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  • What is the relation between ContentPane and JPanel?

    - by Roman
    I found one example in which buttons are added to panels (instances of JPanel) then panels are added to the the containers (instances generated by getContentPane) and then containers are, by the construction, included into the JFrame (the windows). I tried two things: I got rid of the containers. In more details, I added buttons to a panel (instance of JPanel) and then I added the panel to the windows (instance of JFrame). It worked fine. I got rid of the panels. In more details, I added buttons directly to the container and then I added the container to the window (instance of JFrame). So, I do not understand two things. Why do we have two competing mechanism to do the same things. What is the reason to use containers in combination with the panels (JPanel)? (For example, what for we include buttons in JPanels and then we include JPanels in the Containers). Can we include JPanel in JPanel? Can we include a container in container?

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  • Lackadaisical One-to-One between Char and Byte Streams

    - by Vaibhav Bajpai
    I expected to have a one-to-one correspondence between the character streams and byte streams in terms of how the classes are organized in their hierarchy. FilterReader and FilterWriter (character streams) correspond back to FilterInputStream and FilterOutputStream (byte stream) classes. However I noticed few changes as - BufferedInputStream extends FilterInputStream, but BufferedReader does NOT extend FilterReader. BufferedOutputStream and PrintStream both extend FilterOutputStream, but BufferedWriter and PrintWriter does NOT extend FilterWriter. FilterInputStream and FilterOutputStream are not abstract classes, but FilterReader and FilterWriter are. I am not sure if I am being too paranoid to point out such differences, but was just curious to know if there was design reasoning behind such decision.

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  • HttpPost request unsuccessful

    - by The Thom
    I have written a web service and am now writing a tester to perform integration testing from the outside. I am writing my tester using apache httpclient 4.3. Based on the code here: http://hc.apache.org/httpcomponents-client-4.3.x/quickstart.html and here: http://hc.apache.org/httpcomponents-client-4.3.x/tutorial/html/fundamentals.html#d5e186 I have written the following code. Map<String, String> parms = new HashMap<>(); parms.put(AirController.KEY_VALUE, json); postUrl(SERVLET, parms); ... protected String postUrl(String servletName, Map<String, String> parms) throws AirException{ String url = rootUrl + servletName; HttpPost post = new HttpPost(url); List<NameValuePair> nvps = new ArrayList<NameValuePair>(); for(Map.Entry<String, String> entry:parms.entrySet()){ BasicNameValuePair parm = new BasicNameValuePair(entry.getKey(), entry.getValue()); nvps.add(parm); } try { post.setEntity(new UrlEncodedFormEntity(nvps)); } catch (UnsupportedEncodingException use) { String msg = "Invalid parameters:" + parms; throw new AirException(msg, use); } CloseableHttpResponse response; try { response = httpclient.execute(post); } catch (IOException ioe) { throw new AirException(ioe); } String result; if(HttpStatus.SC_OK == response.getStatusLine().getStatusCode()){ result = processResponse(response); } else{ String msg = MessageFormat.format("Invalid status code {0} received from query {1}.", new Object[]{response.getStatusLine().getStatusCode(), url}); throw new AirException(msg); } return result; } This code successfully reaches my servlet. In my servlet, I have (using Spring's AbstractController): protected ModelAndView post(HttpServletRequest request, HttpServletResponse response) { String json = String.valueOf(request.getParameter(KEY_VALUE)); if(json.equals("null")){ log.info("Received null value."); response.setStatus(406); return null; } And this code always falls into the null parameter code and returns a 406. I'm sure I'm missing something simple, but can't see what it is.

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  • What is viewstate in JSF, and how is it used?

    - by MatthieuF
    In JSF, there is a viewstate associated with each page, which is passed back and forth with submits etc. I know that viewstate is calculated using the states of the various controls on the page, and that you can store it either client side or server side. The question is: how is this value used? Is it used to validate the values sent at submit, to ensure that the same request is not sent twice? Also, how is it calculated - I realise that richfaces may be calculated differently from myfaces, but an idea would be nice. Thanks.

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  • Attributes in XML subtree that belong to the parent

    - by Bart van Heukelom
    Say I have this XML <doc:document> <objects> <circle radius="10" doc:colour="red" /> <circle radius="20" doc:colour="blue" /> </objects> </doc:document> And this is how it is parsed (pseudo code): // class DocumentParser public Document parse(Element edoc) { doc = new Document(); doc.objects = ObjectsParser.parse(edoc.getChild("objects")); for ( ...?... ) { doc.objectColours.put(object, colour); } return doc; } ObjectsParser is responsible for parsing the objects bit, but is not and should not be aware of the existence of documents. However, in Document colours are associated with objects by use of a Map. What kind of pattern would you recommend to give the colour settings back to DocumentParser.parse from ObjectsParser.parse so it can associate it with the objects they belong to in a map? The alternative would be something like this: <doc:document> <objects> <circle id="1938" radius="10" /> <circle id="6398" radius="20" /> </objects> <doc:objectViewSettings> <doc:objectViewSetting object="1938" colour="red" /> <doc:objectViewSetting object="6398" colour="blue" /> </doc:objectViewSettings> </doc:document> Ugly!

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  • Semantic stuff (RDF, OWL) on mobile phones - is it possible?

    - by Brian Schimmel
    I'm thinking about using semantic (web) technogies like RDF and OWL in an application on mobile devices. Currently I'm targeting android, but I'd also be interested in the possibilities on the iPhone and on J2ME. I would like to use a lib instead of implementing everything from scratch. I know that there are some libraries and frameworks like Jena, Redland, Protégé but they don't state on which platforms they are known to work. Having a dynamic object model and parsing from and to XML are must-haves for me. I'd also like to use reasoning, but I've been told it was rather computing-intensive, so that's only a nice-to-have. For all platforms mentioned, the question can be interpreted as Is it possible in theory (especially for J2ME I'm not sure) Are there libs that are known to work on those platforms? Is the performance on a mobile platform good enough for real world usage?

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  • Is it possible to prevent out-of-order execution by using single volatile

    - by Yan Cheng CHEOK
    By referring article, it is using a pair of volatile to prevent out-of-order execution. I was wondering, is it possible to prevent it using single volatile? void fun_by_thread_1() { this.isNuclearFactory = true; this.factory = new NuclearFactory(); } void fun_by_thread_2() { Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } // If out-of-order execution happens, _factory might // be NuclearFactory instance. _factory.operate(); } Factory factory = new FoodFactory(); volatile boolean isNuclearFactory = false; The reason I ask, is because I have a single guard flag (similar to isNuclearFactory flag), to guard against multiple variables (similar to many Factory). I do not wish to mark all the Factory as volatile. Or, shall I fall into the following solution? void fun_by_thread_1() { try { writer.lock(); this.isNuclearFactory = true; this.factory = new NuclearFactory(); } finally { writer.unlock(); } } void fun_by_thread_2() { try { reader.lock(); Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } } finally { reader.unlock(); } _factory.operate(); } Factory factory = new FoodFactory(); boolean isNuclearFactory = false; P/S: I know instanceof. Factory is just an example to demonstrate of out-of-order problem.

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  • JTextArea thread safe?

    - by Dhaivat Pandya
    Hello everyone, I have some code that does some initialization (including making a JTextArea object), starts three seperate threads, and then these threads try to update the JTextArea (i.e. append() to it), but its not working at all. Nothing shows up on the JTextArea (however, during the initialzation, I print some test lines onto it, and that works fine). What's going on? How can I fix this? Also, each of those threads sleeps a random amount of time every time it has to update the JTextArea. Sorry I haven't provided any code, its all spread out over several files.

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  • ExecutorService that interrupts tasks after a timeout

    - by scompt.com
    I'm looking for an ExecutorService implementation that can be provided with a timeout. Tasks that are submitted to the ExecutorService are interrupted if they take longer than the timeout to run. Implementing such a beast isn't such a difficult task, but I'm wondering if anybody knows of an existing implementation.

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  • Checkbox values to varchar via Spring

    - by iowatiger08
    I am trying to get a varchar message from a database to display the selected values of a checkbox field in a jsp for patient's medication's dosage frequency. The possible values will be saved in comma-delimited string in the varchar. For most form fields there is simply a one form value to one database field ratio, but in this case, I am needing to merge the values that would come as a string[] into the comma-delimited string and then when retrieving that record for that medication of that patient, display the selected values from the comma-delimited string as selected from the selectableDosageFrequencyList. You assistance in this is greatly appreciated as I am not sure what I am missing here. In the application context, I created the list of possible values as part of the ServiceBean. <property name="selectableDosageFrequencyList"> <set> <value>On an empty stomach</value> <value>Every other day</value> <value>4 times daily</value> <value>3 times daily</value> <value>Twice daily</value> <value>At bedtime</value> <value>With meal</value> <value>As needed</value> <value>Once daily</value> </set> </property> This is set up in the flow as requestscope. <view-state id="addEditMedication" model="medication"> <on-render> <set name="requestScope.selectableDosageFrequencyList" value="memberService.buildSelectableDosageFrequencyList(patient)" /> </on-render> ... <transition on="next" to="assessment" > <evaluate expression="memberService.updateMedication(patient, medication)" /> </transition> </view-state> I have helper methods in the memberService that need to be executed when the form is init and then when the form is completed. //get the form fields selected and build the new string for db public String setSelectedDosageFrequency(String [] dosageFrequencies){ String frequencies = null; if (dosageFrequencies != null){ for (String s : dosageFrequencies){ frequencies = frequencies + "," + s; } } return frequencies; } //get value from database and build selected Set public LinkedHashSet<String> getSelectedDosageFrequencyList(String dosageFrequency){ String copyOfDosages =dosageFrequency;//may not need to do this LinkedHashSet<String> setofSelectedDosageFrequency = new LinkedHashSet<String> (); while (copyOfDosages!= null && copyOfDosages.length()>0){ for (String aFrequency: selectableDosageFrequencyList){ if (copyOfDosages.contains(aFrequency)){ setofSelectedDosageFrequency.add(aFrequency); if (!copyOfDosages.equals(aFrequency) && copyOfDosages.endsWith(aFrequency)){ copyOfDosages.replaceAll(","+aFrequency, ""); }else if (!copyOfDosages.equals(aFrequency) && copyOfDosages.contains(aFrequency=",")){ copyOfDosages.replaceAll(aFrequency+",", ""); }else copyOfDosages.replaceAll(aFrequency, ""); copyOfDosages.trim(); } } } return setofSelectedDosageFrequency; } The Medication class that backs the form will have a variable for dosage-frequency as a string. private String dosageFrequency; The jsp I currently am doing this. <div class="formField"> <form:label path="dosageFrequency">Dosage Frequency</form:label> <ul class="multi-column double" style="width: 550px;"> <form:checkboxes path="dosageFrequency" items="${selectableDosageFrequencyList}" itemLabel="${selectableDosageFrequencyList}" element="li" /> </ul> </div>

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  • richfaces keepAlive not working

    - by Jurgen H
    I have a mediaOutput tag which, in its createContent attribute, requires the backing bean to be in a certain state. A list of values, which is filled in an init method, must be available. I therefore added a keepAlive tag for the whole backing bean. I now indeed see the backingBean in stead of some (richfaces) proxy bean, but the filled list is null again. How to make this possible? I checked that the init method was called and that the list is filled in in the init method. <a4j:keepAlive beanName="myBean" /> <a4j:mediaOutput createContent="#{myBean.writeChart}" ... /> The backing bean public class MyBean implements Serializable { public List list; public void init(ActionEvent event) { // call some resource to fill the list list = service.getItems(); } public void writeChart(final OutputStream out, final Object data) throws IOException { // list is null } // getters & setters }

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  • NetBeans config file

    - by Ockonal
    Hi guys, my NetBeans has ugly fonts in interface. I'm going to make antialiasing for it. In internet I saw that there is should be -J-Dswing.aatext=true -J-Dawt.useSystemAAFontSettings=on in netbeans_default_options. This file should be located in /etc/netbeans.conf. But there isn't this file. I have NetBeans 6.8. Help, please.

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  • Move 3 rectangles up in their X but keep order of rectangles

    - by Nicolas Martel
    I have 3 rectangles being rendered here. Let's say i wanted to move them all above the line yet keep their order, how would i go about that? I tried subtracting the Y and height rather than adding the Y it but as expected, the lower rectangle goes at the top, middle stays in the middle and top goes to the bottom before: after: So is there any simple solution to render them just above rather than having to change all values ?

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  • Restoring web session in struts2

    - by bozo
    Hi, I have a classical scenario of a website and payment gateway integration, where the request for payment is sent to payment processor, and the payment processor calls back my application once it's done with some parameters I passed to it in the original request. Among parameters, we pass jsessionid and we expect that when the remote server makes request to our server (via customer browser redirect to our server) that the session will be the same as the session used to send the initial payment request. This does not happen, we have two different sessions, although the payment processor includes our original jsessionid in the request to us (https://blabla/?jsessionid=something). How should we go about recreating a session in struts2, in the only thing that connects the 'OLD' and 'NEW' session is the jsessionid in the request URL? Any ideas? Is this possible at all or is the 'OLD' session data deleted when the user moves away from our server onto a completely different domain of a payment processor with their data-entry form? This would explain our innability to recreate the session. Thanks a lot for your replies.

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  • What web UI framework is most suitable for building dynamic pages / forms?

    - by waxwing
    Hello, We are at a stage where we are considering different Web UI frameworks (most likely component based ones such as GWT, JSF, Wicket, Vaadin, etc). One of the main use cases / constraints is that it must support generating dynamic pages. I.e., the page/form layout and components is stored in a database and is changeable at runtime, and from this pages are generated. We are also going to write static layouts, but that is not the main focus of this question. I thought maybe the user community here can share experiences of different frameworks in this context. Are there differences in ease of implementation and what is suitable?

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  • Question about decorator pattern and the abstract decorator class?

    - by es11
    This question was asked already here, but rather than answering the specific question, descriptions of how the decorator pattern works were given instead. I'd like to ask it again because the answer is not immediately evident to me just by reading how the decorator pattern works (I've read the wikipedia article and the section in the book Head First Design Patterns). Basically, I want to know why an abstract decorator class must be created which implements (or extends) some interface (or abstract class). Why can't all the new "decorated classes" simply implement (or extend) the base abstract object themselves (instead of extending the abstract decorator class)? To make this more concrete I'll use the example from the design patterns book dealing with coffee beverages: There is an abstract component class called Beverage Simple beverage types such as HouseBlend simply extend Beverage To decorate beverage, an abstract CondimentDecorator class is created which extends Beverage and has an instance of Beverage Say we want to add a "milk" condiment, a class Milk is created which extends CondimentDecorator I'd like to understand why we needed the CondimentDecorator class and why the class Milk couldn't have simply extended the Beverage class itself and been passed an instance of Beverage in its constructor. Hopefully this is clear...if not I'd simply like to know why is the abstract decorator class necessary for this pattern? Thanks. Edit: I tried to implement this, omitting the abstract decorator class, and it seems to still work. Is this abstract class present in all descriptions of this pattern simply because it provides a standard interface for all of the new decorated classes?

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  • Update JProgressBar from new Thread

    - by Dacto
    How can I update the JProgressBar.setValue(int) from another thread? My secondary goal is do it in the least amount of classes possible. Here is the code I have right now: **Part of the main class....** pp.addActionListener( new ActionListener(){ public void actionPerformed(ActionEvent event) { new Thread(new Task(sd.getValue())).start(); } }); public class Task implements Runnable{ int val; public Task(int value){ this.val = value; } @Override public void run() { for (int i=0; i<=value; i++){ //Progressively increment variable i pbar.setValue(i); //Set value pbar.repaint(); //Refresh graphics try{Thread.sleep(50);} //Sleep 50 milliseconds catch (InterruptedException err){} } } } pp is a JButton and starts the new thread when the JButton is clicked. pbar is the JProgressBar object from the Main class. How can I update its value?(progress) The code above in run() cannot see the pbar.

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  • SWT Drag and Drop support for Text widget

    - by bryantsai
    I've written an application recently using SWT. In one of its dialog box, I have a few widgets, one of which is Text, which is designed to support DND with other widgets. I've first added DND support for the 2 Tree widgets on the same dialog box (both drag source and drop target). Before I added DND support for that Text widget, I noticed that on Linux platform (gtk), SWT Text widget automatically get drag and drop support. That is, I can already drag from the other Tree widgets and drop on this Text (at any position to inserted there), as well as selecting and dragging any text from this Text to other Tree or Text widget. However, this is only working on Linux platform but not on Windows. The same program, if running on Windows, will not have any DND support for that Text widget (Tree widgets of course have DND support since I specifically write for them). So here's what I want to achieve on Windows as well: drop text at any position in Text widget. before dropping and while hovering, able to see the caret position clearly where the intended position to drop. caret position should move along with the mouse cursor. support multi-line in Text widget SOLUTION: DropTarget target = new DropTarget(sytledText, DND.DROP_MOVE | DND.DROP_COPY); target.setTransfer(new Transfer[] { TextTransfer.getInstance() }); target.addDropListener(new StyleTextDropTargetEffect(sytledText)); Use StyledText instead of Text widget Use StyledTextDropTargetEffect (or extend it) and add it as dr op listener

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  • JSF 2.0 method invocation with argument from var of dataGrid

    - by little_b
    Hello I use primefaces with facelets and i have a quastion: for example i have dataGrid and i want to call method of bean, that registered in faces-config, to include some dynamic content: <p:dataGrid var="provider" value="#{paymentFormBean.providers}"> <ui:include src="contentFactory.getSpecificForm('some attribute')"/> </p:dataGrid> How could i invoke getSpecificForm method with argument from var of dataGrid? Something like: <p:dataGrid var="provider" value="#{paymentFormBean.providers}"> <ui:include src="contentFactory.getSpecificForm(provider.formName)"/> </p:dataGrid> Could anyone help me? Thank you

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