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• Getting instance of a class in ArrayList

  - by user1499974

  I have a small problem with ArrayList. You see, I wish to get an instance of RenderNewHUD in my renderer class, which has a list of registered renderers. I did not want to create a variable for this due to limitations and awkwardness. Here is my code. RenderNewHUD hud = renderer.renderList.get(RenderNewHUD()); How exactly can I go along getting the instance of RenderNewHUD without creating a new instance? If you need any more of my code, just ask. Sorry if this is a very dumb question - I have looked EVERYWHERE for an answer.

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• Determining an object's variable name dynamically?

  - by ZenBlender

  Let's say I have some objects: ArrayList<SomeObject> list = new ArrayList<SomeObject>(); SomeObject A = new SomeObject(); SomeObject B = new SomeObject(); SomeObject C = new SomeObject(); SomeObject D = new SomeObject(); These constructors automatically add each object to the ArrayList so I can iterate over them but still maintain the variable names for direct access: public SomeObject(){ // init stuff here list.add(this); } But then, let's say I want to output some debug info, and iterate through list and print out the NAME of each object? How can I do that? Essentially, when "SomeObject A = new SomeObject();" is executed, I want to use reflection (if possible) to determine that this variable's name is "A" (a String) and either store that in the object when the constructor executes, or determine it dynamically through reflection when referencing this object with the variable named "A". Does that make sense? How can I do this? Thanks!

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• Format String become 0001, 0010 etc

  - by trycatch4j

  Hi all.., I have number : 1, 2, 3, 4, 10 But I wanna print that number 0001 0002 0003 0004 0010 I have search in google, the keyword is number format. but I've got nothing, I just get, frmat decimal such ass 1,000,000.00. hope you can suggest me a reference or give me some problem solving. Thanks,

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• Thread help with Android game

  - by Ciph3rzer0

  I need some help dealing with three Threads in Android One thread is the main thread, the other is the GLThread, and the other is a WorkerThread I created to update the game state. The problem I have is they all need to access the same LinkedList of game objects. Both the GLThread and my WorkerThread only read from the LinkedList, so no problem there, but occasionally I have the main thread adding in another game object to the list. How can I manage this? I tried using synchronized in front of the functions involved but it really slows down the application. For some reason, just catching the errors and not rendering or updating the game state that frame, causes it to start lagging permanently. Anyone have any great ideas?

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• Specifiy classpath for maven

  - by Zombies

  Quite new to maven here so let me explain first what I am trying to do: We have certain JAR files which will not be added to the repo. This is because they are specific to Oracle ADF and are already placed on our application server. There is only 1 version to be used for all apps at anyone time. In order to compile though, we need to have these on the class path. There are a LOT of these JARS, so if we were to upgrade to a newer version of ADF, we would have to go into every application and redefine some pretty redundant dependencies. So again, my goal is to just add these JARs to the classpath, since we will control what version is actually used elsewhere. So basically, I want to just add every JAR in a given directory to maven's classpath for when it compiles. And without putting any of these JAR files in a repository. And of course, these JARs are not to be packaged into any EAR/WAR.

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• public (static) swap() method vs. redundant (non-static) private ones...

  - by Helper Method

  I'm revisiting data structures and algorithms to refresh my knowledge and from time to time I stumble across this problem: Often, several data structures do need to swap some elements on the underlying array. So I implement the swap() method in ADT1, ADT2 as a private non-static method. The good thing is, being a private method I don't need to check on the parameters, the bad thing is redundancy. But if I put the swap() method in a helper class as a public static method, I need to check the indices every time for validity, making the swap call very unefficient when many swaps are done. So what should I do? Neglect the performance degragation, or write small but redundant code?

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• Exception handling pattern

  - by treefrog

  It is a common pattern I see where the error codes associated with an exception are stored as Static final ints. when the exception is created to be thrown, it is constructed with one of these codes along with an error message. This results in the method that is going to catch it having to look at the code and then decide on a course of action. The alternative seems to be- declare a class for EVERY exception error case Is there a middle ground ? what is the recommended method ?

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• Getting Frequency Components with FFT

  - by ruhig brauner

  so I was able to solv my last problem but i stubmled upon the next already. So I want to make a simple spectrogram but in oder to do so I want to understand how FFT-libaries work and what they actually calculate and return. (FFT and Signal Processing is the number 1 topic I will get into as soon as I have time but right now, I only have time for some programming exercises in the evening. ;) ) Here I just summarized the most important parts: int framesPerSecond; int samplesPerSecond; int samplesPerCycle; // right now i want to refresh the spectogram every DoubleFFT_1D fft; WAVReader audioIn; double audioL[], audioR[]; double fftL[], fftR[]; ..... framesPerSecond = 30; audioIn= new WAVReader("Strobe.wav"); int samplesPerSecond = (int)audioIn.GetSampleRate(); samplesPerCycle = (int)(audioIn.GetSampleRate()/framesPerSecond); audioL = new double[samplesPerCycle*2]; audioR = new double[samplesPerCycle*2]; fftL = new double[samplesPerCycle]; fftR = new double[samplesPerCycle]; for(int i = 0; i < samplesPerCycle; i++) { // don't even know why,... fftL[i] = 0; fftR[i] = 0; } fft = new DoubleFFT_1D(samplesPerCycle); ..... for(int i = 0; i < samplesPerCycle; i++) { audioIn.GetStereoSamples(temp); audioL[i]=temp[0]; audioR[i]=temp[1]; } fft.realForwardFull(audioL); //still stereo fft.realForwardFull(audioR); System.out.println("Check"); for(int i = 0; i < samplesPerCycle; i++) { //storing the magnitude in the fftL/R arrays fftL[i] = Math.sqrt(audioL[2*i]*audioL[2*i] + audioL[2*i+1]*audioL[2*i+1]); fftR[i] = Math.sqrt(audioR[2*i]*audioR[2*i] + audioR[2*i+1]*audioR[2*i+1]); } So the question is, if I want to know, what frequencys are in the sampled signal, how do I calculate them? (When I want to print the fftL / fftR arrays, I get some exponential formes at both ends of the array.) Thx :)

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• How to find the largest power of 2 less than the given number

  - by nazar_art

  I need to find the largest power of 2 less than the given number. And I stuck and can't find any solution. Code: public class MathPow { public int largestPowerOf2 (int n) { int res = 2; while (res < n) { res =(int)Math.pow(res, 2); } return res; } } This doesn't work correctly. Testing output: Arguments Actual Expected ------------------------- 9 16 8 100 256 64 1000 65536 512 64 256 32 How to solve this issue?

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• getting jcombobox mouse over value

  - by user340225

  Hi people. I have a combo box in my panel and have values in it. I want to get the selection value not the selected value when I moving the mouse through the combobox.

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• Reflection problem - Type Safety Warning

  - by jax

  Class<? extends Algorithm> alg = AlgorithmAllFrom9AndLastFrom10Impl.class Constructor<Algorithm> c = alg.getConstructors()[0]; For "alg.getConstructors()[0];" I am getting a warning in eclipse Type safety: The expression of type Constructor needs unchecked conversion to conform to Constructor How do I fix this?

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• Why do I have to give an identifier?

  - by Knowing me knowing you

  In code: try { System.out.print(fromClient.readLine()); } catch(IOException )//LINE 1 { System.err.println("Error while trying to read from Client"); } In code line marked as LINE 1 compiler forces me to give an identifier even though I'm not using it. Why this unnatural constrain? And then if I type an identifier I'm getting warning that identifier isn't used. It just doesn't make sense to me, forcing a programmer to do something unnecesarry and surplus. And after me someone will revise this code and will be wondering if I didn't use this variable on purpouse or I just forgot. So in order to avoid that I have to write additional comment explaining why I do not use variable which is unnecessary in my code. Thanks

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• Function point count given source code

  - by user354822

  Given the source code of a program, how do I analyze it and count the function points within it? Thanks!

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• What is an appropriate way to programmatically exit an application?

  - by denchr

  I am evaluating user inputs as commands for my application. If the user presses Q, or q, and then hits enter, the application quits and execution terminates. Is there a proper context, or best practices on how to do that? I do not have any resources to release, or anything like that. Should I just use System.exit(0);? Is there a recommended way to do that? As my first approach I do something like this: while (true){ try{ BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); //Other logic goes here... if (br.readLine().equalsIgnoreCase("Q")){ System.exit(0); } } catch (IOException ioe) { System.out.println("IO error trying to read your selection"); } }

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• Is it possible to Hide Text through a Style?

  - by Sandro

  I currently have a JTextPane that will be displaying text coming in from different streams. The way that the user can tell which stream the text came from is that the text from each stream has a different Style to it. Is there a way to make a Style that will hide the text so that I can filter out different pieces of text? Thank you.

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• Iterating over hashmap injsp in struts application

  - by Rozer

  I have a Hashmap object that i am getting on a jsp page. HashMap<Integer,Gift_product> gift_hm = new HashMap<Integer,Gift_product>(); gift_hm.put(17,new Gift_product("doll",67)); now i need to iterate this and display content on jsp. as Gift_product class contains two fields name and price jsp output should be serial no. product name price 17 Doll 67 How can i achieve it..

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• Drop down list population fails after validation fails

  - by sarah

  Hi All, I am polpulating data in drop down reading from request scope,i am doing validaiton of fe w field after submission i wont get data in drop down i am using struts and the corresponding form bean defn is like <action path="/userProcess" name="userForm" type="com.actions.UserManagementAction" parameter="method" input="/views/AddUsers.jsp" scope="request" > <forward name="success" path="/views/User_Management.jsp" /> </action> and the drop down listing is <select name="roleName"> <c:forEach items="${roleNames}" var="role"> <option value="${role}">${role}</option> </c:forEach> </select> how should i handle this ?

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• best way to avoid sql injection

  - by aauser

  I got similar domain model 1) User. Every user got many cities. @OneToMany(targetEntity=adv.domain.City.class...) 2) City. Every city got many districts @OneToMany(targetEntity=adv.domain.Distinct.class) 3) Distintc My goal is to delete distinct when user press delete button in browser. After that controller get id of distinct and pass it to bussiness layer. Where method DistinctService.deleteDistinct(Long distinctId) should delegate deliting to DAO layer. So my question is where to put security restrictions and what is the best way to accomplish it. I want to be sure that i delete distinct of the real user, that is the real owner of city, and city is the real owner of distinct. So nobody exept the owner can't delete ditinct using simple url like localhost/deleteDistinct/5. I can get user from httpSession in my controller and pass it to bussiness layer. After that i can get all cities of this user and itrate over them to be sure, that of the citie.id == distinct.city_id and then delete distinct. But it's rather ridiculous in my opinion. Also i can write sql query like this ... delete from t_distinct where t_distinct.city_id in (select t_city.id from t_city left join t_user on t_user.id = t_city.owner_id where t_user.id = ?) and t_distinct.id = ? So what is the best practice to add restrictions like this. I'm using Hibernate, Spring, Spring MVC by the way.. Thank you

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• Sources from referenced projects are not deployed to Tomcat in Eclipse

  - by Steven De Groote

  Hi, I have setup a dynamic web project in eclipse with JSF in which I trust on code from another project (framework). Therefore, I added the framework project to the build path of the website project. So far so good, Eclipse recognises every class and the project builds without errors. Problem is though that when I do "run on server" to test it on tomcat 6.0.24, the application fails. I get ClassNotFoundException on every class from the framework project. Is this a bug or is some specific configuration necessary for this?

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• Aggregation, Association and Composition (examples of code given)

  - by Bukocen

  I have such a simple example: public class Order { private ArrayList<Product> orders = new ArrayList<Product>(); public void add(Product p) { orders.add(p); } } Is it aggregation or composition? I guess it's composition, because orders will be delated after delete of Order, right? Unfortunately it was a task and answer was different;/ Do you know why? second problem: public class Client extends Person { String adress = ""; Orders orders = new Orders(); public Client(String n, String sn) { name = n; surName = sn; } public String getAddress() { return adress; } public Orders getOrders() { return this.orders; } } Is it Association between Client and Orders? My teacher told me that this is association, but I was wondering why it's not a aggregation/composition - he told me that aggregation or composition occur only when one class contains few instances of different class - is that right? I guess not, because e.g. car contains ONE wheel and it's aggregation I guess? What type of relation is that and why? Greetings

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• how can I enter character "<" in strings.xml?

  - by yrajabi

  I want to enter string " -< " in strings.xml file, the string has character < and I couldn't add it to xml file without error! I even tried to escaping by \ character: <string name="search_target_arrow"> -\< </string> or enclosing it between "" as below: <string name="search_target_arrow">" -< "</string> but none worked. Maybe I'm very amateur at this and the answer is not hard for you. so please tell me how you add such special chars in strings.xml?

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• is it possible to store server returned json data in jqgrid to display columnnames models data dynamically for every request?

  - by user1768246

  is it possible to store server returned json data in jqgrid to display columnnames models data dynamically for every request ? $("#grid").jqGrid({ type: "GET", url: "", var columnNames = $("#grid")[0].p.colNames, var columnModel = $("#grid")[0].p.colNames, var columnData = $("#grid")[0].p.colNames, datatype: 'jsonstring', datastr: columnData, colModel: columnModel, jsonReader: { root: 'innerWrapper.rows', page: "result.gridData.outerWrapper.page", total: "result.gridData.outerWrapper.total", records: "result.gridData.outerWrapper.total", repeatitems: false, }, gridview: true, pager: "pager", height: "auto", rowNum: 10, width:"auto", height:"auto", rowList: [10, 20, 30,40], viewrecords: true, caption:"Graph Data", rownumbers: true, });

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• multiple dataset in jfreechart !

  - by rantravee

  Hi, How could I add to a plot an OHLCSeriesCollection and a TimeSeriesCollection , in order to represent their values in the same chart ?

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• JComboBox to string

  - by gabrielle fregil

  I have a String array of names, and then I added it into an editable JComboBox. The user can either pick his/her name from the choices or just input his/her name if not in the choices. How do I put the user input into a new string variable? String [] chooseName = { Mark, John, Allison, Jessica }; JComboBox combo = new JComboBox (chooseName); combo.setEditable(true); String chosenName = /* how do i place what the user inputed here? */

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• What exactly is GRASP's Controller about?

  - by devoured elysium

  What is the idea behind Grasp's Controller pattern? My current interpretation is that sometimes you want to achieve something that needs to use a couple of classes but none of those classes could or has access to the information needed to do it, so you create a new class that does the job, having references to all the needed classes(this is, could be the information expert). Is this a correct view of what Grasp's Controller is about? Generally when googling or SO'ing controller, I just get results about MVC's (and whatnot) which are topics that I don't understand about, so I'd like answers that don't assume I know ASP.NET's MVC or something :( Thanks

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