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  • Is it ever OK to throw a java.lang.Error?

    - by Abhijeet Kashnia
    I have a plugin module that goes into a web application. If the module does not load correctly, it does not make sense for the web application to go on, and the web application should probably not load at all, we would prefer this module to initialize correctly always. If I were to throw a runtime exception, it would get into the logs, and just get ignored since the application will continue anyway, and the end users would never know... I know that errors are meant to be thrown only under exceptional conditions, and they generally have to do with situations that the system cannot recover from, but what would you do in such a situation?

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  • Is there a a C-like way to get item number from enum in java ?

    - by Hernán Eche
    Perhap this is a simple basic question Having an enum public enum TK{ ID,GROUP,DATA,FAIL; } Can I get the order number for example ID=0, GROUP=2, DATA=3, FAIL=4 ? This is a way to to that, but a weird and long one! =S public enum TK{ ID(0),GROUP(1),DATA(2),FAIL(3); int num; TK(int n) { this.num=n; } public int get() { return num; } }; to get numbers so I write TK.ID.get(), TK.GROUP.get(), etc... I don't like that there is a better way? ( C enums, C macros..I miss you both ) thanks

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  • Lazy loading? Better avoiding it?

    - by Charlie Pigarelli
    I just read about this design pattern: Lazy Load. And, since in the application i'm working on i have all the classes in one folder, i was wondering if this pattern could just make me avoiding the include() function for every class. I mean: It's nice to know that if i forgot to include a class, PHP, before falling into an error, trough an __autoload() function try to get it. But is it fine enough to just don't care about including classes and let PHP do it by your own every time? Or we should write __autoload() just in case it is needed?

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  • How to find all initializations of instance variables in a Java package?

    - by Hank Gay
    I'm in the midst of converting a legacy app to Spring. As part of the transition, we're converting our service classes from an "instantiate new ones whenever you need one" style to a Springleton style, so I need a way to make sure they don't have any state. I'm comfortable on the *nix command-line, and I have access to IntelliJ (this strikes me as a good fit for Structural Search and Replace, if I could figure out how to use it), and I could track down an Eclipse install, if that would help. I just want to make absolutely sure I've found all the possible problems. UPDATE: Sorry for the confusion. I don't have a problem finding places where the old constructor was being called. What I'm looking for is a "bullet-proof" why to search all 100+ service classes for any sort of internal state. The most obvious one I could think of (and the only one I've really found so far) is cases where we use memoization in the classes, so they have instance variables that get initialized internally instead of via Spring. This means that when the same Springleton gets used for different requests, data can leak between them. Thanks.

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  • Java FMJ is not cross platfrom ? How can it be fixed ?

    - by Stackfan
    I was trying to use FMJ (for windows/linux/mac). Where JMF was not working for me (so decided to work with FMJ as it is cross platfaorm). But when ever i am trying FMJ it never works, where you can see the difference in the screen shot. ex: http://i.imgur.com/AjcJh.png Thanks & Regards Note: I have two camera connected in the same PC and Flash detects always both of them without any issue. But FMJ is never working ?????.

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  • Can someone explain this java interface to me please?

    - by Karl Patrick
    I realize that the method run must be declared because its declared in the runnable interface. But my question comes when this class runs how is the Thread object allowed if there is no import call to a particular package? how does runnable know anything about Thread or its methods? does the runnable interface extend the thread class? Obviously i dont understand interfaces very well. thanks in advance. class PrimeFinder implements Runnable{ public long target; public long prime; public boolean finished = false; public Thread runner; PrimeFinder(long inTarget){ target = inTarget; if(runner == null){ runner = new Thread(this); runner.start() } } public void run(){ } }

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  • Is an ArrayList automaticaly declared static in Java, if it is an instance variable?

    - by Alex
    I'm trying to do something like this: private class aClass { private ArrayList<String> idProd; aClass(ArrayList<String> prd) { this.idProd=new ArrayList<String>(prd); } public ArrayList<String> getIdProd() { return this.idProd; } } So if I have multiple instances of ArrayLIst<String> (st1 ,st2 ,st3) and I want to make new objects of aClass: { aClass obj1,obj2,obj3; obj1=new aClass(st1); obj2=new aClass(st2); obj3=new aClass(st3); } Will all of the aClass objects return st3 if I access the method getIdProd() for each of them(obj1..obj3)? Is an ArrayList as an instance variable automatically declared static?

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  • Does the java JFC hash table use seperate chaining resolution? Can I traverse each list in the table

    - by Matt
    I have written a program to store a bunch of strings in a JFC hash table. There are defiantly collisions going on, but I don't really know how it is handling them. My ultimate goal is to print the number of occurrences of each string in the table, and traversing the bucket or list would work nicely. Or maybe counting the collisions? Or do you have another idea of how I could get a count of the elements?

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  • Save Java frame as a Microsoft Word or PDF document?

    - by Jason
    I am working on a billing program - right now when you click the appropriate button it generates a frame that shows the various charges etc, basically an invoice. Is there a way to give the user an option of saving that frame as a document, either Microsoft Word, Microsoft Works or PDF?

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  • Compiling CSS to SWF server side Java, What is the best practice?

    - by DataSurfer
    My project allows users to create custom css for our flex app. In regards to compiling the CSS into SWFs on the server side: Should I use the flex2.compiler.css.Compiler class in mxmlc-3.5.0.12683.jar? Or Should I invoke mxmlc from Runtime.getRuntime().exec()? The css.Compiler class is not very well documented. Does anyone have any examples that use this? For the Runtime exec method, what is the best way to package mxmlc into the maven build so its available to the server at runtime?

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  • Java - Unknown characters passing as [a-zA-z0-9]*?

    - by Twodordan
    Hello, I'm no expert in regex but I need to parse some input I have no control over, and make sure I filter away any strings that don't have A-z and/or 0-9. When I run this, Pattern p = Pattern.compile("^[a-zA-Z0-9]*$"); //fixed typo if(!p.matcher(gottenData).matches()) System.out.println(someData); //someData contains gottenData certain spaces + an unknown symbol somehow slip through the filter (gottenData is the red rectangle): In case you're wondering, it DOES also display Text, it's not all like that. For now, I don't mind the [?] as long as it also contains some string along with it. Please help. [EDIT] as far as I can tell from the (very large) input, the [?]'s are either white spaces either nothing at all; maybe there's some sort of encoding issue, also perhaps something to do with #text nodes (input is xml)

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  • Is there anything inherently wrong with long variable/method names in Java?

    - by Doug Smith
    I know this is probably is a question of personal opinion, but I want to know what's standard practice and what would be frowned upon. One of my profs in university always seems to make his variable and method names as short as possible (getAmt() instead of getAmount) for instance. I have no objection to this, but personally, I prefer to have mine a little longer if it adds descriptiveness so the person reading it won't have to check or refer to documentation. For instance, we made a method that given a list of players, returns the player who scored the most goals. I made the method getPlayerWithMostGoals(), is this wrong? I toiled over choosing a way to make it shorter for awhile, but then I thought "why?". It gets the point across clearly and Eclipse makes it easy to autocomplete it when I type. I'm just wondering if the short variable names are a piece of the past due to needing everything to be as small as possible to be efficient. Is this still a requirement?

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  • Is an ArrayList automatically declared static in Java, if it is an instance variable?

    - by Alex
    I'm trying to do something like this: private class aClass { private ArrayList<String> idProd; aClass(ArrayList<String> prd) { this.idProd=new ArrayList<String>(prd); } public ArrayList<String> getIdProd() { return this.idProd; } } So if I have multiple instances of ArrayLIst<String> (st1 ,st2 ,st3) and I want to make new objects of aClass: { aClass obj1,obj2,obj3; obj1=new aClass(st1); obj2=new aClass(st2); obj3=new aClass(st3); } Will all of the aClass objects return st3 if I access the method getIdProd() for each of them(obj1..obj3)? Is an ArrayList as an instance variable automatically declared static?

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  • Better Java method Syntax? Return early or late? [closed]

    - by Gandalf
    Duplicate: Should a function have only one return statement? and Single return or multiple return statements? Often times you might have a method that checks numerous conditions and returns a status (lets say boolean for now). Is it better to define a flag, set it during the method, and return it at the end : boolean validate(DomainObject o) { boolean valid = false; if (o.property == x) { valid = true; } else if (o.property2 == y) { valid = true; } ... return valid; } or is it better/more correct to simply return once you know the method's outcome? boolean validate(DomainObject o) { if (o.property == x) { return true; } else if (o.property2 == y) { return true; } ... return false; } Now obviously there could be try/catch blocks and all other kinds of conditions, but I think the concept is clear. Opinions?

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  • How to fill a two Dimensional ArrayList in java with Integers?

    - by eNetik
    I have to create a 2d array with unknown size. So I have decided to go with a 2d ArrayList the problem is I'm not sure how to initialize such an array or store information. Say I have the following data 0 connects 1 2 connects 3 4 connects 5 ....etc up to a vast amount of random connections and I want to insert true(1) into [0][1], true(1) into [2][3], true(1) into [4][5]. Can the array automatically update the column/rows for me Any help is appreciated thanks

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  • How to proceed jpeg Image file size after read--rotate-write operations in Java?

    - by zamska
    Im trying to read a JPEG image as BufferedImage, rotate and save it as another jpeg image from file system. But there is a problem : after these operations I cannot proceed same file size. Here the code //read Image BufferedImage img = ImageIO.read(new File(path)); //rotate Image BufferedImage rotatedImage = new BufferedImage(image.getHeight(), image.getWidth(), BufferedImage.TYPE_3BYTE_BGR); Graphics2D g2d = (Graphics2D) rotatedImage.getGraphics(); g2d.rotate(Math.toRadians(PhotoConstants.ROTATE_LEFT)); int height=-rotatedImage.getHeight(null); g2d.drawImage(image, height, 0, null); g2d.dispose(); //Write Image Iterator iter = ImageIO.getImageWritersByFormatName("jpeg"); ImageWriter writer = (ImageWriter)iter.next(); // instantiate an ImageWriteParam object with default compression options ImageWriteParam iwp = writer.getDefaultWriteParam(); try { FileImageOutputStream output = null; iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); iwp.setCompressionQuality(0.98f); // an integer between 0 and 1 // 1 specifies minimum compression and maximum quality File file = new File(path); output = new FileImageOutputStream(file); writer.setOutput(output); IIOImage iioImage = new IIOImage(image, null, null); writer.write(null, iioImage, iwp); output.flush(); output.close(); writer.dispose(); Is it possible to access compressionQuality parameter of original jpeg image in the beginning. when I set 1 to compression quality, the image gets bigger size. Otherwise I set 0.9 or less the image gets smaller size. How can i proceed the image size after these operations? Thank you,

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  • Where to store global variables like file paths in java ?

    - by Jules Olléon
    In my application I use some icons. Where should I store the path of the directory containing those icons ? The icons are used in different classes so it doesn't really make sense to store them in one of those classes in particular. I read that global variables are evil, but is it acceptable to use a class (eg Commons) containing only public static final fields to store this king of data ? What solution is used in professional applications ?

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