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  • Shortcut for adding to List in a HashMap

    - by Damo
    I often have a need to take a list of objects and group them into a Map based on a value contained in the object. Eg. take a list of Users and group by Country. My code for this usually looks like: Map<String, List<User>> usersByCountry = new HashMap<String, List<User>>(); for(User user : listOfUsers) { if(usersByCountry.containsKey(user.getCountry())) { //Add to existing list usersByCountry.get(user.getCountry()).add(user); } else { //Create new list List<User> users = new ArrayList<User>(1); users.add(user); usersByCountry.put(user.getCountry(), users); } } However I can't help thinking that this is awkward and some guru has a better approach. The closest I can see so far is the MultiMap from Google Collections. Are there any standard approaches? Thanks!

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  • Need help make these classes use Visitor Pattern and generics

    - by Shervin
    Hi. I need help to generify and implement the visitor pattern. We are using tons of instanceof and it is a pain. I am sure it can be modified, but I am not sure how to do it. Basically we have an interface ProcessData public interface ProcessData { public setDelegate(Object delegate); public Object getDelegate(); //I am sure these delegate methods can use generics somehow } Now we have a class ProcessDataGeneric that implements ProcessData public class ProcessDataGeneric implements ProcessData { private Object delegate; public ProcessDataGeneric(Object delegate) { this.delegate = delegate; } } Now a new interface that retrieves the ProcessData interface ProcessDataWrapper { public ProcessData unwrap(); } Now a common abstract class that implements the wrapper so ProcessData can be retrieved @XmlSeeAlso( { ProcessDataMotorferdsel.class,ProcessDataTilskudd.class }) public abstract class ProcessDataCommon implements ProcessDataWrapper { protected ProcessData unwrapped; public ProcessData unwrap() { return unwrapped; } } Now the implementation public class ProcessDataMotorferdsel extends ProcessDataCommon { public ProcessDataMotorferdsel() { unwrapped = new ProcessDataGeneric(this); } } similarly public class ProcessDataTilskudd extends ProcessDataCommon { public ProcessDataTilskudd() { unwrapped = new ProcessDataGeneric(this); } } Now when I use these classes, I always need to do instanceof ProcessDataCommon pdc = null; if(processData.getDelegate() instanceof ProcessDataMotorferdsel) { pdc = (ProcessDataMotorferdsel) processData.getDelegate(); } else if(processData.getDelegate() instanceof ProcessDataTilskudd) { pdc = (ProcessDataTilskudd) processData.getDelegate(); } I know there is a better way to do this, but I have no idea how I can utilize Generics and the Visitor Pattern. Any help is GREATLY appreciated.

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  • Trouble adding Image to a JPanel

    - by user1276078
    I'm making a video game, and I need to add an image to a JPanel and then add that JPanel to a JFrame. All of the tutorials I've seen say to add it to a JLabel, but the image needs to be able to move around. Unless you can move a JLabel around, I can't do that. How would I be able to add an Image directly to a JPanel. This is what I have so far, but it is just like it was on a JApplet class Penguin extends JPanel { public Image image; public void paintComponent( Graphics g ) { image = getImage( getDocumentBase(), "Penguins.jpg" ); g.drawImage( image, 0, 0, this ); } }

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  • Maven Cobertura: unit test failed but build success

    - by Pavel Drobushevich
    Hi all, I've configured cobertura code coverage in my pom: <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <version>2.4</version> <configuration> <instrumentation> <excludes> <exclude>**/*Exception.class</exclude> </excludes> </instrumentation> <formats> <format>xml</format> <format>html</format> </formats> </configuration> </plugin> And start test by following command: mvn clean cobertura:cobertura But if one of unit test fail Cobertura only log this information and doesn't mark build fail. Tests run: 287, Failures: 1, Errors: 1, Skipped: 0 Flushing results... Flushing results done Cobertura: Loaded information on 139 classes. Cobertura: Saved information on 139 classes. [ERROR] There are test failures. ................................. [INFO] BUILD SUCCESS How to configure Cobertura marks build failed in one of unit test fail? Thanks in advance.

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  • File Hierarchy system with a web application logic question: List searching

    - by molleman
    I need to search through a list of folders that could have more folders inside it, and add a new folder depending what folder is its parent.(the path is stored as a String for eg = "root/MyCom/home/") Then i fill in a field with a new folder name and add it to the final folder(eg "home/"). Below as you can see , I can navigate to the right location and add the new folder to a current folder, My trouble is that i cannot ensure that currentFolder element is placed back in the list it came from how could i add a folder to a list of folders, that could be within a list of folders,that could be within a list of folders and endless more? YFUser user = (YFUser)getSession().getAttribute(SESSION_USER); Folder newFolder = new Folder(); newFolder.setFolderName(foldername); // this is the path string (root/MyCom/home/) split in the different folder names String folderNames[] = folderLocationString.split("/"); int folderNamesLength = folderNames.length; Folder root = user.getRoot(); Folder currentFolder = root; for(int i=0;i<=folderNamesLength; i++){ // because root is folderNames[i] String folderName = folderNames[i++]; int currentFolderSize = currentFolder.getChildren.getSize(); for(int o=1; o<= currentFolderSize ; o++){ if(currentFolder.getChildren().get(o) instanceof Folder){ if(folderName.equals(currentFolder.getChildren().get(o).getFolderName())){ currentFolder = currentFolder.getChildren().get(o); if (i == counter){ //now i am inside the correct folder and i add it to the list of folders within it //the trouble is knowing how to re add this changed folder back to the list before it currentFolder.getChildren.add(newFolder); } } } } }

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  • Allow for modular development while still running in same JVM?

    - by Marcus
    Our current app runs in a single JVM. We are now splitting up the app into separate logical services where each service runs in its own JVM. The split is being done to allow a single service to be modified and deployed without impacting the entire system. This reduces the need to QA the entire system - just need to QA the interaction with the service being changed. For inter service communication we use a combination of REST, an MQ system bus, and database views. What I don't like about this: REST means we have to marshal data to/from XML DB views couple the systems together which defeats the whole concept of separate services MQ / system bus is added complexity There is inevitably some code duplication between services You have set up n JBoss server configurations, we have to do n number of deployments, n number of set up scripts, etc, etc. Is there a better way to structure an internal application to allow modular development and deployment while allowing the app to run in a single JVM (and achieving the associated benefits)?

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  • How to use a regular expression and assign the result to variables in Android?

    - by ChengYing
    I have a string named s_Result which will be parsed from the Internet. The format may be "Distance: 2.8km (about 9 mins)", and there are 4 variables which are f_Distance, m_DistanceUnit, f_timeEst, m_timeEstUnit. My question is how to parse s_Result and assign 2.8, km, 9, mins into f_Distance, m_distanceUnit, f_timeEst and m_timeEstUnit respectively using regular expression? I tried using "\d+(\.\d+)?" in RegEx Tester and the result showed 2 matches found, but if I use "\\d+(\\.\\d+)?" in Android code, it showed no matches! Any suggestions what might be going wrong?

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  • readUTF timeout

    - by Hassan Voyeau
    I am getting a timeout with the following code at readUTF. Any idea why? hc = (HttpConnection) Connector.open("http://twitter.com/statuses/user_timeline/" + username + ".json"); int rc = hc.getResponseCode(); if (rc != HttpConnection.HTTP_OK) { throw new IOException("HTTP response code: " + rc); } DataInputStream dataInputStream = hc.openDataInputStream(); String list = dataInputStream.readUTF();

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  • Where do I put javaassist code?

    - by DutrowLLC
    I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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  • Put together tiles in android sdk and use as background

    - by Jon
    In a feeble attempt to learn some Android development am I stuck at graphics. My aim here is pretty simple: Take n small images and build a random image, larger than the screen with possibility to scroll around. Have an animated object move around on it I have looked at the SDK examples, Lunar Lander especially but there are a few things I utterly fail to wrap my head around. I've got a birds view plan (which in my head seems reasonably sane): How do I merge the tiles into one large image? The background is static so I figure I should do like this: Make a 2d array with refs to the tiles Make a large Drawable and draw the tiles on it At init draw this big image as the background At each onDraw redraw the background of the previous spot of the moving object, and the moving object at its new location The problem is the hands on things. I load the small images with "Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1)", but then what? Should I make a canvas and draw the images on it with "canvas.drawBitmap (img1, x, y, null);"? If so how to get a Drawable/Bitmap from that? I'm totally lost here, and would really appreciate some hands on help (I would of course be grateful for general hints as well, but I'm primarily trying to understand the Graphics objects). To make you, dear reader, see my level of confusion will I add my last desperate try: Drawable drawable; Canvas canvas = new Canvas (); Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1); // 50 x 100 px image Bitmap img2 = BitmapFactory.decodeResource (res, R.drawable.img2); // 50 x 100 px image canvas.drawBitmap (img1, 0, 0, null); canvas.drawBitmap (img2, 50, 0, null); drawable.draw (canvas); // obviously wrong as draw == null this.setBackground (drawable); Thanks in advance

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  • How a servlet can get the absolute path to a file outside of the servlet?

    - by WolfmanDragon
    We have been using System.getProperties("user.dir") to get the location of a properties file. Now that it has been deployed on Tomcat(via servlet), the System call is giving the location as tomcat and not at the location at where the properties file exist. How can we call the the properties file dynamically? Given: Tomcat is not the only way the app will be deployed We have no control on where the app may be placed. Relative paths will not work as that Vista is being used and Vista breaks relative paths. This must work on all OS, including(but not limited to) Linux, XP and Vista. EDIT I implied this, but in case I was not clear enough, I have no way of knowing the path String.

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  • How to create Chat application using Servlets & JSP

    - by Crazy boy
    I want to create chat application using Servlets & JSP. May I know how can I create chat application as I have never created before? How much knowledge I need to have to create chat application? Is there any need of networking API to create chat application? What's the design pattern I need to follow to create that application? Is there any need of database?

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  • Relation many-to-many with attributes : how ?

    - by mada
    Hi, Excuse me for my poor english in advance as it is not my mother tongue. Like in this example: http://www.xylax.net/hibernate/manytomany.html But i have in the table foo-bar 2 attributes which are not part of the primary or foreign keys.: one boolean(A) & one string(B). I know how to map it without attributes but not in this case. I have not found an answer in the documentation. I need to know please how to map it & what kind of collection i have to declare in my class Foo. Thanks in advance for your answer. I really appreciate the time given by you.

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  • Eager fetching of children with JDO (Datanucleus)

    - by Jan
    Hi, can JDO fetch all children of a database model at once? Like: class Parent { @Persistent(mappedBy="parent") private Set<Children> children; } class Children { @Persistent private Parent parent; @Persistent private String name; } In my case, I have a large number of Parents which I fetch at once. Accessing their children then takes a lot of time because they are fetched lazily. Does JDO (Datanucleus) support their fetching at once, togehter with the Parents? I also tried to fetch all Children independantly with another quey and put them into the Level2 cache afterwards, but still they are fetched (maybe jdo doesn't know about their relationship? Because the ForeignKey (parent-id) hasn't been fetched at first?) Any ideas how to read the data structure faster? Cheers, Jan

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  • Debugging stack data not assigned to a named variable

    - by gibbss
    Is there a way to view stack elements like un-assigned return values or exceptions that not assigned to a local variable? (e.g. throw new ...) For example, suppose I have code along the lines of: public String foo(InputStream in) throws IOException { NastyObj obj = null; try { obj = new NastyObj(in); return (obj.read()); } finally { if (obj != null) obj.close(); } } Is there any way to view the return or exception value without stepping to a higher level frame where it is assigned? This is particularly relevant with exceptions because you often have to step back up through a number of frames to find an actual handler. I usually use the Eclipse debugging environment, but any answer is appreciated. Also, if this cannot be done, can you explain why? (JVM, JPDA limitation?)

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  • Why is this JLabel continuously repainting?

    - by Morinar
    I've got an item that appears to continuously repaint when it exists, causing the CPU to spike whenever it is in any of my windows. It directly inherits from a JLabel, and unlike the other JLabels on the screen, it has a red background and a border. I have NO idea why it would be different enough to continuously repaint. The callstack looks like this: Thread [AWT-EventQueue-1] (Suspended (breakpoint at line 260 in sItem)) sItem.paint(Graphics) line: 260 sItem(JComponent).paintToOffscreen(Graphics, int, int, int, int, int, int) line: 5124 RepaintManager$PaintManager.paintDoubleBuffered(JComponent, Image, Graphics, int, int, int, int) line: 1475 RepaintManager$PaintManager.paint(JComponent, JComponent, Graphics, int, int, int, int) line: 1406 RepaintManager.paint(JComponent, JComponent, Graphics, int, int, int, int) line: 1220 sItem(JComponent)._paintImmediately(int, int, int, int) line: 5072 sItem(JComponent).paintImmediately(int, int, int, int) line: 4882 RepaintManager.paintDirtyRegions(Map<Component,Rectangle>) line: 803 RepaintManager.paintDirtyRegions() line: 714 RepaintManager.seqPaintDirtyRegions() line: 694 [local variables unavailable] SystemEventQueueUtilities$ComponentWorkRequest.run() line: 128 InvocationEvent.dispatch() line: 209 summitEventQueue(EventQueue).dispatchEvent(AWTEvent) line: 597 summitEventQueue(SummitHackableEventQueue).dispatchEvent(AWTEvent) line: 26 summitEventQueue.dispatchEvent(AWTEvent) line: 62 EventDispatchThread.pumpOneEventForFilters(int) line: 269 EventDispatchThread.pumpEventsForFilter(int, Conditional, EventFilter) line: 184 EventDispatchThread.pumpEventsForHierarchy(int, Conditional, Component) line: 174 EventDispatchThread.pumpEvents(int, Conditional) line: 169 EventDispatchThread.pumpEvents(Conditional) line: 161 EventDispatchThread.run() line: 122 [local variables unavailable] It basically just continually hits that over and over again as fast as I can press continue. The code that is "unique" to this particular label looks approximately like this: bgColor = OurColors.clrWindowTextAlert; textColor = Color.white; setBackground(bgColor); setOpaque(true); setSize(150, getHeight()); Border border_warning = BorderFactory.createCompoundBorder( BorderFactory.createMatteBorder(1, 1, 1, 1, OurColors.clrXBoxBorder), Global.border_left_margin); setBorder(border_warning); It obviously does more, but that particular block only exists for these labels that are causing the spike/continuous repaint. Any ideas why it would keep repainting this particular label?

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  • Hibernate Query for a List of Objects that matches a List of Objects' ids

    - by sal
    Given a classes Foo, Bar which have hibernate mappings to tables Foo, A, B and C public class Foo { Integer aid; Integer bid; Integer cid; ...; } public class Bar { A a; B b; C c; ...; } I build a List fooList of an arbitrary size and I would like to use hibernate to fetch List where the resulting list will look something like this: Bar[1] = [X1,Y2,ZA,...] Bar[2] = [X1,Y2,ZB,...] Bar[3] = [X1,Y2,ZC,...] Bar[4] = [X1,Y3,ZD,...] Bar[5] = [X2,Y4,ZE,...] Bar[6] = [X2,Y4,ZF,...] Bar[7] = [X2,Y5,ZG,...] Bar[8] = ... Where each Xi, Yi and Zi represents a unique object. I know I can iterate fooList and fetch each List and call barList.addAll(...) to build the result list with something like this: List<bar> barList.addAll(s.createQuery("from Bar bar where bar.aid = :aid and ... ") .setEntity("aid", foo.getAid()) .setEntity("bid", foo.getBid()) .setEntity("cid", foo.getCid()) .list(); ); Is there any easier way, ideally one that makes better use of hibernate and make a minimal number of database calls? Am I missing something? Is hibernate not the right tool for this?

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  • How to inject ServletContext for JUnit tests with Spring?

    - by Juri Glass
    Hi I want to unit test a RESTful interface written with Apache CXF. I use a ServletContext to load some resources, so I have: @Context private ServletContext servletContext; If I deploy this on Glassfish, the ServletContext is injected and it works like expected. But I don't know how to inject the ServletContext in my service class, so that I can test it with a JUnit test. I use Spring 3.0, JUnit 4, CXF 2.2.3 and Maven.

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  • Problem Formating in Eclipse

    - by fastcodejava
    I have method in eclipse as below : public String toString() { return "HouseVo [ " + "Name : " + this.name == null ? "" : this.name + "Address : " + this.address == null ? "" : this.address; } When I format it becomes : return "HouseVo [ " + "Name : " + this.name == null ? "" : this.name + "Address : " + this.address == null ? "" : this.address; Any way to fix it so it correctly formats?

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  • Avoid having a huge collection of ids by calling a DAO.getAll()

    - by Michael Bavin
    Instead of returning a List<Long> of ids when calling PersonDao.getAll() we wanted not to have an entire collection of ids in memory. Seems like returning a org.springframework.jdbc.support.rowset.SqlRowSet and iterate over this rowset would not hold every object in memory. The only problem here is i cannot cast this row to my entity. Is there a better way for this?

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