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  • How to deferentiate between Programmer and JVM Exceptions

    - by Haxed
    As the title suggests, how can I tell a JVM thrown exception from a Programmatically(does this mean, thrown by a programmer or the program) thrown exception ? JVM Exceptions 1) ArrayIndexOutOfBoundsException 2) ClassCastException 3) NullPointerException Programmatically thrown 1) NumberFormatException 2) AssertionError Many Thanks

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  • Partially constructed object / Multi threading

    - by reto
    Heya! I'm using joda due to it's good reputation regarding multi threading. It goes great distances to make multi threaded date handling efficient, for example by making all Date/Time/DateTime objects immutable. But here's a situation where I'm not sure if Joda is really doing the right thing. It probably is correct, but I'd be very interested to see the explanation for it. When a toString() of a DateTime is being called Joda does the following: /* org.joda.time.base.AbstractInstant */ public String toString() { return ISODateTimeFormat.dateTime().print(this); } All formatters are thread safe, as they are as well ready-only. But what's about the formatter-factory: private static DateTimeFormatter dt; /* org.joda.time.format.ISODateTimeFormat */ public static DateTimeFormatter dateTime() { if (dt == null) { dt = new DateTimeFormatterBuilder() .append(date()) .append(tTime()) .toFormatter(); } return dt; } This is a common pattern in single threaded applications. I see the following dangers: Race condition during null check -- worst case: two objects get created. No Problem, as this is solely a helper object (unlike a normal singleton pattern situation), one gets saved in dt, the other is lost and will be garbage collected sooner or later. the static variable might point to a partially constructed object before the objec has been finished initialization (before calling me crazy, read about a similar situation in this Wikipedia article. So how does Joda ensure that not partially created formatter gets published in this static variable? Thanks for your explanations! Reto

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  • Ubuntu terminal questions

    - by Camran
    I am wondering about my VPS providers ubuntu terminal. Are all these terminals the same? I think they are so user-UN-friendly. I can't copy-paste into the terminal, when I try opening textfiles, I can't scroll up and down easily. I cant save easily. Nothing is easy... Is it always like this with Ubuntu? Is there any way to make it easier? I use windows but I login to my vps provider with login details and then simply click "terminal" to open the terminal. Please help me out here

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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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  • Display the message depend on time

    - by sairam333
    Hi i am getting current time using the following statements Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); String b= sdf.format(cal.getTime()); Now I want to display the message as if time is before 12 Good Morning like that......... for this how can i compare that time with integers 1 , 12,16 like that. Thanks in advance

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  • How do I implement a listener pattern over RMI using Spring?

    - by predhme
    So here is a generalized version of our application desgin: @Controller public class MyController { @Autowired private MyServiceInterface myServiceInterface; @RequestMapping("/myURL") public @ResponseBody String doSomething() { MyListenerInterface listener = new MyListenerInterfaceImpl(); myServiceInterface.doThenCallListener(listener); // do post stuff } } public interface MyListenerInterface { public void callA(); public void callB(); } public class MyListenerInterfaceImpl implements MyListenerInterface { // ... omitted for clarity } public interface MyServiceInterface { public void doThenCallListener(MyListenerInterface listener); } public class MyServiceImpl { public void doThenCallListener(MyListenerInterface listener) { // do stuff listener.callA(); } } Basically I have a controller that is being called via AJAX in which I am looking to return a response as a string. However, I need to make a call to the backend (MyServiceInterface). That guy is exposed through RMI by using Spring (man that was easy). But the service method as described requires a listener to be registered for invokation completion purposes. So what I assume I need to achieve is transparently to the backend make it so that when the listener methods are called, really the call is going over RMI. I would have thought Spring would have a simple way to wrap a POJO (not a service singleton) with RMI calls. I looked through their documentation but they had nothing besides exposing services via RMI. Could someone point me in the right direction?

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  • Changing the direction of a Combo box dropdown in SWT

    - by Kris
    Hi, I'm building an Eclipse plugin in SWT, and I have the following problem: one of my fields is a combo box, and in some cases it may have fairly long items as selection options. My plugin runs on the right side of the screen, so when you go to use the combo-box, the right side of the combo box is cut off. So, my question is: is there any way to change the dropdown's alignment relative to the combo control? It seems to be permanently left-aligned... and I'm pretty sure you can change the direction in Swing (though the only place I've seen it done is in the Substance UI demo. The Combo Box tab has boxes with North, South East, and West flyout directions... for my application, I need something like the West flyout) Note: Setting actual text limits is a last-case-scenario option; it would be quite a bit of guesswork to set the text limit dynamically (since the widget's view can be resized). Here's a picture (sorry, I can only have one link and no images :( ... I need some more rep :p) Left side of the line: Proper width - the view is the wide enough for the combo dropdown to display all the text; you can see the scrollbars on the right side. Right side of the line: Too small - Here, the view has been resized, and the combo dropdown scrollbar (as well as some of the text) is cut off by the right side of the screen. I always have more screen space available to the left (since this is always on the right hand side of the screen), but the combo dropdown always appears to the lower right. Hopefully this is clear enough.

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  • Configuring a Context specific Tomcat Security Realm

    - by Andy Mc
    I am trying to get a context specific security Realm in Tomcat 6.0, but when I start Tomcat I get the following error: 09-Dec-2010 16:12:40 org.apache.catalina.startup.ContextConfig validateSecurityRoles INFO: WARNING: Security role name myrole used in an <auth-constraint> without being defined in a <security-role> I have created the following context.xml file: <Context debug="0" reloadable="true"> <Resource name="MyUserDatabase" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/my-users.xml" /> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="MyUserDatabase"/> </Context> Created a file: my-users.xml which I have placed under WEB-INF/conf which contains the following: <tomcat-users> <role rolename="myrole"/> <user username="test" password="changeit" roles="myrole" /> </tomcat-users> Added the following lines to my web.xml file: <web-app ...> ... <security-constraint> <web-resource-collection> <web-resource-name>Entire Application</web-resource-name> <url-pattern>/*</url-pattern> </web-resource-collection> <auth-constraint> <role-name>myrole</role-name> </auth-constraint> </security-constraint> <login-config> <auth-method>BASIC</auth-method> </login-config> ... </web-app> But seem to get the error wherever I put conf/my-users.xml. Do I have to specify an explicit PATH in the pathname or is it relative to somewhere? Ideally I would like to have it packaged up as part of my WAR file. Any ideas?

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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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  • How could I send live video stream to remote server from my phone !!!

    - by poc
    Hello , I have a problem about streaming my video to server in real-time from my phone. that is , let my phone be a IP Camera , and server can watch the live video from my phone I have googled many many solutions, but there is no one can solve my problem. I use MediaRecorder to record . it can save video file in the SD card correctly. then , I refered this page and used some method as followings skt = new Socket(InetAddress.getByName(hostname),port); pfd =ParcelFileDescriptor.fromSocket(skt); mediaRecorder.setOutputFile(pfd.getFileDescriptor()); now it seems I can send the video stream while recording however, I wrote a receiver-side program to receive the video stream from Android , but it doesn't work . is there any error? I can receive file , but I can not open the video file . I guess the problem may caused by file format ? there are outline of my code. in android side Socket skt = new Socket(hostIP,port); ParcelFileDescriptor pfd =ParcelFileDescriptor.fromSocket(skt); .... .... mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT); mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4); mediaRecorder.setOutputFile(pfd.getFileDescriptor()); ..... mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT); mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP); ..... mediaRecorder.start(); in receiver side (my ACER notebook) // anyway , I don't think the file extentions will do any effect File video = new File (strDate+".3gpp"); FileOutputStream fos; try { fos = new FileOutputStream(video); byte[] data = new byte[1024]; int count =-1; while( (count = fin.read(data,0,1024) ) !=-1) { fos.write(data,0,count); fos.flush(); } fos.close(); fin.close(); I confused a long time.... thanks in advance

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  • dynamically change bitmap in imageView, android

    - by Junfei Wang
    All, I have a problem related to imageView, android. I have array which contains of 10 bitmap objects, called bm. I have a imageView, called im. Now I wanna show the bitmaps in the array in im one by one, so I did the following: new Thread(new Runnable() { public void run() { for(int j=0;j<10;j++){ im.setImageBitmap(bm[j]); } } }).start(); But the result only shows the last bitmap in the array. Can someone tell me what to do with this issue? Millions of thanks!

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  • Catching constraint violations in JPA 2.0.

    - by Dennetik
    Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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  • How do I define and standardize units in my 3D app?

    - by Omega
    I'm starting to design my object graph for an OpenGL ES 1.1 on Android. What's advisable when it comes to actually drawing my triangles when it comes to controlling their size? Should I store all the vertices in units relative to each other and then multiply them by a value I pass during a draw(GL10 gl)? Would this approach have any impact when it comes time to do frustum culling?

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  • Need to map classes to different databases at runtime in Hibernate

    - by serg555
    I have MainDB database and unknown number (at compile time) of UserDB_1, ..., UserDB_N databases. MainDB contains names of those UserDB databases in some table (new UserDB can be created at runtime). All UserDB have exactly the same table names and fields. How to handle such situation in Hibernate? (database structure cannot be changed). Currently I am planning to create generic User classes not mapped to anything and just use native SQL for all queries: session.createSQLQuery("select * from " + db + ".user where id=1") .setResultTransformer(Transformers.aliasToBean(User.class)); Is there anything better I can do? Ideally I would want to have mappings for UserDB tables and relations and use HQL on required database.

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  • Stripes link event triggering validation that is incorrect.

    - by Davoink
    I have stripes:link tag in a jsp with an event attribute: <stripes:link href="${actionBean.context.currentStage.stripesForwardAction}" addSourcePage="true" event="showTab2Link"> This triggers the validation to trigger on nested properties: @ValidateNestedProperties({ @Validate(field="county", required=true, minlength=2, maxlength=2, mask="\\d\\d"), @Validate(field="parish", required=true, minlength=3, maxlength=3, mask="\\d\\d\\d"), @Validate(field="holding", required=true, minlength=4, maxlength=4, mask="\\d\\d\\d\\d") }) However this would been fine if the actual values it is validation are not present, but they are present within the html and when debugging the bean. Why would the stripes:link trigger this? If I change it to an stripes:submit then it is fine. thanks, Dave

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  • JSF don't find component in view root with the form id

    - by kenzokujpn
    I have a t:inputFileUpload inside the form, in the html of the display page the id of this component is form:inputFile but when I tried to get the component from the view root using "form:inputFile" the return is null, but when the "form:" is removed the return is the component. The component don't set the value in my managed bean, someone have this problem? EDIT: <h:form id="form" enctype="multipart/form-data"> <t:inputFileUpload id="inputFile" size="40" value="#{managedBean.inputFile}"/> </h:form> In the managed bean: private UploadedFile inputFile; with the gets and sets provided by Eclipse. //This method scans the view root and returns the component with the id passed as parameter findComponentInRoot("form:inputFile"); This returns null, but when I use: //This method scans the view root and returns the component with the id passed as parameter findComponentInRoot("inputFile"); The return is the component I'm looking for, but when I use the View Source in Internet Explorer the id of this component is "form:inputFile". I don't know if this is related, but the component don't set the value in my managed bean and it's strange the fact that the id of the component is different from the HTML source. I'm using JSF 1.2 Mojarra. Someone else has this problem? Or know why this happens?

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  • Android Convert Video To MP4

    - by Isaac Waller
    I have a Android app. It recieves videos in .flv format which is unplayable by the Android phone. I was wondering how to convert the file to MP4. I could use FFMPEG, but I do not know how I would get it onto the phone, and how it would work on multiple phones if it was compiled for a single one.

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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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  • Recursion Question : Revision

    - by stan
    My slides say that: A recursive call should always be on a smaller data structure than the current one There must be a non recursive option if the data structure is too small You need a wrapper method to make the recursive method accessible Just reading this from the slides makes no sense, especially seeing as it was a topic from before christmas! Could anyone try and clear up what it means please? Thank you

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  • Cleanly handling events

    - by nkr1pt
    I have code similar to this in all my observer classes that handle events fired by an event bus class. As you can see there are a lot of instanceof checks to choose the path of action needed to appropriately handle events, and I was wondering if this could be done more cleanly, eliminating the instanceof tests? @Override public void handleEvent(Event event) { if (event instanceof DownloadStartedEvent) { DownloadStartedEvent dsEvent = (DownloadStartedEvent)event; dsEvent.getDownloadCandidateItem().setState(new BusyDownloadingState()); } else if (event instanceof DownloadCompletedEvent) { DownloadCompletedEvent dcEvent = (DownloadCompletedEvent)event; dcEvent.getDownloadCandidateItem().setState(new FinishedDownloadingState()); DownloadCandidate downloadCandidate = dcEvent.getDownloadCandidateItem(). getDownloadCandidate(); if (downloadCandidate.isComplete()) { // start extracting } } else if (event instanceof DownloadFailedEvent) { DownloadFailedEvent dfEvent = (DownloadFailedEvent)event; dfEvent.getDownloadCandidateItem().setState(new FailedDownloadingState()); } }

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  • Compute weighted averages for large numbers

    - by Travis
    I'm trying to get the weighted average of a few numbers. Basically I have: Price - 134.42 Quantity - 15236545 There can be as few as one or two or as many as fifty or sixty pairs of prices and quantities. I need to figure out the weighted average of the price. Basically, the weighted average should give very little weight to pairs like Price - 100000000.00 Quantity - 3 and more to the pair above. The formula I currently have is: ((price)(quantity) + (price)(quantity) + ...)/totalQuantity So far I have this done: double optimalPrice = 0; int totalQuantity = 0; double rolling = 0; System.out.println(rolling); Iterator it = orders.entrySet().iterator(); while(it.hasNext()) { System.out.println("inside"); Map.Entry order = (Map.Entry)it.next(); double price = (Double)order.getKey(); int quantity = (Integer)order.getValue(); System.out.println(price + " " + quantity); rolling += price * quantity; totalQuantity += quantity; System.out.println(rolling); } System.out.println(rolling); return totalQuantity / rolling; The problem is I very quickly max out the "rolling" variable. How can I actually get my weighted average? Thanks!

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  • Remove Empty Attributes from XML

    - by er4z0r
    Hi, I have a buggy xml that contains empty attributes and I have a parser that coughs on empty attributes. I have no control over the generation of the xml nor over the parser that coughs on empty attrs. So what I want to do is a pre-processing step that simply removes all empty attributes. I have managed to find the empty attribus, but now I don't know how to remove them: XPathFactory xpf = XPathFactory.newInstance(); XPath xpath = xpf.newXPath(); XPathExpression expr = xpath.compile("//@*"); Object result = expr.evaluate(d, XPathConstants.NODESET); if (result != null) { NodeList nodes = (NodeList) result; for(int node=0;node<nodes.getLength();node++) { Node n = nodes.item(node); if(isEmpty(n.getTextContent())) { this.log.warn("Found empty attribute declaration "+n.toString()); NamedNodeMap parentAttrs = n.getParentNode().getAttributes(); parentAttrs.removeNamedItem(n.getNodeName()); } } } This code gives me a NPE when accessing n.getParentNode().getAttributes(). But how can I remove the empty attribute from an element, when I cannot access the element?

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