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  • JTextField that has inner fields or preformated format, something like the ip field in windows

    - by dimitar
    Hello guys, i want to create a text field that will be for date and will have dd.mm.YYYY format. Now what i want to do is the user to type only the numbers, not the dots to. So the field would be like: _ _. _ _ . _ _ _ _ So when the user wants to type the date: 15.05.2010 for example, he will only type the numbers in the sequence 15052010. Also i would like, when he preses on left or right arrow, the cursor to go from one field(not JTextField, but field in the JTextField). So lets say i have JTextField with text in it: 15.05.2010, so if user is on the beginning and he preses right arrow, the cursor to go to the .05 field. I hope you understand me 'cos right now i don't any idea how to make this, or at least how to look for it on google. Thank you.

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  • simple process rollback question

    - by OckhamsRazor
    hi folks! while revising for an exam, i came across this simple question asking about rollbacks in processes. i understand how rollbacks occur, but i need some validation on my answer. The question: my confusion results from the fact that there is interprocess communication between the processes. does that change anything in terms of where to rollback? my answer would be R13, R23, R32 and R43. any help is greatly appreciated! thanks!

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  • Are multiply-thrown Exceptions checked or runtime?

    - by froadie
    I have an Exception chain in which method1 throws an Exception to method2 which throws the Exception on to main. For some reason, the compiler forces me to deal with the error in method2 and marks it as an error if I don't, indicating that it's a checked Exception. But when the same Exception is thrown further down the line to main, the compiler allows me to ignore it and doesn't display any errors. The original Exception in method1 is a ParseException, which is checked. But the method has a generic throws Exception clause in the header, and the same object is thrown to method2, which has an identical throws Exception clause. When and how does this Exception lose the status of being checked / caught by the compiler? Edited to clarify: public void method1() throws Exception{ // code that may generate ParseException } public void method2() throws Exception{ method1(); //compiler error } public static void main(String[] args){ method2(); //ignored by compiler }

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  • Is using the break statement bad practice?

    - by Lchi
    I've been told by professors and peers at my university that using the break statement is bad practice, but through my coursework haven't come up with a great reason why. Those who claim that it is bad say that it's a "get out of jail free card" and that you can always avoid using it. My guesses for why its considered bad would be that you could possibly skip some cleanup code after the break, or similarly exit some control structure in an inconsistent state. Is there any reason why using break is(n't) bad practice?

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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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  • Best way to implement refusing a value change by the user in Swing?

    - by Michael Borgwardt
    I have a JCheckBox that should not be checked by the user when a certain other field is empty. So now I want to have an error popup and then reset the checkbox (I've considered disabling the checkbox, but the connection to the other field is non-obvious, and a tooltip text IMO not visible enough). What's the correct way to do that in Swing? Through a PropertyVetoException? Where do I throw it and where do I catch it? My first (probably ugly) idea would be to add a ChangeListener that itself shows the popup and resets the value.

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  • JVMTI: FollowReferences : how to skip Soft/Weak/Phantom references?

    - by Jayan
    I am writing a small code to detect number of objects left behind after certain actions in our tool. This uses FollowReferences() JVMTI-API. This counts instances reachable by all paths. How can I skip paths that included weak/soft/phantom reference? (IterateThroughHeap counts all objects at the moment, so the number is not fully reliable) Thanks, Jayan

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  • Why aren't arrays expandable?

    - by Mustafa
    When we create an array, we cannot change its size; it's fixed. OK, seems nice, we can create a new bigger array and copy the values one by one and that's little slow. What's the technical background of it?

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  • Inheritance or identifier

    - by Lina
    Hi! Does anyone here have opinions about when to user inheritance and when to use an identifier instead? Inheritance example: class Animal { public int Name { get; set; } } class Dog : Animal {} class Cat : Animal {} Identifier example: class Animal { public int Name { get; set; } public AnimalType { get; set; } } In what situations should i prefer which solution and what are the pros and cons for them? /Lina

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  • Hibernate: Querying objects by attributes of inherited classes

    - by MichaelD
    Hi all, I ran into a problem with Hibernate concerning queries on classes which use inheritance. Basically I've the following class hierarchy: @Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } The hierarchy is already given like this and I cannot change it easily. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes which sometimes even have the same names (but I can't move them to ClassA since there are possible more sub-classes which do not use them). The Recording class references one instance of one of this classes. Now my question: What I want to do is selecting all Recording objects in my database which refer to an instance of either ClassB1 or ClassB2 with e.g. the field P1300 == 15.5 (so this could be ClassB1 or ClassB2 instances since the P1300 attribute is declared in both classes). What I tried is something like this: Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); But since P1300 is not an attribute of ClassA hibernate throws an exception telling me: could not resolve property: P1300 of: ClassA How can I tell hibernate that it should search in all subclasses to find the attribute I want to filter? Thanks MichaelD

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  • ArrayBlockingQueue - How to "interrupt" a thread that is wating on .take() method

    - by bernhard
    I use an ArrayBlockingQueue in my code. Clients will wait untill an element becomes available: myBlockingQueue.take(); How can I "shutdown" my service in case no elements are present in the queue and the take() ist wating indefenitely for an element to become available? This method throws an InterruptedException. My question is, how can I "evoke" an Interrupted Exception so that take() will quit? (I also tought about notify(), but it seems I doesnt help here..) I know I could insert an special "EOF/QUIT" marker Element but is this really the only solution? UPDATE (regarding the comment, that points to another question with two solutions: one mentioned above using a "Poisoning Pill Object" and the second one is Thread.interrupt(): The myBlockingQueue.take() is used NOT in a Thread (extending Thread) but rather implements Runnable. It seems a Runnable does not provide the .interrupt() method? How could I interrupt the Runnable? Million Thanks Bernhard

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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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  • How to remove duplicate line in a file

    - by Abs
    Hi I'm using the below method to write to a file from the Jtextarea and I call this method every 30 second within a Timer but instead to add only new line in file it rewrite the entire lines contained in Jtextarea so then I have duplicate lines. I want to avoid this and update the file just with new lines. Could you help me please. public void loger() { FileWriter writer = null; try { writer = new FileWriter("MBM_Log_"+date()+".txt" , true); textArea.write(writer); } catch (IOException exception) { System.err.println("log error"); exception.printStackTrace(); } finally { if (writer != null) { try { writer.close(); } catch (IOException exception) { System.err.println("Error closing writer"); exception.printStackTrace(); } } } }

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  • Questions about serving static files from a servlet

    - by Geo
    I'm very new to servlets. I'd like to serve some static files, some css and some javascript. Here's what I got so far: in web.xml: <servlet> <description></description> <display-name>StaticServlet</display-name> <servlet-name>StaticServlet</servlet-name> <servlet-class>StaticServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>StaticServlet</servlet-name> <url-pattern>/static/*</url-pattern> </servlet-mapping> I'm assuming in the StaticServlet I'd have to work with request.getPathInfo to see what was requested, get a mime type, read the file & write it to the client. If this is not the way to go, or is not a viable way of doing things, please suggest a better way. I'm not really sure where to place the static directory, because if I try to print new File(".") it gives me the directory of my Eclipse installation. Is there a way to find out the project's directory?

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  • logging problems for swing applications

    - by mengmenger
    what kind of logging frame work or API to use for swing applications which is used by multiple users in Unix. Is it possible to log all verbose/exception in one file per day or event one user one file per day? Since the user can open the same application with multiple instance. I also have another solution is to save the exceptions into database. But if I miss the excetpions, those will not be saved in DB. anybody has better solutions? Thank you very much!

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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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  • 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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  • Does Hibernate always need a setter when there is a getter?

    - by Marcus
    We have some Hibernate getter methods annotated with both @Column and @Basic. We get an exception if we don't have the corresponding setter. Why is this? In our case we are deriving the value returned from the getter (to get stored in the DB) and the setter has no functional purpose. So we just have an empty method to get around the error condition..

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  • how to know which special character is there in a file?

    - by Pangea
    My app needs to process text files during a batch process. Occassionally I receive a file with some special character at the end of the file. I am not sure what that special character is. Is there anyway I can find what that character is so that I can tell the other team which is producing that file. I have used mozilla's library to guess the file encoding and it says UTF-8.

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  • inline images in email using javamail

    - by manu1001
    I want to send an email with an inline image using javamail. I'm doing something like this. MimeMultipart content = new MimeMultipart("related"); BodyPart bodyPart = new MimeBodyPart(); bodyPart.setContent(message, "text/html; charset=ISO-8859-1"); content.addBodyPart(bodyPart); bodyPart = new MimeBodyPart(); DataSource ds = new ByteArrayDataSource(image, "image/jpeg"); bodyPart.setDataHandler(new DataHandler(ds)); bodyPart.setHeader("Content-Type", "image/jpeg; name=image.jpg"); bodyPart.setHeader("Content-ID", "<image>"); bodyPart.setHeader("Content-Disposition", "inline"); content.addBodyPart(bodyPart); msg.setContent(content); I've also tried bodyPart.setHeader("inline; filename=image.jpg"); and bodyPart.setDisposition("inline"); but no matter what, the image is being sent as an attachment and the Content-Dispostion is turning into "attachment". How do I send an image inline in the email using javamail?

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  • Regex to match CSV file nested quotes

    - by user361970
    Hi, I know this has been discussed a million times. I tried searching through the forums and have seen some close regex expressions and tried to modify them but to no avail. Say there is a line in a csv file like this: "123", 456, "701 "B" Street", 910 Is there an easy regex to detect "B" (since its a non-escaped set of quotes within the normal CSV quotes) and replace it with something like \"B\" ? The final string would end up looking like this: "123", 456, "701 \"B\" Street", 910 Help would be greatly appreciated!

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  • Loading data in constructors and not in constructors

    - by Richeve S. Bebedor
    I just want to know the difference between loading the data inside the constructor and loading the data outside the constructor but not inside any methods example: Loading inside constructor public class Model{ Object testobject; public Model(){ testobject=new Object(); } } VS example: Loading outside constructor public class Model{ Object testobject=new Object(); public Model(){ } }

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  • How to move point on arc?

    - by bbZ
    I am writing an app that is simulating RobotArm movement. What I want to achieve, and where I have couple of problems is moving a Point on arc (180degree) that is arm range of movement. I am moving an arm by grabbing with mouse end of arm (Elbow, the Point I was talking about), robot can have multiple arms with diffrent arm lenghts. If u can help me with this part, I'd be grateful. This is what I have so far, drawing function: public void draw(Graphics graph) { Graphics2D g2d = (Graphics2D) graph.create(); graph.setColor(color); graph.fillOval(location.x - 4, location.y - 4, point.width, point.height); //Draws elbow if (parentLocation != null) { graph.setColor(Color.black); graph.drawLine(location.x, location.y, parentLocation.x, parentLocation.y); //Connects to parent if (arc == null) { angle = new Double(90 - getAngle(parentInitLocation)); arc = new Arc2D.Double(parentLocation.x - (parentDistance * 2 / 2), parentLocation.y - (parentDistance * 2 / 2), parentDistance * 2, parentDistance * 2, 90 - getAngle(parentInitLocation), 180, Arc2D.OPEN); //Draws an arc if not drawed yet. } else if (angle != null) //if parent is moved, angle is moved also { arc = new Arc2D.Double(parentLocation.x - (parentDistance * 2 / 2), parentLocation.y - (parentDistance * 2 / 2), parentDistance * 2, parentDistance * 2, angle, 180, Arc2D.OPEN); } g2d.draw(arc); } if (spacePanel.getElbows().size() > level + 1) {//updates all childElbows position updateChild(graph); } } I just do not know how to prevent moving Point moving outside of arc line. It can not be inside or outside arc, just on it. Here I wanted to put a screenshot, sadly I don't have enough rep. Am I allowed to put link to this? Maybe you got other ways how to achieve this kind of thing. Here is the image: Red circle is actual state, and green one is what I want to do. EDIT2: As requested, repo link: https://github.com/dspoko/RobotArm

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