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  • Resolving type parameter values passed to ancester type using reflection

    - by Tom Tucker
    I've asked a similar question before, but this one is much more challenging. How do I find a value of a specific type parameter that is passed to an ancestor class or an interface implemented by one of its ancestor classes using reflection? I basically need to write a method that looks like this. // Return the value of the type parameter at the index passed to the parameterizedClass from the clazz. Object getParameterValue(Class<?> clazz, Class<?> parameterizedClass, int index) For the example below, getParameterValue(MyClass.class, Map.class, 1) would return String.class public class Foo<K, V> implements Map<K, V>{ } public class Bar<V> extends Foo<Integer, V> { } public class MyClass extends Bar<String> { } Thanks!

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  • Updating position of JSlider Swing

    - by GLRockwell
    My apologies for posting tons of questions as of late. I'm trying to get a JSlider to update its position based on a constantly updating variable. The setValue(n) method doesn't seem to work. Is there any alternative? We're using this as a time marker for a music player.

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  • using volatile keyword

    - by sap
    As i understand, if we declare a variable as volatile, then it will not be stored in the local cache. Whenever thread are updating the values, it is updated to the main memory. So, other threads can access the updated value. But in the following program both volatile and non-volatile variables are displaying same value. The volatile variable is not updated for the second thread. Can anybody plz explain this why testValue is not changed. class ExampleThread extends Thread { private int testValue1; private volatile int testValue; public ExampleThread(String str){ super(str); } public void run() { if (getName().equals("Thread 1 ")) { testValue = 10; testValue1= 10; System.out.println( "Thread 1 testValue1 : " + testValue1); System.out.println( "Thread 1 testValue : " + testValue); } if (getName().equals("Thread 2 ")) { System.out.println( "Thread 2 testValue1 : " + testValue1); System.out.println( "Thread 2 testValue : " + testValue); } } } public class VolatileExample { public static void main(String args[]) { new ExampleThread("Thread 1 ").start(); new ExampleThread("Thread 2 ").start(); } } output: Thread 1 testValue1 : 10 Thread 1 testValue : 10 Thread 2 testValue1 : 0 Thread 2 testValue : 0

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  • Hibernate many-to-many mapping not saved in pivot table

    - by vincent
    I having problems saving many to many relationships to a pivot table. The way the pojos are created is unfortunately a pretty long process which spans over a couple of different threads which work on the (to this point un-saved) object until it is finally persisted. I associate the related objects to one another right after they are created and when debugging I can see the List of related object populated with their respective objects. So basically all is fine to this point. When I persist the object everything get saved except the relations in the pivot table. mapping files: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="ShowObject" table="show_object"> <id name="id"> <generator class="native" /> </id> <property name="name" /> <set cascade="all" inverse="true" name="venues" table="venue_show"> <key column="show_id"/> <many-to-many class="VenueObject"/> </set> </class> </hibernate-mapping> and the other <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="VenueObject" table="venue_object"> <id name="id"> <generator class="native"/> </id> <property name="name"/> <property name="latitude" type="integer"/> <property name="longitude" type="integer"/> <set cascade="all" inverse="true" name="shows" table="venue_show"> <key column="venue_id"/> <many-to-many class="ShowObject"/> </set> </class> </hibernate-mapping> pojos: public class ShowObject extends OrmObject { private Long id; private String name; private Set venues; public ShowObject() { } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getVenues() { return venues; } public void setVenues(Set venues) { this.venues = venues; } } and the other: public class VenueObject extends OrmObject { private Long id; private String name; private int latitude; private int longitude; private Set shows = new HashSet(); public VenueObject() { } @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { return id; } public void setId(Long id) { this.id = id; } public int getLatitude() { return latitude; } public void setLatitude(int latitude) { this.latitude = latitude; } public int getLongitude() { return longitude; } public void setLongitude(int longitude) { this.longitude = longitude; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getShows() { return shows; } public void setShows(Set shows) { this.shows = shows; } } Might the problem be related to the lack of annotations?

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  • need help with parseInt

    - by cmona
    hello, how can i get for example the integer codeInt=082 from String code='A082' i have tried this: int codeInt = Integer.parseInt(code.substring(1,4)); and i get codeInt=82 ,it leaves the first 0 but i want the full code '082'. i thought of parseInt(String s, int radix) but i don't know how . any help will be appreciated . thanks.

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  • Declare two classes from eachother.

    - by tumba25
    I'm writing a app in NetBeans. I have two classes MyApp_View and MyApp_Functions. The MyApp_View class starts like this public class MyApp_View extends FrameView { MyApp_Functions My_functions = new MyApp_Functions(); public MyApp_View(SingleFrameApplication app) { super(app); In MyApp_Functions I have MyApp_View my_view = new MyApp_View(null); I want to access the public variables in MyApp_View from MyApp_Functions and the public methods in functions from view, but have no success with this. Is this doable? And how?

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  • get string from outside run programm

    - by Alex Berd
    Hello I have jsp page with text field and button. Also i have jar of another project. When i click on the button the MAIN.class of the jar is called and program is running in independent window(JFrame). After user is finished with the program and exits, I need to get the String of program that is generated on exit and paste it into the textbox (The String is HTML code) Is anyone else having this problem and has a solution? Thanks Alex

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  • How to add two label in one gridbox?

    - by Jessy
    Hello everyone, How can I add two label in the same grid box? e.g. in row 1, col 1 the will be 2 labels? The code below will add the label in two different grid. JPanel chckBox = new JPanel(new GridLayout(1,8,3,3)); JLabel label1 = new JLabel("A"); JLabel label2 = new JLabel("B"); ... chckBox.add(label1); chckBox.add(label2); ...

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  • log4j/log4cxx : exclusive 1 to 1 relation between logger and appender

    - by Omry
    Using the xml configuration of log4cxx (which is identical in configuration to log4j). I want to have a certain logger output exclusively to a specific appender (have it the only logger which outputs to that appender). I found that it's possible to bind a logger to a specific appender like this: <logger name="LoggerName"> <level value="info"/> <appender-ref ref="AppenderName"/> </logger> but it that logger still outputs to the root appender because I have this standard piece in the conf file: <root> <priority value="DEBUG"/> <appender-ref ref="OtherAppender"/> </root> How can I exclude that logger from the root logger? in other words, how do I configure the log such that all loggers inherit the appenders of the root logger except a specific logger?

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  • Autocomplete server-side implementation

    - by toluju
    What is a fast and efficient way to implement the server-side component for an autocomplete feature in an html input box? I am writing a service to autocomplete user queries in our web interface's main search box, and the completions are displayed in an ajax-powered dropdown. The data we are running queries against is simply a large table of concepts our system knows about, which matches roughly with the set of wikipedia page titles. For this service obviously speed is of utmost importance, as responsiveness of the web page is important to the user experience. The current implementation simply loads all concepts into memory in a sorted set, and performs a simple log(n) lookup on a user keystroke. The tailset is then used to provide additional matches beyond the closest match. The problem with this solution is that it does not scale. It currently is running up against the VM heap space limit (I've set -Xmx2g, which is about the most we can push on our 32 bit machines), and this prevents us from expanding our concept table or adding more functionality. Switching to 64-bit VMs on machines with more memory isn't an immediate option. I've been hesitant to start working on a disk-based solution as I am concerned that disk seek time will kill performance. Are there possible solutions that will let me scale better, either entirely in memory or with some fast disk-backed implementations? Edits: @Gandalf: For our use case it is important the the autocompletion is comprehensive and isn't just extra help for the user. As for what we are completing, it is a list of concept-type pairs. For example, possible entries are [("Microsoft", "Software Company"), ("Jeff Atwood", "Programmer"), ("StackOverflow.com", "Website")]. We are using Lucene for the full search once a user selects an item from the autocomplete list, but I am not yet sure Lucene would work well for the autocomplete itself. @Glen: No databases are being used here. When I'm talking about a table I just mean the structured representation of my data. @Jason Day: My original implementation to this problem was to use a Trie, but the memory bloat with that was actually worse than the sorted set due to needing a large number of object references. I'll read on the ternary search trees to see if it could be of use.

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  • Getting a nicely formatted timestamp without lots of overhead?

    - by Brad Hein
    In my app I have a textView which contains real-time messages from my app, as things happen, messages get printed to this text box. Each message is time-stamped with HH:MM:SS. Up to now, I had also been chasing what seemed to be a memory leak, but as it turns out, it's just my time-stamp formatting method (see below), It apparently produces thousands of objects that later get gc'd. For 1-10 messages per second, I was seeing 500k-2MB of garbage collected every second by the GC while this method was in place. After removing it, no more garbage problem (its back to a nice interval of about 30 seconds, and only a few k of junk typically) So I'm looking for a new, more lightweight method for producing a HH:MM:SS timestamp string :) Old code: /** * Returns a string containing the current time stamp. * @return - a string. */ public static String currentTimeStamp() { String ret = ""; Date d = new Date(); SimpleDateFormat timeStampFormatter = new SimpleDateFormat("hh:mm:ss"); ret = timeStampFormatter.format(d); return ret; }

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  • How can i use Stopwatch [ apache ] to calculate the time taken by a method?

    - by Rakesh Juyal
    I am using StopWatch [ apache ] to get the time taken by my method. The approach i am following is StopWatch stopWatch = new StopWatch(); stopWatch.start(); myMethod(); stopWatch.stop(); logger.info( "Time taken by myMethod: " + stopWatch.getTime() + " millisecs"); stopWatch.reset(); stopWatch.start(); anotherMethod(); stopWatch.stop(); logger.info( "Time taken by anotherMethod: " + stopWatch.getTime() + " millisecs"); Thats the only thing i know about StopWatch :). How/when to use split(), unsplit(), getSplitTime(),suspend()... ?

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  • Servlet unit test

    - by Thomman
    Currently I'm using TestNG framework for testing application business logic, i added some Servlet classes recently. How do I unit test these Servlet classes in TestNg framework?

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  • Commercial Website architecture question

    - by Maxime ARNSTAMM
    Hello everyone, I have to write an architecture case study but there are some things that i don't know, so i'd like some pointers on the following : The website must handle 5k simultaneous users. The backend is composed by a commercial software, some webservices, some message queues, and a database. I want to recommend to use Spring for the backend, to deal with the different elements, and to expose some Rest services. I also want to recommend wicket for the front (not the point here). What i don't know is : must i install the front and the back on the same tomcat server or two different ? and i am tempted to put two servers for the front, with a load balancer (no need for session replication in this case). But if i have two front servers, must i have two back servers ? i don't want to create some kind of bottleneck. Based on what i read on this blog a really huge charge is handle by one tomcat only for the first website mentionned. But i cannot find any info on this, so i can't tell if it seems plausible. If you can enlight me, so i can go on in my case study, that would be really helpful. Thanks :)

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  • Returning the element number of the longest string in an array

    - by JohnRoberts
    I'm trying to get the longestS method to take the user-inputted array of strings, then return the element number of the longest string in that array. I got it to the point where I was able to return the number of chars in the longest string, but I don't believe that will work for what I need. My problem is that I keep getting incompatible type errors when trying to figure this out. I don't understand the whole data type thing with strings yet. It's confusing me how I go about return a number of the array yet the array is of strings. The main method is fine, I got stuck on the ???? part. { public static void main(String [] args) { Scanner inp = new Scanner( System.in ); String [] responseArr= new String[4]; for (int i=0; i<4; i++) { System.out.println("Enter string "+(i+1)); responseArr[i] = inp.nextLine(); } int highest=longestS(responseArr); } public static int longestS(String[] values) { int largest=0 for( int i = 1; i < values.length; i++ ) { if ( ????? ) } return largest; } }

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  • In Intellij, how can I get a List on the left hand side when I extract a variable that's an ArrayList?

    - by tieTYT
    As an example, if I extract a variable from this: return new ArrayList<CrudTestData<Foo>>(); It will turn the code into this: ArrayList<CrudTestData<Foo>> list = new ArrayList<CrudTestData<Foo>>(); return list; How can I automatically get a list on the left hand side like this? List<CrudTestData<Foo>> list = new ArrayList<CrudTestData<Foo>>(); return list; Theoretically, Intellij should know to use a List instead of a Collection because the method returns a List.

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  • Why is Log4j rootLogger not filtering log events according to event level?

    - by Derek Mahar
    Why is the Log4j rootLogger in my application not filtering log events according to level? In my log4j.properties, I have several loggers: log4j.rootLogger=info,stdout log4j.logger.com.name.myapp=debug,myapp log4j.logger.org.castor=debug,castor log4j.logger.org.exolab.castor=debug,castor log4j.logger.org.hibernate=debug,hibernate log4j.logger.org.springframework=debug,spring Each of the loggers receive and record numerous log events at levels DEBUG and above, which is what I expect. The rootLogger, however, despite being set to level INFO, is displaying all of these events, too, including the DEBUG events, which is not what I expect. Instead, I would expect it to filter the DEBUG events, but display only the events at level INFO and higher (WARN, ERROR, and FATAL). Why is rootLogger displaying all of the events?

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  • I Want to get a week value

    - by satya
    I wan to get the value of only one week. I am using the following JPA query: SELECT a FROM questions.dao.hibernate.Questions a WHERE (a.posted_date-CURRENT_DATE)>= 7 But I am getting an error message like org.hibernate.QueryException: could not resolve property: posted_date of: questions.dao.hibernate.Questions [SELECT a FROM questions.dao.hibernate.Questions a WHERE (a.posted_date-CURRENT_DATE)>=7] Please help me. Thanks

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  • Counting viable sublist lengths from an array.

    - by Ben B.
    This is for a genetic algorithm fitness function, so it is important I can do this as efficiently as possible, as it will be repeated over and over. Lets say there is a function foo(int[] array) that returns true if the array is a "good" array and false if the array is a "bad" array. What makes it good or bad does not matter here. Given the full array [1,6,8,9,5,11,45,16,9], lets say that subarray [1,6,8] is a "good" array and [9,5,11,45] is a "good" array. Furthermore [5,11,45,16,9] is a "good" array, and also the longest "good" subarray. Notice that while [9,5,11,45] is a "good" array, and [5,11,45,16,9] is a "good" array, [9,5,11,45,16,9] is a "bad" array. We wants the length counts of all "good" arrays, but not subarrays of "good" arrays. Furthermore, as described above, a "good" array might begin in the middle of another "good" array, but the combination of the two might be a "bad" array.

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  • Using a Session Scoped Bean

    - by jboyd
    The following code is returning null: private MyAppUser getMyAppUser(HttpSession session) { MyAppUser myAppUser = (MyAppUser) session.getAttribute("myAppUserManager"); return myAppUser; } Despite the fact that I have the following in my context: <bean id="myAppUserManager" class="com.myapp.profile.MyAppUser" scope="session"/> This doesn't make any sense to me, the "myAppUser" bean is a bean that absolutely can never be null, and I need to be able to reference it from controllers, I don't need it in services or repositories, just controllers, but it doesn't seem to be getting stored in the session, the use case is extremely simple, but I haven't been able to get to the bottom of what's wrong, or come up with a good workaround

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  • Swing's KeyListener and multiple keys pressed at the same time.

    - by Negai
    Hi everyone, is there any conventional way in swing of tracking down the events, when two keyboard keys are pressed at the same time? I have a couple of ideas e.g. remembering the key and event generation time so that we could in a consecutive event handler invocation check the time difference between these two events and decide, whether it's a two-button event or not. Phew. But it looks like a kludge. Thanks in advance.

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