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  • Delete an entity by key without fetching it first in app engine (using JDO)

    - by Peter Recore
    Is there a way to delete an entity without having to fetch it from the datastore first? I am assuming I already have the key or id for the entity. I'm thinking of something like deleteObjectById that would be an analogue to getObjectById on PersistenceManager. The closest I can think of is using Query.deletePersistentAll() (as seen here) and specifying a query that only relies on the key, but I can't tell if that is going to fetch the entity before deleting it. thanks EDIT: I know how to do this using the low level API, as well as in the python API. I was wondering if there was a way to do it within the JDO layer.

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  • How to schedule an alarm so that the intent is broadcast everytime the date changes?

    - by rogerstone
    I want to schedule an alarm which throws an intent when the date changes. I know that this would do this the job alarms.setRepeating(AlarmManager.RTC_WAKEUP,triggerAtTime, interval,alarmIntent); But what is confusing me is what to put in the triggerAtTime and the interval.It says System.currentTimeMillis() timebase. I might be installing the app on any day so the TriggerAtTime should be midnight of that day and the interval would be 24 hours from there on. How can I acheive this.Can someone tell me what to put in TriggerAtTime and interval in the required format. Thanks

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  • Given a number of rectangles that can be rotated, find an enclosing rectangle of minimum area

    - by efficiencyIsBliss
    So, I'm trying to implement an algorithm that takes in a number of rectangles as input and tries to pack them into a rectangle of minimum area. The rectangles can all be rotated by 90 degrees. I realize that this is similar to the bin packing problem, but I am unable to find a good algorithm that accounts for the rotation. I found a paper that discusses this at length here and while I understand the article itself, I was hoping to find something simpler. Any suggestions? -Edit- I think I misstated the problem earlier. We are given a number of rectangles, such that each can be rotated by 90 degrees. We need to find a rectangle that fits all the given rectangles such that no two rectangles overlap, while minimizing the area of the enclosing rectangle. The problem I face here is that we are asked to find the minimum, as opposed to being given an enclosing rectangle and checking if the given rectangles fit or something of that sort.

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  • How to know file type without extension

    - by Ayusman
    While trying to come-up with a servlet based application to read files and manipulate them (image type conversion) here is a question that came up to me: Is it possible to inspect a file content and know the filetype? Is there a standard that specifies that each file MUST provide some type of marker in their content so that the application will not have to rely on the file extension constraints? Consider an application scenario: I am creating an application that will be able to convert different file formats to a set of output formats. Say user uploads an PDF, my application can suggest that the possible conversion formats are microsoft word or TIFF or JPEG etc. As my application will gradually support different file formats (over a period of time), I want my application to inspect the input file instead of having the user to specify the format. And suggest to user the possible formats of output. I understand this is an open ended, broad question. Please let me know if it needs to be modified. Thanks, Ayusman

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  • Inserting an element into a sorted list

    - by Russell Cargill
    Ok I'm using getSharedPreferences to store my high score but before I fill it up I wanted to sort the scores into ascending order via and array, but if it finds a Score less than it in the first pos then it wont check the rest for the smallest? //function to add score to array and sort it public void addscoretoarray(int mScore){ for(int pos = 0; pos< score.length; pos++){ if(score[pos] > mScore){ //do nothing }else { //Add the score into that position score[pos] = mScore; break; } } sortArray(score); } should I call sortArray() before and after the loop to fix this problem or is there a better method to achive the same results? I should also mention that the sortArray(score) funtion is just calling Arrays.sort(score) where score is an array of mScore

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  • How can I store large amount of data from a database to XML (memory problem)?

    - by Andrija
    First, I had a problem with getting the data from the Database, it took too much memory and failed. I've set -Xmx1500M and I'm using scrolling ResultSet so that was taken care of. Now I need to make an XML from the data, but I can't put it in one file. At the moment, I'm doing it like this: while(rs.next()){ i++; xmlStringBuilder.append("\n\t<row>"); xmlStringBuilder.append("\n\t\t<ID>" + Util.transformToHTML(rs.getInt("id")) + "</ID>"); xmlStringBuilder.append("\n\t\t<JED_ID>" + Util.transformToHTML(rs.getInt("jed_id")) + "</JED_ID>"); xmlStringBuilder.append("\n\t\t<IME_PJ>" + Util.transformToHTML(rs.getString("ime_pj")) + "</IME_PJ>"); //etc. xmlStringBuilder.append("\n\t</row>"); if (i%100000 == 0){ //stores the data to a file with the name i.xml storeKBR(xmlStringBuilder.toString(),i); xmlStringBuilder= null; xmlStringBuilder= new StringBuilder(); } and it works; I get 12 100 MB files. Now, what I'd like to do is to do is have all that data in one file (which I then compress) but if just remove the if part, I go out of memory. I thought about trying to write to a file, closing it, then opening, but that wouldn't get me much since I'd have to load the file to memory when I open it. P.S. If there's a better way to release the Builder, do let me know :)

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  • Add a listener inside or outside get method

    - by James P.
    I'm learning Swing and have composed an interface using a series of get methods to add components. Is it a good practise to add a Listener inside a get method as follows? I'd like to make things as decoupled as possible. private JButton getConnectButton() { if (connectButton == null) { connectButton = new JButton(); connectButton.setText("Connect"); connectButton.setSize(new Dimension(81, 16)); connectButton.setLocation(new Point(410, 5)); connectButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // actionPerformed code goes here } }); } return connectButton; }

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  • Image Uploading in a web aplication.

    - by sandeep manglani
    actually i m devloping a web application that provides facility to users upload the image as we see in orkut and facebook through a form and a upload button.but the actually problem I am facing is : 1.should i store the image in database using Large data objects ie BLOB and the problem arises of retrieving it back from the database and then displaying it on the form. 2.sholud i store the absolute path of the the image in database and provide it to the source tag of the image in the html form.

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  • JBoss envers and huge audit tables

    - by LeChe
    All, I am auditing my JEE application with JBoss Evers and the nature of my application causes the audit table to grow very fast. The historic data is queried infrequently and access time is not really an issue, apart from the data from the last week. This data IS queried frequently and access needs to be fast. Ideally, I would split the data and distribute it over two tables, with the older data in compressed format. Unfortunately, Envers does not allow spreading data over multiple tables as far as I can tell from the docs. Does somebody have any idea what would be the best way to achieve this (if possible while still using Envers)? Cheers, LeChe

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  • Relative path in JLabel HTML

    - by kroiz
    Hi, I am trying to make JLabel show an html which is referencing an image using a relative path. But I cannot make JLabel locate the image. It works fine when I am using absolute path. I have tried running the program from the command line or from eclipse and add dialog to show me where is the current working directory but for avail. I have therefor came to the conclusion that the image is not searched in the current directory - which brings me to the point. where is the image looked for? here is a test code that show what I am doing: import javax.swing.*; public class HTMLLabel extends JFrame { public HTMLLabel() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JOptionPane.showMessageDialog( this, System.getProperty("user.dir")); String html = "<html>\n" + " <body>\n" + " <div style=\"text-align: center;\">\n" + " <img src=\"file://s.png\">\n"+ " </div>\n"+ " </body>\n"+ "</html>"; JLabel label = new JLabel(html); add(label); pack(); setVisible(true); } public static void main(String[] args) { new HTMLLabel(); } }

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  • Sad logic on types

    - by user2972231
    Code base is littered with code like this: BaseRecord record = // some BaseRecord switch(record.source()) { case FOO: return process((FooRecord)record); case BAR: return process((BarRecord)record); case QUUX: return process((QuuxRecord)record); . . // ~25 more cases . } and then private SomeClass process(BarRecord record) { } private SomeClass process(FooRecord record) { } private SomeClass process(QuuxRecord record) { } It makes me terribly sad. Then, every time a new class is derived from BaseRecord, we have to chase all over our code base updating these case statements and adding new process methods. This kind of logic is repeated everywhere, I think too many to add a method for each and override in the classes. How can I improve this?

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  • Method with throws Exception: Where is it actually handled?

    - by Esq
    Here is an example code, I am throwing an exception here, it works perfectly fine without the try/catch block of code for some reason. Do I have to handle this inside this method "EntryDelete" or Do I have to handle this where the method is called from? If so can I see an example, what do I have to import in there? What is the acceptable syntax or method to do this? public boolean EntryDelete(int entryId) throws SQLException{ this.open(); kDatabase.delete(kENTRY_TABLE, kENTRY_ENTRY_ID + "=" + entryId, null); this.close(); return true; } Thanks

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  • How to update only certain items in a list when using MVC?

    - by Eugen
    I'm building a GUI that includes a list with quite a lot of items. I allow the user to add/delete/edit those items. Up until now my update method called in the controller implied an entire JList reset (with its obvious performance issues). Now that there are hundreds of items available, updating the entire list is not fezable any longer. Does anyone know of a tutorial or can share an example (I haven't found any to suit my needs so far) in which the JList is updated something like JList.update(startIndex, endIndex);? Thanks for taking the time to answer.

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  • Defining tokens at runtime

    - by Peter Crenshaw
    I want to write a parser for EDIFACT messages with JavaCC. My problem is that I cannot define all terminal symbols before parsing a message because at the begining of each message there is a so called "Advice Segment" ("UNA" Segment) which defines things like element seperator symbol, escape symbol, segment terminator symbol and decimal notation (e.g. '.' or ','). So I think/guess the production rules need some kind of variables which must be set at runtime during parsing. Can this be done with JavaCC and if so how? Or is there another way I am missing?

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  • In this example, would Customer or AccountInfo properly be the entity group parent?

    - by Badhu Seral
    In this example, the Google App Engine documentation makes the Customer the entity group parent of the AccountInfo entity. Wouldn't AccountInfo encapsulate Customer rather than the other way around? Normally I would think of an AccountInfo class as including all of the information about the Customer. import javax.jdo.annotations.IdGeneratorStrategy; import javax.jdo.annotations.PersistenceCapable; import javax.jdo.annotations.Persistent; import javax.jdo.annotations.PrimaryKey; import com.google.appengine.api.datastore.Key; import com.google.appengine.api.datastore.KeyFactory; @PersistenceCapable public class AccountInfo { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; public void setKey(Key key) { this.key = key; } } // ... KeyFactory.Builder keyBuilder = new KeyFactory.Builder(Customer.class.getSimpleName(), "custid985135"); keyBuilder.addChild(AccountInfo.class.getSimpleName(), "acctidX142516"); Key key = keyBuilder.getKey(); AccountInfo acct = new AccountInfo(); acct.setKey(key); pm.makePersistent(acct);

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  • Connecting to an RMI object without registry

    - by Mark Probst
    I think I need to connect to a remote RMI object without going through the registry, but I don't know how. My situation is this: I'm implementing a simple job distribution service which consists of one distributor and multiple workers. The distributor has a registered RMI object to which clients connect to send jobs, and workers connect to accept jobs. Unfortunately the distributor and worker hosts are behind a firewall. To get to the distributor host I am tunneling two ports (one for the registry, one for the distributor object) via SSH, so I can get to the registry and the distributor from outside the firewall. To make that work I have to set "-Djava.rmi.server.hostname=localhost" on the distributor JVM so that the clients connect to their local, tunneled port, instead of the port on the actual distributor host, which is blocked. This creates a problem for the workers, though, because they need to connect to the distributor directly, but because of the "localhost" redirection they behave like clients and try to connect to a port on their own host, which is not available, because I'm not tunneling on the workers (it is impractical). Now, if I could connect to a remote object directly by giving the hostname and port, I could do away both with the registry on the distributor and the "localhost" hack, and make the workers connect properly. How do I do that? Or is there a different solution to this problem?

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  • problem to create session of facebook

    - by khoyendra
    try { HttpClient http = new HttpClient(); http.setParams(new HttpClientParams()); //http.getHostConfiguration().setHost("http://www.facebook.com/"); http.setState(new HttpState()); String api_key = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; String secret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; // String appId=124812364218050; //http://www.facebook.com/developers/editapp.php?app_id=124812364218050 FacebookRestClient client = new FacebookRestClient(api_key, secret); client.setIsDesktop(true); // String sessionKey = request.getParameter(FacebookParam.SESSION_KEY.toString()); // boolean b = client.users_setStatus("This is a test..."); // System.out.println("User Status RESULT : " + b); String token = client.auth_createToken(); final String loginId = "http://www.facebook.com/login.php"; GetMethod get = new GetMethod(loginId + "?api_key=" + api_key + "&v=1.0&auth_token=" +token); System.out.println("Get="+get); http.executeMethod(get); PostMethod post = new PostMethod(loginId); post.addParameter(new NameValuePair("api_key", api_key)); post.addParameter(new NameValuePair("v", "1.0")); post.addParameter(new NameValuePair("auth_token", token)); post.addParameter(new NameValuePair("fbconnect","true")); post.addParameter(new NameValuePair("return_session","true")); post.addParameter(new NameValuePair("session_key_only","true")); post.addParameter(new NameValuePair("req_perms","read_stream,publish_stream")); post.addParameter(new NameValuePair("email", email)); post.addParameter(new NameValuePair("pass", password)); System.out.println("Token ="+token); int postStatus = http.executeMethod(post); System.out.println("Response : " + postStatus); session = client.auth_getSession(token); // Here I am getting error System.out.println("Session string: " + session); long userid = client.users_getLoggedInUser(); System.out.println("User Id is : " + userid); } catch (Exception e) { e.printStackTrace(); } please solve my problem i cannot create session of facebook.

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  • Should I close sockets from both ends?

    - by Roman
    I have the following problem. My client program monitor for availability of server in the local network (using Bonjour, but it does not rally mater). As soon as a server is "noticed" by the client application, the client tries to create a socket: Socket(serverIP,serverPort);. At some point the client can loose the server (Bonjour says that server is not visible in the network anymore). So, the client decide to close the socket, because it is not valid anymore. At some moment the server appears again. So, the client tries to create a new socket associated with this server. But! The server can refuse to create this socket since it (server) has already a socket associated with the client IP and client port. It happens because the socket was closed by the client, not by the server. Can it happen? And if it is the case, how this problem can be solved? Well, I understand that it is unlikely that the client will try to connect to the server from the same port (client port), since client selects its ports randomly. But it still can happen (just by chance). Right?

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  • Headless build of eclipse features - PDE Tools or Buckminster?

    - by Max
    I am trying to set up a headless build for a big eclipse feature, containing other features and plugins. As some needed plugins are generated using GMF and EMF, the build workflow must be something like this: SVN Check-out Invoke Generation Run Tests Build all Publish update-site Over the last couple of weeks, i played around with PDE Headless Build and Buckminster. Anyhow i still got problems with both and can't decide on which i should spent my effort. So what would you prefer? What experience you made? Anybody out there who needed to set up a similiar workflow before? Thank you for all answers :)

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  • Is it against best practice to throw Exception on most JUnit tests?

    - by Chris Knight
    Almost all of my JUnit tests are written with the following signature: public void testSomething() throws Exception My reasoning is that I can focus on what I'm testing rather than exception handling which JUnit appears to give me for free. But am I missing anything by doing this? Is it against best practice? Would I gain anything by explicitly catching specific exceptions in my test and then fail()'ing on them?

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  • Injecting EntityManager Vs. EntityManagerFactory

    - by SB
    A long question, please bear with me. We are using Spring+JPA for a web application. My team is debating over injecting EntityManagerFactory in the GenericDAO(a DAO based on Generics something on the lines provided by APPFUSE, we do not use JpaDaosupport for some reason) over injecting an EntityManager. We are using "application managed persistence". The arguments against injecting a EntityManagerFactory is that its too heavy and so is not required, the EntityManager does what we need. Also, as Spring would create a new instance of a DAO for every web request(I doubt this) there are not going to be any concurrency issues as in the same EntityManager instance is shared by two threads. The argument for injecting EFM is that its a good practice over all its always good to have a handle to a factory. I am not sure which is the best approach, can someone please enlighten me? SB

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  • Multi-module Maven build

    - by Don
    Hi, My project has a fairly deep graph of Maven modules. The root POM has the following plugin configured <plugins> <plugin> <groupId>org.jvnet</groupId> <artifactId>animal-sniffer</artifactId> <version>1.2</version> <configuration> <signature> <groupId>org.jvnet.animal-sniffer</groupId> <artifactId>java1.4</artifactId> <version>1.0</version> </signature> </configuration> </plugin> </plugins> If I invoke this target from the command line in the root directory via: mvn animal-sniffer:check Then it works fine as long as the current module extends (either directly or indirectly) from the root POM. However there are many children (or grandchildren) of the root module, which do not inherit from that module's POM. In this case, the goal fails because it cannot find the necessary configuration [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] One or more required plugin parameters are invalid/missing for 'animal-sniffer:check' [0] Inside the definition for plugin 'animal-sniffer' specify the following: <configuration> ... <signature>VALUE</signature> </configuration>. When configuring this plugin in the root module, is there any way to exclude a list of sub-modules either by name, or by packaging type? Thanks, Donal

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