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  • How to make a thread try to reconnect to the Database x times using JDBCTemplate

    - by gillJ
    Hi, I have a single thread trying to connect to a database using JDBCTemplate as follows: JDBCTemplate jdbcTemplate = new JdbcTemplate(dataSource); try{ jdbcTemplate.execute(new CallableStatementCreator() { @Override public CallableStatement createCallableStatement(Connection con) throws SQLException { return con.prepareCall(query); } }, new CallableStatementCallback() { @Override public Object doInCallableStatement(CallableStatement cs) throws SQLException { cs.setString(1, subscriberID); cs.execute(); return null; } }); } catch (DataAccessException dae) { throw new CougarFrameworkException( "Problem removing subscriber from events queue: " + subscriberID, dae); } I want to make sure that if the above code throws DataAccessException or SQLException, the thread waits a few seconds and tries to re-connect, say 5 more times and then gives up. How can I achieve this? Also, if during execution the database goes down and comes up again, how can i ensure that my program recovers from this and continues running instead of throwing an exception and exiting?

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  • ArrayList<String> NullPointerException

    - by Carlucho
    Am trying to solve a labyrinth by DFS, using adj List to represent the vertices and edges of the graph. In total there are 12 nodes (3 rows[A,B,C] * 4 cols[0,..,3]). My program starts by saving all the vertex labels (A0,..C3), so far so good, then checks the adjacent nodes, also no problems, if movement is possible, it proceeds to create the edge, here its where al goes wrong. adjList[i].add(vList[j].label); I used the debugger and found that vList[j].label is not null it contains a correct string (ie. "B1"). The only variables which show null are in adjList[i], which leads me to believe i have implemented it wrongly. this is how i did it. public class GraphList { private ArrayList<String>[] adjList; ... public GraphList(int vertexcount) { adjList = (ArrayList<String>[]) new ArrayList[vertexCount]; ... } ... public void addEdge(int i, int j) { adjList[i].add(vList[j].label); //NULLPOINTEREXCEPTION HERE } ... } I will really appreaciate if anyone can point me on the right track regrading to what its going wrong... Thanks!

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  • question about polynomial multiplication

    - by davit-datuashvili
    i know that horners method for polynomial pultiplication is faster but here i dont know what is happening here is code public class horner{ public static final int n=10; public static final int x=7; public static void main(String[] args){ //non fast version int a[]=new int[]{1,2,3,4,5,6,7,8,9,10}; int xi=1; int y=a[0]; for (int i=1;i<n;i++){ xi=x*xi; y=y+a[i]*xi; } System.out.println(y); //fast method int y1=a[n-1]; for (int i=n-2;i>=0;i--){ y1=x*y+a[i]; } System.out.println(y1); } } result of this two methods are not same result of first method is 462945547 and result of second method is -1054348465 please help

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  • Why acegi (Spring Security) converts password to uppercase before comparing ?

    - by Tony
    One of my colleague in QA team reported a bug to me, the bug said that can't change password to lowercase, otherwise login is rejected,using number or uppercase is all fine. The login system was implemented using acegi 1.0 (now called Spring Security). This was a very strange bug,changing password is done by encrypting the user input string into MD5 string, I implemented this without using anything related acegi, I don't if the is the origin cause of the problem. When the login is rejected, through debugging, I find that, the user input is converted into uppercase by acegi when passing to the acegi comparing logic. At first, I didn't believe this, when I checkout the acegi source and debugging with it, I find it does convert both username and password to uppercase (source code line 121), Can you tell me why it does this? This can cause password encoding mismatch!

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  • A simple two column layout with Swing

    - by Derk
    How to get a sidebar JPanel of a fixed with with Swing. Now I'm trying this: public SidebarPanel() { this.setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS)); this.setPreferredSize(new Dimension(200, this.getPreferredSize().height)); ... But when I resize the window also the width of the sidebar changes. How to fix this?

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  • How to access a variable in other class?

    - by Christine
    Hi! I've problem regarding GUI with one Menu and one Order Class. I've created a variable to store how many items have been selected in the Menu Class. private int totalSelected; The var totalSelected is live updated. It can be changed anytime depending on actionPerformed() function.(Exp: totalSelected will add up all the selected items) In the Order Class, how can I access to the live update variable totalSelected in order to retrieve the live update value? When I invoke getTotalSelected() function inside the Menu Class, I will only obtain a 0 value. Thanks for your help ^^! Please allow me to specify my question clearer. public class MenuTab extends JPanel { private JLabel display; private int totalSelected; public MenuTab() { .... } } public getTotalSelected(){ return totalSelected; } private class SelectedListener implements ActionListener { public void actionPerformed() { ....... //Assume that totalSelected has been updated! display = new JLabel("Total: " + totalSelected); // OK to display totalSelected live value here. } } // A new class is the confirmation of order public class OrderConfirmedTab extends JPanel{ private JLabel displayTotal; private MenuTab order = new MenuTab(); public OrderConfirmedTab() { ...... int totalSelected = order.getTotalSelected(); displayTotal = new JLabel("Total: " + totalSelected); // Problem to display totalSelected live value here. // Will obtain 0; // How can I obtain the live updated value from class MenuTab? Thanks! } }

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  • OPTICS Clustering algorithm. How to get the best epsilon

    - by Marco Galassi
    I am implementing a project which needs to cluster geographical points. OPTICS algorithm seems to be a very nice solution. It needs just 2 parameters as input(MinPts and Epsilon), which are, respectively, the minimum number of points needed to consider them as a cluster, and the distance value used to compare if two points are in can be placed in same cluster. My problem is that, due to the extreme variety of the points, I can't set a fixed epsilon. Just look at the image below. The same points structure but in a different scale would result very different. Suppose to set MinPts=2 and epsilon = 1Km. On the left, the algorithm would create 2 clusters(red and blue), but on the right it would create one single cluster containing all of the points(red), but I would like to obtain 2 clusters even on the right. So my question is: is there any kind of way to calculate dynamically the epsilon value to get this result? Thank you very much and excuse my for my poor english. Marco

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  • How do you refactor a large messy codebase?

    - by Ricket
    I have a big mess of code. Admittedly, I wrote it myself - a year ago. It's not well commented but it's not very complicated either, so I can understand it -- just not well enough to know where to start as far as refactoring it. I violated every rule that I have read about over the past year. There are classes with multiple responsibilities, there are indirect accesses (I forget the technical term - something like foo.bar.doSomething()), and like I said it is not well commented. On top of that, it's the beginnings of a game, so the graphics is coupled with the data, or the places where I tried to decouple graphics and data, I made the data public in order for the graphics to be able to access the data it needs... It's a huge mess! Where do I start? How would you start on something like this? My current approach is to take variables and switch them to private and then refactor the pieces that break, but that doesn't seem to be enough. Please suggest other strategies for wading through this mess and turning it into something clean so that I can continue where I left off!

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  • Parsing a String into date with pattern:"dd/MM/yyyy"

    - by kawtousse
    Hi, I want to insert a date having this format MM/dd/YYYY for example:04/29/2010 to 29/04/2010 to be inserted into mysql database in a field typed Date. So i have this code: String dateimput=request.getParameter("datepicker"); DateFormat df = new SimpleDateFormat("dd/MM/yyyy"); Date dt = null; try { dt = df.parse(dateimput); System.out.println("date imput is:" +dt); } catch (ParseException e) { e.printStackTrace(); } but it gives me those error: 1-date imput is:Fri May 04 00:00:00 CEST 2012 (it is not the correct value that have been entered). 2-dismatching with mysql date type. I can not detect the error exactly. Please help.

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  • Files written with FileWriter are either 32 KB, 24 KB, 16 KB, ... big or empty

    - by Bernhard V
    Hi, I read a file into a string, change the first line and then write this string into a new file. I do this through the following code (a little bit shortened): while(jspIterator.hasNext()){ String line = (String) jspIterator.next(); if (i == 0) { if (line.startsWith("bla bla") && line.endsWith("yada")) { line = line.replaceFirst("this", "that"); } } jspAsString += line; i++; } FileWriter newJspWriter = new FileWriter(newJspFile); newJspWriter.write(jspAsString); Now the files written this way are either 32, 24, 16, 8 KByte big or completely empty. When debugging I see that the String is assembled correctly. When I print the variable jspAsString to the console it also appears correct. Do you know why FileWriter behaves this way?

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  • How can a link within a WebView load another layout using javascript?

    - by huffmaster
    So I have 2 layout files (main.xml, featured.xml) and both each have a single WebView. When the application starts "main.xml" loads a html file into it's WebView. In this html file I have a link that calls javascript that runs code in the Activity that loaded the html. Once back in this Activity code though I try running setContentView(R.layout.featured) but it just bombs out on me. If I debug it just dies without any real error and if I run it the application just Force closes. Am I going about this correctly or should I be doing something differently? final private int MAIN = 1; final private int FEATURED = 2; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); webview = (WebView) findViewById(R.id.wvMain); webview.getSettings().setJavaScriptEnabled(true); webview.getSettings().setSupportZoom(false); webview.addJavascriptInterface(new EHJavaScriptInterface(), "eh"); webview.loadUrl("file:///android_asset/default.html"); } final class EHJavaScriptInterface { EHJavaScriptInterface() { } public void loadLayout(final String lo) { int i = Integer.parseInt(lo.trim()); switch (i) { /****** THIS IS WHERE I'M BOMBING OUT *********/ case FEATURED: setContentView(R.layout.featured);break; case MAIN: setContentView(R.layout.main);break; } } }

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  • JBoss classloading when 2 WARs have the same class

    - by Pacman
    I have a web applications A.war which has two servlets AServlet and BServlet. Both instantiate a helper class com.mycompany.Foo.class (this is my own class, not a third party library). Now I want to split the two servlets into two separate WARs: A.war will have only AServlet and a new B.war will have BServlet. AServlet will invoke BServlet via HTTP GET. Both WARs will have com.mycompany.Foo.class. I want to deploy both WARs on the same JBoss instance. The question is, will there be any classloading issues due to the same class being present in both WARs, and the WARs being deployed on the same JBoss instance?

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  • Get interface constant name using its value

    - by Ravisha
    This might not have a major usecase in projects ,but i was just trying a POC kind of project where in i get the key code,and using its value i want to print the key name on screen so i want to relive myself off writing switch cases ,so thinking of going by reflection. Is there a way to get the constant integer of interface's name using its value?

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  • how to use JComboBox using Enum in Dialog Box

    - by Edan
    Hi, I define enums: enum itemType {First, Second, Third}; public class Item { private itemType enmItemType; ... } How do I use it inside Dialog box using JComboBox? Means, inside the dialog box, the user will have combo box with (First, Second, Third). Also, is it better to use some sort of ID to each numerator? (Integer) thanks.

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  • CGLIB proxy error after spring bean definition loading into XmlWebApplicationContext at runtime

    - by VasylV
    I load additional singleton beans definitions at runtime from external jar file into existing XmlWebApplicationContext of my application: BeanFactory beanFactory = xmlWebApplicationContext.getBeanFactory(); DefaultListableBeanFactory defaultFactory = (DefaultListableBeanFactory)beanFactory; final URL url = new URL("external.jar"); final URL[] urls = {url}; ClassLoader loader = new URLClassLoader(urls, this.getClass().getClassLoader()); defaultFactory.setBeanClassLoader(loader); final ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(defaultFactory); final DefaultResourceLoader resourceLoader = new DefaultResourceLoader(); resourceLoader.setClassLoader(loader); scanner.setResourceLoader(resourceLoader); scanner.scan("com.*"); Object bean = xmlWebApplicationContext.getBean("externalBean"); After all above xmlWebApplicationContext contains all external definitions of beans. But when i am trying to get bean from context exception is thrown: Couldn't generate CGLIB proxy for class ... I saw in debug mode that in the bean initialization process first time proxy is generated by org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator and than it is tried to generate proxy with org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator but fails with mentioned exception.

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  • @NamedQuery select parameter meaning

    - by sergionni
    Found some examples of @NamedQuery annotations,e.g.: @NamedQuery(name="employeeBySsn" query="select e from Employee e where e.ssn = :ssn") what does parameter e mean? the second usage of it seems like alias name of table and what does "select e" part mean?

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  • How to allow for modular development while still running in same JVM?

    - by Marcus
    Our current app runs in a single JVM. We are now splitting up the app into separate logical services where each service runs in its own JVM. The split is being done to allow a single service to be modified and deployed without impacting the entire system. This reduces the need to QA the entire system - just need to QA the interaction with the service being changed. For interservice communication we use a combination of REST, an MQ system bus, and database views. What I don't like about this: REST means we have to marshal data to/from XML DB views couple the systems together which defeats the whole concept of separate services MQ / system bus is added complexity There is inevitably some code duplication between services You have set up n JBoss server configurations, we have to do n number of deployments, n number of set up scripts, etc, etc. Is there a better way to structure an internal application to allow modular development and deployment while allowing the app to run in a single JVM (and achieving the associated benefits)?

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  • How to set the transaction isolation level of a

    - by Michael Wiles
    How do I set the global transaction isolation level for a postgres data source. I'm running on jboss and I'm using hibernate to connect. I know that I can set the isolation level from hibernate, does this work for Postgres? This would be by setting the hibernate.connection.isolation hibernate property to 1,2,4,8 - the various values of the relevant static fields. I'm using the org.postgresql.xa.PGXADataSource

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  • Synchronization between hibernate running locally and on a server

    - by linead
    Is there an easy way using a library to facilitate the synchronization of two hibernate instances. One running locally on a client and one running on a central server exposed via a web service. So Client tracks changes it makes, pushes them to the Server. The server ensures that the clients is not updating out of sync objects and stores the clients changes. The Client can also sync with the Server so that it can see the changes made by other clients. The idea is that the client can be run offline, without access to the server and only come online to synchronize when needed.

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  • escaping a dollar in the middle of an ant property

    - by jk
    I have a property whose value contains a $. I'd like to use this property as a regexp in a propertyregexp. Ant appears to resolve the property as a paramater to the propertyregexp, but then the dollar gets interpreted as a regexp symbol. Example: <property name="a" value="abc$" /> <property name="b" value="xyz" /> <path id="paths"> <pathelement location="abc$/def" /> <pathelement location="abc$/ghi" /> </path> <pathconvert property="list" refid="paths" pathsep="${line.separator}" dirsep="/" /> <propertyregex property="list" input="${list}" override="true" regexp="${a}(.*)" replace="${b}\1" /> <echo message="${list}" /> I'd like to the pair xyz/def and xyz/ghi. Is this possible? I'm using Ant 1.8.

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  • Apply Quaternion to Camera in libGDX

    - by Alex_Hyzer_Kenoyer
    I am trying to rotate my camera using a Quaternion in libGDX. I have a Quaternion created and being manipulated but I have no idea how to apply it to the camera, everything I've tried hasn't moved the camera at all. Here is how I set up the rotation Quaternion: public void rotateX(float amount) { tempQuat.set(tempVector.set(1.0f, 0.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = rotation.mul(tempQuat); } public void rotateY(float amount) { tempQuat.set(tempVector.set(0.0f, 1.0f, 0.0f), amount * MathHelper.PIOVER180); rotation = tempQuat.mul(rotation); } Here is how I am trying to update the camera (Same update method as the original libGDX version but I added the part about the rotation matrix to the top): public void update(boolean updateFrustum) { float[] matrix = new float[16]; rotation.toMatrix(matrix); Matrix4 m = new Matrix4(); m.set(matrix); camera.view.mul(m); //camera.direction.mul(m).nor(); //camera.up.mul(m).nor(); float aspect = camera.viewportWidth / camera.viewportHeight; camera.projection.setToProjection(Math.abs(camera.near), Math.abs(camera.far), camera.fieldOfView, aspect); camera.view.setToLookAt(camera.position, tempVector.set(camera.position).add(camera.direction), camera.up); camera.combined.set(camera.projection); Matrix4.mul(camera.combined.val, camera.view.val); if (updateFrustum) { camera.invProjectionView.set(camera.combined); Matrix4.inv(camera.invProjectionView.val); camera.frustum.update(camera.invProjectionView); } }

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  • Overriding or overloading?

    - by atch
    Guys I know this question is silly but just to make sure: Having in my class method: boolean equal(Document d) { //do something } I'm overloading this method nor overriding right? I know that this or similiar question will be on upcoming egzam and would be stupid to not get points for such a simple mistake;

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