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  • Programmatically loading Entity classes with JPA 2.0?

    - by Dennetik
    With Hibernate you can load your Entity classes as: sessionFactory = new AnnotationConfiguration() .addPackage("test.animals") .addAnnotatedClass(Flight.class) .addAnnotatedClass(Sky.class) .addAnnotatedClass(Person.class) .addAnnotatedClass(Dog.class); Is there a way to do the same thing - programmatically loading your Entity classes - in a JPA 2.0 compliant way?

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  • What to do when ServerSocket throws IOException and keeping server running

    - by s5804
    Basically I want to create a rock solid server. while (keepRunning.get()) { try { Socket clientSocket = serverSocket.accept(); ... spawn a new thread to handle the client ... } catch (IOException e) { e.printStackTrace(); // NOW WHAT? } } In the IOException block, what to do? Is the Server socket at fault so it need to be recreated? For example wait a few seconds and then serverSocket = ServerSocketFactory.getDefault().createServerSocket(MY_PORT); However if the server socket is still OK, then it is a pity to close it and kill all previously accepted connections that are still communicating. EDIT: After some answers, here my attempt to deal with the IOException. Would the implementation be guaranteeing keeping the server up and only re-create server socket when only necessary? while (keepRunning.get()) { try { Socket clientSocket = serverSocket.accept(); ... spawn a new thread to handle the client ... bindExceptionCounter = 0; } catch (IOException e) { e.printStackTrace(); recreateServerSocket(); } } private void recreateServerSocket() { while (keepRunning) { try { logger.info("Try to re-create Server Socket"); ServerSocket socket = ServerSocketFactory.getDefault().createServerSocket(RateTableServer.RATE_EVENT_SERVER_PORT); // No exception thrown, then use the new socket. serverSocket = socket; break; } catch (BindException e) { logger.info("BindException indicates that the server socket is still good.", e); bindExceptionCounter++; if (bindExceptionCounter < 5) { break; } } catch (IOException e) { logger.warn("Problem to re-create Server Socket", e); e.printStackTrace(); try { Thread.sleep(30000); } catch (InterruptedException ie) { logger.warn(ie); } } } }

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  • Using inheritance and polymorphism to solve a common game problem

    - by Barry Brown
    I have two classes; let's call them Ogre and Wizard. (All fields are public to make the example easier to type in.) public class Ogre { int weight; int height; int axeLength; } public class Wizard { int age; int IQ; int height; } In each class I can create a method called, say, battle() that will determine who will win if an Ogre meets and Ogre or a Wizard meets a Wizard. Here's an example. If an Ogre meets an Ogre, the heavier one wins. But if the weight is the same, the one with the longer axe wins. public Ogre battle(Ogre o) { if (this.height > o.height) return this; else if (this.height < o.height) return o; else if (this.axeLength > o.axeLength) return this; else if (this.axeLength < o.axeLength) return o; else return this; // default case } We can make a similar method for Wizards. But what if a Wizard meets an Ogre? We could of course make a method for that, comparing, say, just the heights. public Wizard battle(Ogre o) { if (this.height > o.height) return this; else if (this.height < o.height) return o; else return this; } And we'd make a similar one for Ogres that meet Wizard. But things get out of hand if we have to add more character types to the program. This is where I get stuck. One obvious solution is to create a Character class with the common traits. Ogre and Wizard inherit from the Character and extend it to include the other traits that define each one. public class Character { int height; public Character battle(Character c) { if (this.height > c.height) return this; else if (this.height < c.height) return c; else return this; } } Is there a better way to organize the classes? I've looked at the strategy pattern and the mediator pattern, but I'm not sure how either of them (if any) could help here. My goal is to reach some kind of common battle method, so that if an Ogre meets an Ogre it uses the Ogre-vs-Ogre battle, but if an Ogre meets a Wizard, it uses a more generic one. Further, what if the characters that meet share no common traits? How can we decide who wins a battle?

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  • Is there a useDirtyFlag option for Tomcat 6 cluster configuration?

    - by kevinjansz
    In Tomcat 5.0.x you had the ability to set useDirtyFlag="false" to force replication of the session after every request rather than checking for set/removeAttribute calls. <Cluster className="org.apache.catalina.cluster.tcp.SimpleTcpCluster" managerClassName="org.apache.catalina.cluster.session.SimpleTcpReplicationManager" expireSessionsOnShutdown="false" **useDirtyFlag="false"** doClusterLog="true" clusterLogName="clusterLog"> ... The comments in the server.xml stated this may be used to make the following work: <% HashMap map = (HashMap)session.getAttribute("map"); map.put("key","value"); %> i.e. change the state of an object that has already been put in the session and you can be sure that this object still be replicated to the other nodes in the cluster. According to the Tomcat 6 documentation you only have two "Manager" options - DeltaManager & BackupManager ... neither of these seem to allow this option or anything like it. In my testing the default setup: <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> where you get the DeltaManager by default, it's definitely behaving as useDirtyFlag="true" (as I'd expect). So my question is - is there an equivalent in Tomcat 6? Looking at the source I can see a manager implementation "org.apache.catalina.ha.session.SimpleTcpReplicationManager" which does have the useDirtyFlag but the javadoc comments in this state it's "Tomcat Session Replication for Tomcat 4.0" ... I don't know if this is ok to use - I'm guessing not as it's not mentioned in the main cluster configuration documentation.

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  • Getting the instance when Constructor#newInstance throws?

    - by Shtééf
    I'm working on a simple plugin system, where third party plugins implement a Plugin interface. A directory of JARs is scanned, and the implementing classes are instantiated with Constructor#newInstance. The thing is, these plugins call back into register* methods of the plugin host. These registrations use the Plugin instance as a handle. My problem is how to clean up these registrations if the constructor decides to fail and throw halfway through. InvocationTargetException doesn't seem to have anything on it to get the instance. Is there a way to get at the instance of an exception throwing constructor? P.S.: It's typically strongly advised to users that the constructor not do anything, but in practice people are doing it any ways.

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  • Can Hibernate default a Null String to Empty String

    - by sliver
    In our application we are pulling data from a DB2 mainframe database. If the database has "low values" in a field, hibernate sends a "null" value in the object. This occurs even if the column is defined as "not null". As we are doing XML parsing on this, Castor is having trouble with it. I would like to fix this in Hibernate. Also, all of the hibernate hbm files are generated, so we can't mess with them (they are regened from time to time.) Any way to intercept all Strings and replace nulls with ""?

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  • Available message types in JMS?

    - by Caylem
    This is based on a past exam question. The question is asking to describe the four types of message available using JMS. The problem is it says the four, not just four. So it assumes their is only four, no more no less. However according to this site their seems to be five; streams maps text objects bytes *Another book states that XML is another potential type in future versions of JMS. Is XML already available? Am I missing something or is the question just wrong? Thanks.

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  • In a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the as

    - by Bytecode Ninja
    In these examples on TopLink JPA Annotation Reference: Example 1-59 @OneToMany - Customer Class With Generics @Entity public class Customer implements Serializable { ... @OneToMany(cascade=ALL, mappedBy="customer") public Set<Order> getOrders() { return orders; } ... } Example 1-60 @ManyToOne - Order Class With Generics @Entity public class Order implements Serializable { ... @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } ... } It seams to me that the Customer entity is the owner of the association. However, in the explanation for the mappedBy attribute in the same document, it is written that: if the relationship is bidirectional, then set the mappedBy element on the inverse (non-owning) side of the association to the name of the field or property that owns the relationship as Example 1-60 shows. However, if I am not wrong, looks like in the example the mappedBy is actually specified on the owning side of the association, rather than the non-owning side. So my question is basically: In a bidirectional (one-to-many/many-to-one) association, which of the entities is the owner? How can we designate the One side as the owner? How can we designate the Many side as the owner? What is meant by "the inverse side of the association"? How can we designate the One side as the inverse? How can we designate the Many side as the inverse? Thanks in advance.

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  • Checkbox values to varchar via Spring

    - by iowatiger08
    I am trying to get a varchar message from a database to display the selected values of a checkbox field in a jsp for patient's medication's dosage frequency. The possible values will be saved in comma-delimited string in the varchar. For most form fields there is simply a one form value to one database field ratio, but in this case, I am needing to merge the values that would come as a string[] into the comma-delimited string and then when retrieving that record for that medication of that patient, display the selected values from the comma-delimited string as selected from the selectableDosageFrequencyList. You assistance in this is greatly appreciated as I am not sure what I am missing here. In the application context, I created the list of possible values as part of the ServiceBean. <property name="selectableDosageFrequencyList"> <set> <value>On an empty stomach</value> <value>Every other day</value> <value>4 times daily</value> <value>3 times daily</value> <value>Twice daily</value> <value>At bedtime</value> <value>With meal</value> <value>As needed</value> <value>Once daily</value> </set> </property> This is set up in the flow as requestscope. <view-state id="addEditMedication" model="medication"> <on-render> <set name="requestScope.selectableDosageFrequencyList" value="memberService.buildSelectableDosageFrequencyList(patient)" /> </on-render> ... <transition on="next" to="assessment" > <evaluate expression="memberService.updateMedication(patient, medication)" /> </transition> </view-state> I have helper methods in the memberService that need to be executed when the form is init and then when the form is completed. //get the form fields selected and build the new string for db public String setSelectedDosageFrequency(String [] dosageFrequencies){ String frequencies = null; if (dosageFrequencies != null){ for (String s : dosageFrequencies){ frequencies = frequencies + "," + s; } } return frequencies; } //get value from database and build selected Set public LinkedHashSet<String> getSelectedDosageFrequencyList(String dosageFrequency){ String copyOfDosages =dosageFrequency;//may not need to do this LinkedHashSet<String> setofSelectedDosageFrequency = new LinkedHashSet<String> (); while (copyOfDosages!= null && copyOfDosages.length()>0){ for (String aFrequency: selectableDosageFrequencyList){ if (copyOfDosages.contains(aFrequency)){ setofSelectedDosageFrequency.add(aFrequency); if (!copyOfDosages.equals(aFrequency) && copyOfDosages.endsWith(aFrequency)){ copyOfDosages.replaceAll(","+aFrequency, ""); }else if (!copyOfDosages.equals(aFrequency) && copyOfDosages.contains(aFrequency=",")){ copyOfDosages.replaceAll(aFrequency+",", ""); }else copyOfDosages.replaceAll(aFrequency, ""); copyOfDosages.trim(); } } } return setofSelectedDosageFrequency; } The Medication class that backs the form will have a variable for dosage-frequency as a string. private String dosageFrequency; The jsp I currently am doing this. <div class="formField"> <form:label path="dosageFrequency">Dosage Frequency</form:label> <ul class="multi-column double" style="width: 550px;"> <form:checkboxes path="dosageFrequency" items="${selectableDosageFrequencyList}" itemLabel="${selectableDosageFrequencyList}" element="li" /> </ul> </div>

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  • Problem with setVisible (true)

    - by Jessy
    The two examples shown below are same. Both are supposed to produce same result e.g. generate the coordinates of images displayed on JPanel. Example 1, works perfectly (print the coordinates of images), however example 2 returning 0 for the coordinate. I was wondering why because, I have put the setvisible (true) after adding the panel, in both examples. The only difference is that example 1 used extends JPanel and example 2 extends JFrame EXAMPLE 1: public class Grid extends JPanel{ public static void main(String[] args){ JFrame jf=new JFrame(); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final Grid grid = new Grid(); jf.add(grid); jf.pack(); Component[] components = grid.getComponents(); for (Component component : components) { System.out.println("Coordinate: "+ component.getBounds()); } jf.setVisible(true); } } EXAMPLE 2: public class Grid extends JFrame { public Grid () { setLayout(new GridBagLayout()); GridBagLayout m = new GridBagLayout(); Container c = getContentPane(); c.setLayout (m); GridBagConstraints con = new GridBagConstraints(); //construct the JPanel pDraw = new JPanel(); ... m.setConstraints(pDraw, con); pDraw.add (new GetCoordinate ()); // call new class to generate the coordinate c.add(pDraw); pack(); setVisible(true); } public static void main(String[] args) { new Grid(); } }

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  • How can I tell NetBeans to use the latest available version of a JAR for a library?

    - by Freiheit
    I have a Netbeans project with a library defined which includes several JARs. These JARs are versioned like lib\blah\com.blah.wibble.jar_0.6.1.201004161543 . These are nightly builds from another project so that version changes often. I know I can point NetBeans at the specific JARs with the version name, but this means that every time I get a new version I have to update the NetBeans library. I can also strip the version name from the JARs, but this makes it hard to track down bugs. "What version of the blah JARs?" is usually the second thing we ask when we find a bug. Is it possible to tell Netbeans to use included com.blah.wibble.jar_[??????] where ???? is some sort of automatic pointer to use the latest available version?

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  • How to avoid repetition when working with primitive types?

    - by I82Much
    I have the need to perform algorithms on various primitive types; the algorithm is essentially the same with the exception of which type the variables are. So for instance, /** * Determine if <code>value</code> is the bitwise OR of elements of <code>validValues</code> array. * For instance, our valid choices are 0001, 0010, and 1000. * We are given a value of 1001. This is valid because it can be made from * ORing together 0001 and 1000. * On the other hand, if we are given a value of 1111, this is invalid because * you cannot turn on the second bit from left by ORing together those 3 * valid values. */ public static boolean isValid(long value, long[] validValues) { for (long validOption : validValues) { value &= ~validOption; } return value != 0; } public static boolean isValid(int value, int[] validValues) { for (int validOption : validValues) { value &= ~validOption; } return value != 0; } How can I avoid this repetition? I know there's no way to genericize primitive arrays, so my hands seem tied. I have instances of primitive arrays and not boxed arrays of say Number objects, so I do not want to go that route either. I know there are a lot of questions about primitives with respect to arrays, autoboxing, etc., but I haven't seen it formulated in quite this way, and I haven't seen a decisive answer on how to interact with these arrays. I suppose I could do something like: public static<E extends Number> boolean isValid(E value, List<E> numbers) { long theValue = value.longValue(); for (Number validOption : numbers) { theValue &= ~validOption.longValue(); } return theValue != 0; } and then public static boolean isValid(long value, long[] validValues) { return isValid(value, Arrays.asList(ArrayUtils.toObject(validValues))); } public static boolean isValid(int value, int[] validValues) { return isValid(value, Arrays.asList(ArrayUtils.toObject(validValues))); } Is that really much better though? Any thoughts in this matter would be appreciated.

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  • Logic for controll concurrent in block/method

    - by Hlex
    1)My environment is web application, I develop servlet to receive request. A) In some block/method i want to control concurrent to not greater than 5 B) if there are 5 request in that block , the new coming must wait up to 60 second then throws error C) if there are sleep/waiting request more then 30, the 31th request will be throwed an error How I do this? 2)(Optional Question) from above I have to distribute control logic to all clustered host. I plan to use hazelcast to share the control logic (e.g. current counter) I see they provide BlockingQueue & ExectorService but I have no idea how to use in my case. Please recommend if you have idea.

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  • Servlet request getparameter's performance

    - by Bob
    Hi, I noticed that my app is very slow sometimes, so I've done some tests. It's a very simple web app. One servlet gets some parameters than stores them. Everything's fine except one thing. It takes too long to get a parameter for the first time. It doesn't matter which parameter I try to get, but for the first time it is very slow. The strange thing is this doesn't happen always. Sometimes getting a parameter for the first time is not slow. My code looks like this request.getParameter("paramName"); request.getParameter("paramName2"); request.getParameter("paramName3"); Getting "paramName" is slow. Getting the others is very fast. By slow I mean : 200-800 millisec By very fast I mean: ~0 millisec (in the code snippet, I didn't write the performance test, but I'm using System.currentTimeMillis())

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  • Using SiteMesh with RequestDispatcher's forward()

    - by Rob Hruska
    I'm attempting to integrate SiteMesh into a legacy application using Tomcat 5 as my a container. I have a main.jsp that I'm decorating with a simple decorator. In decorators.xml, I've just got one decorator defined: <decorators defaultdir="/decorators"> <decorator name="layout-main" page="layout-main.jsp"> <pattern>/jsp/main.jsp</pattern> </decorator> </decorators> This decorator works if I manually go to http://example.com/my-webapp/jsp/main.jsp. However, there are a few places where a servlet, instead of doing a redirect to a jsp, does a forward: getServletContext().getRequestDispatcher("/jsp/main.jsp").forward(request, response); This means that the URL remains at something like http://example.com/my-webapp/servlet/MyServlet instead of the jsp file and is therefore not being decorated, I presume since it doesn't match the pattern in decorators.xml. I can't do a <pattern>/*</pattern> because there are other jsps that do not need to be decorated by layout-main.jsp. I can't do a <pattern>/servlet/MyServlet*</pattern> because MyServlet may forward to main.jsp sometimes and perhaps error.jsp at other times. Is there a way to work around this without expansive changes to how the servlets work? Since it's a legacy app I don't have as much freedom to change things, so I'm hoping for something configuration-wise that will fix this. SiteMesh's documentation really isn't that great. I've been working mostly off the example application that comes with the distribution. I really like SiteMesh, and am hoping I can get it to work in this case.

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  • Using jmock how to reuse parameter

    - by BenZen
    I'm building a test, in wich i need to send question, and wait for the answer. Message passing is not the problem. In fact to figure out wich answer correspond to wich question, i use an id. My id is generated using an UUID. an i want to retrieve this id, wich is given as a parameter to a mocked object. It look like this: oneOf(message).setJMSCorrelationID(with(correlationId)); inSequence(sequence); Where correlationId is the string i'd like to keep for an other expecteation like this one: oneOf(session).createBrowser(with(inputChannel), with("JMSType ='pong' AND JMSCorrelationId = '"+correlationId+"'")); have you got an answer?

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  • ExecutorService memory leak on exception

    - by TofuBeer
    I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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  • Case Insensitive Ternary Search Tree

    - by Yan Cheng CHEOK
    I had been using Ternary Search Tree for a while, as the data structure to implement a auto complete drop down combo box. Which means, when user type "fo", the drop down combo box will display foo food football The problem is, my current used of Ternary Search Tree is case sensitive. My implementation is as follow. It had been used by real world for around 1++ yeas. Hence, I consider it as quite reliable. My Ternary Search Tree code However, I am looking for a case insensitive Ternary Search Tree, which means, when I type "fo", the drop down combo box will show me foO Food fooTBall Here are some key interface for TST, where I hope the new case insentive TST may have similar interface too. /** * Stores value in the TernarySearchTree. The value may be retrieved using key. * @param key A string that indexes the object to be stored. * @param value The object to be stored in the tree. */ public void put(String key, E value) { getOrCreateNode(key).data = value; } /** * Retrieve the object indexed by key. * @param key A String index. * @return Object The object retrieved from the TernarySearchTree. */ public E get(String key) { TSTNode<E> node = getNode(key); if(node==null) return null; return node.data; } An example of usage is as follow. TSTSearchEngine is using TernarySearchTree as the core backbone. Example usage of Ternary Search Tree // There is stock named microsoft and MICROChip inside stocks ArrayList. TSTSearchEngine<Stock> engine = TSTSearchEngine<Stock>(stocks); // I wish it would return microsoft and MICROCHIP. Currently, it just return microsoft. List<Stock> results = engine.searchAll("micro");

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  • Getting .jar file onto a mobile phone error

    - by me123
    Hello, I am trying to get a .jar file onto my mobile device. I have written a j2me application and I want to get it onto my phone. I have developed it in eclipse galileo and I export my project folder to a jar. When I try to download the jar file from the internet onto my phone I get an "incorrect description" error. Does anyone know how to get a j2me application onto a mobile device or why I may be getting this error? Thanks in advance.

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  • JTextPane insert component, faulty vertical alignment

    - by John O
    I have a JTextPane, into which I need to insert a JComponent. I'm using JTextPane.insertComponent(Component). The item is indeed inserted, but the vertical positioning is too high. Instead of having the bottom of the component aligned with the baseline of the current line of text, the component is way above that position, blocking out/over-painting lines of text appearing above. I have tried calling setAlignmentY(float) with various values, on both the inserted component and the JTextPane, but it doesn't affect the behavior at all. My guess: there seems to be some state inside my JTextPane or its Document that I need to be changing. But I don't know what it is. John

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  • Detecting client disconnect in tomcat servlet?

    - by Seth
    How can I detect that the client side of a tomcat servlet request has disconnected? I've read that I should do a response.getOutputStream().print(), then a response.getOutputStream().flush() and catch an IOException, but is there a way I can detect this without writing any data?

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  • Magi squares, recursive

    - by user310827
    Hi, my problem is, I'm trying to permute all posibilities for 3x3 square and check if the combination is magic. I've added a tweak with (n%3==0) if statement that if the sum of numbers in row differs from 15 it breaks the creation of other two lines... but it doesn't work, any suggestions, I call the function with Permute(1). public static class Global { //int[] j = new int[6]; public static int[] a= {0,0,0,0,0,0,0,0,0}; public static int[] b= {0,0,0,0,0,0,0,0,0}; public static int count = 0; } public static void Permute(int n) { int tmp=n-1; for (int i=0;i<9;i++){ if (Global.b[i]==0 ) { Global.b[i]=1; Global.a[n-1]=i+1; if ((n % 3) == 0) { if (Global.a[0+tmp]+Global.a[1+tmp]+Global.a[2+tmp] == 15) { if (n<9) { Permute(n+1); } else { isMagic(Global.a); } } else break; } else { Permute(n+1); } Global.b[i]=0; } } }

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  • Junit exception test

    - by Prithis
    I have two tests to check the expected exception throw. I am using Junit 4 and has following syntax. @Test(expected=IllegalArgumentException.class) public void testSomething(){ .......... } One of the tests fail even though IllegalArgumentException is thrown and the other passes. Any idea whats missing?? I modified the test which is failing to following and it passes. public void testSomething(){ try{ ............ //line that throws exception fail(); }catch(IllegalArgumentException e) { } }

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