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  • how to share a variable between two threads

    - by prmatta
    I just inherited some code, two threads within this code need to perform a system task. One thread should do the system task before the other thread. They should not be performing the system task together. The two threads do not have references to each other. Now, I know I can use some sort of a semaphore to achieve this. But my question is what is the right way to get both threads to access this semaphore. I could create a static variable/method a new class : public class SharedSemaphore { private static Semaphore s = new Semaphore (1, true); public static void performSystemTask () { s.acquire(); } public static void donePerformingSystemTask() { s.release(); } } This would work (right?) but this doesn't seem like the right thing to do. Because, the threads now have access to a semaphore, without ever having a reference to it. This sort of thing doesn't seem like a good programming practice. Am I wrong?

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  • Using exponential smoothing with NaN values

    - by Eric
    I have a sample of some kind that can create somewhat noisy output. The sample is the result of some image processing from a camera, which indicates the heading of a blob of a certain color. It is an angle from around -45° to +45°, or a NaN, which means that the blob is not actually in view. In order to combat the noisy data, I felt that exponential smoothing would do the trick. However, I'm not sure how to handle the NaN values. On the one hand, involving them in the math would result in a NaN average, which would then prevent any meaningful results. On the other hand, ignoring NaN values completely would mean that a "no-detection" scenario would never be reported. And just to complicate things, the data is also noisy in that it can get false NaN value, which ideally would be smoothed somehow to prevent random noise. Any ideas about how I could implement such an exponential smoother?

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  • DB2 Query to Hibernate Criteria

    - by Fortega
    Hi, I have a specific DB2 query, and I would like to execute this query using criteria. The query: SELECT sum(units) as volume, location_id, aged FROM ( SELECT units, location_id, CASE WHEN daysinstock < 61 THEN 'NOT_AGED' WHEN daysinstock < 91 THEN 'AGED' ELSE 'OVER_AGED' END AS AGED FROM STOCK_TABLE ) x group by location_id, aged the STOCK_TABLE contains the following fields: units, location_id, daysinstock. This table is matched by a StockDataSource object, with the same fields.

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  • Android HTTP Connection

    - by Ubersoldat
    Can anybody tell my why this doesn't work in the Android emulator? From the browser I have access and the server is internal. All I can think of is that I'm missing some configuration on my app so it can access the network layer. try { InetAddress server = Inet4Address.getByName("thehost"); //Doesn't work either //or InetAddress server2 = Inet4Address.getByAddress(new String("192.168.1.30").getBytes()); if(server.isReachable(5000)){ Log.d(TAG, "Ping!"); } Socket clientsocket = new Socket(server, 8080); } catch (UnknownHostException e) { Log.e(TAG, "Server Not Found"); } catch (IOException e) { Log.e(TAG, "Couldn't open socket"); } Throws an UnknownHostException Thanks

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  • Problem with button addition when double clicking a command label

    - by mistique
    Hy, I got an intersting problem which I stumbled upon. When I double click a label in a JLabel I want to add another button in a JPanel, its a shorter way to make a dragg and drop. The problem is that the button doesn't appears only if i'll position the mouse on the area the button should appear. Why does it happens this way? Anyone got a clue? Are there some thread related issues involved? Thanks in advance

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  • displaying data from database in to text box

    - by srinayak
    I have 2 JSP pages as below: projectcategory.jsp <% Connection con = DbConnect.connect(); Statement s = con.createStatement(); ResultSet rs = s.executeQuery("select * from projectcategory"); %> <DIV class="TabbedPanelsContent" align="center"> <TABLE border="1"> <TR> <TH>CATEGORY ID</TH> <TH>CATEGORY NAME</TH> <TH>Edit/Update</TH> </TR> <% while (rs.next()) { %> <%String p=rs.getString(1);%> <TR> <TD><%=rs.getString(1)%></TD> <TD><%=rs.getString(2)%></TD> <TD> <FORM action="EditPcat.jsp?pcatid=p"><INPUT type="submit" value='edit/update'></INPUT> </FORM> </TD> </TR> <% } %> </TABLE> </DIV> another is Editpcat.jsp: </head> <body> <%String s=request.getParameter("p"); %> <form action="ProjCatServlet" method="post"> <div align="right"><a href="projectcategory.jsp">view</a></div> <fieldset> <legend>Edit category</legend> <table cellspacing="2" cellpadding="2" border="0"> <tr> <td align="left">Category Id</td> <td><input type="text" name="pcatid" value="<%=s%>" ></td> </tr> <tr> <td align="right">Category Name</td> <td><input type="text" name="pcatname"></td> </tr> <tr> <td><input type="submit" value="submit"></td> </tr> </table> <input type="hidden" name="FUNCTION_ID" value="UPDATE"> </fieldset> </form> How to display value from one JSP page which we get from database in to text box of another JSP?

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  • auto resize content of label

    - by user161004
    i have got a label in my program which displays a image. The problem id if an image is selected which is greater than the size of the label,only some part of the image is displayed while others are not displayed. What should i do so that the enire image is displayed???

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  • Why can't i create a RESTful web service in ejb module?

    - by Nitesh Panchal
    Hello, I am using Netbeans 6.8. I can see an option to create a web service in my independent ejb module but i can't seem to find an option to create a RESTful based web service in my ejb module. Is there any kind of restriction in ejb module that i can only create SOAP based web service and not RESTful? or is it the bug of Netbeans 6.8?

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  • How to get result size from an SQL query and check size

    - by Jimmy
    Hi I'm trying to write a piece of code for a simple verification method as part of a MVC. At present the SQL is not written as a prepared statement so obviously it is at risk to a SQL injection so any help in regards to writing the SQL as a prepared statement would be really helpful. The method which is in the User model. public boolean getLoginInfo() { try { DBAccess dbAccess = new DBAccess(); String sql = "SELECT username, password FROM owner WHERE username = '" + this.username + "'AND password = '" + this.password + "';"; dbAccess.close();dbAccess.executeQuery(sql); dbAccess.close(); return true; } catch (Exception e) { return false; } } I want to get the size of the result set which is generated by the SQL query and if the size of it is 1 return true else it's false. If you need more info on the rest of the MVC just post and I'll get it up here.

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  • Testing code that uses SoftReference<T>

    - by bmargulies
    To get any code with SoftReference<T> to be fully tested, one must come up with some way to test the 'yup, it's been nulled' case. One might more or less mock this by using a 'for-test' code path to force the reference to be null, but that won't manage the queue exactly as the GC does. I wonder if anyone out can share experience in setting up a repeatable, controlled, environment, in which the GC is, in fact, provoked into collecting and nulling?

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  • Hibernate/JPA DB Schema Generation Best Practices

    - by Bytecode Ninja
    I just wanted to hear the opinion of Hibernate experts about DB schema generation best practices for Hibernate/JPA based projects. Especially: What strategy to use when the project has just started? Is it recommended to let Hibernate automatically generate the schema in this phase or is it better to create the database tables manually from earliest phases of the project? Pretending that throughout the project the schema was being generated using Hibernate, is it better to disable automatic schema generation and manually create the database schema just before the system is released into production? And after the system has been released into production, what is the best practice for maintaining the entity classes and the DB schema (e.g. adding/renaming/updating columns, renaming tables, etc.)? Thanks in advance.

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  • Tomcat Http and Https on the same port

    - by Ofri Dagan
    Hi, I have a web-service endpoint and a http connector on port X. At some point this endpoint needs to switch to https, but on the same port! (I know this is not the normal way of doing things, but this is what my clients expect from an old server they are using...) Is there a way to do it in tomcat?

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  • spring mvc forward to jsp

    - by jerluc
    I currently have my web.xml configured to catch 404s and send them to my spring controller which will perform a search given the original URL request. The functionality is all there as far as the catch and search go, however the trouble begins to arise when I try to return a view. <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver" p:order="1"> <property name="mediaTypes"> <map> <entry key="json" value="application/json" /> <entry key="jsp" value="text/html" /> </map> </property> <property name="defaultContentType" value="application/json" /> <property name="favorPathExtension" value="true" /> <property name="viewResolvers"> <list> <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" /> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/jsp/" /> <property name="suffix" value="" /> </bean> </list> </property> <property name="defaultViews"> <list> <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" /> </list> </property> <property name="ignoreAcceptHeader" value="true" /> </bean> This is a snippet from my MVC config file. The problem lies in resolving the view's path to the /WEB-INF/jsp/ directory. Using a logger in my JBoss setup, I can see that when I test this search controller by going to a non-existent page, the following occurs: Server can't find the request Request is sent to 404 error page (in this case my search controller) Search controller performs search Search controller returns view name (for this illustration, we'll assume test.jsp is returned) Based off of server logger, I can see that org.springframework.web.servlet.view.JstlView is initialized once my search controller returns the view name (so I can assume it is being picked up correctly by the InternalResourceViewResolver) Server attempts to return content to browser resulting in a 404! A couple things confuse me about this: I'm not 100% sure why this isn't resolving when test.jsp clearly exists under the /WEB-INF/jsp/ directory. Even if there was some other problem, why would this result in a 404? Shouldn't a 404 error page that results in another 404 theoretically create an infinite loop? Thanks for any help or pointers! Controller class [incomplete]: @Controller public class SiteMapController { //-------------------------------------------------------------------------------------- @Autowired(required=true) private SearchService search; @Autowired(required=true) private CatalogService catalog; //-------------------------------------------------------------------------------------- @RequestMapping(value = "/sitemap", method = RequestMethod.GET) public String sitemap (HttpServletRequest request, HttpServletResponse response) { String forwardPath = ""; try { long startTime = System.nanoTime() / 1000000; String pathQuery = (String) request.getAttribute("javax.servlet.error.request_uri"); Scanner pathScanner = new Scanner(pathQuery).useDelimiter("\\/"); String context = pathScanner.next(); List<ProductLightDTO> results = new ArrayList<ProductLightDTO>(); StringBuilder query = new StringBuilder(); String currentValue; while (pathScanner.hasNext()) { currentValue = pathScanner.next().toLowerCase(); System.out.println(currentValue); if (query.length() > 0) query.append(" AND "); if (currentValue.contains("-")) { query.append("\""); query.append(currentValue.replace("-", " ")); query.append("\""); } else { query.append(currentValue + "*"); } } //results.addAll(this.doSearch(query.toString())); System.out.println("Request: " + pathQuery); System.out.println("Built Query:" + query.toString()); //System.out.println("Result size: " + results.size()); long totalTime = (System.nanoTime() / 1000000) - startTime; System.out.println("Total TTP: " + totalTime + "ms"); if (results == null || results.size() == 0) { forwardPath = "home.jsp"; } else if (results.size() == 1) { forwardPath = "product.jsp"; } else { forwardPath = "category.jsp"; } } catch (Exception ex) { System.err.println(ex); } System.out.println("Returning view: " + forwardPath); return forwardPath; } }

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  • how to query an embedded entity by using a query builder

    - by user577719
    I've searched quite a time for an answer to this question. Following Codesmell: @Entity public class Person { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) protected Integer id; @Column(nullable = true, length = 50) @Size(max = 50) private String name; @Embedded @Valid protected Adress adress; public void setId(Integer id) { this.id = id; } public Integer getId() { return this.id; } public void setName(String name) { this.name = name; } public void getName() { return this.name; } public void setAdress(Adress adress) { this.adress = adress; } public void getAdress() { return this.adress; } } @Embeddable public class Adress { @Column(nullable = false, length = 50) @Size(max = 50) @NotNull private String place; public void setPlace(String place) { this.place = place; } public void getPlace() { return this.place; } } public class PersonDaoJpa { public List<Ort> findByPerson(final Person person) { CriteriaBuilder builder = this.entityManager.getCriteriaBuilder(); CriteriaQuery<Person> query = builder.createQuery(Person.class); Root<Person> rootPerson = query.from(Person.class); List<Predicate> wherePredicates = new ArrayList<Predicate>(); if (person.getName() != null) { wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("name")), ort.getName().toLowerCase()) ); } Adresse adresse = ort.getAdresse(); if (adresse != null) { if(adresse.getPlace() != null) { // this won't work wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("person.adress.place")), adresse.getPlace().toLowerCase()) ); } } Predicate whereClause = builder.and(wherePredicates.toArray(new Predicate[0])); query.where(whereClause); return this.entityManager.createQuery(query).getResultList(); } } How can I access the Adress.place through rootPerson? rootPerson.get("place"), or rootPerson.get("adress.place") won't work...

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  • What is Chain Matrix Multiplication ?

    - by Hellnar
    Hello, I am trying to understand what is a chain matrix multiplication and how it is different from a regular multiplication. I have checked several sourcers yet all seem to be very academically explained for me to understand. I guess it is a form of dynamic programming algorithm to achieve the operation in an optimised way but I didn't go any further. Thanks

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  • Spring Web application internal visual monitoring heap space and permgen.

    - by Veniamin
    If I have created web application used Spring framework(based on maven), can I include some module/dependency/plugin into my app to monitor Heap space, Permgen, etc. It whould be greate to get some charts output likes as in VisuaVM. For example: http://localhost:8080/monitoring = Including something likes VisualVM I have found next dependency without link to repo: <dependency> <groupId>com.sun.tools.visualvm</groupId> <artifactId>core</artifactId> <version>1.3.3</version> </dependency> How to use it?

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  • calendar.getInstance() or calendar.clone()

    - by Pangea
    I need to make a copy of a given date 100s of times (I cannot pass-by-reference). I am wondering which of the below two are better options newTime=Calendar.getInstance().setTime(originalDate); OR newTime=originalDate.clone(); Performance is of main conern here. thx.

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  • Play Framework: Generate PDF from template that uses Javascript for graphing

    - by digiarnie
    I have a template that has some Javascript used to generate graphs in the browser. I would like to use that same template to create a PDF and send as an attachment in an e-mail. In this scenario, there would be no browser/client interaction. I am using the PDF module that is available from the Play website and I have managed to get the PDF rendering to work. The only issue is that the graphs don't show up in the PDF but all other static text does. I'm assuming the graphs aren't appearing in the PDF due to the Javascript not being executed prior to the PDF generation. Does anyone have any ideas on how to get around this problem?

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  • Ref to map vs. map to refs vs. multiple refs

    - by mikera
    I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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  • longest common subsequence

    - by davit-datuashvili
    i have following code public class LCS1 { public static String lcs(String a,String b) { String x; String y; int alen=a.length(); int blen=b.length(); if (alen==0 || blen==0) { return ""; } else if (a.charAt(alen-1)==b.charAt(blen-1)) { return lcs(a.substring(0,alen-1),b.substring(0,blen-1)); } else { x=lcs(a,b.substring(0,blen-1)); y=lcs(a.substring(0,alen-1),b); } return (x.length()>y.length()) ? x : y; } public static void main(String[]args){ String a="computer"; String b="houseboat"; System.out.println(lcs(a,b)); } } it should return "out" but returns nothing what is problem?

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  • Is J2SE a framework?

    - by Alvin
    Hello, I want to know is this legitimate to say J2SE a framework? If J2SE is a framework, then why there is a collection framework? Isn't collection framework inside J2SE? Please help me!

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  • oracle connectivity

    - by jayprakash
    String serverName = "127.0.0.1"; String portNumber = "1521"; String sid = "database"; String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid; String username = "scott"; String password = "tiger"; connection = DriverManager.getConnection(url, username, password); Could not connect to the database

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