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  • Modular Inverse and BigInteger division

    - by dano82
    I've been working on the problem of calculating the modular inverse of an large integer i.e. a^-1 mod n. and have been using BigInteger's built in function modInverse to check my work. I've coded the algorithm as shown in The Handbook of Applied Cryptography by Menezes, et al. Unfortunately for me, I do not get the correct outcome for all integers. My thinking is that the line q = a.divide(b) is my problem as the divide function is not well documented (IMO)(my code suffers similarly). Does BigInteger.divide(val) round or truncate? My assumption is truncation since the docs say that it mimics int's behavior. Any other insights are appreciated. This is the code that I have been working with: private static BigInteger modInverse(BigInteger a, BigInteger b) throws ArithmeticException { //make sure a >= b if (a.compareTo(b) < 0) { BigInteger temp = a; a = b; b = temp; } //trivial case: b = 0 => a^-1 = 1 if (b.equals(BigInteger.ZERO)) { return BigInteger.ONE; } //all other cases BigInteger x2 = BigInteger.ONE; BigInteger x1 = BigInteger.ZERO; BigInteger y2 = BigInteger.ZERO; BigInteger y1 = BigInteger.ONE; BigInteger x, y, q, r; while (b.compareTo(BigInteger.ZERO) == 1) { q = a.divide(b); r = a.subtract(q.multiply(b)); x = x2.subtract(q.multiply(x1)); y = y2.subtract(q.multiply(y1)); a = b; b = r; x2 = x1; x1 = x; y2 = y1; y1 = y; } if (!a.equals(BigInteger.ONE)) throw new ArithmeticException("a and n are not coprime"); return x2; }

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  • Eclipse Plugin: Enablement of an Action based on the current selection - before the

    - by Itay
    Here's my problem: I am using the org.eclipse.ui.popupMenus extension point for adding a sub-menu whose Action that is bounded to the following class: public class MyAction implements IObjectActionDelegate { private Logic logic = Logic.getInstance(); // Singleton public void setActivePart(IAction a, IWorkbenchPart targetPart) { // Nothing here } public void run(IAction a) { // Do something... } public void selectionChanged(IAction a, ISelection s) { a.setEnabled(logic.isEnabled(s)); } } This action is working correctly in most cases (including the call a.setEnabled() in selectionChanged()). My problem at the very first time my action is being invoked. The selectionChanged method is called only after the menu item has been displayed (and not when the user has made the selection) which means that the call to a.setEnabled() will have no affect. Any ideas on how to make my action receive selectionChanged() notifications even before the fist time it is being invoked?

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  • Chat client with GWT

    - by user284016
    What would be the best way to create a JS chat client with GWT? The bit that I'm having trouble with is the persistence and transfer of the messages. Should I store the messages in a DB and check the db for new messages? Is there a much better way to do this?

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  • Directory Hierarchy

    - by niveditha
    How to build a folder structure using morphia or the mongodb API? I am looking for something like this. folderA --->folderB --->folderC ------>fileC ------>folderCA ---------->fileCA

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  • Wait between tasks with SingleThreadExecutor

    - by Lord.Quackstar
    I am trying to (simply) make a blocking thread queue, where when a task is submitted the method waits until its finished executing. The hard part though is the wait. Here's my 12:30 AM code that I think is overkill: public void sendMsg(final BotMessage msg) { try { Future task; synchronized(msgQueue) { task = msgQueue.submit(new Runnable() { public void run() { sendRawLine("PRIVMSG " + msg.channel + " :" + msg.message); } }); //Add a seperate wait so next runnable doesn't get executed yet but //above one unblocks msgQueue.submit(new Runnable() { public void run() { try { Thread.sleep(Controller.msgWait); } catch (InterruptedException e) { log.error("Wait to send message interupted", e); } } }); } //Block until done task.get(); } catch (ExecutionException e) { log.error("Couldn't schedule send message to be executed", e); } catch (InterruptedException e) { log.error("Wait to send message interupted", e); } } As you can see, there's alot of extra code there just to make it wait 1.7 seconds between tasks. Is there an easier and cleaner solution out there or is this it?

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  • change a frame's attribute by pressing a button

    - by asavu
    Hi. Suppose we have a JFrame named frame1 with a String attribute named credentials set inittially to null. I have a jButton named button1 attached to the frame and I want to change the frame1 String credentials attribute by pressing button1. I need some piece of advice regarding the ActionListener code especially. Could you guys pls help me? Thank you.

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  • Best way to force Spring shutdown from a bean?

    - by xcut
    My application uses a Spring DefaultMessageListenerContainer to process incoming messages. The main method of the app already registers a shutdown hook. Question is this: what is the best way to force the application context to shut down? If I throw a RuntimeException in the message listener, it is handled by the container, and not passed on. Is calling System.exit acceptable? Do I pass along the ApplicationContext to every class that needs to shut down, so I can call close() on it?

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  • Hibernate Persistence problems with Bean Mapping (Dozer)

    - by BuffaloBuffalo
    I am using Hibernate 3, and having a particular issue when persisting a new Entity which has an association with an existing detached entity. Easiest way to explain this is via code samples. I have two entities, FooEntity and BarEntity, of which a BarEntity can be associated with many FooEntity: @Entity public class FooEntity implements Foo{ @Id private Long id; @ManyToOne(targetEntity = BarEntity.class) @JoinColumn(name = "bar_id", referencedColumnName = "id") @Cascade(value={CascadeType.ALL}) private Bar bar; } @Entity public class BarEntity implements Bar{ @Id private Long id; @OneToMany(mappedBy = "bar", targetEntity = FooEntity.class) private Set<Foo> foos; } Foo and Bar are interfaces that loosely define getters for the various fields. There are corresponding FooImpl and BarImpl classes that are essentially just the entity objects without the annotations. What I am trying to do is construct a new instance of FooImpl, and persist it after setting a number of fields. The new Foo instance will have its 'bar' member set to an existing Bar (runtime being a BarEntity) from the database (retrieved via session.get(..)). After the FooImpl has all of its properties set, Apache Dozer is used to map between the 'domain' object FooImpl and the Entity FooEntity. What Dozer is doing in the background is instantiating a new FooEntity and setting all of the matching fields. BarEntity is cloned as well via instantiation and set the FooEntity's 'bar' member. After this occurs, passing the new FooEntity object to persist. This throws the exception: org.hibernate.PersistentObjectException: detached entity passed to persist: com.company.entity.BarEntity Below is in code the steps that are occurring FooImpl foo = new FooImpl(); //returns at runtime a persistent BarEntity through session.get() Bar bar = BarService.getBar(1L); foo.setBar(bar); ... //This constructs a new instance of FooEntity, with a member 'bar' which itself is a new instance that is detached) FooEntity entityToPersist = dozerMapper.map(foo, FooEntity.class); ... session.persist(entityToPersist); I have been able to resolve this issue by either removing or changing the @Cascade annotation, but that limits future use for say adding a new Foo with a new Bar attached to it already. Is there some solution here I am missing? I would be surprised if this issue hasn't been solved somewhere before, either by altering how Dozer Maps the children of Foo or how Hibernate reacts to a detached Child Entity.

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  • AsyncTask never finishes when other tasks are running

    - by rebeccamaher
    In my app, I show a menu screen immediately to the user and then use an AsyncTask to load some data from disk. Loading takes about 3 seconds if that's all the app had to do. When the user hits a menu option and the data hasn't loaded yet, a "Please wait, loading" screen appears. I have two problems: I recently added ads to my app and have found this is making my app hang sometimes because the AsyncTask never finishes loading. What seems to be happening is that the ad banner (I'm using admob and this happens when adsense ads are shown which admob do occasionally) is using resources by playing a simple animation and the AsyncTask never gets a chance to finish. I want to play a simple looping animation (e.g. making a view rotate) on my menu screen and this makes the AsyncTask take about 5 times longer to finish which renders the background loading pointless. How can I avoid situations where my background data never finishes loading or has such a low priority it takes a long time? I can't seem to find a way to increase the priority of an AsyncTask.

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  • Tomcat does not persist UserPrinciple during restart

    - by mabuzer
    How to force Tomcat to serialize UserPrinciple so that the user is kept logged in when Tomcat has restarted? Right now the user has to login again everytime. Added the following lines into web-app context.xml: <Manager className="org.apache.catalina.session.PersistentManager"> <Store className="org.apache.catalina.session.FileStore"/> </Manager> but still I see login page after Tomcat restart, I use Tomcat 6.0.26

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  • Problem detaching entire object graph in GAE-J with JDO

    - by tempy
    I am trying to load the full object graph for User, which contains a collection of decks, which then contains a collection of cards, as such: User: @PersistenceCapable(detachable = "true") @Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE) @FetchGroup(name = "decks", members = { @Persistent(name = "_Decks") }) public abstract class User { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) protected Key _ID; @Persistent protected String _UniqueIdentifier; @Persistent(mappedBy = "_Owner") @Element(dependent = "true") protected Set<Deck> _Decks; protected User() { } } Each Deck has a collection of Cards, as such: @PersistenceCapable(detachable = "true") @FetchGroup(name = "cards", members = { @Persistent(name = "_Cards") }) public class Deck { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key _ID; @Persistent String _Name; @Persistent(mappedBy = "_Parent") @Element(dependent = "true") private Set<Card> _Cards = new HashSet<Card>(); @Persistent private Set<String> _Tags = new HashSet<String>(); @Persistent private User _Owner; } And finally, each card: @PersistenceCapable public class Card { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key _ID; @Persistent private Text _Question; @Persistent private Text _Answer; @Persistent private Deck _Parent; } I am trying to retrieve and then detach the entire object graph. I can see in the debugger that it loads fine, but then when I get to detaching, I can't make anything beyond the User object load. (No Decks, no Cards). At first I tried without a transaction to simply "touch" all the fields on the attached object before detaching, but that didn't help. Then I tried adding everything to the default fetch group, but that just generated warnings about GAE not supporting joins. I tried setting the fetch plan's max fetch depth to -1, but that didn't do it. Finally, I tried using FetchGroups as you can see above, and then retrieving with the following code: PersistenceManager pm = _pmf.getPersistenceManager(); pm.setDetachAllOnCommit(true); pm.getFetchPlan().setGroup("decks"); pm.getFetchPlan().setGroup("cards"); Transaction tx = pm.currentTransaction(); Query query = null; try { tx.begin(); query = pm.newQuery(GoogleAccountsUser.class); //Subclass of User query.setFilter("_UniqueIdentifier == TheUser"); query.declareParameters("String TheUser"); List<User> results = (List<User>)query.execute(ID); //ID = Supplied parameter //TODO: Test for more than one result and throw if(results.size() == 0) { tx.commit(); return null; } else { User usr = (User)results.get(0); //usr = pm.detachCopy(usr); tx.commit(); return usr; } } finally { query.closeAll(); if (tx.isActive()) { tx.rollback(); } pm.close(); } This also doesn't work, and I'm running out of ideas...

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  • Draw Circle on the Map once the application gets loaded

    - by TechGeeky
    Background:- In my application what is happening currently- Whenever I am opening the application, In the top half of the android screen, it draws a Map and in the bottom half of the android screen it show's a list view. And then as soon as the location gets changed, it draw's a Circle with the current location as the center of the circle and show's an image at the current location(center of circle). Everything is working fine till here- Problem Statement:- What I want is when the user opens my application, circle should get draw immediately on the Google Map (this is currently not happening, it draw's circle only on the location changed), without waiting for the location to get changed and without any image on the center of circle and then if the location get's changed, take the current location as the center of circle and draw the circle with an image at the center of circle. And this is my below code which fulfills the scenario that I mentioned in my Background- How can I make this code to work the way I wanted to? hope I am clear enough in my question. Any suggestions will be appreciated. @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mapView = (MapView) findViewById(R.id.mapView); listView = (ListView) findViewById(R.id.mylist); locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); locationListener = new GPSLocationListener(mapView); locationManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 35000, 10, locationListener); mapView.setStreetView(true); mapView.setBuiltInZoomControls(true); mapController = mapView.getController(); mapController.setZoom(14); } Location Update class where I am sending the request to Overlay to draw the circle private class GPSLocationListener implements LocationListener { MapOverlay mapOverlay; public GPSLocationListener(MapView mapView) { } @Override public void onLocationChanged(Location location) { if (location != null) { GeoPoint point = new GeoPoint( (int) (location.getLatitude() * 1E6), (int) (location.getLongitude() * 1E6)); mapController.animateTo(point); mapController.setZoom(15); if (mapOverlay == null) { mapOverlay = new MapOverlay(this,android.R.drawable.star_on); List<Overlay> listOfOverlays = mapView.getOverlays(); listOfOverlays.add(mapOverlay); } mapOverlay.setPointToDraw(point); mapView.invalidate(); } } @Override public void onProviderDisabled(String provider) { } @Override public void onProviderEnabled(String provider) { } @Override public void onStatusChanged(String provider, int status, Bundle extras) { } } Class in which circle is getting drawn. class MapOverlay extends Overlay { private GeoPoint pointToDraw; int[] imageNames=new int[6]; private Point mScreenPoints; private Bitmap mBitmap; private Paint mCirclePaint; public MapOverlay(GPSLocationListener gpsLocationListener, int currentUser) { imageNames[0]=currentUser; mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG); mCirclePaint.setColor(0x30000000); mCirclePaint.setStyle(Style.FILL_AND_STROKE); mBitmap = BitmapFactory.decodeResource(getResources(),imageNames[0]); mScreenPoints = new Point(); } public void setPointToDraw(GeoPoint point) { pointToDraw = point; } public GeoPoint getPointToDraw() { return pointToDraw; } @Override public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) { super.draw(canvas, mapView, shadow); if (pointToDraw == null) { return true; } mScreenPoints = mapView.getProjection().toPixels(pointToDraw, mScreenPoints); int totalCircle=5; int radius=40; int centerimagesize=35; for (int i = 1; i <= totalCircle; i ++) { canvas.drawCircle(mScreenPoints.x,mScreenPoints.y, i*radius, mCirclePaint); } canvas.drawBitmap(mBitmap, (mScreenPoints.x-(centerimagesize/2)),(mScreenPoints.y-(centerimagesize/2)), null); super.draw(canvas,mapView,shadow); return true; } }

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  • Move and rename file in android

    - by Andre Fróes
    I am trying to copy a file to another folder in the android, but so far, i got no success. I manage to do so with a selected image and when taking a photo, but not with files. I've read and tried several solutions passed by the community (searched over the forum and the internet), but none of it was able to solve my problem when copying. First things first. I added the permissions to my manifest: <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> after that, before copying a file, i print its filepath and the directory file path: 06-10 11:11:11.700: I/System.out(1442): /mimetype/storage/sdcard/Misc/Javascript erros for Submit and Plan buttons in IE.doc 06-10 11:11:11.710: I/System.out(1442): /storage/sdcard/mywfm/checklist-files both exists: to copy the file to the expected folder I used the FileUtils: try { FileUtils.copyFile(selectedFile, dir); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } The problem is: I get no exception and the file isn't there. I tried this solution either: How to move/rename file from internal app storage to external storage on Android? same thing, no exception, but no file either.

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  • How to handle dependency files in a cross-platform manner?

    - by Brian Knoblauch
    I'm working on updating an old app. It has some dependency files that live in the same directory as the app. Obviously this broke when Windows Vista came out (since it violates the API and Vista/7 now enforce that (XP didn't)). Ideally, I'd like to avoid hardcoding anything into the app for just Windows. I can live with that if I have to though. I've already been down that path with pulling the APPDATA and LOCALAPPDATA environment variables, but that doesn't help any since they just give you the current user area... I need these to live somewhere accessible for all users, and I'd like to obey the Windows API expectations that they go into the all user appdata area. Suggestions?

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  • How do I limit JPQ output?

    - by den-javamaniac
    I need to limit number of entities returned by a query to some certain value inside a JPA query (through JPQL). Particularly: select m from Manual m //constraint e.g. in sql (mysql syntax) I would do it like: select * from Manual limit 1 The only solution that comes up is simply to get all entities and then choose first one, which is out of the issue. Any ideas?

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  • Trying to write junit test missing some basisc

    - by Gandalf StormCrow
    When I try to use assertNotLesser or assertNotGreater I get compile error .. and eclipse suggest me to create a new method called like this .. http://junit-addons.sourceforge.net/junitx/framework/ComparableAssert.html I found it here I never used these options before but I need to write this test, I can do it jmock as well but I don't know how .. I need to compare my expected results let say 0, if the real result is greater that the test should fail.

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  • What is an appropriate way to separate lifecycle events in the logging system?

    - by Hanno Fietz
    I have an application with many different parts, it runs on OSGi, so there's the bundle lifecycles, there's a number of message processors and plugin components that all can die, can be started and stopped, have their setup changed etc. I want a way to get a good picture of the current system status, what components are up, which have problems, how long they have been running for etc. I think that logging, especially in combination with custom appenders (I'm using log4j), is a good part of the solution and does help ad-hoc analysis as well as live monitoring. Normally, I would classify lifecycle events as INFO level, but what I really want is to have them separate from what else is going on in INFO. I could create my own level, LIFECYCLE. The lifecycle events happen in various different areas and on various levels in the application hierarchy, also they happen in the same areas as other events that I want to separate them from. I could introduce some common lifecycle management and use that to distinguish the events from others. For instance, all components that have a lifecycle could implement a particular interface and I log by its name. Are there good examples of how this is done elsewhere? What are considerations?

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  • CodeModel help needed for right-hand singleton.getinstance() assignment.

    - by antarti
    I've been able to generate 99% of what I need with the CodeModel API, but I am stumped here... Using the various "directXX" methods does not add import statements to the generated code, and I can work without the "directXXX" type of methods except for one place in a generated class. Suppose I desire a generated method like: /** * Copies data from this Value-Obj instance, to the returned PERSON instance. * * @return PERSON * */ public PERSON mapVOToPERSON() throws MappingException { Mapper mapper = (com.blah.util.MapperSingleton.getMapperInstance()); return mapper.map(this, PERSON.class); } You can see the right hand of the Mapper assignment in parens. Emitting the entire package+class was the only way I could find to just declare "SomeSingleton.someMethod()" on the right hand side and have the generated code compile. Without the MapperSingleton being added to the object model, there is no import generated... Questions: 1) Is there a way to force an import to be generated? 2) How to declare an expression that gives me the right side of the Mapper assignment within the object model (so that an import of MapperSingleton gets generated. Any help appreciated...

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