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  • What are the pros and cons of using an in memeory DB rather than a ThreadLocal

    - by Pangea
    we have been using ThreadLocal so far to carry some data so as to not clutter the API. However below are some of issues of using thread local that which I dont like 1) over the years the data items being carried in thread local has increased 2) Since we started using threads (for some light weight processing), we have also migrating these data to the threads in the pool and copying them back again I am thinking of using an in memory DB for these (we doesnt want to add this to the API). I wondering if this approach is good. What r the pros and cons. thx in advance.

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  • Is an "infinite" iterator bad design?

    - by Adamski
    Is it generally considered bad practice to provide Iterator implementations that are "infinite"; i.e. where calls to hasNext() always(*) return true? Typically I'd say "yes" because the calling code could behave erratically, but in the below implementation hasNext() will return true unless the caller removes all elements from the List that the iterator was initialised with; i.e. there is a termination condition. Do you think this is a legitimate use of Iterator? It doesn't seem to violate the contract although I suppose one could argue it's unintuitive. public class CyclicIterator<T> implements Iterator<T> { private final List<T> l; private Iterator it; public CyclicIterator<T>(List<T> l) { this.l = l; this.it = l.iterator(); } public boolean hasNext() { return !l.isEmpty(); } public T next() { T ret; if (!hasNext()) { throw new NoSuchElementException(); } else if (it.hasNext()) { ret = it.next(); } else { it = l.iterator(); ret = it.next(); } return ret; } public void remove() { it.remove(); } }

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  • how can I convert String to SecretKey

    - by Alaa
    I want to convert String to secretKey public void generateCode(String keyStr){ KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128); // 192 and 256 bits may not be available // Generate the secret key specs. secretKey skey=keyStr; //How can I make the casting here //SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); } I try to use BASE64Decoder instead of secretKey, but I face a porblem which is I cannot specify key length. EDIT: I want to call this function from another place static public String encrypt(String message , String key , int keyLength) throws Exception { // Get the KeyGenerator KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(keyLength); // 192 and 256 bits may not be available // Generate the secret key specs. //decode the BASE64 coded message SecretKey skey = key; //here is the error raw = skey.getEncoded(); SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); // Instantiate the cipher Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); System.out.println("msg is" + message + "\n raw is" + raw); byte[] encrypted = cipher.doFinal(message.getBytes()); String cryptedValue = new String(encrypted); System.out.println("encrypted string: " + cryptedValue); return cryptedValue; } Any one can help, i'll be very thankful.

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  • Learning Hibernate: too many connections

    - by stivlo
    I'm trying to learn Hibernate and I wrote the simplest Person Entity and I was trying to insert 2000 of them. I know I'm using deprecated methods, I will try to figure out what are the new ones later. First, here is the class Person: @Entity public class Person { private int id; private String name; @Id @GeneratedValue(strategy = GenerationType.TABLE, generator = "person") @TableGenerator(name = "person", table = "sequences", allocationSize = 1) public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } Then I wrote a small App class that insert 2000 entities with a loop: public class App { private static AnnotationConfiguration config; public static void insertPerson() { SessionFactory factory = config.buildSessionFactory(); Session session = factory.getCurrentSession(); session.beginTransaction(); Person aPerson = new Person(); aPerson.setName("John"); session.save(aPerson); session.getTransaction().commit(); } public static void main(String[] args) { config = new AnnotationConfiguration(); config.addAnnotatedClass(Person.class); config.configure("hibernate.cfg.xml"); //is the default already new SchemaExport(config).create(true, true); //print and execute for (int i = 0; i < 2000; i++) { insertPerson(); } } } What I get after a while is: Exception in thread "main" org.hibernate.exception.JDBCConnectionException: Cannot open connection Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections Now I know that probably if I put the transaction outside the loop it would work, but mine was a test to see what happens when executing multiple transactions. And since there is only one open at each time, it should work. I tried to add session.close() after the commit, but I got Exception in thread "main" org.hibernate.SessionException: Session was already closed So how to solve the problem?

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  • How I can get logged in user's info like email id,name,city etc. in Facebook with uId

    - by vaibhavbhalke
    Hi all Can any one help me to get logged in user's info like email id,name,city etc. with the help of Facebook uId . " Long uid = apiClient.getLoggedInUser ();" Users_getInfo is not useful. It returns No of users connected to _User & according that there info gets. If user login successfully using fb connect, Facebook gives us uid. However, I need to match the logged in user with our member's account If that member is not present in DB then want to register him and I'm trying to do that with e-mail(hashed) address and other info.

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  • Try all available WSDL IPs with JAX-WS

    - by Asaf
    I'm using JAX-WS to open a service port. When the DNS exposes two IPs for the DNS entry (of the WSDL), the Service tries to use only the first - resulting in a "Failed to access the WSDL at: http://some.url.com/someDocument?wsdl. It failed with: Connection refused: connect" exception. I've found an issue filed against JAX-WS, but with no resolution. this is the comment that describes my problem best. The code is just a one-liner: Service service = Service.create("http://some.url.com/someDocument?wsdl", engineQName); the smarts is exposing those two A records on http://some.url.com/ at the DNS. Can anyone help? 10x,

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  • Hibernate Mapping Annotation Question?

    - by paddydub
    I've just started using hibernate and I'm trying to map walking distance between two coordinates into a hashmap, There can be many connections from one "FromCoordinate" to another "ToCoordinate". I'm not sure if i've implemented this correctly, What annotations do i need to map this MashMap? Thanks @Entity @Table(name = "COORDCONNECTIONS") public class CoordinateConnection implements Serializable{ private static final long serialVersionUID = -1624745319005591573L; /** auto increasing id number */ @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ID") @id private int id; @Embedded public FromCoordinate fromCoord; @Embedded public ToCoordinate toCoord; HashMap<Coordinate, ArrayList<Coordinate>> coordWalkingConnections = new HashMap<Coordinate, ArrayList<Coordinate>>(); } public class FromCoordinate implements ICoordinate { @Column(name = "FROM_LAT") private double latitude; @Column(name = "FROM_LNG") private double longitude; } public class ToCoordinate implements ICoordinate { @Column(name = "TO_LAT") private double latitude; @Column(name = "TO_LNG") private double longitude; @Column(name = "DISTANCE") private double distance; } DATABASE STRUCTURE id FROM_LAT FROM_LNG TO_LAT TO_LNG Dist 1 43.352669 -6.264341 43.350012 -6.260653 0.38 2 43.352669 -6.264341 43.352669 -6.264341 0.00 3 46.352669 -6.264341 43.353373 -6.262013 0.17 4 47.352465 -6.265865 43.351290 -6.261200 0.25 5 45.452578 -6.265768 43.352788 -6.264396 0.01 6 45.452578 -6.265768 45.782788 -6.234523 0.01 ..... ... . Example HashMap for HashMap<Coordinate, ArrayList<Coordinate>> <KEY{43.352669 -6.264341}, Arraylist VALUES{(43.350012,-6.260653,0.383657), (43.352669, -6.264341, 0.000095), (43.353373, -6.262013, 0.173201)}> <KEY{47.352465 -6.265865}, Arraylist VALUES{(43.351290,-6.261200,0.258781)}> <KEY{45.452578 -6.265768}, Arraylist VALUES{(43.352788,-6.264396,0.013726),(45.782788,-6.234523,0.017726)}>

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  • JAXB does not call setter when unmarshalling objects

    - by Yaneeve
    Hi all, I am using JAXB 2.0 JDK 6 in order to unmarshall an XML instance into POJOs. In order to add some custom validation I have inserted a validation call into the setter of a property, yet despite it being private, it seems that the unmarshaller does not call the setter but directly modifies the private field. It is crucial to me that the custom validation occurs for this specific field every unmarshall call. What should I do? Code: @XmlAccessorType(XmlAccessType.FIELD) @XmlType(name = "LegalParams", propOrder = { "value" }) public class LegalParams { private static final Logger LOG = Logger.getLogger(LegalParams.class); @XmlTransient private LegalParamsValidator legalParamValidator; public LegalParams() { try { WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext(); LegalParamsFactory legalParamsFactory = (LegalParamsFactory) webApplicationContext.getBean("legalParamsFactory"); HttpSession httpSession = SessionHolder.getInstance().get(); legalParamValidator = legalParamsFactory.newLegalParamsValidator(httpSession); } catch (LegalParamsException lpe) { LOG.warn("Validator related error occurred while attempting to construct a new instance of LegalParams"); throw new IllegalStateException("LegalParams creation failure", lpe); } catch (Exception e) { LOG.warn("Spring related error occurred while attempting to construct a new instance of LegalParams"); throw new IllegalStateException("LegalParams creation failure", e); } } @XmlValue private String value; /** * Gets the value of the value property. * * @return * possible object is * {@link String } * */ public String getValue() { return value; } /** * Sets the value of the value property. * * @param value * allowed object is * {@link String } * @throws TestCaseValidationException * */ public void setValue(String value) throws TestCaseValidationException { legalParamValidator.assertValid(value); this.value = value; } }

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  • Background settings for a JDesktopPane

    - by EricR
    I'm using a self-made DesktopPaneUI for a JDesktopPane, I've written the proper methods for the class, and I'm running into trouble. When I resize the JDesktopPane, the background image doesn't resize with the frame. The image appears to be clipped at the size it was when the window initially opened. I'm giving it an image larger than the window, and I'm still having this problem. Here's my method call inside the constructor of my desktopUI class. super(); this.background = javax.imageio.ImageIO.read(new File(fileName)); Is there a way I can change my main class where I set the UI, or the myDesktopPaneUI class such that the background still fills the window when the JDesktopPane changes size? setUI(new myDesktopPaneUI("media/bg.jpg"));

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  • How mature is apache sshd (MINA)?

    - by Yaneeve
    Has anyone ever used apache sshd (based on Apache MINA)? I would like to get some user input. Is it mature? Does it have (annoying) bugs? How is the API? Can useful documentation/tutorials be found? etc. Thanks all for your feedback.

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  • Swing - how to mix JTextField and JTextAreas and have same visual appearance?

    - by I82Much
    I am using miglayout to create a form in which there are JTextFields (short input answers) as well as JTextAreas (Longer answers). The problem is twofold. The border placed around a Scrollpane wrapped text area does not match that of a Text Field. The width and placement of the textarea/textfield differ, causing them not to line up correctly. Source code: package test2; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.JTextField; import net.miginfocom.swing.MigLayout; public class Test extends JPanel { private static final int NUM_CHARACTERS_WIDTH = 20; private static final int NUM_ROWS = 5; public Test() { setLayout(new MigLayout( "wrap 2", // Align text labels on the so their right edge meets left edge of the text fields "[right][left]" )); add(new JLabel("Text field:")); add(new JTextField(NUM_CHARACTERS_WIDTH)); add(new JLabel("No scrollpane text area:")); add(new JTextArea(NUM_ROWS, NUM_CHARACTERS_WIDTH)); add(new JLabel("Scrollpane text area:")); add(new JScrollPane(new JTextArea(NUM_ROWS, NUM_CHARACTERS_WIDTH))); add(new JLabel("Text field:")); add(new JTextField(NUM_CHARACTERS_WIDTH)); } public static void main(String[] args) { JFrame frame = new JFrame(""); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new Test(); frame.add(panel); frame.pack(); frame.setVisible(true); } } What's the preferred way to mix and match jtextfield and jtextareas, while still maintaining visual harmony? I notice now that the text field has a blue highlight around it when focus is in it, as opposed to the text area... another source of visual discontinuity.

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  • why i can't start orbd service CORBA IIOP?

    - by user326801
    why i can't start orbd service CORBA IIOP? C:start orbd -ORBInitialPort 1050 C:orbd -ORBInitialPort 1050 Failed to start ORBD because of an Internal Exception. Possible Causes: 1. Specified ORBInitialPort or ORBActivationPort is already in use 2. No Write Permission to write orb.db C:

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  • Acquiring Table Lock in Database - Interview Question

    - by harigm
    One of my interview Questions, if multiple users across the world are accessing the application, in which it uses a Table which has a Primary Key as Auto Increment Field. The Question how can you prevent the other user getting the Same Primary key when the other user is executing? My answer was I will obtain the Lock on the table and I will make the user to wait Until that user is released with the Primary key. But the Question How do you acquire the Table lock programmatically and implement this? If there are 1000 users coming every minute to the application, if you explicity hold the lock on the table, then the application will become slower? How do you manage this? Please suggest the possible answers for the above question

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  • file.createNewFile() creates files with last-modified time before actual creation time

    - by Kaleb Pederson
    I'm using JPoller to detect changes to files in a specific directory, but it's missing files because they end up with a timestamp earlier than their actual creation time. Here's how I test: public static void main(String [] files) { for (String file : files) { File f = new File(file); if (f.exists()) { System.err.println(file + " exists"); continue; } try { // find out the current time, I would hope to assume that the last-modified // time on the file will definitely be later than this System.out.println("-----------------------------------------"); long time = System.currentTimeMillis(); // create the file System.out.println("Creating " + file + " at " + time); f.createNewFile(); // let's see what the timestamp actually is (I've only seen it <time) System.out.println(file + " was last modified at: " + f.lastModified()); // well, ok, what if I explicitly set it to time? f.setLastModified(time); System.out.println("Updated modified time on " + file + " to " + time + " with actual " + f.lastModified()); } catch (IOException e) { System.err.println("Unable to create file"); } } } And here's what I get for output: ----------------------------------------- Creating test.7 at 1272324597956 test.7 was last modified at: 1272324597000 Updated modified time on test.7 to 1272324597956 with actual 1272324597000 ----------------------------------------- Creating test.8 at 1272324597957 test.8 was last modified at: 1272324597000 Updated modified time on test.8 to 1272324597957 with actual 1272324597000 ----------------------------------------- Creating test.9 at 1272324597957 test.9 was last modified at: 1272324597000 Updated modified time on test.9 to 1272324597957 with actual 1272324597000 The result is a race condition: JPoller records time of last check as xyz...123 File created at xyz...456 File last-modified timestamp actually reads xyz...000 JPoller looks for new/updated files with timestamp greater than xyz...123 JPoller ignores newly added file because xyz...000 is less than xyz...123 I pull my hair out for a while I tried digging into the code but both lastModified() and createNewFile() eventually resolve to native calls so I'm left with little information. For test.9, I lose 957 milliseconds. What kind of accuracy can I expect? Are my results going to vary by operating system or file system? Suggested workarounds? NOTE: I'm currently running Linux with an XFS filesystem. I wrote a quick program in C and the stat system call shows st_mtime as truncate(xyz...000/1000).

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  • Knight's tour / recursion

    - by Layne
    Hey, I'm trying to learn a little bit more about recursion but somehow I can't solve the knight's tour and I'm hoping someone can point out my logic error. public class main { static int fsize = 5; static int board[][] = new int[fsize][fsize]; static int[] sprung_x = {1,2,2,1,-1,-2,-2,-1}; static int[] sprung_y = {-2,-1,1,2,2,1,-1,-2}; static void SucheWeg(int schrittnummer, int x, int y) { board[x][y] = schrittnummer; if( schrittnummer == ((fsize*fsize)-1)) { for(int i = 0; i<fsize; i++) { for(int c=0; c<fsize; c++) { System.out.printf("%3d", board[i][c]); } System.out.println("\n"); } } else { for(int i = 0; i<8; i++) { for(int c = 0; c<8; c++) { if( (x+sprung_x[i]) >= 0 && (x+sprung_x[i]) < fsize && (y+sprung_y[c]) >= 0 && (y+sprung_y[c]) < fsize ) { if(board[x+sprung_x[i]][y+sprung_y[c]] == -1) { System.out.println("Move: "+schrittnummer + "\n"); SucheWeg(schrittnummer+1, (x+sprung_x[i]), (y+sprung_y[c])); } } } } board[x][y] = -1; } } public static void main(String[] args) { System.out.println("Begin: \n"); for(int i = 0; i<fsize; i++) { for(int c = 0; c<fsize; c++) { board[i][c] = -1; } } SucheWeg(0, 0, 0); System.out.println("\nEnd"); } }

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  • unable to start .bat file from JSP

    - by Stardust
    I have a batch file runthis.bat If I double click on this a text file is being created with name dir.txt Now I have to run this batch file using JSP. <% Runtime run =Runtime.getRuntime(); run.exec("C:/Program Files/Apache Software Foundation/Tomcat 5.5/webapps/try/runthis.bat"); out.println("SUCCESS"); %> I'm getting the output SUCCESS on a webpage but this batch file is not running. Whats might be the problem?

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  • Regarding jdbc Realm

    - by Priyanka
    I want to do login using form based authentication. i have been followed all steps for creating jdbc realm but run time error is coming. error is like-SEVERE: SEC1111: Cannot load group for JDBC realm user [pqr]. WARNING: Web login failed: Login failed: javax.security.auth.login.LoginException: Security Exception

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  • how can I handle user defined exceptions and after handling them resume the flow of program. here is

    - by fari
    /** * An exception thrown when an illegal side pit was * specified (i.e. not in the range 1-6) for a move */ public class IllegalSidePitNumException extends RuntimeException { /** * Exception constructor. * @param sidePitNum the illegal side pit that was selected. */ public IllegalSidePitNumException(int sidePitNum) { super("No such side pit number: "+sidePitNum); } } how do i use this ina program and then resume for there. I do not want the program to end but want to handle the exception and continue.

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  • Displaying large file in JTextArea.

    - by Sathish Gopal
    Hi All, I'm currently working in Swing UI Assignment. This work involves showing large file content in JTextArea. The file size can be as large as 2 GB. My initial idea is to lazily load content from the file, say 1 MB of content will be shown to the user. As the user scrolls i will retrieve the next 1 MB of content to be shown. All these operation will be happening in background thread (Swing Worker). I looked at the JTextArea API, the method insert takes String and int(position of the insert) as the parameter. This will suffice, but i'm worried about performance, because the content (1 MB at a time) retrieved will have to be converted to String object. Is there any other work around or any other alternative/better solution for this.

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  • Accessing selected node of richfaces tree from Javascript

    - by kazanaki
    Hello This should be a very simple question. I have a richfaces tree that is rendered using JSF. When the user clicks on a node I want a javascript function to run. Nothing more nothing less. No redirects, no re-submit, no-rerender, no Ajax. Just plain old Javascript. I have seen the onselected attribute of the tree and it indeed fires a Javascript method. But of course I want to know which node was clicked. Here is what I have so far <head> <script type="text/javascript"> function documentClicked(nodeRef) { alert("Node is "+nodeRef); } </script> </head> <rich:tree switchType="client" value="#{ajaxDocumentTree.rootNode}" var="document" onselected="documentClicked()" > <rich:treeNode iconLeaf="../images/tree/doc.gif" icon="../images/tree/doc.gif"> <h:outputText value="#{doc.friendlyName}" /> </rich:treeNode> But this does not work because nodeRef is undefined. I expected that the first argument of the callback would be the selected node but this is not the case. So the question is this: How do I fire a Javascript function with the selected node from a richfaces tree?

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  • How do I draw part of parabola using iText ? Or how do I create quadratic bezier curves from cubic b

    - by drasto
    I need to draw a shape whose boundaries are parts of parabola (that is quadratic bezier curves) using iText. I have found only method for drawing cubic bezier curves in PdfContentByte class. So how do I draw quadratic bezier curves using iText ? One way would be to use method for cubic bezier curves. Is it possible to draw quadratic bezier curves as a cubic bezier curves (with 2 control points). I gues it is but I cannot make up the formula. If somebody states the formula tu "translate" cubic bezier curves to quadratic that would solve the problem. Any other ways to draw quadratic bezier(parts of parabola) curves in iText (and filled shapes made of them) is also the solution. Thanks

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