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  • How do I manipulate a tree of immutable objects?

    - by Frederik
    I'm building an entire application out of immutable objects so that multi-threading and undo become easier to implement. I'm using the Google Collections Library which provides immutable versions of Map, List, and Set. My application model looks like a tree: Scene is a top-level object that contains a reference to a root Node. Each Node can contain child Nodes and Ports. An object graph might look like this: Scene | +-- Node | +-- Node | +- Port +-- Node | +- Port +- Port If all of these objects are immutable, controlled by a top-level SceneController object: What is the best way to construct this hierarchy? How would I replace an object that is arbitrarily deep in the object tree? Is there a way to support back-links, e.g. a Node having a "parent" attribute?

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  • Read a file to multiple array byte[]

    - by hankol
    I have an encryption algorithm (AES) that accepts file converted to array byte and encrypt it. Since I am going to process a very big size files, the JVM may go out of memory. I am planing to read the files in multiple array byte. each containing some part of the file. Then I teratively feed the algorithm. Finally merge them to produce encrypted file. So my question is: there any way to read a file part by part to multiple array byte? I thought I can use the following to read the file to array byte: IOUtils.toByteArray(InputStream input). And then split the array into multiple bytes using: Arrays.copyOfRange(). But I am afraid that the first code that reads file to byte will make the JVM to go out of memory. any suggestion please ? thanks

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  • Is there some way to assume @Nullable as default? (using FindBugs or any other free tool).

    - by alex2k8
    Consider such code public void m1(String text) { if(text == null) text = "<empty>"; System.out.println(text.toLowerCase()); } And this is a buggy version: public void m1(String text) { System.out.println(text.toLowerCase()); } If null value passed, the NullPointerException may be thrown. I would like the static-analysis tool (e.g. FindBugs) to report this issue. Unsuccessfully the FindBugs (at least by default) requires me to specify @Nullable annotation explicitly. public void m1(@Nullable String text) { System.out.println(text.toLowerCase()); // FindBugs: text must be nonnull but is marked as nullable } The problem is that if I forget to annotate it, the bug will be missed!!! How can I make the FindBugs (or any other free tool) to assume @Nullable by default?

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  • Inheritance question / problem

    - by Itsik
    I'm creating a custom Layout for android. The layout implementation is exactly the same, but once I need to extend from RelativeLayout, and once from LinearLayout. class Layout1 extends LinearLayout { // methods and fields } class Layout2 extends RelativeLayout { // the same EXACT methods and fields } How can I use inheritance to avoid DRY and implement my methods once.

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  • When to use new layouts and when to use new activities?

    - by cmdfrg
    I'm making a game in Android and I'm trying to add a set of menu screens. Each screen takes up the whole display and has various transitions available to other screens. As a rough summary, the menu screens are: Start screen Difficult select screen Game screen. Pause screen. Game over screen. And there are several different ways you can transition between screen: 1 - 2 2 - 3 3 - 4 (pause game) 4 - 1 (exit game) 4 - 3 (resume game) 3 - 5 (game ends) Obviously, I need some stored state when moving between screens, such as the difficulty level select when starting a game and what the player's score is when the game over screen is shown. Can anyone give me some advice for the easiest way to implement the above screens and transitions in Android? All the create/destroy/pause/resume methods make me nervous about writing brittle code if I'm not careful. I'm not fond of using an Activity for each screen. It seems too heavy weight, having to pass data around using intents seems like a real pain and each screen isn't a useful module by itself. As the "back" button doesn't always go back to the previous screen either, my menu layout doesn't seem to fit the activity model well. At the moment, I'm representing each screen as an XML layout file and I have one activity. I set the different buttons on each layout to call setContentView to update the screen the main activity is showing (e.g. the pause button changes the layout to the pause screen). The activity holds onto all the state needed (e.g. the current difficulty level and the game high score), which makes it easy to share data between screens. This seems roughly similar to the LunarLander sample, except I'm using multiple screens. Does what I have at the moment sound OK or am I not doing things the typical Android way? Is there a class I can use (e.g. something like ViewFlipper) that could make my life easier? By the way, my game screen is implemented as a SurfaceView that stores the game state. I need the state in this view to persist between calls to setContentView (e.g. to resume from paused). Is the right idea to create the game view when the activity starts, keep a reference to it and then use this reference with setContentView whenever I want the game screen to appear?

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  • How to use a photo that has just been uploaded to Tomcat v6?

    - by Zombie_Colonel
    In an android application a user can upload a picture to a Tomcat server v6 in (Projet\WebContent\images) A second user can come at the same time display the picture thing not work it shows me: The requested resource is not available. I did what? I have to reboot the server? refresh? in a PHP page I upload pictures and then they are simply viewed by the user, for cons there I find difficulty with JEE

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  • Twitter friends timeline not returning full history

    - by twofivesevenzero
    I am using twitter4J to get a user's friends timeline, but it is not returning the full available history. I know there are pagination limits (200 per request and 3200 total as per http://bit.ly/ck8ysq) and I am well within those. I make a request like so: private static final int MAX_COUNT = 200; private List<Status> getAllStatuses(long sinceID) throws TwitterException { Twitter twitter = new Twitter(username, password); List<Status> friendsTimelineList = new ArrayList<Status>(); List<Status> tempList; int page = 0; do { page++; tempList = twitter.getFriendsTimeline( new Paging(page, MAX_COUNT, sinceID)); if(tempList == null ) break; friendsTimelineList.addAll(tempList); } while(true); return friendsTimelineList; } This results in only 423 statuses being returned across 3 pages. Any idea why this might be happening?

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  • Not reaction to pressing button

    - by Orange91
    I have a ring in primefaces: <h:form> <p:ring id="ring" value="#{ringBean.images}" var="image" styleClass="image-ring" easing="easeInOutBack"> <p:graphicImage value="./../../images/#{image.image}" width="150" height="150"/> <p:commandButton value="#{image.name}" action="#{image.action}" /> </p:ring> </h:form> My RingBean: @ManagedBean @RequestScoped public class RingBean implements Serializable{ private List<PersonImage> images; private PersonImage selectedPerson; public RingBean() { images = new ArrayList<PersonImage>(); images.add(new PersonImage("person3.png", "Pacjent", "patientList")); images.add(new PersonImage("person4.png", "Admin", "adminList")); images.add(new PersonImage("person5.png", "Lekarz", "doctorList")); images.add(new PersonImage("person6.png", "Sekretarka", "secretaryList")); images.add(new PersonImage("person7.png", "Nieaktywni", "inactiveList")); } public List<PersonImage> getImages() { return images; } public PersonImage getSelectedPerson() { return selectedPerson; } public void setSelectedPerson(PersonImage selectedPerson) { this.selectedPerson = selectedPerson; } } PersonImage class: public class PersonImage { String image; String name; String action; public PersonImage() { } public PersonImage(String image, String name, String action) { this.image = image; this.name = name; this.action = action; } public String getImage() { return image; } public void setImage(String image) { this.image = image; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAction() { return action; } public void setAction(String action) { this.action = action; } } faces-config: <navigation-case> <from-outcome>adminList</from-outcome> <to-view-id>/protected/admin/adminList.xhtml</to-view-id> <redirect/> </navigation-case> <navigation-case> <from-outcome>doctorList</from-outcome> <to-view-id>/protected/admin/doctorList.xhtml</to-view-id> <redirect/> </navigation-case> <navigation-case> <from-outcome>patientList</from-outcome> <to-view-id>/protected/admin/patientList.xhtml</to-view-id> <redirect/> </navigation-case> <navigation-case> <from-outcome>secretaryList</from-outcome> <to-view-id>/protected/admin/secretaryList.xhtml</to-view-id> <redirect/> </navigation-case> When i pressed my button, not reaction. Why? I added the action in button: And in Ring I add: images.add(new PersonImage("person4.png", "Admin", "adminList")); action is adminList. Why this not work? When i changed in button: <p:commandButton value="#{image.name}" action="adminList" /> all work. Why? Both construction returned identical string.

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  • Should member variables of global objects be made global as well?

    - by David Wong
    I'm developing plugins in Eclipse which mandates the use of singleton pattern for the Plugin class in order to access the runtime plugin. The class holds references to objects such as Configuration and Resources. In Eclipse 3.0 plug-in runtime objects are not globally managed and so are not generically accessible. Rather, each plug-in is free to declare API which exposes the plug-in runtime object (e.g., MyPlugin.getInstance() In order for the other components of my system to access these objects, I have to do the following: MyPlugin.getInstance().getConfig().getValue(MyPlugin.CONFIGKEY_SOMEPARAMETER); , which is overly verbose IMO. Since MyPlugin provides global access, wouldn't it be easier for me to just provide global access to the objects it manages as well? MyConfig.getValue(MyPlugin.CONFIGKEY_SOMEPARAMETER); Any thoughts? (I'm actually asking because I was reading about the whole "Global variable access and singletons are evil" debates)

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  • Date or String declaration in a javabean

    - by Jeff
    Should I declare an attribute in a javabean that holds a date value a user types in on an HTML form as a String or Date? I feel I should declare as a Date, however, since I do server validation on all form data, if the date doesn't validate, when I pass the form bean back to the jsp view for correcting, I lose the date value that the user tried to type in. If I declare as a String, if the date doesn't validate, I'm able to set the string value in the bean and pass the bean back to the view and the user can see what they incorrectly typed. But with a String declaration for Date inputs I forsee problems down the road with my DAO. I want to be able to use a DAO utility which generates a prepare statement using setObject. In my html form I request dates to be mm/dd/yyyy and in DAO i'm using Oracle Date. I can not use hibernate or such, since this is a corporate intranet. What is the best practice "pattern" I should be following??

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  • Generate a Constant expression from a function

    - by Lee
    For my Google Wave robot, on the onDocumentChanged event I want to apply a filter as follows: @Capability(filter = FILTER) @Override public void onDocumentChanged(DocumentChangedEvent event) { ... } I want the filter to be generated the first time the robot is run, which I'm trying to do as follows: private static final String FILTER = generateFilter(); private static final String generateFilter(){ ... } However, it complains FILTER isn't a constant expression when used within @Capability. generateFilter() will return the same string every time it is called, I'm only using it to create the string so that when I make changes, I don't need to worry about updating the filter. Now I could be going about this all wrong, so wondered if anyone knew what I'm doing wrong, or knew a better way in which I could generate a constant expression from the function.

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  • proper way to use list to array?

    - by cometta
    public class TestClass{ private String divisions[] ={}; public void doAction(){ Collection testArray = new ArrayList(); // put testArray will data divisions = (String [] ) testArray.toArray(division); //should i use this divisions = (String [] ) testArray.toArray(new String [] {}); //should i use this? } } if i use case 1, and i call doaction multiple time, the division, something will show wrong records if i use case2, divisions will always show the correct records. is my assumption should use case 2?

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  • Swing: Programmatically select a text

    - by HH
    Hey everyone, I have a very simple Swing GUI with just a JTetxtArea. I am trying to programmatically select a part of text using: textArea.select(startSelection,endSelection); This work. However as soon as I add some other components to the GUI I do not see selection anymore frame.getContentPane().add(button); frame.getContentPane().add(textArea); textArea.select(startSelection,endSelection); I suspect that during layouting the gui, some event causes the text to be deselected. Am I right? And could anybody suggest a solution? My goal is to have a program which displays a text, and allows the user to input start and end selection position, and a selection appears between these two position. Thank you.

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  • Better way to catch trouble points

    - by mac
    User submits a CSV file which is consumed by a program. Values which are used throughout the program come from the CSV, natually if values are missed it is a problem. Below is my solution. Ip on top private List<String> currentFieldName = new ArrayList<String>(); As part of the method: try { setCurrentFieldName("Trim Space"); p.setTrimSpace(currentLineArray[dc.getTRIM_POSITION()].equals("yes") ? true : false); setCurrentFieldName("Ignore Case"); p.setIgnoreCase(currentLineArray[dc.getIGNORE_CASE_POSITION()].equals("yes") ? true : false); } catch (NullPointerException e) { throw new InputSpreadsheetValueUnassignedException("\"Type\" field not set: " + currentFieldName); } And the method which keeps track of a current field being looked at: private void setCurrentFieldName(String fieldName) { currentFieldName.clear(); currentFieldName.add(fieldName); } The idea there is that if user fails to submit value and i will end up getting null, before throwing an exception, i will know what value was not assigned. So, this being said, specific questions: Is what i have shown below an acceptable solution? Can you suggest something more elegant?

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  • Replace carriage returns and line feeds in out.println?

    - by Mike
    I am a novice coder and I am using the following code to outprint a set of Image keywords and input a "|" between them. <% Set allKeywords = new HashSet(); for (AlbumObject ao : currentObjects) { XmpManager mgr = ao.getXmpManager(); if (mgr != null) { allKeywords.addAll(mgr.getKeywordSet()); } } //get the Iterator Iterator itr = allKeywords.iterator(); while(itr.hasNext()){ String str = itr.next(); out.println(str +"|"); } %> I want the output to be like this: red|blue|green|yellow but it prints out: red| blue| green| yellow which breaks my code. I've tried this: str.replaceAll("\n", ""); str.replaceAll("\r", ""); and str.replaceAll("(?:\\n|\\r)", ""); No luck. I'd really appreciate some help!

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  • Project works in eclipse but not when exported

    - by Mike
    I wrote an application that uses GraphViz to generate some graphs as .gif's according to the DOT syntax. When I run from Eclipse the images are generated fine but when I export it as a jar the images are created but there is no data in them. When I view them in Microsoft Picture Viewer its just the red X. It was working as an exported jar until I put the picture generation in its own thread. I can't seem to figure out whats going on here. Are there any problems exporting multi-threaded projects? Any one have any ideas? Thanks

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  • Junit before class ( non static )

    - by Roman
    Are there any best practices to get Junit execute a function once in a test file , and it should also not be static. like @BeforeClass on non static function? Here is an ugly solution : @Before void init(){ if (init.get() == false){ init.set(true); // do once block } } well this is something i dont want to do , and i am looking for an integrated junit solution.

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  • Major inconsistencies in Zend Framework

    - by John Nall
    Okay first of all let me just say Zend Framework is the greatest tool I have ever used in 30+ years of programming (well, for web development, Qt wins the desktop market). However, through my use I have noticed some glaring and annoying inconsistencies. For instance, Zend_Form_Element's have a setAttrib() method. Now why the hell is this the only method in that API which is abbrev.? Why then am I using setRequired() instead of setReq()? I have more examples, I am extremely nerd raged about this. It is completely ruining what could have been God's gift to web development. FOR FUTURE REFERENCE NEVER ABBREV. THINGS WHEN MAKING AN API. also always filter data before storing it i m o Who do we talk to about this, where something will actually get done about it?

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  • connection.setRequestProperty and excplicitly writing to the urloutputstream are they same ?

    - by Bunny Rabbit
    URL url = new URL("http://www.example.com/comment"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setDoOutput(true); connection.setRequestMethod("POST"); Is connection.setRequestProperty(key, value); same as OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream()); writer.write("key=" + value); writer.close(); if not please correct me .

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  • My method is too specific. How can I make it more generic?

    - by EricBoersma
    I have a class, the outline of which is basically listed below. import org.apache.commons.math.stat.Frequency; public class WebUsageLog { private Collection<LogLine> logLines; private Collection<Date> dates; WebUsageLog() { this.logLines = new ArrayList<LogLine>(); this.dates = new ArrayList<Date>(); } SortedMap<Double, String> getFrequencyOfVisitedSites() { SortedMap<Double, String> frequencyMap = new TreeMap<Double, String>(Collections.reverseOrder()); //we reverse order to sort from the highest percentage to the lowest. Collection<String> domains = new HashSet<String>(); Frequency freq = new Frequency(); for (LogLine line : this.logLines) { freq.addValue(line.getVisitedDomain()); domains.add(line.getVisitedDomain()); } for (String domain : domains) { frequencyMap.put(freq.getPct(domain), domain); } return frequencyMap; } } The intention of this application is to allow our Human Resources folks to be able to view Web Usage Logs we send to them. However, I'm sure that over time, I'd like to be able to offer the option to view not only the frequency of visited sites, but also other members of LogLine (things like the frequency of assigned categories, accessed types [text/html, img/jpeg, etc...] filter verdicts, and so on). Ideally, I'd like to avoid writing individual methods for compilation of data for each of those types, and they could each end up looking nearly identical to the getFrequencyOfVisitedSites() method. So, my question is twofold: first, can you see anywhere where this method should be improved, from a mechanical standpoint? And secondly, how would you make this method more generic, so that it might be able to handle an arbitrary set of data?

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