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  • How can I find out if two arguments are instances of the same, but unknown class?

    - by Ingmar
    Let us say we have a method which accepts two arguments o1 and o2 of type Object and returns a boolean value. I want this method to return true only when the arguments are instances of the same class, e.g.: foo(new Integer(4),new Integer(5)); Should return true, however: foo(new SomeClass(), new SubtypeSomeClass()); should return false and also: foo(new Integer(3),"zoo"); should return false. I believe one way is to compare the fully qualified class names: public boolean foo(Object o1, Object o2){ Class<? extends Object> c1 = o1.getClass(); Class<? extends Object> c2 = o2.getClass(); if(c1.getName().equals(c2.getName()){ return true;} return false; } An alternative conditional statement would be : if (c1.isAssignableFrom(c2) && c2.isAssignableFrom(c1)){ return true; } The latter alternative is rather slow. Are there other alternatives to this problem?

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  • How do JVM's implicit memory barriers behave when chaining constructors

    - by Joonas Pulakka
    Referring to my earlier question on incompletely constructed objects, I have a second question. As Jon Skeet pointed out, there's an implicit memory barrier in the end of a constructor that makes sure that final fields are visible to all threads. But what if a constructor calls another constructor; is there such a memory barrier in the end of each of them, or only in one being called from outside? That is, when the "wrong" solution is: public class ThisEscape { public ThisEscape(EventSource source) { source.registerListener( new EventListener() { public void onEvent(Event e) { doSomething(e); } }); } } And the correct one would be a factory method version: public class SafeListener { private final EventListener listener; private SafeListener() { listener = new EventListener() { public void onEvent(Event e) { doSomething(e); } } } public static SafeListener newInstance(EventSource source) { SafeListener safe = new SafeListener(); source.registerListener(safe.listener); return safe; } } Would the following work too, or not? public class MyListener { private final EventListener Listener; private MyListener() { listener = new EventListener() { public void onEvent(Event e) { doSomething(e); } } } public MyListener(EventSource source) { this(); source.register(listener); } }

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  • How can I create a user registration form using datastore - google appengine ??

    - by srivigneshwar
    I am very new to jsp and google appengine , but still I can do something if I get some basic idea , I wanna create an user registration form with fields like name, user id , password, confirm password, etc,. using google appengine datastore feature. and I wanna retrieve user information . Please help me .. Thanks in advance. Thanks for the replies, I need to get some information from user and I want to store it in database, and I will use that information for my application. How can I do that?

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  • Deploy maven generated site on Google Code svn?

    - by xamde
    Using a google code svn as a basic maven repository is easy. However, using mvn site:deploy efficiently on google code seems hard. So far, I found only these solutions: * Deploy to a local file:/// and use a PERL script to delete the old and copy the new * Use wagen-svn to deploy. This is very slow (hours!) and does not delete old files * Plus all mime-types are wrong I am looking for a solution that allows new developers in my projects to check out the current source and just use it, without requiring to install PERL or learn weird steps to perform or wait hours.

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  • How would you code a washing machine?

    - by Dan
    Imagine I have a class that represents a simple washing machine. It can perform following operations in the following order: turn on - wash - centrifuge - turn off. I see two basic alternatives: A) I can have a class WashingMachine with methods turnOn(), wash(int minutes), centrifuge(int revs), turnOff(). The problem with this is that the interface says nothing about the correct order of operations. I can at best throw InvalidOprationException if the client tries to centrifuge before machine was turned on. B) I can let the class itself take care of correct transitions and have the single method nextOperation(). The problem with this on the other hand, is that the semantics is poor. Client will not know what will happen when he calls the nextOperation(). Imagine you implement the centrifuge button’s click event so it calls nextOperation(). User presses the centrifuge button after machine was turned on and ups! machine starts to wash. I will probably need a few properties on my class to parameterize operations, or maybe a separate Program class with washLength and centrifugeRevs fields, but that is not really the problem. Which alternative is better? Or maybe there are some other, better alternatives that I missed to describe?

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  • Webapp: safetly update a shared List/Map in the AppContext

    - by al nik
    I've Lists and Maps in my WebAppContext. Most of the time these are only read by multiple Threads but sometimes there's the need to update or add some data. I'm wondering what's the best way to do this without incurring in a ConcurrentModificationException. I think that using CopyOnWriteArrayList I can achieve what I want in terms of - I do not have to sync on every read operation- I can safety update the list while other threads are reading it. Is this the best solution? What about Maps?

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  • How do these user/userParam references relate to the Customer and Account lookups?

    - by marmalade
    In the following code example how do the user/userParam references relate to the Customer and Account lookups and what is the relationship between Customer and Account? // PersistenceManager pm = ...; Transaction tx = pm.currentTransaction(); User user = userService.currentUser(); List<Account> accounts = new ArrayList<Account>(); try { tx.begin(); Query query = pm.newQuery("select from Customer " + "where user == userParam " + "parameters User userParam"); List<Customer> customers = (List<Customer>) query.execute(user); query = pm.newQuery("select from Account " + "where parent-pk == keyParam " + "parameters Key keyParam"); for (Customer customer : customers) { accounts.addAll((List<Account>) query.execute(customer.key)); } } finally { if (tx.isActive()) { tx.rollback(); } }

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  • How do these user/userParam references relate to the Customer and Account lookups?

    - by plath
    In the following code example how do the user/userParam references relate to the Customer and Account lookups and what is the relationship between Customer and Account? // PersistenceManager pm = ...; Transaction tx = pm.currentTransaction(); User user = userService.currentUser(); List<Account> accounts = new ArrayList<Account>(); try { tx.begin(); Query query = pm.newQuery("select from Customer " + "where user == userParam " + "parameters User userParam"); List<Customer> customers = (List<Customer>) query.execute(user); query = pm.newQuery("select from Account " + "where parent-pk == keyParam " + "parameters Key keyParam"); for (Customer customer : customers) { accounts.addAll((List<Account>) query.execute(customer.key)); } } finally { if (tx.isActive()) { tx.rollback(); } }

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  • Why is my file being cleared if I don't save it?

    - by Kat
    My program is suppose to maintain a collection of Photos in a PhotoAlbum. It begins by reading a folder of photos and adds them to my PhotoAlbum. It then prints a menu that allows the user to list all the photos, add a photo, find a photo, save, and quit the program. Right now if I run my program it will add the 100 photos to the PhotoAlbum, but if I quit the program without saving, it clears the file I am reading from even if I haven't added a photo or done anything to the PhotoAlbum and I'm not sure why. Here is my method for printing to a file: private static void saveFile(PrintWriter writer) { String result; ArrayList<Photo> temp = album.getPhotoAlbum(); for (int i = 0; i < temp.size(); i++){ result = temp.get(i).toString() + "\n"; writer.println(result); } writer.close(); } And where the PrintWriter is instantiated: File file = new File(args[0] + File.separator + "album.dat"); try { PrintWriter fout = new PrintWriter(new FileWriter(file)); fileWriter = fout; } catch (IOException e){ System.out.println("ReadFromFile: Folder " + args[0] + " is not found."); System.exit(0); } And where it is called in my runMenu Method: private static void runMainMenu(Scanner scan) { String input; do { showMainMenu(); input = scan.nextLine().toLowerCase(); switch (input.charAt(0)) { case 'p': System.out.println(album.toString()); break; case 'a': album.addPhoto(readPhoto(scan, t)); break; case 'f': findMenu(scan); break; case 's': saveFile(fileWriter); System.exit(0); break; case 'q': break; default: System.out.println("Invalid entry: " + input.charAt(0)); break; } } while (!input.equalsIgnoreCase("q")); }

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  • Using JLabels as pseudo buttons.

    - by FreeThinker
    Currently I am developing a small todo list manager and would like to use labels in place of buttons on the 'context' bar. If any one could provide me with information on how I could go about doing this I would appreciate it greatly.

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  • Making change recursively: How do I modify my algorithm to print all combinations?

    - by cb
    I have an algorithm that recursively makes change in the following manner: public static int makeChange(int amount, int currentCoin) { //if amount = zero, we are at the bottom of a successful recursion if (amount == 0){ //return 1 to add this successful solution return 1; //check to see if we went too far }else if(amount < 0){ //don't count this try if we went too far return 0; //if we have exhausted our list of coin values }else if(currentCoin < 0){ return 0; }else{ int firstWay = makeChange(amount, currentCoin-1); int secondWay = makeChange(amount - availableCoins[currentCoin], currentCoin); return firstWay + secondWay; } } However, I'd like to add the capability to store or print each combination as they successfully return. I'm having a bit of a hard time wrapping my head around how to do this. The original algorithm was pretty easy, but now I am frustrated. Any suggestions? CB

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  • How To Keep Size Of JTextArea constant?

    - by Supereme
    Hi! I'm using an object of JTextArea in my application which deals with sending sms. I've used a DocumentFilter so as to allow only 160 characters to be typed in the textarea but now, I want the size of the textarea to be constant. it goes on increasing if I keep writing on the same line without pressing 'enter' key or even when I keep on pressing only 'enter' key. I tried once using 'scrollbar' too but the problem remains same. Suggest me something over this.

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  • JavaEE Application Server or Lightweight Container?

    - by Jeff Storey
    Let me preface this by saying this is not an actual situation of mine but I'm asking this question more for my own knowledge and to get other people's inputs here. I've used both Spring and EJB3/JBoss, and for the smaller types of applications I've built, Spring (+Tomcat when needed) has been much simpler to use. However, when scaling up to larger applications that require things like load balancing and clustering, is Spring still a viable solution? Or is it time to turn to a solution like EJB3/JBoss when you start to get big enough to need that? I'm not sure if I've scoped the problem well enough to get a good answer, so please let me know. Thanks, Jeff

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  • How Can i click on this element using XPATH in Web driver?

    - by Mike
    Here is the html..... <li> <input type="checkbox" checked="" name="selectedMstrPrivGroupList[9].mstrAuthorities[0].status"/> Add Dexter </li> How will I be able to click on this element. It is a check box. And I want to use XPath as I have close to 30+ checkboxes in the page, so that I can create a generic method and pass only the Webelement.. I tried the following but didn't work. Driver.findElement(By.xpath("//input[contains(.,'Add Dexter')]")).click(); Please help!! Thanks, Mike

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  • Element to string in HTMLDocument

    - by kalpesh
    i have a Element object its a HTMLDocument object and i want to string value of this element. i want this result Christina Toth, Pharm. D. ======================= plz see below code. public static void main(String args[]) throws Exception { InputStream is = Nullsoft.getInputStream(); InputStreamReader isr = new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); HTMLEditorKit htmlKit = new HTMLEditorKit(); HTMLDocument htmlDoc = (HTMLDocument) htmlKit.createDefaultDocument(); HTMLEditorKit.Parser parser = new ParserDelegator(); HTMLEditorKit.ParserCallback callback = htmlDoc.getReader(0); parser.parse(br, callback, true); // Parse ElementIterator iterator = new ElementIterator(htmlDoc); Element element; while ((element = iterator.next()) != null) { AttributeSet attributes = element.getAttributes(); Object name = attributes.getAttribute(StyleConstants.NameAttribute); if ((name instanceof HTML.Tag) && ((name == HTML.Tag.DIV) || (name == HTML.Tag.H2) || (name == HTML.Tag.H3))) { StringBuffer text = new StringBuffer(); int count = element.getElementCount(); for (int i = 0; i < count; i++) { Element child = element.getElement(i); AttributeSet childAttributes = child.getAttributes(); // if (childAttributes.getAttribute(StyleConstants.NameAttribute) == HTML.Tag.CONTENT) { int startOffset = child.getStartOffset(); int endOffset = child.getEndOffset(); int length = endOffset - startOffset; text.append(htmlDoc.getText(startOffset, length)); } } System.out.println(name + ": " + text.toString()); } } System.exit(0); } public static InputStream getInputStream() { String text = "<html>\n" + "<head>\n" + "<title>pg_0001</title>\n" + "\n" + "<style type=\"text/css\">\n" + ".ft3{font-style:normal;font-weight:bold;font-size:11px;font-family:Helvetica;color:#000000;}\n" + "</style>\n" + "</head>\n" + "<body vlink=\"#FFFFFF\" link=\"#FFFFFF\" bgcolor=\"#ffffff\">\n" + "\n" + "\n" + "<div style=\"position:absolute;top:597;left:252\"><nobr><span class=\"ft3\">Christina Toth, Pharm. D.</span></nobr></div>\n" + "\n" + "\n" + "</body>\n" + "</html>"; InputStream is = null; try { is = new ByteArrayInputStream(text.getBytes("UTF-8")); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return is; }

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  • JSONArray does not work when I am getting the JSON string from the server

    - by Taehoon A Kim
    I've looked up some answers but am not sure why mine is failing exactly... The code looks something like this HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); String json = EntityUtils.toString(httpEntity); //Convert to JsonArray JSONArray jsonArray = new JSONArray(json); Log.i(DEBUG_TAG, Integer.toString(jsonArray.length())); for (int i = 0; i < jsonArray.length(); i++) { JSONObject jsonObject = jsonArray.getJSONObject(i); Log.i(DEBUG_TAG, jsonObject.getString(KEY_ID)); // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); // adding each child node to HashMap key => value map.put(KEY_ID, jsonObject.getString(KEY_ID)); map.put(KEY_TITLE, jsonObject.getString(KEY_TITLE)); map.put(KEY_ARTIST, jsonObject.getString(KEY_ARTIST)); map.put(KEY_DURATION, jsonObject.getString(KEY_DURATION)); map.put(KEY_VOTECOUNT, jsonObject.getString(KEY_VOTECOUNT)); map.put(KEY_THUMB_URL, jsonObject.getString(KEY_THUMB_URL)); map.put(KEY_GENRE, jsonObject.getString(KEY_GENRE)); //Adding map to ArrayList if (Integer.parseInt(jsonObject.getString(KEY_VOTECOUNT)) == -1){ //If VoteCount is -1 then add to header headerList.add(map); }else { songsList.add(map); } } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } When I run logcat on String json, it seems to show correct info which is kind of like this... { "userdata": [ { "id": "8", "title": "Baby One More Time", "artist": "Britney Spears", "duration": "03:24:00", "votes": "0", "thumb_url": "http://api.androidhive.info/music/images/dido.png", "genre": null }, { "id": "2", "title": "As Long As You Love Me", "artist": "Justin Bieber", "duration": "05:26:00", "votes": "0", "thumb_url": "http://api.androidhive.info/music/images/enrique.png", "genre": "Rock" } ] } and the logcat on JSONArray jsonArray = new JSONArray(json); tells me that jsonArray.length() 10-31 22:57:28.433: W/CustomizedListView(26945): error! Invalid index 0, size is 0 Please let me know Thank you,

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  • Lucene wildcard queries

    - by Javi
    Hello, I have this question relating to Lucene. I have a form and I get a text from it and I want to perform a full text search in several fields. Suppose I get from the input the text "textToLook". I have a Lucene Analyzer with several filters. One of them is lowerCaseFilter, so when I create the index, words will be lowercased. Imagine I want to search into two fields field1 and field2 so the lucene query would be something like this (note that 'textToLook' now is 'texttolook'): field1: texttolook* field2:texttolook* In my class I have something like this to create the query. I works when there is no wildcard. String text = "textToLook"; String[] fields = {"field1", "field2"}; //analyser is the same as the one used for indexing Analyzer analyzer = fullTextEntityManager.getSearchFactory().getAnalyzer("customAnalyzer"); MultiFieldQueryParser parser = new MultiFieldQueryParser(fields, analyzer); org.apache.lucene.search.Query queryTextoLibre = parser.parse(text); With this code the query would be: field1: texttolook field2:texttolook but If I set text to "textToLook*" I get field1: textToLook* field2:textToLook* which won't find correctly as the indexes are in lowercase. I have read in lucene website this: " Wildcard, Prefix, and Fuzzy queries are not passed through the Analyzer, which is the component that performs operations such as stemming and lowercasing" My problem cannot be solved by setting the behaviour case insensitive cause my analyzer has other fields which for examples remove some suffixes of words. I think I can solve the problem by getting how the text would be after going through the filters of my analyzer, then I could add the "*" and then I could build the Query with MultiFieldQueryParser. So in this example I woud get "textToLower" and after being passed to to these filters I could get "texttolower". After this I could make "textotolower*". But, is there any way to get the value of my text variable after going through all my analyzer's filters? How can I get all the filters of my analyzer? Is this possible? Thanks

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  • What is jasper report's algorithm for using a data source?

    - by spderosso
    Hi, I have created my custom data source by implementing the interface JRDataSource. This interface looks like this: public interface JRDataSource { /** * Tries to position the cursor on the next element in the data source. * @return true if there is a next record, false otherwise * @throws JRException if any error occurs while trying to move to the next element */ public boolean next() throws JRException; /** * Gets the field value for the current position. * @return an object containing the field value. The object type must be the field object type. */ public Object getFieldValue(JRField jrField) throws JRException; } My question is the following: In what way does jasper report call this functions for obtaining the fields in the .jrxml. E.g: if( next() )){ call getFieldValue for every field present in the page header while( next() ){ call getFieldValue for every field present in detail part } call getFieldValue for every field present the footer } The previous is just an example, experimentally in fact I found out that it is actually not like that. So my question arised. Thanks!

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  • Flex/Flash 4 ExternalInterface.call - trying to get a string from HTML to Actionscript.

    - by Setori
    Dear all, I need to obtain a string from HTML and put it into Actionscript. the actionscript: import flash.external.ExternalInterface; protected function getUserName():void{ var isAvailable:Boolean = ExternalInterface.available; var findUserName:String = "findUserName"; if(isAvailable){ var foundUserName:String = ExternalInterface.call(findUserName); Alert.show(foundUserName);}} the javascript: function findUserName() { var label = document.getElementById("username-label"); if(label.value != ""){ alert("the name in the box is: " + label.value); return label.value;} else return "nothing in the textbox";}} the JSP: <%IUserSession userSession = SessionManager.getSession();%> <logic:notEmpty name="userSession"> <logic:notEqual value="anonymous" name="userSession" property="userLoginId"> <td align="right" width="10%" > <input id="username-label" type="text" value="<bean:write name="userSession" property="userLoginId"/>" /> </td> </logic:notEqual> </logic:notEmpty> the rendered HTML: <td align="right" width="10%"> <input id="username-label" type="text" value="a-valid-username" /> </td> when the javascript execution hits var label = document.getElementById("username-label"); a null is returned and crashes, no alert shows no error message is shown. firfox 3.5 windows, container is Tomcat. Please advise, and thank you in advance.

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