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  • Singletons vs. Application Context in Android?

    - by mschonaker
    Recalling this post enumerating several problems of using singletons and having seen several examples of Android applications using singleton pattern, I wonder if it's a good idea to use Singletons instead of single instances shared through global application state (subclassing android.os.Application and obtaining it through context.getApplication()). What advantages/drawbacks would have both mechanisms? To be honest, I expect the same answer in this post http://stackoverflow.com/questions/2709071/singleton-pattern-with-web-application-not-a-good-idea but applied to Android. Am I correct? What's different in DalvikVM otherwise? EDIT: I would like to have opinions on several aspects involved: Synchronization Reusability Testing Thanks in advance.

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  • Has anyone tried the "objectify" library for Google App Engine?

    - by Spines
    I was using JDO for my google app engine project but got fed up with the additional 5 seconds it adds to my cold start time. I was planning on just writing stuff directly to the database with the low level datastore api, but then I came accross the objectify project ( http://code.google.com/p/objectify-appengine/ ). Apparently its a super light wrapper above the low level api. Does anyone have experiences with this library that they could share?

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  • Refactoring common method header and footer

    - by David Wong
    I have the following chunk of header and footer code appearing in alot of methods. Is there a cleaner way of implementing this? Session sess = factory.openSession(); Transaction tx; try { tx = sess.beginTransaction(); //do some work ... tx.commit(); } catch (Exception e) { if (tx!=null) tx.rollback(); throw e; } finally { sess.close(); } The class in question is actually an EJB 2.0 SessionBean which looks like: public class PersonManagerBean implements SessionBean { public void addPerson(String name) { // boilerplate // dostuff // boilerplate } public void deletePerson(Long id) { // boilerplate // dostuff // boilerplate } }

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  • How to use a delay in a swing application

    - by M.R.
    I am building a swing application. At some point, I have to start an "animation": ... jpanel1.setBackground(Color.Black); Delay(milli) jpanel1.setBackground(Color.White); ... and so on. The gui itself and all the logic behind it work.It is just this time depended color-changing that does not. I have read, that swing is not thread safe, but all the examples I found showed me how to start another thread (for example in the background) but never how to stop the current swing-gui thread.

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  • Does NavigationHandler.handleNavigation() clear the flash?

    - by kgrad
    I am using JSF2.0 Mojarra 2.0.2. I have a method that logs out a user and puts a logout message in the flash, forwards to the login page (which has a div that prints out the flash). However, when I use navigationHandlers handleNavigation method for some reason the flash is not being displayed. I have a similar method that forwards a user to the login page if he/she isn't logged in. If I handle the navigation through an h:link and just call the logout method directly, the flash is displayed as normal, but if I use the handleNavigation() method, the flash is cleared for some reason. The code in question is: public void performLogout() { getFacesContext().getExternalContext().invalidateSession(); setCurrentUser(null); getFlash().put("notice", "Successfully logged out."); super.getFacesContext().getApplication().getNavigationHandler() .handleNavigation(getFacesContext(), null, "login"); } Is there some way I can keep the flash when navigating like this? thanks.

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  • How to face observable object containing an observable field

    - by iseek
    Hello, I need a hint concerning MVC and Observer-Pattern. For example a model contains the classes "Address" and "Person". The Address class contains the fields street:String, zipcode:String, location:String. Whereas the Person class contains the fields name:String, firstName:String, address:Address. My approach so far looks something like this: Both, Address and Person are observable. If one of their setters is being called, I validate whether the current value and new value differ. Only in this case an update event is fired. The event contains the source, the name of the changed field, the old and the new value. The class for the view contains text fields to display and edit the information of a person: name, firstname, street, zipcode, location. It knows the Person model and is an subscribed observer for the person. So it gets the update events from the person object. My questions concerns the address field from type Address in the person class, since an address is observable on its own. If the view gets an update event from person when a new address has been set, I can update all of the address related fields in the view. But what if a field of the address changes? Should the view also register for update events from the address? Any hints about common design approaches would be appreciated. Greetings.

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  • Hibernate is performing unwanted SELECTs on call to saveOrUpdate

    - by digiarnie
    Let's say I have a House entity which maps to many Person entities. I then load an existing House which has 20 occupants. beginTransaction(); House house = houseDao.find(1L); commitTransaction(); Later in the code, I can then add a new Person to the House: ... List<Person> people = house.getPeople(); people.add(new Person("Dilbert")); .... When I make the call: session.saveOrUpdate(house); Hibernate performs 21 queries: 1 to SELECT the House and 20 to SELECT each existing Person in the House. I'm sure it's a small issue on my part, however, what should I do so that I can add a new Person to the house without having such a heavy hit on the database in this situation? This is all done within the same session.

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  • any way to use ajax with jstl customtags without duplicating tags in javascript?

    - by CodeMonkeyB
    I am working on a page where part of the content is loaded normally and the pages are rendered using jsps. The product images and links generated on that page are by custom jstl tags. When the user scrolls more products are requested from the server in a JSON response and then using UnderscoreJS templates they are rendered and added to the bottom of the page. Is there any way I can use the JSTL tags in Javascript without recreating them using a javascript function (it won't be possible to re-create all of them in javascript). What is the best way to handle this scenario? I guess I could return a rendered html response for the ajax call, but that would mean I have some ajax requests which use json and some that use rendered html...

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  • Is it possible to optimize maven dependencies automatically?

    - by AlexR
    I am working on a big project that consists of about 40 sub-projects with very not optimized dependencies. There are declared dependencies that are not in use as well as used but undeclared dependencies. The second case is possible when dependency is added via other dependency. I want to remove redundant and add required dependencies. I ran mvn dependency:analyze and got a long list of warnings I have to fix now. I wonder whether there is maven plugin or any other utility that can update my pom.xml files automatically. I tried to do it manually but it takes a lot of time. It seems it will take a couple of days of copy/paste to complete the task. In worse case I can write such script myself but probably ready stuff exists? Here is how mvn dependency:analyze reports dependency warnings: [WARNING] Used undeclared dependencies found: [WARNING] org.apache.httpcomponents:httpcore:jar:4.1:compile [WARNING] Unused declared dependencies found: [WARNING] commons-lang:commons-lang:jar:2.4:compile [WARNING] org.json:json:jar:20090211:compile

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  • Whats wrong with this method?

    - by David
    Here's the method: public static String CPUcolor () { System.out.println ("What color am I?") ; String s = getIns() ; System.out.println ("are you sure I'm "+s+"? (Y/N)") ; String a = getIns() ; while (!((a.equals ("y")) || (a.equals ("Y")) || (a.equals ("n")) || (a.equals ("N")))) { System.out.println ("try again") ; a = getIns () ; } if (a.equals ("n") || a.equals("N")) {CPUcolor() ;} System.out.println ("I am "+s) ; return s ; } here is a possible output of this method (y's and n's are user inputs): What color am I? red are you sure I'm red? (Y/N) N What color am I? blue are you sure I'm blue? (Y/N) N What color am I? Yellow are you sure I'm Yellow? (Y/N) y I am Yellow I am blue I am red Why is it that the line's "I am blue" and "I am Blue" printed? Why are they printed in reverse order with red, the first entered, printed last?

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  • why Observable snapshot observer vector

    - by han14466
    In Observable's notifyObservers method, why does the coder use arrLocal = obs.toArray();? Why does not coder iterate vector directly? Thanks public void notifyObservers(Object arg) { Object[] arrLocal; synchronized (this) { /* We don't want the Observer doing callbacks into * arbitrary code while holding its own Monitor. * The code where we extract each Observable from * the Vector and store the state of the Observer * needs synchronization, but notifying observers * does not (should not). The worst result of any * potential race-condition here is that: * 1) a newly-added Observer will miss a * notification in progress * 2) a recently unregistered Observer will be * wrongly notified when it doesn't care */ if (!changed) return; arrLocal = obs.toArray(); clearChanged(); } for (int i = arrLocal.length-1; i>=0; i--) ((Observer)arrLocal[i]).update(this, arg); }

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  • Help file not working

    - by meryl
    Hi, can anyone help me ? I wanto to play an audio file and whenever I press the stop button , the already played part of the file should be saved. Unfortunately , what I get is an audio file (.wav) which actually is unplayable. Thanks //**************************** void play_cut() { try { // First, we get the format of the input file final AudioFileFormat.Type fileType = AudioSystem.getAudioFileFormat(inputAudio).getType(); // Then, we get a clip for playing the audio. c = AudioSystem.getClip(); // We get a stream for playing the input file. AudioInputStream ais = AudioSystem.getAudioInputStream(inputAudio); // We use the clip to open (but not start) the input stream c.open(ais); // We get the format of the audio codec (not the file format we got above) final AudioFormat audioFormat = ais.getFormat(); c.start(); AudioInputStream startStream = new AudioInputStream(new FileInputStream(inputAudio), audioFormat, c.getLongFramePosition()); AudioSystem.write(startStream, fileType, outputAudio); } catch (UnsupportedAudioFileException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (LineUnavailableException e) { e.printStackTrace(); } }// end play_cut //****************************

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  • get content from website with utf8 format

    - by zahir
    i want how to get the content from websites with utf8 format,, i have writing the following code is try { String webnames = "http://pathivu.com"; URL url = new URL(webnames); URLConnection urlc = url.openConnection(); //BufferedInputStream buffer = new BufferedInputStream(urlc.getInputStream()); BufferedReader buffer = new BufferedReader(new InputStreamReader(urlc.getInputStream(), "UTF8")); StringBuilder builder = new StringBuilder(); int byteRead; while ((byteRead = buffer.read()) != -1) builder.append((char) byteRead); buffer.close(); String text=builder.toString(); System.out.println(text); } catch (IOException e) { e.printStackTrace(); } but i cant get the correct format... thanks and advance..

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  • How can I intercept a Tomcat request at socket level?

    - by Miguel Pardal
    Hi, I'm doing a performance study for a web application framework running on Apache Tomcat 6. I'm trying to measure the time overhead of handling HTTP requests. What I would like to do is: / // just before first request byte is read long t1 = System.nanoTime(); // request is processed... // just after final byte is written to response long t2 = System.nanoTime(); / Then I would compute the total time (t2 - t1). Is there a way to do this? Thanks for your help!

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  • Setting custom HTTP request headers in an URL object doesn't work.

    - by Blagovest Buyukliev
    I am trying to fetch an image from an IP camera using HTTP. The camera requires HTTP basic authentication, so I have to add the corresponding request header: URL url = new URL("http://myipcam/snapshot.jpg"); URLConnection uc = url.openConnection(); uc.setRequestProperty("Authorization", "Basic " + new String(Base64.encode("user:pass".getBytes()))); // outputs "null" System.out.println(uc.getRequestProperty("Authorization")); I am later passing the url object to ImageIO.read(), and, as you can guess, I am getting an HTTP 401 Unauthorized, although user and pass are correct. What am I doing wrong? I've also tried new URL("http://user:pass@myipcam/snapshot.jpg"), but that doesn't work either.

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  • How do I find resources in a .jar on the classpath?

    - by Brabster
    If I have a collection of resource files in a directory on my classpath, I can enumerate them using ClassLoader.getResources(location). For example if I have /mydir/myresource.properties on the classpath, I can call the classloader's getResources("mydir") and get an enumeration of URLs containing myresource.properties. When I pack up the exact same resources into a .jar, I don't get anything in the enumeration of URLs when I make the call. I've only replaced the folder structure with a jar containing those folders (it's a webapp, so the jar is going into /WEB-INF/lib). I've also got a number of other calls using getResourceAsStream(location) to get other resources individually by name and they're all working fine. What's different about enumerating resources when the resources are in a .jar?

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  • How to view my Android app created database, via my android app?

    - by suufang
    I'm creating an application that collects users location (Cell broadcast location code) and saves that location with a name of users option, for example say my CB location code is 546034, now my app allows me to store that location code with a name of my choice say 'Home'. So, essentially my app has that following modules, To collect users CB location. To collect a custom name from user of that location. To store these values in a database. I've succeeded in doing all the above modules. I have a sub-module for my third module which has an option for user, of showing and deleting the database values, the screen shot looks as follows, Now, Users should be able to view and delete entries when he chooses the option 'View my database of locations' I've learned how to query my database values and I'm stuck with creating a list view and providing the delete option. My code for getting the database values and querying values goes as follows, submit.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { String locname = name.getText().toString(); if(locname.length()==0) { Toast.makeText(getBaseContext(), "Please enter the location name, for example 'Home'.", Toast.LENGTH_LONG).show(); } else { SQLiteDatabase cd = openOrCreateDatabase("mydata", MODE_WORLD_READABLE, null); cd.execSQL("CREATE TABLE IF NOT EXISTS MLITable (CblocationCode INT(10), CblocationName VARCHAR);"); cd.execSQL("INSERT INTO MLITable VALUES ('"+str+ "','"+locname+ "');"); cd.close(); Toast.makeText(getBaseContext(), "value successfully entered.", Toast.LENGTH_LONG).show(); } } }); viewdb.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // here comes the code for viewing the database and deleting SQLiteDatabase db = openOrCreateDatabase("mydata", MODE_WORLD_READABLE, null); Cursor c = db.rawQuery("SELECT * FROM MLITble", null); db.close(); } }); I can see that I've read the table values, but I'm not able to create a display for those values. Help required. Thank you.

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  • android - How to draw only the sprite from an image on the canvas

    - by user1320494
    this is the first time for me here, so I hope I'm doing this right :) My question is the following: how do I draw the sprite from an image on the canvas, so that I don't get the entire (squared) image to show, but only the parts of the image I want (= the sprite). For example, I have an image of a robot on a white background and I only want to see the robot, and not the white background. I hope someone here can help me with this problem, because it's giving me headaches of not knowing how to do it :P

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  • BufferedReader ready method in a while loop to determine EOF?

    - by BobTurbo
    I have a large file (wikipedia english arcticles only database as xml file) I am using to read one character at a time using BufferedReader. The psuedo code is: file = BufferedReader... while (file.ready()) character = file.read() is this actually valid? Or will ready just return false when it is waiting for the HDD to return data and not actually when the EOF has been reached? I tried to use if (file.read() == -1) but seemed to run into an infinite loop that I literally could not find. I am just wondering if it is reading the whole file as my statistics say 444 380 wikipedia pages have been read but I thought there were many more articles..

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  • how to handle empty selection in a jface bound combobox?

    - by guido
    I am developing a search dialog in my eclipse-rcp application. In the search dialog I have a combobox as follows: comboImp = new CCombo(grpColSpet, SWT.BORDER | SWT.READ_ONLY); comboImp.setBounds(556, 46, 184, 27); comboImpViewer = new ComboViewer(comboImp); comboImpViewer.setContentProvider(new ArrayContentProvider()); comboImpViewer.setInput(ImpContentProvider.getInstance().getImps()); comboImpViewer.setLabelProvider(new LabelProvider() { @Override public String getText(Object element) { return ((Imp)element).getImpName(); } }); Imp is a database entity, ManyToOne to the main entity which is searched, and ImpContentProvider is the model class which speaks to embedded sqlite database via jpa/hibernate. This combobox is supposed to contain all instances of Imp, but to also let empty selection; it's value is bound to a service bean as follows: IObservableValue comboImpSelectionObserveWidget = ViewersObservables.observeSingleSelection(comboImpViewer); IObservableValue filterByImpObserveValue = BeansObservables.observeValue(searchPrep, "imp"); bindingContext.bindValue(comboImpSelectionObserveWidget, filterByImpObserveValue , null, null); As soon as the user clicks on the combo, a selection (first element) is made: I can see the call to a selectionlistener i added on the viewer. My question is: after a selection has been made, how do I let the user change his mind and have an empty selection in the combobox? should I add a "fake" empty instance of Imp to the List returned by the ImpContentProvider? or should I implement an alternative to ArrayContentProvider? and one additional related question is: why calling deselectAll() and clearSelection() on the combo does NOT set a null value to the bound bean?

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