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  • How to find out efficiently the auto-generated id for a new object when using JPA?

    - by webstarg
    Hello, I have an attribute which is annotated with @Id. The ID is going to be generated automatically when persisting the object. That means that the ID-value is not defined before I persist the object. After persisting it, it has an ID (in the database), but unfortunately the field still remains null as long as I don't reload it from the DB. is there any easy way to find out the generated id? Or better: To configure that it will be written into the field? Thanks in advance

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  • replace capturing group

    - by Don
    Hi, If I have a regex with a capturing group, e.g. foo(_+f). If I match this against a string and want to replace the first capturing group in all matches with baz so that foo___f blah foo________f is converted to: foobaz blah foobaz There doesn't appear to be any easy way to do this using the standard libraries. If I use Matcher.replaceAll() this will replace all matches of the entire pattern and convert the string to baz blah baz Obviously I can just iterate through the matches, store the start and end index of each capturing group, then go back and replace them, but is there an easier way? Thanks, Don

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  • Find messages from certain key till certain key while being able to remove stale keys.

    - by Alfred
    My problem Let's say I add messages to some sort of datastructure: 1. "dude" 2. "where" 3. "is" 4. "my" 5. "car" Asking for messages from index[4,5] should return: "my","car". Next let's assume that after a while I would like to purge old messages because they aren't useful anymore and I want to save memory. Let's say at time x messages[1-3] became stale. I assume that it would be most efficient to just do the deletion once every x seconds. Next my datastructure should contain: 4. "my" 5. "car" My solution? I was thinking of using a concurrentskiplistset or concurrentskiplist map. Also I was thinking of deleting the old messages from inside a newSingleThreadScheduledExecutor. I would like to know how you would implement(efficiently/thread-safe) this or maybe use a library?

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  • Counting the number of occurrences of characters in an array

    - by Anthony Pittelli
    This is what I have but it is not working, this is confusing for me. If you scroll down I commented on someones post the exact problem I am having and what I am trying to do. I was thinking maybe the problem is my code to generate the random characters: public void add (char fromChar, char toChar){ Random r = new Random(); //creates a random object int randInt; for (int i=0; i<charArray.length; i++){ randInt = r.nextInt((toChar-fromChar) +1); charArray[i] = (char) randInt; //casts these integers as characters } }//end add public int[] countLetters() { int[] count = new int[26]; char current; for (int b = 0; b <= 26; b++) { for (int i = 97; i <= 123; i++) { char a = (char) i; for (int ch = 0; ch < charArray.length; ch++) { current = charArray[ch]; if (current == a) { count[b]++; } } } } return count; }

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  • Validation - Data Integrity

    - by Thomas
    A table can only store 10 records in a particular state, 10 users over 30 years for example, the others must be less than 30 years. It is a business rule and as such should be respected. How to ensure that state? Think: multiple users accessing this table.

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  • How can find out the system default currency symbol on BlackBerry?

    - by ageektrapped
    I have a need to display a currency value in my application. There doesn't seem to be an easy way to do this with the RIM API, so I'm reduced to creating my own solution (a common refrain for BlackBerry development, unfortunately) Currently I'm using the Formatter class, from javax.microedition.locale like so protected String formatResult(double result) { try { Locale l = Locale.getDefaultForSystem(); Formatter formatter = new Formatter(l.toString()); return formatter.formatCurrency(result); } catch (UnsupportedLocaleException e) { return "This fails for the default locale because BlackBerry sucks"; } } I always hit the catch block in the simulator. Since this doesn't work by default on the simulator, I'm hesitant to put it in the application. So I have two questions: Can anyone tell me if the above solution is the way to go? And how to fix it, of course. Is there a way I can retrieve the currency symbol for the current locale programmatically so I can format myself?

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  • How to see full compile path in Eclipse?

    - by alleywayjack
    I have looked for an answer for this nearly every where that I can think of, but there doesn't seem to be any way to actually SEE what Eclipse "runs" to compile the projects (as it does need the JDK installed and visible to actually build). I ask because I imported a few jars into my project, and even though I've looked through all the javac documentation, I can't seem to figure out how to mimic it quite like Eclipse does. I really, really need to be able to compile on the command line in this case - Eclipse or any other IDE just isn't what is needed. I started to look through the Eclipse source, and although this sounds lazy, I just became overwhelmed and figured I would ask here first, hoping someone else had the same question at one point.

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  • How do you search through a map?

    - by Jack Null
    I have a map: Map<String, String> ht = new HashMap(); and I would like to know how to search through it and find anything matching a particular string. And if it is a match store it into an arraylist. The map contains strings like this: 1,2,3,4,5,5,5 and the matching string would be 5. So for I have this: String match = "5"; ArrayList<String> result = new ArrayList<String>(); Enumeration num= ht.keys(); while (num.hasMoreElements()) { String number = (String) num.nextElement(); if(number.equals(match)) { result.add(number); } }

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  • getting node value exception

    - by Aswan
    Hi Folks <amount currency="USD">1000500</amount> while parsing above string i am getting only attribute value .when i try to get node value null pointer exception for getting node value using NodeList amountList= estimateElement.getElementsByTagName("amount"); Element amtElement= (Element)amountList.item(0); String amount=amtElement.getFirstChild().getnodevalue() Thanks in advance Aswan

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  • pass Value from class to JFrame

    - by MYE
    Hello everybody! i have problem between pass value from Class to another JFrame my code write follow MVC Model. Therefore i have 1 class is controller , one jframe is view and 1 class is model. i have some handle process on controller to get value on it and i want this value to jframe but not pass by constructor . How can i pass value from class to jframe and when value be pass jframe will use it to handle. Ex: public class A{ private String str; public A(){ } public void handle(){ ViewFrame v = new ViewFrame(); v.setVisible(true); v.pack(). v.setSize(330,600); str = "Hello World"; //init value here v.getString(str);// pass value to jframe here. } } ======================= public class ViewFrame extends JFrame{ private String str; public ViewFrame (){ System.out.println(str); } public String getString(String str){ return this.str = str; } } but it return null??

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  • Reading http file on url

    - by Nkunzis
    I am trying to read an xml file on an http url. "Unexpected end of file from server" keeps on coming . the page is password protected, I would like to know if I am properly giving in my url authentication details. I tried with non protected pages and I can read them properly. Here is my code: URL url = new URL("http://username:[email protected]:0000/test.xml"); URLConnection yc = url.openConnection(); BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream())); String inputLine; while ((inputLine = in.readLine()) != null) System.out.println(inputLine); in.close();

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  • What are the suggested alternatives for Class<T>.isAssignableFrom(Class<?> cls)?

    - by Wing C. Chen
    Currently I am doing the profiling to a piece of code. During the profiling, I discovered that this very method call, Class<T>.isAssignableFrom(Class<?> cls) takes up to quite amount of the entire time. Because this is a method from reflection, it takes a lot of time compared to normal keywords or method calls. I am wondering if there are some good alternatives for this method calls?

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  • No Hibernate Session bound to thread exception

    - by Benchik
    I have Hibernate 3.6.0.Final and Spring 3.0.0.RELEASE I get "No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here" If I add the thread specification back in, I get "saveOrUpdate is not valid without active transaction" Any ideas? The spring-config.xml: <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="org.hsqldb.jdbcDriver"/> <property name="url" value="jdbc:hsqldb:mem:jsf2demo"/> <property name="username" value="sa"/> <property name="password" value=""/> </bean> <bean id="sampleSessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="dataSource" ref="sampleDataSource"/> <property name="annotatedClasses"> <list> <value>com.maxheapsize.jsf2demo.Book</value> </list> </property> <property name="hibernateProperties"> <props> <!-- prop key="hibernate.connection.pool_size">0</prop--> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop> <!-- prop key="transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</prop> <prop key="hibernate.current_session_context_class">thread</prop--> <prop key="hibernate.hbm2ddl.auto">create</prop> </props> </property> </bean> <bean id="sampleDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName"> <value>org.hsqldb.jdbcDriver</value> </property> <property name="url"> <value> jdbc:hsqldb:file:/spring/db/springdb;SHUTDOWN=true </value> </property> <property name="username" value="sa"/> <property name="password" value=""/> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sampleSessionFactory"/> </bean> <bean id="daoTxTemplate" abstract="true" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"> <property name="transactionManager" ref="transactionManager"/> <property name="transactionAttributes"> <props> <prop key="create*"> PROPAGATION_REQUIRED,ISOLATION_READ_COMMITTED </prop> <prop key="get*"> PROPAGATION_REQUIRED,ISOLATION_READ_COMMITTED </prop> </props> </property> </bean> <bean name="openSessionInViewInterceptor" class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor"> <property name="sessionFactory" ref="sampleSessionFactory"/> <property name="singleSession" value="true"/> </bean> <bean id="nameDao" parent="daoTxTemplate"> <property name="target"> <bean class="com.maxheapsize.dao.NameDao"> <property name="sessionFactory" ref="sampleSessionFactory"/> </bean> </property> </bean> and the DAO: public class NameDao { private SessionFactory sessionFactory; public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } public SessionFactory getSessionFactory() { return sessionFactory; } @Transactional @SuppressWarnings("unchecked") public List<Name> getAll() { Session session = this.sessionFactory.getCurrentSession(); List<Name> names = (List<Name>)session.createQuery("from Name").list(); return names; } //@Transactional(propagation= Propagation.REQUIRED, readOnly=false) @Transactional public void save(Name name){ Session session = this.sessionFactory.getCurrentSession(); session.saveOrUpdate(name); session.flush(); } }

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  • Why does Eclipse crash with Xmx, XX:MaxPermSize above certain values?

    - by alex
    Running Eclipse 3.5.1, JDK 1.6.0_17 on WinXP SP3 32Bit with 3.5 gigs of RAM. I'm aware of the known Eclipse best practices, still trying to figure out eclipse.ini. This will launch: -Xmx588m and this won't: -Xmx589m. Same with -XX:MaxPermSize. Anything above -XX:MaxPermSize=140m won't launch. The screen of death is simlar to this (taken from here). Any ideas on why might this be happening?

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  • im writing this code so the user would enter his/her name and followed by his/her marks to get the a

    - by WM
    What if the user wanted to enter his/her grades in the following way: Will 23, 34, 45, 45 how would i get rid of the commas public class StudentAverage { public static void main(String[] args) { int markSum = 0; double average = 0; Scanner input1 = new Scanner(System.in); System.out.print("Enter student record : "); String name = input1.next(); Scanner input2 = new Scanner(input1.nextLine()); int countTotal = 0; while (input2.hasNextInt()) { countTotal++; markSum += input2.nextInt(); } average = markSum / countTotal; // to calculate the total average System.out.print( name + " " + average ); } }

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  • What else I must do allow my method to handle any type of objects

    - by NewHelpNeeder
    So to allow any type object I must use generics in my code. I have rewrote this method to do so, but then when I create an object, for example Milk, it won't let me pass it to my method. Ether there's something wrong with my generic revision, or Milk object I created is not good. How should I pass my object correctly and add it to linked list? This is a method that causes error when I insert an item: public void insertFirst(T dd) // insert at front of list { Link newLink = new Link(dd); // make new link if( isEmpty() ) // if empty list, last = newLink; // newLink <-- last else first.previous = newLink; // newLink <-- old first newLink.next = first; // newLink --> old first first = newLink; // first --> newLink } This is my class I try to insert into linked list: class Milk { String brand; double size; double price; Milk(String a, double b, double c) { brand = a; size = b; price = c; } } This is test method to insert the data: public static void main(String[] args) { // make a new list DoublyLinkedList theList = new DoublyLinkedList(); // this causes: // The method insertFirst(Comparable) in the type DoublyLinkedList is not applicable for the arguments (Milk) theList.insertFirst(new Milk("brand", 1, 2)); // insert at front theList.displayForward(); // display list forward theList.displayBackward(); // display list backward } // end main() } // end class DoublyLinkedApp Declarations: class Link<T extends Comparable<T>> {} class DoublyLinkedList<T extends Comparable<T>> {}

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