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  • Question about factory classes

    - by devoured elysium
    Currently I have created a ABCFactory class that has a single method creating ABC objects. Now that I think of it, maybe instead of having a factory, I could just make a static method in my ABC Method. What are the pro's and con's on making this change? Will it not lead to the same? I don't foresee having other classes inherit ABC, but one never knows! Thanks

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  • Is unnecessary error handling recommended in business logic? eg. Null check/Percentage limit check etc

    - by novice_at_work
    We usually put unnecessary checks in our business logic to avoid failures. Eg. 1. public ObjectABC funcABC(){ ObjectABC obj = new ObjectABC; .......... .......... //its never set to null here. .......... return obj; } ObjectABC o = funABC(); if(o!=null){ //do something } Why do we need this null check if we are sure that it will never be null? Is it a good practice or not? 2. int pplReached = funA(..,..,..); int totalPpl = funB(..,..,..); funA() just puts a few more restriction over result of funB(). Double percentage = (totalPpl==0||totalPpl<pplReached) ? 0.0 : pplReached/totalPpl; Do we again need this check? The questions is: Aren't we swallowing some fundamental issue by putting such checks? Issues which should be shown ideally, are avoided by putting these checks. What is the recommended way?

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  • Child Activity in Android

    - by Martin Marinov
    So I have two Activities. The main is called Main, and the child one is called Child. When a button is clicked in the main activity it triggers the following piece of code: Intent i = new Intent(Main.this, Child.class); Main.this.startActivity(i); That opens the Child activity. As soon as I call finish() or press the back button within the child activity instead of going back to the main one, the app just closes. Can you give me a hint where the problem might be :( P.S. By trial and error I found out that if edit AndroidManifest.xml and add android:theme="@android:style/Theme.Dialog" within the declaration of Child the back button and calling finish() behaves as expected: closes the child activity and brings the main into focus. The problem is that when I start typing in an EditText the screen starts flickering (rather bizzare). So I can't use it as a dialog. My main activity uses the camera, so that might be making problems. Although when the child activity is started, the onPause event is fired and it stops the camera until onResume is called.

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  • Two pass JSP page rendering

    - by dotsid
    Suppose an example. I have following interface: public interface DataSource<T> { Future<T> fetch(); } This datasource can do asynchronous data fetching. And we have following tag for using datasource in JSP: <html> <d:fetch from="${orderDS}" var="orders"> <c:foreach in="${orders}" var="order"> <div class="order"> <c:out value="${order.title}" /> </div> </c:foreach> </d:fetch> </html> So, what I want? I want JSP rendering engine to call my custom tag (FetchTag in this example) twice. On first call FetchTag will do DataSource.fetch() call and save Future locally as a object field. On second call FetchTag do Future.get() call and will be blocked until data becomes available. Is there any way to do such a thing?

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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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  • JAXB Annotated class - setting of a variable which is not an element

    - by sswdeveloper
    I have a JAXB annotated class say @XmlRootElement(namespace = "http://www.abc.com/customer") Class Customer{ @XmlElement(namespace = "http://www.abc.com/customer") private String Name; @XmlElement(namespace = "http://www.abc.com/customer") private String Address; @XmlTransient private HashSet set = new HashSet(); public String getName(){ return Name; } public void setName(String name){ this.Name = name; set.add("Name"); } public String getAddress(){ return Address; } public void setAddress(String address){ this.Address = address; set.add("Address"); } public void getSet(){ return set; } I have a XML of the form <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Customer xmlns="http://www.abc.com/customer" > <Name>Ralph</Name> <Address>Newton Street</Address> </Customer> I use JAXB unmarshalling to get the object representation of the XML input. The values for Name and Address are set correctly. However the value of set gets lost(since it is @XMLTransient it gets ignored) Is there any way of ensuring that it is still set in the object which has been unmarshalled? Some other annotation which I can use?

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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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  • stop thread that does not get interrupted

    - by prmatta
    I have a thread that sits and reads objects off of an ObjectInputStream: public void run() { try { ois = new ObjectInputStream(clientSocket.getInputStream()); Object o; while ((o = ois.readObject()) != null) { //do something with object } } catch (Exception ex) { //Log exception } } readObject does not throw InterruptedException and as far as I can tell, no exception is thrown when this thread is interrupted. How do I stop this thread?

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  • Android app crashes on Async Task

    - by Telmo Vaz
    why is my APP crashing when I invoke the AsyncTask? public class Login extends Activity { String mail; EditText mailIn; Button btSubmit; @Override protected void onCreate(Bundle tokenArg) { super.onCreate(tokenArg); setContentView(R.layout.login); mailIn = (EditText)findViewById(R.id.usermail); btSubmit = (Button)findViewById(R.id.submit); btSubmit.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View thisView) { new LoginProc().execute(); } }); } public class LoginProc extends AsyncTask<String, Void, Void> { @Override protected void onPreExecute() { mailIn = (EditText)findViewById(R.id.usermail); mail = mailIn.getText().toString(); super.onPreExecute(); } @Override protected Void doInBackground(String... params) { Toast.makeText(getApplicationContext(), mail, Toast.LENGTH_SHORT).show(); return null; } } } I'm trying to make the String name get it's value on the preExecute method, but it happens that the app crashes on that point. Even if I take the preExecute and do that on the doInBrackground, it still crashes. What's wrong?

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  • Strange problems with the Spring RestTemplate in Android application

    - by HarryCater
    I begin to use RESTful api of the Spring Framework in my android client application. But I have encountered with problems when I tried to execute HTTP request via postForObject/postForEntity methods. Here is my code: public String _URL = "https://noticemed.com/app/mobile/login"; public void BeginAuthorization(View view) { HttpHeaders requestHeaders = new HttpHeaders(); requestHeaders.setContentType(MediaType.APPLICATION_JSON); HttpEntity<String> _entity = new HttpEntity<String>(requestHeaders); RestTemplate templ = new RestTemplate(); templ.setRequestFactory(new HttpComponentsClientHttpRequestFactory()); templ.getMessageConverters().add(new MappingJacksonHttpMessageConverter()); ResponseEntity<String> _response = templ.postForEntity(_URL,_entity,String.class); //HERE APP CRASHES String _body = _response.getBody(); And here is a stack trace in logcat after app crashing. As you see there is no definite error message. So the question what am I doing wrong? How to fix this? May there is other way to do it?I really need a help. Thanks in advance!

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  • Interpret a rule applying multiple xpath queries on multiple XML documents

    - by Damien
    Hi, I need to build a component which would take a few XML documents in input and check the following kind of rules: XML1:/bookstore/book[price>35.00] != null and (XML2:/city/name = 'Montreal' or XML3://customer[@language] contains 'en') Basically my component should be able to: substitute the XML tokens with the corresponding XML document(before colon) apply xpath query on this XML document check the xpath output against expected result ("=", "!=", "contains") follow the basic syntax ("and", "or" and parentheses) tell if the rule is true or false Do you know any library which could help me? maybe JavaCC? Thanks

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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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  • 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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  • How to retrieve the ordered list of best articles having a minimum number of votes by using HSQL ?

    - by fabien7474
    I have a Vote domain class from my grails application containing properties like article_id and note I want to HQL query the Vote domain class in order to retrieve the 5 best rated articles having at least 10 votes. I tried : SELECT v.article_id, avg(v.note), count(*) FROM vote v where count(*) >= 10 group by v.article_id order by avg(v.note) desc limit 5; But unfortunately the insertion of where count(*) >= 10 throws an error. How can I do that in a simple way? Thank you for your help.

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  • How to create updateable panel using AjaxLink of Wicket?

    - by Arne
    I try to realize a link (in fact many links) that update a table in an website using an AjaxLink of Wicket. But I fail, the table is never updated (I have "setOutputMarkupId(true)" and call "addComponent", but there must be something other thats wrong). How can I realize a panel with a number of links and a table that displays dynamic data, dependent on the link clicked? Can someone give an example (Maybe two links, when the first one is clicked the table displays two random numbers from 1-10, when the second is clicked the table displays random numbers from 1-100)? Without reloading the entire page, but only the html for the table?

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  • Using switch and enumerations as substitute for named methods

    - by MatthewMartin
    This pattern pops up a lot. It looks like a very verbose way to move what would otherwise be separate named methods into a single method and then distinguished by a parameter. Is there any good reason to have this pattern over just having two methods Method1() and Method2() ? The real kicker is that this pattern tends to be invoked only with constants at runtime-- i.e. the arguments are all known before compiling is done. public enum Commands { Method1, Method2 } public void ClientCode() { //Always invoked with constants! Never user input. RunCommands(Commands.Method1); RunCommands(Commands.Method2); } public void RunCommands(Commands currentCommand) { switch (currentCommand) { case Commands.Method1: // Stuff happens break; case Commands.Method2: // Other stuff happens break; default: throw new ArgumentOutOfRangeException("currentCommand"); } }

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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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  • business object and codelist

    - by feiroox
    Hi How to design a business object? I have a library which returns me an Object which have ten lists of other different objects. I need to store it into database all. List of objects are often like: class Item { private int id; private String name; private double point; } But the name is often the same. Like basic title of the product or code. Containing from 3 characters up to 70characters. Should I make conversion for every Object to: (or something similar) class ConvertedItem { private int id; private int code; private double point; } And have a separated table of codes ( I guess around 60). Or do not bother with duplicated stuff? It's not mission critical app. What would you do in my case? thanks in advance

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  • Extracting startup errors from Spring contexts

    - by sehugg
    Consider the following output from a Tomcat server under Eclipse: INFO: Initializing Coyote HTTP/1.1 on http-8080 INFO: Initialization processed in 634 ms INFO: Starting service Catalina INFO: Starting Servlet Engine: Apache Tomcat/6.0.20 SEVERE: Error listenerStart SEVERE: Context [/MyServlet] startup failed due to previous errors I would like to figure out what exception caused "Error listenerStart", but Spring seems to be preventing me from finding the error via Eclipse. I'd love to start Catalina manually, but that doesn't seem to do anything. What's the best way to find the hidden exception? I'm not afraid to use torture methods.

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  • Implement the business logic in an app server with spring

    - by HenryOS
    Hi everybody, i have a doub... Is posible implement the business logic in an App Server remote using pojos instead of either EJB or Servlets???. The main idea is apply a model of 3 layers where the clients may be both web browsers and desktop applications, and they share the business logic in an App Server. Sorry for my english... im from Argentina and my english is poor. Thank you to everybody and i hope that anybody can help me soon. Regards! this would be the architecture browser----- Web Server --------|App Server(Business Logic common)|-------|RDBMS common| desktop App(Swing for example)-|App Server(Business Logic common)|-------|RDBMS common|

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  • How to use double buffering inside a thread and applet

    - by russell
    I have a question about when paint and update method is called?? i have game applet where i want to use double buffering.But i cant use it.the problem is In my game there is a ball which is moving inside run() method.I want to know how to use double buffering to swap the offscreen image and current image.Someone plz help. And when there is both update() and paint() method.which are called first,when and why ???

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