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  • Primitive type 'short' - casting in Java

    - by gemm
    Hello, I have a question about the primitive type 'short' in Java. I am using JDK 1.6. If I have the following: short a = 2; short b = 3; short c = a + b; the compiler does not want to compile - it says that it "cannot convert from int to short" and suggests that I make a cast to short, so this: short c = (short) (a + b); really works. But my question is why do I need to cast? The values of a and b are in the range of short - the range of short values is {-32,768, 32767}. I also need to cast when I want to perform the operations -, *, / (I haven't checked for others). If I do the same for primitive type int, I do not need to cast aa+bb to int. The following works fine: int aa = 2; int bb = 3; int cc = aa +bb; I discovered this while designing a class where I needed to add two variables of type short, and the compiler wanted me to make a cast. If I do this with two variables of type int, I don't need to cast. Thank you very much in advance. A small remark: the same thing also happens with the primitive type byte. So, this workes: byte a = 2; byte b = 3; byte c = (byte) (a + b); but this not: byte a = 2; byte b = 3; byte c = a + b; For long, float, double, and int, there is no need to cast. Only for short and byte values.

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  • What is a good embeddable Java LDAP server?

    - by LeedsSideStreets
    I'm working on a Java web application that integrates with a few other external applications that are deployed along with it. Authentication information must be synchronized across everything and the other applications want to authenticate against LDAP. The application will be deployed in environments where there will be no other LDAP server for everything to use; I have to provide it. My solution so far has been to use Penrose Server as a standalone app, which I set up to examine tables in the main application's database and publish LDAP based on that. It works well, but it would be nice to have something that can be embedded into the main application itself to simplify deployment. It looks like Penrose can be embedded, but the documentation can be a bit spotty or out-of-date (though it seems to be actively developed). It could be an acceptable solution, but if there is another out there that is known to work well in an embedded configuration I might want to check it out. I'm also concerned about GPL issues with Penrose. I'm not at liberty to GPL the source code for the application. I don't believe it was an issue running it standalone, but embedding it may be no-no... anybody know for sure? A permissive license would be good in order to avoid these issues. Requirements: LDAP v3 Must be able to be have the directory contents updated while running, either programmatically or by another means like syncing with the database as Penrose does Easy to configure (no additional configuration for the app at deployment time would be ideal) So far I've briefly looked at ApacheDS and OpenDS which seem to be embeddable. Does anyone have experience with this kind of thing?

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  • Duration of Excessive GC Time in "java.lang.OutOfMemoryError: GC overhead limit exceeded"

    - by jilles de wit
    Occasionally, somewhere between once every 2 days to once every 2 weeks, my application crashes in a seemingly random location in the code with: java.lang.OutOfMemoryError: GC overhead limit exceeded. If I google this error I come to this SO question and that lead me to this piece of sun documentation which expains: The parallel collector will throw an OutOfMemoryError if too much time is being spent in garbage collection: if more than 98% of the total time is spent in garbage collection and less than 2% of the heap is recovered, an OutOfMemoryError will be thrown. This feature is designed to prevent applications from running for an extended period of time while making little or no progress because the heap is too small. If necessary, this feature can be disabled by adding the option -XX:-UseGCOverheadLimit to the command line. Which tells me that my application is apparently spending 98% of the total time in garbage collection to recover only 2% of the heap. But 98% of what time? 98% of the entire two weeks the application has been running? 98% of the last millisecond? I'm trying to determine a best approach to actually solving this issue rather than just using -XX:-UseGCOverheadLimit but I feel a need to better understand the issue I'm solving.

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  • Java synchronized seems ignored

    - by viraptor
    Hi, I've got the following code, which I expected to deadlock after printing out "Main: pre-sync". But it looks like synchronized doesn't do what I expect it to. What happens here? import java.util.*; public class deadtest { public static class waiter implements Runnable { Object obj; public waiter(Object obj) { this.obj = obj; } public void run() { System.err.println("Thead: pre-sync"); synchronized(obj) { System.err.println("Thead: pre-wait"); try { obj.wait(); } catch (Exception e) { } System.err.println("Thead: post-wait"); } System.err.println("Thead: post-sync"); } } public static void main(String args[]) { Object obj = new Object(); System.err.println("Main: pre-spawn"); Thread waiterThread = new Thread(new waiter(obj)); waiterThread.start(); try { Thread.sleep(1000); } catch (Exception e) { } System.err.println("Main: pre-sync"); synchronized(obj) { System.err.println("Main: pre-notify"); obj.notify(); System.err.println("Main: post-notify"); } System.err.println("Main: post-sync"); try { waiterThread.join(); } catch (Exception e) { } } } Since both threads synchronize on the created object, I expected the threads to actually block each other. Currently, the code happily notifies the other thread, joins and exits.

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  • ADT-like polymorphism in Java (without altering class)

    - by ffriend
    In Haskell I can define following data type: data Tree = Empty | Leaf Int | Node Tree Tree and then write polymorphic function like this: depth :: Tree -> Int depth Empty = 0 depth (Leaf n) = 1 depth (Node l r) = 1 + max (depth l) (depth r) In Java I can emulate algebraic data types with interfaces: interface Tree {} class Empty implements Tree {} class Leaf implements Tree { int n; } class Node implements Tree { Tree l; Tree r; } But if I try to use Haskell-like polymorphism, I get an error: int depth(Empty node) { return 0; } int depth(Leaf node) { return 1; } int depth(Node node) { return 1 + Math.max(depth(node.l), depth(node.r)); // ERROR: Cannot resolve method 'depth(Tree)' } Correct way to overcome this is to put method depth() to each class. But what if I don't want to put it there? For example, method depth() may be not directly related to Tree and adding it to class would break business logic. Or, even worse, Tree may be written in 3rd party library that I don't have access to. In this case, what is the simplest way to implement ADT-like polymorpism? Just in case, for the moment I'm using following syntax, which is obviously ill-favored: int depth(Tree tree) { if (tree instanceof Empty) depth((Empty)tree) if (tree instanceof Leaf) depth((Leaf)tree); if (tree instanceof Node) depth((Node)tree); else throw new RuntimeException("Don't know how to find depth of " + tree.getClass()); }

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  • java.lang.IllegalStateException: missing behavior definition for the preceding method call getMessag

    - by user362199
    Hi All, I'm using EasyMock(version 2.4) and TestNG for writing UnitTest. I have a following scenario and I cannot change the way class hierarchy is defined. I'm testing ClassB which is extending ClassA. ClassB look like this public class ClassB extends ClassA { public ClassB() { super("title"); } @Override public String getDisplayName() { return ClientMessages.getMessages("ClassB.title"); } } ClassA code public abstract class ClassA { private String title; public ClassA(String title) { this.title = ClientMessages.getMessages(title); } public String getDisplayName() { return this.title; } } ClientMessages class code public class ClientMessages { private static MessageResourse messageResourse; public ClientMessages(MessageResourse messageResourse) { this.messageResourse = messageResourse; } public static String getMessages(String code) { return messageResourse.getMessage(code); } } MessageResourse Class code public class MessageResourse { public String getMessage(String code) { return code; } } Testing ClassB import static org.easymock.classextension.EasyMock.createMock; import org.easymock.classextension.EasyMock; import org.testng.Assert; import org.testng.annotations.Test; public class ClassBTest { private MessageResourse mockMessageResourse = createMock(MessageResourse.class); private ClassB classToTest; private ClientMessages clientMessages; @Test public void testGetDisplayName() { EasyMock.expect(mockMessageResourse.getMessage("ClassB.title")).andReturn("someTitle"); clientMessages = new ClientMessages(mockMessageResourse); classToTest = new ClassB(); Assert.assertEquals("someTitle" , classToTest.getDisplayName()); EasyMock.replay(mockMessageResourse); } } When I'm running this this test I'm getting following exception: java.lang.IllegalStateException: missing behavior definition for the preceding method call getMessage("title") While debugging what I found is, it's not considering the mock method call mockMessageResourse.getMessage("ClassB.title") as it has been called from the construtor (ClassB object creation). Can any one please help me how to test in this case. Thanks.

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  • How to create Fibonacci Sequence in Java

    - by rfkrocktk
    I really suck at math. I mean, I REALLY suck at math. I'm trying to make a simple fibonacci sequence class for an algorithm I'll be using. I have seen the python example which looks something like this: a = 0 b = 1 while b < 10: print b a, b = b, b+a The problem is that I can't really make this work in any other language. I'd like to make it work in Java, since I can pretty much translate it into the other languages I use from there. This is the general thought: public class FibonacciAlgorithm { private Integer a = 0; private Integer b = 1; public FibonacciAlgorithm() { } public Integer increment() { a = b; b = a + b; return value; } public Integer getValue() { return b; } } All that I end up with is doubling, which I could do with multiplication :( Can anyone help me out? Math pwns me.

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  • Format Java Code in Netbeans / Eclipse, but save it differently

    - by Walter White
    Hi all, I asked a related question before, but I guess the root of the question is. Let's say I have 2 developers on the team and they both like to look at code in different formats. One likes the braces to be on a new line and the other doesn't. The approach I was using before is that anytime we run a build, the code is automatically formatted according to the Java/Sun standards using Jalopy; however, I would like the developers to be as happy as possible. They can change the font size, font color, background color, etc. If I am currently using the Jalopy Maven plugin to format code, can/should I write a hook to SVN that calls mvn jalopy:format on the project when it's checked in? Is this reliable? That solution doesn't work 100% because it requires the developer to manually format the source code to their liking every time they open a file that hasn't been formatted yet. I was thinking an IDE plugin would be nice as it could automatically format the source to their liking and then save it as another. What other options do I have to ensure the code is formatted nicely on checkin? Thanks, Walter

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  • Twitter4J throws exception in TwitterFactory

    - by Philipp Andre
    Hello Guys, i'm trying to access twitter via oauth. Therefore, i registered my app, downloaded Twitter4j, added the jars in my Eclipse-Project, and then tried to execute the following code: Twitter twitter = new TwitterFactory().getOAuthAuthorizedInstance("[key]","[secretKey]); RequestToken requestToken = twitter.getOAuthRequestToken(); System.out.println(requestToken.getAuthorizationURL()); But it raises the following exception: [Sat May 29 11:19:11 CEST 2010]Using class twitter4j.internal.logging.StdOutLoggerFactory as logging factory. [Sat May 29 11:19:11 CEST 2010]Use twitter4j.internal.http.alternative.HttpClientImpl as HttpClient implementation. Exception in thread "main" java.lang.AssertionError: java.lang.reflect.InvocationTargetException at twitter4j.internal.http.HttpClientFactory.getInstance(HttpClientFactory.java:71) at twitter4j.internal.http.HttpClientWrapper.<init>(HttpClientWrapper.java:59) at twitter4j.http.OAuthAuthorization.init(OAuthAuthorization.java:83) at twitter4j.http.OAuthAuthorization.<init>(OAuthAuthorization.java:74) at twitter4j.TwitterFactory.getOAuthAuthorizedInstance(TwitterFactory.java:112) at MainProgram.main(MainProgram.java:18) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at twitter4j.internal.http.HttpClientFactory.getInstance(HttpClientFactory.java:65) ... 5 more Caused by: java.lang.NoClassDefFoundError: org/apache/http/impl/client/DefaultHttpClient at twitter4j.internal.http.alternative.HttpClientImpl.<init>(HttpClientImpl.java:63) ... 10 more I currently can't figure out why ... can you please give me some suggestions? Best regards Philipp

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  • Unit Testing a Java Chat Application

    - by Epitaph
    I have developed a basic Chat application in Java. It consists of a server and multiple client. The server continually monitors for incoming messages and broadcasts them to all the clients. The client is made up of a Swing GUI with a text area (for messages sent by the server and other clients), a text field (to send Text messages) and a button (SEND). The client also continually monitors for incoming messages from other clients (via the Server). This is achieved with Threads and Event Listeners and the application works as expected. But, how do I go about unit testing my chat application? As the methods involve establishing a connection with the server and sending/receiving messages from the server, I am not sure if these methods should be unit tested. As per my understanding, Unit Testing shouldn't be done for tasks like connecting to a database or network. The few test cases that I could come up with are: 1) The max limit of the text field 2) Client can connect to the Server 3) Server can connect to the Client 4) Client can send message 5) Client can receive message 6) Server can send message 7) Server can receive message 8) Server can accept connections from multiple clients But, since most of the above methods involve some kind of network communication, I cannot perform unit testing. How should I go about unit testing my chat application?

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  • Java Swing MVC question

    - by juFo
    I'm following this MVC model: http://java.sun.com/developer/technicalArticles/javase/mvc/ In my model I have an "ArrayList shapes" field and I need the shapes in my view. Is the only way of getting my shapes by getting them in the modelPropertyChange method? public void modelPropertyChange(PropertyChangeEvent evt) { if (evt.getPropertyName().equals(MyController.PROPERTY_TEXT)) { ArrayList<Shape> shapes = (ArrayList<Shape>) evt.getNewValue(); } } or should I also create a generic getter method in my controller? like this generic setter method: protected void setModelProperty(String propertyName, Object newValue) { for (AbstractModel model: registeredModels) { try { Method method = model.getClass(). getMethod("set"+propertyName, new Class[] { newValue.getClass() } ); method.invoke(model, newValue); } catch (Exception ex) { // Handle exception. } } } If I need such a generic getter method, I have no clue how to transform this generic setter above to a generic getter method. If I don't need such a generic getter method to retreive my data from the model, if I only need the modelPropertyChange method from my View. How would I get my data from the model the first time the application starts? :o Pfft I need to get my arraylist of shapes from my model in my view :( (and later I need to get some other data also) So confusing :(

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  • FIlling a Java Bean tree structure from a csv flat file

    - by Clem
    Hi, I'm currently trying to construct a list of bean classes in Java from a flat description file formatted in csv. Concretely : Here is the structure of the csv file : MES_ID;GRP_PARENT_ID;GRP_ID;ATTR_ID M1 ; ;G1 ;A1 M1 ; ;G1 ;A2 M1 ;G1 ;G2 ;A3 M1 ;G1 ;G2 ;A4 M1 ;G2 ;G3 ;A5 M1 ; ;G4 ;A6 M1 ; ;G4 ;A7 M1 ; ;G4 ;A8 M2 ; ;G1 ;A1 M2 ; ;G1 ;A2 M2 ; ;G2 ;A3 M2 ; ;G2 ;A4 It corresponds to the hierarchical data structure : M1 ---G1 ------A1 ------A2 ------G2 ---------A3 ---------A4 ---------G3 ------------A5 ------G4 ---------A7 ---------A8 M2 ---G1 ------A1 ------A2 ---G2 ------A3 ------A4 Remarks : A message M can have an infinite number of groups G and attributes A A group G can have an infinite number of attributes and an infinite number of under-groups each of them having under-groups too That beeing said, I'm trying to read this flat csv decription to store it in this structure of beans : Map<String, MBean> messages = new HashMap<String, Mbean>(); == public class MBean { private String mes_id; private Map<String, GBean> groups; } public class GBean { private String grp_id; private Map<String, ABean> attributes; private Map<String, GBean> underGroups; } public class ABean { private String attr_id; } Reading the csv file sequentially is ok and I've been investigating how to use recursion to store the description data, but couldn't find a way. Thanks in advance for any of your algorithmic ideas. I hope it will put you in the mood of thinking about this ... I've to admit that I'm out of ideas :s

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  • Using Java PDFBox library to write Russian PDF

    - by Brad
    Hello , I am using a Java library called PDFBox trying to write text to a PDF. It works perfect for English text, but when i tried to write Russian text inside the PDF the letters appeared so strange. It seems the problem is in the font used, but i am not so sure about that, so i hope if anyone could guide me through this. Here is the important code lines : PDTrueTypeFont font = PDTrueTypeFont.loadTTF( pdfFile, new File( "fonts/VREMACCI.TTF" ) ); // Windows Russian font imported to write the Russian text. font.setEncoding( new WinAnsiEncoding() ); // Define the Encoding used in writing. // Some code here to open the PDF & define a new page. contentStream.drawString( "??????? ????????????" ); // Write the Russian text. The WinAnsiEncoding source code is : Click here --------------------- Edit on 18 November 2009 After some investigation, i am now sure it is an Encoding problem, this could be solved by defining my own Encoding using the helpful PDFBox class called DictionaryEncoding. I am not sure how to use it, but here is what i have tried until now : COSDictionary cosDic = new COSDictionary(); cosDic.setString( COSName.getPDFName("Ercyrillic"), "0420 " ); // Russian letter. font.setEncoding( new DictionaryEncoding( cosDic ) ); This does not work, as it seems i am filling the dictionary in a wrong way, when i write a PDF page using this it appears blank. The DictionaryEncoding source code is : Click here Thanks . . .

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  • AES Encryption Java Invalid Key length

    - by wuntee
    I am trying to create an AES encryption method, but for some reason I keep getting a 'java.security.InvalidKeyException: Key length not 128/192/256 bits'. Here is the code: public static SecretKey getSecretKey(char[] password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException{ SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWithMD5AndDES"); // NOTE: last argument is the key length, and it is 256 KeySpec spec = new PBEKeySpec(password, salt, 1024, 256); SecretKey tmp = factory.generateSecret(spec); SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES"); return(secret); } public static byte[] encrypt(char[] password, byte[] salt, String text) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException{ SecretKey secret = getSecretKey(password, salt); Cipher cipher = Cipher.getInstance("AES"); // NOTE: This is where the Exception is being thrown cipher.init(Cipher.ENCRYPT_MODE, secret); byte[] ciphertext = cipher.doFinal(text.getBytes("UTF-8")); return(ciphertext); } Can anyone see what I am doing wrong? I am thinking it may have something to do with the SecretKeyFactory algorithm, but that is the only one I can find that is supported on the end system I am developing against. Any help would be appreciated. Thanks.

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  • Java Nimbus LAF with transparent text fields

    - by Software Monkey
    I have an application that uses disabled JTextFields in several places which are intended to be transparent - allowing the background to show through instead of the text field's normal background. When running the new Nimbus LAF these fields are opaque (despite setting setOpaque(false)), and my UI is broken. It's as if the LAF is ignoring the opaque property. Setting a background color explicitly is both difficult in several places, and less than optimal due to background images actually doesn't work - it still paints it's LAF default background over the top, leaving a border-like appearance (the splash screen below has the background explicitly set to match the image). Any ideas on how I can get Nimbus to not paint the background for a JTextField? Note: I need a JTextField, rather than a JLabel, because I need the thread-safe setText(), and wrapping capability. Note: My fallback position is to continue using the system LAF, but Nimbus does look substantially better. See example images below. Conclusions The surprise at this behavior is due to a misinterpretation of what setOpaque() is meant to do - from the Nimbus bug report: This is a problem the the orginal design of Swing and how it has been confusing for years. The issue is setOpaque(false) has had a side effect in exiting LAFs which is that of hiding the background which is not really what it is ment for. It is ment to say that the component my have transparent parts and swing should paint the parent component behind it. It's unfortunate that the Nimbus components also appear not to honor setBackground(null) which would otherwise be the recommended way to stop the background painting. Setting a fully transparent background seems unintuitive to me. In my opinion, setOpaque()/isOpaque() is a faulty public API choice which should have been only: public boolean isFullyOpaque(); I say this, because isOpaque()==true is a contract with Swing that the component subclass will take responsibility for painting it's entire background - which means the parent can skip painting that region if it wants (which is an important performance enhancement). Something external cannot directly change this contract (legitimately), whose fulfillment may be coded into the component. So the opacity of the component should not have been settable using setOpaque(). Instead something like setBackground(null) should cause many components to "no long have a background" and therefore become not fully opaque. By way of example, in an ideal world most components should have an isOpaque() that looks like this: public boolean isOpaque() { return (background!=null); }

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  • Simulating pass by reference for an array in Java

    - by Leif Andersen
    I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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  • Infinite loop in regex in java

    - by carpediem
    Hello, My purpose is to match this kind of different urls: url.com my.url.com my.extended.url.com a.super.extended.url.com and so on... So, I decided to build the regex to have a letter or a number at start and end of the url, and to have a infinite number of "subdomains" with alphanumeric characters and a dot. For example, in "my.extended.url.com", "m" from "my" is the first class of the regex, "m" from "com" is the last class of the regex, and "y.", "extended." and "url." are the second class of the regex. Using the pattern and subject in the code below, I want the find method to return me a false because this url must not match, but it uses 100% of CPU and seems to stay in an infinite loop. String subject = "www.association-belgo-palestinienne-be"; Pattern pattern = Pattern.compile("^[A-Za-z0-9]\\.?([A-Za-z0-9_-]+\\.?)*[A-Za-z0-9]\\.[A-Za-z]{2,6}"); Matcher m = pattern.matcher(subject); System.out.println(" Start"); boolean hasFind = m.find(); System.out.println(" Finish : " + hasFind); Which only prints: Start I can't reproduce the problem using regex testers. Is it normal ? Is the problem coming from my regex ? Could it be due to my Java version (1.6.0_22-b04 / JVM 64 bit 17.1-b03) ? Thanks in advance for helping.

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  • java.io.IOException: Premature EOF

    - by jouzef19
    Hi: I am trying to download an xml file using Stream and things was fine , until the xml size became bigger than 9 MB , so i've got this error java.io.IOException: Premature EOF this is the code BufferedInputStream bfi = null; try { bfi = new BufferedInputStream(new URL("The URL").openStream()); String name = "name.xml"; FileOutputStream fb = new FileOutputStream(name); BufferedOutputStream bout = new BufferedOutputStream(fb, 1024); byte[] data = new byte[1024]; int x = 0; while ((x = bfi.read(data, 0, 1024)) >= 0) { bout.write(data, 0, x); } this.deletePhishTankDatabase(this.recreateFileName()); ptda.insertDownloadTime(hour, day, month, year); bout.close(); bfi.close(); } catch (IOException ex) { Logger.getLogger(PhishTankDataBase.class.getName()).log(Level.SEVERE, null, ex); } finally { try { bfi.close(); } catch (IOException ex) { Logger.getLogger(PhishTankDataBase.class.getName()).log(Level.SEVERE, null, ex); } } } else { System.out.println("You can't do anything"); return; } thanks in advanced

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  • Java Playing Cards Game Framework

    - by isme
    My friends and I at uni love playing Shithead into the wee hours. But soon we graduate and will leave town, so probably won't get together for a game for a while. I want to develop a Java app we can use to play Shithead and our other favorites over a network. An app like this already exists, but is ugly, buggy and does not support our house rules. The source is available, but is such a mess that I would really rather start from scratch than try to refactor it! Building my game using some standard playing card api or framework, if such a thing exists, would be better than starting from scratch. The answer to a similar SO question was to use the JPC-API, which allegedly provides basic playing card services and rendering. But this Sourceforge project currently makes available no files or source code! Is there an alternative, or somewhere else to find this framework? Soon I will need help with the following as well: Lobby services (finding other players) Gaming network protocol (to communicate moves between players) Gaming theory (to write the computer opponent) Winning condition detection Game UI development

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  • Custom Java ListCellRenderer - Can't click JCheckBox

    - by Spencer
    Made a custom ListCellRenderer: import java.awt.Component; import javax.swing.JCheckBox; import javax.swing.JLabel; import javax.swing.JList; import javax.swing.JPanel; import javax.swing.ListCellRenderer; /** * * @author Spencer */ public class TaskRenderer implements ListCellRenderer { private Task task; private JPanel panel = new JPanel(); private JCheckBox checkbox = new JCheckBox(); private JLabel label = new JLabel(); public TaskRenderer() { panel.add(checkbox); panel.add(label); } public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) { task = (Task) value; label.setText(task.getName()); return panel; } } Have a JList with each cell in it rendered using the above class, but the checkboxes in the panels for each cell cannot be clicked. Thought it had to do with it not getting focus. Any ideas? Thanks, Spencer

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  • Open Source CMS (.Net vs Java)

    - by CmsAndDotNetKindaGuy
    I must say up-front that this is not a strictly programming-related question and a very opinionated one. I am the lead developer of the dominant .Net CMS in my country and I don't like my own product :). Managerial decisions over what is important or not and large chunks of legacy code done before I joined gives me headache every day I go for work. Anyway, having a vast amount of experience in web industry and a very good grasp of C# and programming practices I'm designing my own CMS the past few months. Now the problem is that I'm an open source kinda guy so I have a dilemma. Should I use C# and .Net which has crippled multi-platform support or should I drop .Net entirely and start learning Java where I can create a truly open-source and cross-platform CMS? Please don't answer that I should contribute to an existing open source CMS. I ruled that out after spending a great deal of time searching for something similar in structure to what I have in mind. I am not a native speaker, so feel free to correct my syntax or rephrase my question.

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  • LPX-00607 for ora:contains in java but not sqlplus

    - by Windle
    Hey all, I am trying to doing some sql querys out of Oracle 11g and am having issues using ora:contains. I am using spring's jdbc impl and my code generates the sql statement: select * from view_name where column_a = ? and column_b = ? and existsNode(xmltype(clob_column), 'record/name [ora:contains(text(), "name1") 0]', 'xmlns:ora="http://xmlns.oralce.com/xdb"') = 1 I have removed the actual view / column names obviously, but when I copy that into sqlplus and substitute in random values, the select executes properly. When I try to run it in my DAO code I get this stack trace: org.springframework.jdbc.UncatergorizedSQLException: PreparedStatementCallback; uncatergorizedSQLException for SQL [the big select above]; SQL state [99999]; error code [31011]; ORA-31011: XML parsing failed. ORA-19202: Error occured in XML processing LPX-00607: Invalid reference: 'contains' ;nested exception is java.sql.SQLException: ORA-31011: XML parsing failed ORA-19202: Error occured in XML processing LPX-00607: Invalid reference: 'contains' (continues on like this for awhile....) I think it is worth mentioning that I am using maven and it is possible I am missing some dependency that is required for this. Sorry the post is so long, but I wanted to err on the side of too much info. Thanks for taking the time to read this at least =) -Windle

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  • NoSuchMethodError in Java using XStream

    - by Brad Germain
    I'm trying to save a database into a file using XStream and then open it again later using XStream and deserialize it back into the objects it was in previously. The database consists of an arraylist of tables, which consists of an arraylist of a data class where the data class contains an arraylist of objects. I'm basically trying to create an sql compiler. I'm currently getting a java.lang.NoSuchMethodError because of the last line in the load method. Here's what I have: Save Method public void save(Database DB){ File file = new File(DB.getName().toUpperCase() + ".xml"); //Test sample DB.createTable("TBL1(character(a));"); DB.tables.getTable("TBL1").rows.add(new DataList()); DB.tables.getTable("TBL1").rows.getRow(0).add(10); XStream xstream = new XStream(); //Database xstream.alias("Database", Database.class); //Tables xstream.alias("Table", Table.class); //Rows xstream.alias("Row", DataList.class); //Data //xstream.alias("Data", Object.class); //String xml = xstream.toXML(DB); Writer writer = null; try { writer = new FileWriter(file); writer.write(xstream.toXML(DB)); writer.close(); } catch (IOException e) { e.printStackTrace(); } } Load Method public void Load(String dbName){ XStream xstream = new XStream(); BufferedReader br; StringBuffer buff = null; try { br = new BufferedReader(new FileReader(dbName + ".xml")); buff = new StringBuffer(); String line; while((line = br.readLine()) != null){ buff.append(line); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } database = (Database)xstream.fromXML(buff.toString()); }

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  • In Java, send commands to another command-line program

    - by bradvido
    I am using Java on Windows XP and want to be able to send commands to another program such as telnet. I do not want to simply execute another program. I want to execute it, and then send it a sequence of commands once it's running. Here's my code of what I want to do, but it does not work: (If you uncomment and change the command to "cmd" it works as expected. Please help.) try { Runtime rt = Runtime.getRuntime(); String command = "telnet"; //command = "cmd"; Process pr = rt.exec(command); BufferedReader processOutput = new BufferedReader(new InputStreamReader(pr.getInputStream())); BufferedWriter processInput = new BufferedWriter(new OutputStreamWriter(pr.getOutputStream())); String commandToSend = "open localhost\n"; //commandToSend = "dir\n" + "exit\n"; processInput.write(commandToSend); processInput.flush(); int lineCounter = 0; while(true) { String line = processOutput.readLine(); if(line == null) break; System.out.println(++lineCounter + ": " + line); } processInput.close(); processOutput.close(); pr.waitFor(); } catch(Exception x) { x.printStackTrace(); }

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  • Synchronization of Nested Data Structures between Threads in Java

    - by Dominik
    I have a cache implementation like this: class X { private final Map<String, ConcurrentMap<String, String>> structure = new HashMap...(); public String getValue(String context, String id) { // just assume for this example that there will be always an innner map final ConcurrentMap<String, String> innerStructure = structure.get(context); String value = innerStructure.get(id); if(value == null) { synchronized(structure) { // can I be sure, that this inner map will represent the last updated // state from any thread? value = innerStructure.get(id); if(value == null) { value = getValueFromSomeSlowSource(id); innerStructure.put(id, value); } } } return value; } } Is this implementation thread-safe? Can I be sure to get the last updated state from any thread inside the synchronized block? Would this behaviour change if I use a java.util.concurrent.ReentrantLock instead of a synchronized block, like this: ... if(lock.tryLock(3, SECONDS)) { try { value = innerStructure.get(id); if(value == null) { value = getValueFromSomeSlowSource(id); innerStructure.put(id, value); } } finally { lock.unlock(); } } ... I know that final instance members are synchronized between threads, but is this also true for the objects held by these members? Maybe this is a dumb question, but I don't know how to test it to be sure, that it works on every OS and every architecture.

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