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  • What is the best way to restore(rollback) data in an application to a specified state(date) ?

    - by panzerschreck
    Hello, An example would set the context right, the example below captures the various states of the entity, which needs to be reverted(rolled back) . State 1 - Recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 State 2 - Recorded on 02-Mar-2010 Column1 Column2 Data1 0.57 State 3 - Recorded on 03-Mar-2010 Column1 Column2 Data1 0.58 User notices that state3 is not what he intended to be in, decides to revert back to state2. One approach that I can think of, without modifying the entity is via "auditing" all the inserts/updates, as below, the rollback information captures the data just before the updates/modifications on the entity, so that it can be applied in an order when you need to revert.Please note that changing the entity's schema, is not an option. Rollback - R1 recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R2 Recorded on 02-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R3 Recorded on 03-Mar-2010 Column1 Column2 Data1 0.57 So, to get to state2 , we would start with rollback information R1,apply R2 onto it. Is there a better approach to achieve this ? Thanks for your time.

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  • using Hibernate to loading 20K products, modifying the entity and updating to db

    - by Blankman
    I am using hibernate to update 20K products in my database. As of now I am pulling in the 20K products, looping through them and modifying some properties and then updating the database. so: load products foreach products session begintransaction productDao.MakePersistant(p); session commit(); As of now things are pretty slow compared to your standard jdbc, what can I do to speed things up? I am sure I am doing something wrong here.

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  • Speed of Synchronization vs Normal

    - by Swaranga Sarma
    I have a class which is written for a single thread with no methods being synchronized. class MyClass implements MyInterface{ //interface implementation methods, not synchronized } But we also needed a synchronized version of the class. So we made a wrapper class that implements the same interface but has a constructor that takes an instance of MyClass. Any call to the methods of the synchronized class are delegated to the instance of MyClass. Here is my synchronized class.. class SynchronizedMyClass implements MyInterface{ //the constructor public SynchronizedMyClass(MyInterface i/*this is actually an instance of MyClass*/) //interface implementation methods; all synchronized; all delegated to the MyInterface instance } After all this I ran numerous amounts of test runs with both the classes. The tests involve reading log files and counting URLs in each line. The problem is that the synchronized version of the class is consistently taking less time for the parsing. I am using only one thread for the teste, so there is no chance of deadlocks, race around condition etc etc. Each log file contains more than 5 million lines which means calling the methods more than 5 million times. Can anyone explain why synchronized versiuon of the class migt be taking less time than the normal one?

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  • JPA 2.0 Provider Hibernate Spring MVC 3.0

    - by user558019
    Dear All i have very strange problem we are using jpa 2.0 with hibernate and spring 3.0 mvc annotations based Database generated through JPA DDL is true and MySQL as Database; i will provide some refference classes and then my porblem. public abstract class Common implements serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; @ManyToOne @JoinColumn private Address address; //with all getter and setters //as well equal and hashCode } public class Parent extends Common{ private String name; @OneToMany(cascade = {CascadeType.MERGE,CascadeType.PERSIST}, mappedBy = "parent") private List<Child> child; //setters and rest of class } public class child extends Common{ //some properties with getter/setters } public class Address implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; private String street; //rest of class with get/setter } as in code you can see that parents and child classes extends Common class so both have address property and id , the problem occurs when change the address refference in parent class it reflect same change in all child objects in list and if change address refference in child class then on merge it will change address refference of parent as well i am not able to figure out is it is problem of jpa or hibernate or spring thanks in advance

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  • Background image JFrame with content

    - by Petr Safar
    I have a JFrame with BorderLayout, there are panels on all sides (North, East ,...). In the panels there are labels and buttons mostly. Now I want the frame to have a background image, some research told me that i had to change the content pane of my frame. When I try this however, the content gets put in the background and isn't visible. Also, I don't know how to resize the image if the frame is resized. Is there an easy fix for this or will I have to rework most of my code?

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  • Can I bypass an intermediate object in hibernate

    - by Jherico
    I have top level entities TRACK, MEDIA_GROUP and MEDIA, each with an integer primary key. I also have a join table from TRACK to MEDIA_GROUP which is 1:1 and MEDIA has a FK column into MEDIA_GROUP. I'm trying to find a way in hibernate to map a collection of Media directly into the Track object, bypassing the creation of a MediaGroup object. Basically I want to turn this: TRACK <-> MEDIA_TRACK_MAP <-> MEDIA_GROUP <-> MEDIA into this: TRACK <-> MEDIA_TRACK_MAP <-> MEDIA But the join column between MEDIA_TRACK_MAP and MEDIA isn't the primary key of MEDIA.

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  • Why a new instance uses logger from old instances?

    - by Roman
    I generate 2 instances in this way: gameManager manager1 = new CTManager(owner,players1,"en"); manager1.start(); gameManager manager2 = new CTManager(owner,players2,"en"); manager2.start(); The start() method of the gameManager looks like that: void start() { game.start(); } When I create the game instance I create a loger: log = Logger.getLogger("TestLog"); (log is a public field of the class in which the game belongs). In the game.start() I run many processes and give them a reference to the corresponding log. So, I expect that manager1 and manager2 will write to different files. But manager2 writes to its own file and to the log file of the manager1. Why can it happen?

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  • Spring OpenSessionInViewFilter with @Transactional annotation

    - by Gautam
    This is regarding Spring OpenSessionInViewFilter using with @Transactional annotation at service layer. i went through so many stack overflow post on this but still confused about whether i should use OpenSessionInViewFilter or not to avoid LazyInitializationException It would be great help if somebody help me find out answer to below queries. Is it bad practice to use OpenSessionInViewFilter in application having complex schema. using this filter can cause N+1 problem if we are using OpenSessionInViewFilter does it mean @Transactional not required? Below is my Spring config file <context:component-scan base-package="com.test"/> <context:annotation-config/> <bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource"> <property name="basename" value="resources/messages" /> <property name="defaultEncoding" value="UTF-8" /> </bean> <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" p:location="/WEB-INF/jdbc.properties" /> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.databaseurl}" p:username="${jdbc.username}" p:password="${jdbc.password}" /> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation"> <value>classpath:hibernate.cfg.xml</value> </property> <property name="configurationClass"> <value>org.hibernate.cfg.AnnotationConfiguration</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${jdbc.dialect}</prop> <prop key="hibernate.show_sql">true</prop> <!-- <prop key="hibernate.hbm2ddl.auto">create</prop> --> </props> </property> </bean> <tx:annotation-driven /> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean>

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  • Getting Frequency Components with FFT

    - by ruhig brauner
    so I was able to solv my last problem but i stubmled upon the next already. So I want to make a simple spectrogram but in oder to do so I want to understand how FFT-libaries work and what they actually calculate and return. (FFT and Signal Processing is the number 1 topic I will get into as soon as I have time but right now, I only have time for some programming exercises in the evening. ;) ) Here I just summarized the most important parts: int framesPerSecond; int samplesPerSecond; int samplesPerCycle; // right now i want to refresh the spectogram every DoubleFFT_1D fft; WAVReader audioIn; double audioL[], audioR[]; double fftL[], fftR[]; ..... framesPerSecond = 30; audioIn= new WAVReader("Strobe.wav"); int samplesPerSecond = (int)audioIn.GetSampleRate(); samplesPerCycle = (int)(audioIn.GetSampleRate()/framesPerSecond); audioL = new double[samplesPerCycle*2]; audioR = new double[samplesPerCycle*2]; fftL = new double[samplesPerCycle]; fftR = new double[samplesPerCycle]; for(int i = 0; i < samplesPerCycle; i++) { // don't even know why,... fftL[i] = 0; fftR[i] = 0; } fft = new DoubleFFT_1D(samplesPerCycle); ..... for(int i = 0; i < samplesPerCycle; i++) { audioIn.GetStereoSamples(temp); audioL[i]=temp[0]; audioR[i]=temp[1]; } fft.realForwardFull(audioL); //still stereo fft.realForwardFull(audioR); System.out.println("Check"); for(int i = 0; i < samplesPerCycle; i++) { //storing the magnitude in the fftL/R arrays fftL[i] = Math.sqrt(audioL[2*i]*audioL[2*i] + audioL[2*i+1]*audioL[2*i+1]); fftR[i] = Math.sqrt(audioR[2*i]*audioR[2*i] + audioR[2*i+1]*audioR[2*i+1]); } So the question is, if I want to know, what frequencys are in the sampled signal, how do I calculate them? (When I want to print the fftL / fftR arrays, I get some exponential formes at both ends of the array.) Thx :)

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  • Find all numbers that appear in each of a set of lists

    - by Ankur
    I have several ArrayLists of Integer objects, stored in a HashMap. I want to get a list (ArrayList) of all the numbers (Integer objects) that appear in each list. My thinking so far is: Iterate through each ArrayList and put all the values into a HashSet This will give us a "listing" of all the values in the lists, but only once Iterate through the HashSet 2.1 With each iteration perform ArrayList.contains() 2.2 If none of the ArrayLists return false for the operation add the number to a "master list" which contains all the final values. If you can come up with something faster or more efficient, funny thing is as I wrote this I came up with a reasonably good solution. But I'll still post it just in case it is useful for someone else. But of course if you have a better way please do let me know.

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  • @ExceptionHandler doesn't handle the thrown exceptions

    - by Javi
    Hello, I have a method in my controller which will handle the exceptions thrown by the application. So I have a method like this one. @Controller public class ExceptionController { @RequestMapping(value="/error") @ExceptionHandler(value={Exception.class, NullPointerException.class}) public String showError(Exception e, Model model){ return "tiles:error"; } } And to try I if it works I throw a NullPointerException in another method in other method controller: boolean a = true; if(a){ throw new NullPointerException(); } After the exception is thrown it is printed in the JSP, but it doesn't go throw my showError() method (I've set a breakpoint there and it never enters). showError() method will catch the exception and will show different error pages depending on the exception type (though now it always shows the same error page). If I go to the url /error it shows the error page so the showError() method is OK. I'm using Spring 3. What can be the problem? Thanks.

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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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  • How to deploy to Tomcat from NetBeans?

    - by deamon
    I've added Tomcat in the "Tools Servers" menu and as you can see it appears in the list of servers: But when I try to run my project, I cannot select Tomcat! The drop-down with servers is empty. I tried it with NetBeans 6.8 and 6.9 Beta. Any idea?

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  • Creating an instance within the Class itself

    - by didxga
    What's going on when the assignment statement executed at Line 4, does compiler ignore the new operator and keep the foo variable being null or something else happen to handle this awkward moment? public class Foo { // creating an instance before its constructor has been invoked, suppose the "initializing" // gets printed in constructor as a result of the next line, of course it will not print it private Foo foo = new Foo();//Line 4 public Foo() { System.out.println("initializing"); } }

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  • Should filters write to the response during or after filtering?

    - by Mark
    I have a filter which processes generated HTML and rewrites certain elements. For example, it adds class attributes to some anchors. Finally, it writes the processed HTML to the response (a subclass of HttpServletResponseWrapper). Naturally, this means that the processed HTML is a different length after it has passed through the filter. I can see two ways of approaching this. One is to iterate over the HTML, using a StringBuilder to build up the processed HTML, and write the processed HTML to the response once all filtering is complete. The other is to iterate over the HTML but to write it to the response as soon as each element has been processed. Which is the better way for this operation, or is there another option which would be preferable? I am looking to minimise temporary memory usage primarily.

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  • servlet ArrayList and HashMap problem witch result

    - by nonameplum
    Hi, I have that code List<Map<String, Object>> data = new ArrayList<Map<String, Object>>(); Map<String, Object> item = new HashMap<String, Object>(); data.clear(); item.clear(); int i = 0; while (i < 5){    item.put("id", i);    i++;    out.println("id: " + item.get("id"));    out.println("--------------------------");    data.add(item); } for(i=0 ; i<5 ; i++){    out.println("print data[" + i + "]" + data.get(i)); } Result of that is: id: 0 -------------------------- id: 1 -------------------------- id: 2 -------------------------- id: 3 -------------------------- id: 4 -------------------------- print data[0]{id=4} print data[1]{id=4} print data[2]{id=4} print data[3]{id=4} print data[4]{id=4} Why only last element is stored?

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  • Logger.setLevel() doesn't enable logging correctly

    - by ripper234
    Situation: I have this log4j logger: private static final Logger logger = Logger.getLogger(ThisClassName.class); And am trying to set it programatically through: Logger.getLogger(ThisClassName.class).setLevel(Level.DEBUG); Still, DEBUG level prints are swalloed (while INFO prints are printed successfully). Even this bit has no effect: Logger.getRootLogger().setLevel(Level.DEBUG); Calling logger.debug("foo") reaches Category.forcedLog() and ConsoleAppender.doAppend(), and then fails (quits) at: if(!isAsSevereAsThreshold(event.getLevel())) Any idea why this is happening?

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  • Should i use lock.lock(): in this method?

    - by user962800
    I wrote this method whose purpose is to give notice of the fact that a thread is leaving a specific block of code A thread stands for a car which is leaving a bridge so other cars can traverse it . The bridge is accessible to a given number of cars (limited capacity) and it's one way only. public void getout(int diection){ // release the lock semaphore.release(); try{ lock.lock(); //access to shared data if(direction == Car.NORTH) nNordTraversing--; //decreasing traversing threads else nSudTraversing--; bridgeCond.signal(); }finally{ lock.unlock(); } } My question is: should I use lock.lock(); or it's just nonsense? thanks in advance

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  • Spring noHandlerFound

    - by Justin
    I am trying to set up my Spring MVC testing environment. But I always get this noHandlerFound error: Aug 21, 2014 4:43:25 PM org.springframework.web.servlet.DispatcherServlet noHandlerFound WARNING: No mapping found for HTTP request with URI [/restful/firstPage] in DispatcherServlet with name 'spring' Aug 21, 2014 4:47:21 PM org.springframework.web.servlet.DispatcherServlet noHandlerFound WARNING: No mapping found for HTTP request with URI [/restful/firstPage2] in DispatcherServlet with name 'spring' Aug 21, 2014 5:10:27 PM org.springframework.web.servlet.DispatcherServlet noHandlerFound WARNING: No mapping found for HTTP request with URI [/restful/index.html] in DispatcherServlet with name 'spring' I already searched for solution, but none can fix my problem. My spring mvc version: 3.1.3.RELEASE This is my web.xml: <servlet> <servlet-name>spring</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>spring</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/applicationContext.xml </param-value> </context-param> this is my spring-servlet.xml: <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> this is my applicationContext.xml: <context:annotation-config /> <context:component-scan base-package="test.spring" /> <mvc:annotation-driven /> <mvc:resources mapping="/index.html" location="/index.html" /> <mvc:view-controller path="/firstPage" /> This is my Controller: package test.spring; .... @Controller @RequestMapping("/") public class FirstController { @RequestMapping(value = "firstPage2", method = RequestMethod.GET) public String showFirstPage(Map<String,Object> model){ return "firstPage"; } } My server is tomcat 7, there is no error and warning when it is deployed. I also tried this with no luck: <mvc:default-servlet-handler/> Before I start Spring MVC, I can access index.html

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