWebLogic.sh &); sleep 10; firefox http://localhost:7001/consoleUsually, it takes only 10 seconds to start a domain, and 5 more to deploy the Administration Console (on my laptop). :-)Enjoy!

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  • Speaking at Triangle SQL Server User Group 16 Mar 2010!

    - by andyleonard
    I'm excited to present Applied SSIS Design Patterns to the Triangle SQL Server User Group 16 Mar 2010! This is a reprise of my PASS Summit 2009 spotlight session. If you read this blog and make the meeting, introduce yourself! :{> Andy Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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  • self referencing tables, good or bad?

    - by NimChimpsky
    Representing geographical locations within an application, the design of the underlying data model suggests two clear options (or maybe more?). One table with a self referencing parent_id column uk - london (london parent id = UK id) or two tables, with a one to many relationship using a foreign key. My preference is for one self-refercing table as it easily allows to extend into as many sub regions as required. IN general do people veer away from self referencing tables, or are they A-OK ?

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  • Does this factory method pattern example violate open-close?

    - by William
    In Head-First Design Patterns, they use a pizza shop example to demonstrate the factory method pattern. public abstract class PizzaStore { public Pizza orderPizza(String type) { Pizza pizza; pizza = createPizza(type); pizza.prepare(); pizza.bake(); pizza.cut(); pizza.box(); return pizza; } abstract Pizza createPizza(String type) } public class NYPizzaStore extends PizzaStore { Pizza createPizza(String item) { if (item.equals("cheese") { return new NYStyleCheesePizza(); } else if (item.equals("veggie")) { return new NYStyleVeggiePizza(); } else if (item.equals("clam")) { return new NYStyleClamPizza(); } else if (item.equals("pepperoni")) { return new NYStylePepperioniPizza(); } else return null; } } I don't understand how this pattern is not violating open-close. What if we require a beef Pizza, then we must edit the if statement in the NYPizzaStore class.

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  • iOS - Unit tests for KVO/delegate codes

    - by ZhangChn
    I am going to design a MVC pattern. It could be either designed as a delegate pattern, or a Key-Value-Observing(KVO), to notify the controller about changing models. The project requires certain quality control procedures to conform to those verification documents. My questions: Does delegate pattern fit better for unit testing than KVO? If KVO fits better, would you please suggest some sample codes?

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  • I still can't figure out how to program!

    - by Mark K.
    Please help! I've read lots of programming books for various languages, Java, Python, C, etc. I understand and know all of the basics of the languages and I understand algorithms and data structures. (Equivilant of say 2 years of CompSci classes) BUT, I still can't figure how to write a program that does anything useful. All of the programming books show you how to write the language, but NOT how to use it! The programming examples are all very basic like build a card catalog for a library or a simple game or use algorithms etc... They dont't show you how to develop complex programs that actually do anything useful! I've looked a open-source programs on sourceforge, but they don't make much sense to me. There are hundreds of files in each program & thousands of lines of code. But how do I learn how to do this? There's nothing in any book I can buy on Amazon that will give me the tools to write any of these programs. How do you go from reading Intro to Java or Programming Python, or C Programming Language, etc.. to actually being able to say, I have an idea for X Program.. this is how I go about developing it? It seems like there is so much more involved in writing a program than you can learn in a book or from a class. I feel like there is someth Can anyone put me on the right track?

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  • How to refactor a method which breaks "The law of Demeter" principle?

    - by dreza
    I often find myself breaking this principle (not intentially, just through bad design). However recently I've seen a bit of code that I'm not sure of the best approach. I have a number of classes. For simplicity I've taken out the bulk of the classes methods etc public class Paddock { public SoilType Soil { get; private set; } // a whole bunch of other properties around paddock information } public class SoilType { public SoilDrainageType Drainage { get; private set; } // a whole bunch of other properties around soil types } public class SoilDrainageType { // a whole bunch of public properties that expose soil drainage values public double GetProportionOfDrainage(SoilType soil, double blockRatio) { // This method does a number of calculations using public properties // exposed off SoilType as well as the blockRatio value in some conditions } } In the code I have seen in a number of places calls like so paddock.Soil.Drainage.GetProportionOfDrainage(paddock.Soil, paddock.GetBlockRatio()); or within the block object itself in places it's Soil.Drainage.GetProportionOfDrainage(this.Soil, this.GetBlockRatio()); Upon reading this seems to break "The Law of Demeter" in that I'm chaining together these properties to access the method I want. So my thought in order to adjust this was to create public methods on SoilType and Paddock that contains wrappers i.e. on paddock it would be public class Paddock { public double GetProportionOfDrainage() { return Soil.GetProportionOfDrainage(this.GetBlockRatio()); } } on the SoilType it would be public class SoilType { public double GetProportionOfDrainage(double blockRatio) { return Drainage.GetProportionOfDrainage(this, blockRatio); } } so now calls where it used would be simply // used outside of paddock class where we can access instances of Paddock paddock.GetProportionofDrainage() or this.GetProportionOfDrainage(); // if used within Paddock class This seemed like a nice alternative. However now I have a concern over how would I enforce this usage and stop anyone else from writing code such as paddock.Soil.Drainage.GetProportionOfDrainage(paddock.Soil, paddock.GetBlockRatio()); rather than just paddock.GetProportionOfDrainage(); I need the properties to remain public at this stage as they are too ingrained in usage throughout the code block. However I don't really want a mixture of accessing the method on DrainageType directly as that seems to defeat the purpose altogether. What would be the appropiate design approach in this situation? I can provide more information as required to better help in answers. Is my thoughts on refactoring this even appropiate or should is it best to leave it as is and use the property chaining to access the method as and when required?

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  • Do the benefits of Resin/Quercus outweigh the overhead?

    - by Craige
    Lately, I've been looking more and more into Resin + Quercus as a technology to develop an application of mine. The reason I started looking into it was that this application has high reporting needs, a lot of which cannot (or realistically, should not) be created in real-time. Java would offer a nice backend to queue and generate reports. Also, with Quercus I would be able to develop my data models in Hibernate, and use them "from PHP", thus effectively stretching these models across front and back-end. This same concept would also apply to any front/back-end common business logic, which could be developed in Java libraries. Now, the downside is that whichever front-end (PHP) MVC Framework I choose (my goal was Symfony 2), it is unlikely to work without some heavy modification, if it can work at all. Quercus is a pretty close implementation of PHP, and is supposed to be compatible with PHP5.3, so namespaces and closures SHOULDN'T be a problem, but when I tried to run an existing Symfony 1.4 app, I failed miserably. So, my question to you is, do you think the benefits of Resin + Quercus outweigh the overhead of using a not-so-perfect/stable implementation of PHP? If this were your application, and your goal was and end-product, rather than educational purposes, what would you decide?

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  • Algorithm for procedural city generation?

    - by Zove Games
    I am planning on making a (simple) procedural city generator using Java. I need ideas on whan algorithm to use for the layout, and the actual buildings. The city will mostly have skyscrapers, not really much complex stuff. For the layout I already have a simple algorithm implemented: Create a Map with java.awt.Point keys and Integer values. Fill it with all the points in the city's bounds with the value as -1 (unnassigned) Shuffle the map, and assign the 1st 10 of the keys IDs (from 1-10) Loop until all points have IDs: Loop though all points: Assign points next to an assigned point IDs of the point next to them, if 2 or more points border the point, then randomly choose which ID the point will get. You will end up with 10 random regions. Make roads bordering these regions. Fill the inside of each region with a randomly spaced and randomly rotated grid PROBLEM: This is not the fastest way to do it. What algorithm should I use for the layout. And what should I use to make each building's design? I don't even know how I'm going to do that yet (fractals maybe). I just need some ideas, not actual code.

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  • Chapter 7–Enforced Data Protection

    - by drsql
    As the book progresses, I find myself veering from the original stated outline quite a bit, because as I teach about this more (and I am teaching a daylong db design class in August at http://www.sqlsolstice.com/ … shameless plug, but it is on topic :) I start to find that a given order works better. Originally I had slated myself to talk more about modeling here for three chapters, then get back to the more implementation topics to finish out the book, but now I am going to keep plugging through...(read more)

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  • Need help: jBPM installation issue

    - by Kouky
    This is Ms Kahina, I’m getting started with jBPM & Java EE, I tried to install the jBPM 5.4 version by following all the steps stated in the iBPM user guide as below: 1- I’ve installed Java (JDK 1.7) and ant ( Apache-ant-1.9.4). 2- I’ve set both JAVA_HOME and ANT_HOME environement variables. 3- I’ve downloaded the jBPM 5.4 full installer and run the installation script “ant install.demo” and after that the start script “ant start.demo”. But unfortunately jBPM 5.4 is not working. When running the installation Script I’m getting successful message but with the following warnings : [copy] Warning: Could not find file C:\jbpm-installer\db\task-persistence.xml to copy. [copy] Warning: Could not find file C:\jbpm-installer\db\Taskorm.xml to copy. The start demo was successful. Actually when I try to open any tool provided with the jBPM such us the jBPM-console for example I’m getting the following messages: Address not found or sometimes the http status 404 occurred even if the Welcome page of jBoss AS was opened at http://localhost:8080/. Please need your assistance to sort out this issue in order to move forward in my project as I'm blocked in the installation stage since more than a week now, I don’t know if this is related to the jBoss AS7 or to any other thing that I didn’t find out. Looking forward to hearing from you. Thanks Kahina

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  • Should I use multiple column primary keys or add a new column?

    - by Covar
    My current database design makes use of a multiple column primary key to use existing data (that would be unique anyway) instead of creating an additional column assigning each entry an arbitrary key. I know that this is allowed, but was wondering if this is a practice that I might want to use cautiously and possibly avoid (much like goto in C). So what are some of the disadvantages I might see in this approach or reasons I might want a single column key?

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  • tips, guidelines, points to remember for rendering professional code?

    - by ronnieaka
    I'm talking about giving clients professional looking code. The whole nine yards, everything you hardcore professional highly experienced programmers here probably do when coding freelance or for the company you work in. I'm fresh out of college and I'm going into freelance. I just want to be sure that my first few projects leave a good after-taste of professionalism imprinted on the clients' minds. When I Googled what i'm asking here, I was given pages that showed various websites and tools that let you make flashy websites and templates etc. The $N package and such stuff. I can't recall the word experts use for it. Standard, framework [i know that's not it]. English isn't my first language so I'm sorry I don't really don't know the exact phrase for it. That abstract way of writing code so that you don't come across as a sloppy programmer. That above mentioned way for programming websites and desktop software [in python/C/C++/Java]. EDIT: i can work on the accruing vast knowledge and know-how and logic building etc. what i'm asking for is the programming standard/guidelines you guys follow so that the client on seeing code feels that its a professional solution. Like comment blocks, a particular indentation style something like that. Is there any book on it or specific list of points for enterprise type coding by them? Especially here as in my case, for building websites [php for now..], and desktop software [c/c++/java/python]

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  • Designing for visually impaired gamers

    - by Aku
    Globally the number of people of all ages visually impaired is estimated to be 285 million, of whom 39 million are blind. — World Health Organisation, 2010. (That's 4.2% and 0.6% of the world population.) Most videogames put a strong emphasis on visuals in their content delivery. Visually impaired gamers are largely left out. How do I design a game to be accessible to visually impaired gamers?

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  • how to use double buffering in awt? [on hold]

    - by Ishanth
    import java.awt.event.*; import java.awt.*; class circle1 extends Frame implements KeyListener { public int a=300; public int b=70; public int pacx=360; public int pacy=270; public circle1() { setTitle("circle"); addKeyListener(this); repaint(); } public void paint(Graphics g) { g.fillArc (a, b, 60, 60,pacx,pacy); } public void keyPressed(KeyEvent e) { int key=e.getKeyCode(); System.out.println(key); if(key==38) { b=b-5; //move pacman up pacx=135;pacy=270; //packman mouth upside if(b==75&&a>=20||b==75&&a<=945) { b=b+5; } else { repaint(); } } else if(key==40) { b=b+5; //move pacman downside pacx=315; pacy=270; //packman mouth down if(b==645&&a>=20||b==645&&a<=940) { b=b-5; } else{ repaint(); } } else if(key==37) { a=a-5; //move pacman leftside pacx=227; pacy=270; //packman mouth left if(a==15&&b>=75||a==15&&b<=640) { a=a+5; } else { repaint(); } } else if(key==39) { a=a+5; //move pacman rightside pacx=42;pacy=270; //packman mouth right if(a==945&&a>=80||a==945&&b<=640) { a=a-5; } else { repaint(); } } } public void keyReleased(KeyEvent e){} public void keyTyped(KeyEvent e){} public static void main(String args[]) { circle1 c=new circle1(); c.setVisible(true); c.setSize(400,400); } }

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