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  • I have a feeling that adding fields marked with @Transient annotation to entity is very bug-prone. A

    - by Roman
    I have some philosophical feeling that adding to an entity fields which doesn't mapped to the DB is a wrong way of solving problems. But are there any concrete situations where using @Transient fields leads to implicit and hard fixing problems? For example, is it possible that adding/removing 2nd level cache will break our app when there are @Transient fields in our entities?

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  • Accessing inter-schema tables and relations in hibernate

    - by nitesh
    There is a typical situation being faced where different tables are scattered through different schemas in Oracle database and they are related to each other (encompassing all different types of relations). How can they be represented in Hibernate using annotations as when a sessionfactory handle is created for one schema, tables in that schema can't access other related tables (foreign key relation to tables in other schema)? For a query like following, exception is thrown - "from table1 as model where model.table2Name.table2column = "+foo Exception comes as - org.hibernate.QueryException: could not resolve property: table2column of: com.test.table1 [from com.test.table1 as model where model.table2Name.table2column = 1] Here table1 and table2 are present in different schemas.

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  • Iterate over a list and put data in hashmap

    - by sarah
    I am having a list where i need to loop over it and put its data in hashmap,i am using this approach for(int i=0;i<list.size();i++) { HashMap hMap=new HashMap(); hMap.put("Data", list); } But when i need to read the value from hMap i am doing in this way Collection c = hMap.values(); Iterator itr = c.iterator(); while(itr.hasNext()) { System.out.println("next val is--"+itr.next()); } next vali is--- is printed in com.bean.xyz@23032bc[id=1] format ,i need the exact data,how will i do this ?

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  • Check if edit is valid for database ms-access

    - by twodayslate
    I want to be able to check if I can edit a cell in a database with a new object Example method declaration: something.isValid(Object newObject, row, column); Example cases: If the editing cell stores an Number and I give it a String, the method will return false... If the editing cell has to be different than every other entry and the new object is the same as something else, the method will also return false.... My main goal... I want to check a whole row, and if everything is valid, I will edit the whole row. Right now, the only way I can find out if I can actually edit something is by actually editing it and seeing if I get an error.

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  • Calculate the number of ways to roll a certain number

    - by helloworld
    I'm a high school Computer Science student, and today I was given a problem to: Program Description: There is a belief among dice players that in throwing three dice a ten is easier to get than a nine. Can you write a program that proves or disproves this belief? Have the computer compute all the possible ways three dice can be thrown: 1 + 1 + 1, 1 + 1 + 2, 1 + 1 + 3, etc. Add up each of these possibilities and see how many give nine as the result and how many give ten. If more give ten, then the belief is proven. I quickly worked out a brute force solution, as such int sum,tens,nines; tens=nines=0; for(int i=1;i<=6;i++){ for(int j=1;j<=6;j++){ for(int k=1;k<=6;k++){ sum=i+j+k; //Ternary operators are fun! tens+=((sum==10)?1:0); nines+=((sum==9)?1:0); } } } System.out.println("There are "+tens+" ways to roll a 10"); System.out.println("There are "+nines+" ways to roll a 9"); Which works just fine, and a brute force solution is what the teacher wanted us to do. However, it doesn't scale, and I am trying to find a way to make an algorithm that can calculate the number of ways to roll n dice to get a specific number. Therefore, I started generating the number of ways to get each sum with n dice. With 1 die, there is obviously 1 solution for each. I then calculated, through brute force, the combinations with 2 and 3 dice. These are for two: There are 1 ways to roll a 2 There are 2 ways to roll a 3 There are 3 ways to roll a 4 There are 4 ways to roll a 5 There are 5 ways to roll a 6 There are 6 ways to roll a 7 There are 5 ways to roll a 8 There are 4 ways to roll a 9 There are 3 ways to roll a 10 There are 2 ways to roll a 11 There are 1 ways to roll a 12 Which looks straightforward enough; it can be calculated with a simple linear absolute value function. But then things start getting trickier. With 3: There are 1 ways to roll a 3 There are 3 ways to roll a 4 There are 6 ways to roll a 5 There are 10 ways to roll a 6 There are 15 ways to roll a 7 There are 21 ways to roll a 8 There are 25 ways to roll a 9 There are 27 ways to roll a 10 There are 27 ways to roll a 11 There are 25 ways to roll a 12 There are 21 ways to roll a 13 There are 15 ways to roll a 14 There are 10 ways to roll a 15 There are 6 ways to roll a 16 There are 3 ways to roll a 17 There are 1 ways to roll a 18 So I look at that, and I think: Cool, Triangular numbers! However, then I notice those pesky 25s and 27s. So it's obviously not triangular numbers, but still some polynomial expansion, since it's symmetric. So I take to Google, and I come across this page that goes into some detail about how to do this with math. It is fairly easy(albeit long) to find this using repeated derivatives or expansion, but it would be much harder to program that for me. I didn't quite understand the second and third answers, since I have never encountered that notation or those concepts in my math studies before. Could someone please explain how I could write a program to do this, or explain the solutions given on that page, for my own understanding of combinatorics? EDIT: I'm looking for a mathematical way to solve this, that gives an exact theoretical number, not by simulating dice

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  • Synchronize write to two collections

    - by glaz666
    I need to put some value to maps if it is not there yet. The key-value (if set) should always be in two collections (that is put should happen in two maps atomically). I have tried to implement this as follows: private final ConcurrentMap<String, Object> map1 = new ConcurrentHashMap<String, Object>(); private final ConcurrentMap<String, Object> map2 = new ConcurrentHashMap<String, Object>(); public Object putIfAbsent(String key) { Object retval = map1.get(key); if (retval == null) { synchronized (map1) { retval = map1.get(key); if (retval == null) { Object value = new Object(); //or get it somewhere synchronized (map2) { map1.put(key, value); map2.put(key, new Object()); } retval = value; } } } return retval; } public void doSomething(String key) { Object obj1 = map1.get(key); Object obj2 = map2.get(key); //do smth } Will that work fine in all cases? Thanks

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  • Queries with developing a Voice to Text Based Software

    - by harigm
    I am looking for any software which converts the voice to the text. I can get some software which can easily convert the english launguage voice to English text. But my intention is be it any language, whatever the system gets voice that should give the output in the text format in English. Is it possible to get this kind of software? If yes any open source available to help me to use this? If not, Is this feasible to develop this kind of software, Can any one guide how to and where to begin with? I am looking for windows based software

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  • What happens if an exception is thrown during finalize()

    - by Psykocyber
    What would happen if an exception is thrown during the execution of finalize()? Is the stack unwind like normally? Does it continue finalize() and ignore the exception? Does it stop finalize() and continue GC the object? Or something else? I'm not looking for guidelines of using finalize() there are plently of pages explaining that.

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  • Android - Can display a single Activity using two layout.xml files?

    - by Avadhani
    I had developed Android app having some screens with common UI format. The format in top-down approach is: Title Header (Two buttons, ImageView) Content Area- It will differ among Activities (contains ListView, Tabs, Buttons, TextView, WebView....) Footer Layout (Relative Layout with three Imagebuttons) I want to reformat the code in such a way that one xml contains Title Header and Footer Layout and other xml contains ListView,Tabs, Buttons.. based on the usage. Can i acheive this? Please help me with sample code/links....

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  • BeanUtils getPropertyOfMapBean

    - by dx-cp
    Hi, Im wondering if it is possible to get data from property which is map cotaining pairs Key-StringArray (Map) in BeanUtils library. I just simply need to access one of array elements by calling propertyName=string[0]. Current version (1.8.3) does not support indexed properties. If you look into their code you will find in class PropertyUtilsBean in method getPropertyOfMapBean: if (resolver.isIndexed(propertyName) || resolver.isMapped(propertyName)) { throw new IllegalArgumentException( "Indexed or mapped properties are not supported on" + " objects of type Map: " + propertyName); } way too bad:-( Have any of you any tip how to do it somehow differently?

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  • DefaultStyledDocument.styleChanged(Style style) may not run in a timely manner?

    - by Paul Reiners
    I'm experiencing an intermittent problem with a class that extends javax.swing.text.DefaultStyledDocument. This document is being sent to a printer. Most of the time the formatting of the document looks correct, but once in a while it doesn't. It looks like some of the changes in the formatting have not been applied. I took a look at the DefaultStyledDocument.styleChanged(Style style) code: /** * Called when any of this document's styles have changed. * Subclasses may wish to be intelligent about what gets damaged. * * @param style The Style that has changed. */ protected void styleChanged(Style style) { // Only propagate change updated if have content if (getLength() != 0) { // lazily create a ChangeUpdateRunnable if (updateRunnable == null) { updateRunnable = new ChangeUpdateRunnable(); } // We may get a whole batch of these at once, so only // queue the runnable if it is not already pending synchronized(updateRunnable) { if (!updateRunnable.isPending) { SwingUtilities.invokeLater(updateRunnable); updateRunnable.isPending = true; } } } } /** * When run this creates a change event for the complete document * and fires it. */ class ChangeUpdateRunnable implements Runnable { boolean isPending = false; public void run() { synchronized(this) { isPending = false; } try { writeLock(); DefaultDocumentEvent dde = new DefaultDocumentEvent(0, getLength(), DocumentEvent.EventType.CHANGE); dde.end(); fireChangedUpdate(dde); } finally { writeUnlock(); } } } Does the fact that SwingUtilities.invokeLater(updateRunnable) is called, rather than invokeAndWait(updateRunnable), mean that I can't count on my formatting changes appearing in the document before it is rendered? If that is the case, is there a way to ensure that I don't proceed with rendering until the updates have occurred?

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  • Storing Result set into an array

    - by OVERTONE
    i know this should be simpel and im probably staring straight at the problem but once again im stuck and need the help of the code gurus. im trying too take one row from a column in jdbc, and put them in an array. i do this as follows: public void fillContactList() { createConnection(); try { Statement stmt = conn.createStatement(); ResultSet namesList = stmt.executeQuery("SELECT name FROM Users"); try { while (namesList.next()) { contactListNames[1] = namesList.getString(1); System.out.println("" + contactListNames[1]); } } catch(SQLException q) { } conn.commit(); stmt.close(); conn.close(); } catch(SQLException e) { } creatConnection is an already defined method that does what it obviously does. i creat my result set while theres another one, i store the string of that column into an array. then print it out for good measure. too make sure its there. the problem is that its storing the entire column into contactListNames[1] i wanted to make it store column1 row 1 into [1] then column 1 row 2 into [2] i know i could do this with a loop. but i dont know too take only one row at a time from a single column. any ideas? p.s ive read the api, i jsut cant see anything that fits.

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  • Spring @Transactional Annotation Best Practice

    - by Thomas Einwaller
    We are currently discussing the Best Practice for placing the @Transactional annotations in our code. Do you place the @Transactional in the DAO classes and/or their methods or is it better to annotate the Service classed which are calling using the DAO objects? Or does it make sense to annotate both "layers"?

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  • Connecting to Sharepoint using HttpClient

    - by Aravindan R
    I am trying to connect to a Sharepoint 2007 using HttpClient 4. The Authentication scheme is NTLM and i wrote an implementation based on this (http://hc.apache.org/httpcomponents-client-ga/ntlm.html). When i try to connect supplying NTCredentials (username,password,host & domain), i get a 500 error saying "The requested function is not supported". I am trying to understand this error. Does anyone know what this error is? and Why is this occuring? Thanks

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  • how to implement a callback in runnable to update other swing class

    - by wizztjh
    I have a thread like this public class SMS { class Read implements Runnable { Read(){ Thread th = new Thread(this); th.start(); } @Override public void run() { // TODO Auto-generated method stub while (true){ Variant SMSAPIReturnValue = SMSAPIJava.invoke("ReadSMS"); if (SMSAPIReturnValue.getBoolean()){ String InNumber = SMSAPIJava.getPropertyAsString("MN"); String InMessage = SMSAPIJava.getPropertyAsString("MSG"); } } } } } How do I update the message to another GUI class in the same package(I understand how to put nested class to another package ....). Should I implement a callback function in SMS class? But how? Or should I pass in the Jlabel into the class?

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  • How can I force the text go to the button of the panel?

    - by Roman
    At the moment I have the following code which works fine. label = new JLabel(panelLabel,SwingConstants.CENTER); outputPanel.add(label,BorderLayout.CENTER); I get the text in the center of the panel (in terms of the left-right position as well as in terms of the top-bottom). Now I want to set the position to the bottom (and center in terms of "left-right"). I tried to use SOUTH instead of the CENTER in the first line. Compiler does not complains but during the execution i get IllegalArgumentException: HorizontalAlignment. What is that?

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  • Creating parameterized type object using annonymous class

    - by Andrei Fierbinteanu
    This might be a stupid question, but I just saw a question asking how to create a Type variable for a generic type. The consensus seemed to be that you should have a dummy method returning that type, and then use reflection to get it (in this case he wanted Map<String, String>). Something like this : public Map<String, String> dummy() { throw new Error(); } Type mapStringString = Class.forName("ThisClass").getMethod("dummy").getGenericReturnType(); My question is, not having used reflection that much, couldn't you just do something like: Type mapStringString = new ParameterizedType() { public Type getRawType() { return Map.class; } public Type getOwnerType() { return null; } public Type[] getActualTypeArguments() { return new Type[] { String.class, String.class }; } }; Would this work? If not, why not? And what are some of the dangers/problems if it does (besides being able to return some Type like Integer<String> which is obviously not possible.

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  • How can I get an error or a warning from a PreparedStatement?

    - by Geo
    I had an update like this: update table set col1=?,col2=?,col3=? where col4=?; and I filled it up like this: statement.setString(1,"some_value"); statement.setString(2,"some_value"); statement.setString(3,"some_value"); and I forgot to add a fourth value.I did a executeUpdate and of course nothing happened to the database. I spent about 1 hour debugging it, to see where it goes wrong. I then modified my code to print the SQLWarning object returned by the getWarnings method. It always returned null. I even modified the code to the buggy state it was, before I set the fourth parameter, and still no warning. Does anyone know how one can get an error/warning? If it matters, my Connection is set to autoCommit.

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  • JPA atomic query/save for multithreaded app

    - by TofuBeer
    I am in the midst of changing my JPA code around to make use of threads. I have a separate entity manager and transaction for each thread. What I used to have (for the single threaded environment) was code like: // get object from the entity manager X x = getObjectX(jpaQuery); if(x == null) { x = new X(); x.setVariable(foo); entityManager.persist(x); } With that code in the multi threaded environment I am getting duplicate keys since, I assume, getObjectX returns null for a thread, then that thread is swapped out, the next thread calls getObjextX, also getting null, and then both threads will create and persist a new X(). Short of adding in synchronization, is there an atomic way to get/save-if-doesn't-exist a value with JPA or should I rethink my approach EDIT: I am using the latest Eclipselink and MySql 5.1

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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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  • Hibernate Unit tests - Reset schema

    - by Marco
    Hi, I'm testing the CRUD operations of my DAOs in JUnit tests. When i execute the single test, Hibernate always resets the schema and populates the DB in a known state. But when i execute multiple tests in a row, Hibernate resets the schema once, and then the data is accumulated during the execution of the tests. This is an unexpected behavior, so I'd like to add in the @Before method of the tests a function that explicitly resets the schema to avoid the pesistence of side data created by previous tests during the execution chain. Any tips? Thanks

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  • How to avoid StaleObjectStateException when transaction updates thousands of entities?

    - by ThinkFloyd
    We are using Hibernate 3.6.0.Final with JPA 2 and Spring 3.0.5 for a large scale enterprise application running on tomcat 7 and MySQL 5.5. Most of the transactions in application, lives for less than a second and update 5-10 entities but in some use cases we need to update more than 10-20K entities in single transaction, which takes few minutes and hence more than 70% of times such transaction fails with StaleObjectStateException because some of those entities got updated by some other transaction. We generally maintain version column in all tables and in case of StaleObjectStateException we generally retry but since these longs transactions are anyways very long so if we keep on retrying then also I am not very sure that we'll be able to escape StaleObjectStateException. Also lot of activities keep updating these entities in busy hours so we cannot go with pessimistic approach because it can potentially halt many activities in system. Please suggest how to fix such long transaction issue because we cannot spawn thousands of independent and small transactions because we cannot afford messed up data in case of some failed & some successful transactions.

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