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  • How to handle exceptions from an image-generating Servlet?

    - by ssahmed555
    I have a simple (Servlet, JSP, and JSTL) web app whose main functionality is displaying images retrieved from a back-end server. The controller servlet forwards the user to a JSP that in turn uses another Servlet to display the resulting image on that same JSP. Further down, the JSP has a line similar to: <a href="<c:out value='${imageURL}'/>"><img src="<c:out value='${imageURL}'/>" alt="image view" border="1"></a> which invokes a GET request on the image-generating servlet causing it to generate the image. My question is: how do I handle Exceptions thrown by this image-generating servlet? I already have an error page defined (in web.xml) to handle ServletException within my web app but this doesn't work for this image-generating Servlet, and results in the following errors showing up in my Tomcat server logs: SEVERE: Exception Processing ErrorPage[exceptionType=javax.servlet.ServletException, location=/WEB-INF/ExceptionPage.jsp] java.lang.IllegalStateException: Cannot reset buffer after response has been committed What's my recourse in this situation? I'd like to be able to handle Exceptions thrown from this image-generating Servlet, and display some error on the main UI or forward the user to another error page.

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  • Getting rejected value null spring validation

    - by Shabarinath
    Hi in my project when I am trying to validate my form its not showing any error messages even if validation fails (Event Form is not submitted and enters into validation fail block) Here is my code /****************** Post Method *************/ @RequestMapping(value="/property", method = RequestMethod.POST) public String saveOrUpdateProperty(@ModelAttribute("property") Property property, BindingResult result, Model model, HttpServletRequest request) throws Exception { try { if(validateFormData(property, result)) { model.addAttribute("property", new Property()); return "property/postProperty"; } } /********* Validate Block *************/ private boolean validateFormData(Property property, BindingResult result) throws DaoException { if (property.getPropertyType() == null || property.getPropertyType().equals("")) { result.rejectValue("propertyType", "Cannot Be Empty !", "Cannot Be Empty !"); } if (property.getTitle() == null || property.getTitle().equals("")) { result.rejectValue("title", "Cannot Be Empty !", "Cannot Be Empty !"); } return (result.hasFieldErrors() || result.hasErrors()); } But when i debug i can see below one org.springframework.validation.BeanPropertyBindingResult: 1 errors Field error in object 'property' on field 'title': rejected value [null]; codes [Cannot Be Empty !.property.title,Cannot Be Empty !.title,Cannot Be Empty !.java.lang.String,Cannot Be Empty !]; arguments []; default message [Cannot Be Empty !] and this is how i am displaying in jsp file <div class="control-group"> <div class="controls"> <label class="control-label"><span class="required">* </span>Property Type</label> <div class="controls"> <form:input path="title" placeholder="Pin Code" cssClass="form-control border-radius-4 textField"/> <form:errors path="title" style="color:red;"/> </div> </div> </div> Event though when i see the below one when i debug (1 Error its correct) org.springframework.validation.BeanPropertyBindingResult: 1 errors Why it is not displayed in jsp can any one hep me?

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  • Recommendation for using equals in Entities and avoiding LazyInitializationExceptions?

    - by huxendupsel
    In the beginning there is a problem that wants to be solved. In my case i got an LazyInitializationException while using indexof in a Collection to retrieve an Object for manipulation. Here i start to think about using equals in EntityBeans (OR-Mapper at all). I know there are some discussions about overriding equals in association with OR-Mapper as hibernate like [1] Entities equals(), hashCode() and toString(). How to correctly implement them? [2] To equals and hashcode or not on entity classes, that is the question. [3] Overriding equals and hashCode in Java I currently have some entities which implements the equals but inside the code i could not use equals several times because of the LazyInitializationExceptions. So i had to workaround and use eg. the name property of the object to identify it's equality. From my point of view the whole 'LazyInitializationException-thing' is not really mentioned in this questions. I'd like to know have you got some good patterns or real live recommendations how to avoid such exception in an equal-Method. Shall i use some helper Methodes to distinguish if a Object of a class is already initialized (4) or should i apdicate the use of equals and use helper classes instead (2)? And what is about catching LazyInitializationExceptions in the equals? [Edit]: If you put equals in context with the initialization of the Object then it will gain importance. Sometimes it is nessesary to have the Object fully initialized but sometimes you don't want to. Because you just need the Object itself (name, id, ...) not its Collection-Properties. So just for equalization you have to reattach the Object and load the whole bunch you don't realy need? Are there any other solutions for such a problem?

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  • Scope of Groovy's ExpandoMetaClass?

    - by TicketMonster
    Groovy exposes an ExpandoMetaClass that allows you to dynamically add instance and class methods/properties to a POJO. I would like to use it to add an instance method to one of my Java classes: public class Fizz { // ...etc. } Fizz fizz = new Fizz(); fizz.metaClass.doStuff = { String blah -> fizz.buzz(blah) } This would be the equivalent to refactoring the Fizz class to have: public class Fizz { // ctors, getters/setters, etc... public void doStuff(String blah) { buzz(blah); } } My question: Does this add doStuff(String blah) to only this particular instance of Fizz? Or do all instances of Fizz now have a doStuff(String blah) instance method? If the former, how do I get all instances of Fizz to have the doStuff instance method? I know that if I made the Groovy: fizz.metaClass.doStuff << { String blah -> fizz.buzz(blah) } Then that would add a static class method to Fizz, such as Fizz.doStuff(String blah), but that's not what I want. I just want all instances of Fizz to now have an instance method called doStuff. Ideas?

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  • Running Boggle Solver takes over an hour to run. What is wrong with my code?

    - by user1872912
    So I am running a Boggle Solver in java on the NetBeans IDE. When I run it, i have to quit after 10 minutes or so because it will end up taking about 2 hour to run completely. Is there something wrong with my code or a way that will make is substantially faster? public void findWords(String word, int iLoc, int jLoc, ArrayList<JLabel> labelsUsed){ if(iLoc < 0 || iLoc >= 4 || jLoc < 0 || jLoc >= 4){ return; } if(labelsUsed.contains(jLabels[iLoc][jLoc])){ return; } word += jLabels[iLoc][jLoc].getText(); labelsUsed.add(jLabels[iLoc][jLoc]); if(word.length() >= 3 && wordsPossible.contains(word)){ wordsMade.add(word); } findWords(word, iLoc-1, jLoc, labelsUsed); findWords(word, iLoc+1, jLoc, labelsUsed); findWords(word, iLoc, jLoc-1, labelsUsed); findWords(word, iLoc, jLoc+1, labelsUsed); findWords(word, iLoc-1, jLoc+1, labelsUsed); findWords(word, iLoc-1, jLoc-1, labelsUsed); findWords(word, iLoc+1, jLoc-1, labelsUsed); findWords(word, iLoc+1, jLoc+1, labelsUsed); labelsUsed.remove(jLabels[iLoc][jLoc]); } here is where I call this method from: public void findWords(){ ArrayList <JLabel> labelsUsed = new ArrayList<JLabel>(); for(int i=0; i<jLabels.length; i++){ for(int j=0; j<jLabels[i].length; j++){ findWords(jLabels[i][j].getText(), i, j, labelsUsed); //System.out.println("Done"); } } } edit: BTW I am using a GUI and the letters on the board are displayed by using a JLabel.

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  • Preserving the order of annotations

    - by Ragunath Jawahar
    When obtaining the list of fields using getFields() and getDeclaredFields(), the order of the fields in a Java class is undefined. I need this order in my validation library. Since the order is not preserved (though some claim that the order is preserved in JDK 6 and above but is not guaranteed across VMs). I cannot speculate on this because the order of annotations across fields is absolutely essential for the library. One way to get around this is to have an order or an index attribute in my Annotation. What worries me is that the code could become a bit cumbersome for maintaining in the following case. If the use wants to insert a new annotated field then, he might have to renumber all the other annotations in the class. I could have the order or index as a floating point number - float or double but , it wouldn't look good to have order such as 1, 1.5, 2, etc., What would be an elegant solution for this problem? Here is a example code so that you can get an idea about the problem: @Required @TextRule (minLength = 6, message = "You need at least 6 characters.") private EditText usernameEditText; @Password private EditText passwordEditText; @ConfirmPassword private EditText confirmPasswordEditText; @Email private EditText emailEditText;

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  • Fast compiler error messages in Eclipse

    - by Chris Conway
    As a new Eclipse user, I am constantly annoyed by how long it takes compiler error messages to display. This is mostly only a problem for long errors that don't fit in the status bar or the "Problems" tab. But I get enough long errors in Java—especially with generics—that this is a nagging issue. (Note: The correct answer to this question is not "get better at using generics." ;-) The ways I have found to display an error are: Press Ctrl+. or execute the command "Next Annotation". The next error is highlighted and its associated message appears in the status bar (if it is short enough). The error is also highlighted in the "Problems" tab, if it is open, but the tab is not automatically brought to the top. Hover the mouse over the error. After a noticeable lag, the error message appears as a "tool tip", along with any associated "Quick Fixes." Hover the mouse over the error icon on the left side of the editing pane. After a noticeable lag, all of the error messages for that line appear as a "tool tip." Clicking on the icon brings up "Quick Fixes." What I would like is for Ctrl+. to automatically and instantly bring up the complete error message (I don't care where). Is this a configurable option? [UPDATE] @asterite's "Ctrl+. F2" is almost it. How do I make "Next Annotation, then Show Tooltip Description" a macro bound to a single keystroke?

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  • Why does p:panelGrid not work with ui:repeat?

    - by CycDemo
    If I use as below, I get no error, no output. Why does p:panelGrid not work with ui:repeat? Note : I don't want to use c:forEach because of the I already face a lot of JSF issue. <p:panelGrid> <ui:repeat value="#{MyBean.dataList}" var="data"> <p:row> <p:column> <h:outputText value="#{data.name}"/> </p:column> <p:column> <h:outputText value="#{data.description}"/> </p:column> </p:row> </ui:repeat> </p:panelGrid> MyBean.java public List<Data> getDataList(){ List<Data> result = new ArrayList<Data>(); result.add(new Data("Name 1", "Description 1")); result.add(new Data("Name 2", "Description 2")); result.add(new Data("Name 3", "Description 3")); result.add(new Data("Name 4", "Description 4")); return result; } Expected output with primefaces

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  • How to generate R.java by a manual on Linux platform

    - by user305787
    I have a question. I am developing android applcation on Linux platform because i have to make a system.img with a application. When adding a drawable resource and building the project with mm command, i met a below error. "cannot find symbol R.drawable.icon_send_type" At above error, the icon_send_type is the added resource. This error occurred because the mm command did not generate R.java. So, i want to know how to generate R.java by a manual on Linux platform. Please help me.

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  • Hibernate Relationship Mapping/Speed up batch inserts

    - by manyxcxi
    I have 5 MySQL InnoDB tables: Test,InputInvoice,InputLine,OutputInvoice,OutputLine and each is mapped and functioning in Hibernate. I have played with using StatelessSession/Session, and JDBC batch size. I have removed any generator classes to let MySQL handle the id generation- but it is still performing quite slow. Each of those tables is represented in a java class, and mapped in hibernate accordingly. Currently when it comes time to write the data out, I loop through the objects and do a session.save(Object) or session.insert(Object) if I'm using StatelessSession. I also do a flush and clear (when using Session) when my line count reaches the max jdbc batch size (50). Would it be faster if I had these in a 'parent' class that held the objects and did a session.save(master) instead of each one? If I had them in a master/container class, how would I map that in hibernate to reflect the relationship? The container class wouldn't actually be a table of it's own, but a relationship all based on two indexes run_id (int) and line (int). Another direction would be: How do I get Hibernate to do a multi-row insert?

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  • UnknownHostException again!

    - by Nitesh Panchal
    Hello, I posted one question previously and all of them answered that there is some problem with DNS but i changed my DNS to many addressed and now i have the most reliable, google DNS :- 8.8.8.8 Still i get the same UnknownHostException. What can be the problem? This is my code :- DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse("http://rss.news.yahoo.com/rss/india"); Infact if i pass address as something very common like :- http://google.com i still get the same error. Please help me :(. I have my submissions tomorrow. Thanks in advance :) EDIT : If i type the same address in my mozilla, it works great. So, i am sure that there is no DNS problem. 2nd EDIT :- I found this link http://www.ehow.com/how_4747553_fix-unknownhostexception-java-applications-ubuntu.html But when i run the command sudo apt-get install lib32nss-mdns i get package not found. Somebody even mentioned :- -Djava.net.preferIPv4Stack=true But where do i write this statement of Djava? I am using Netbeans 6.8 to run my web application

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  • How to get a specific attribute from an object list?

    - by anarhikos
    I've an array keeping a list of Group objects. I want to set this list to the DropDownChoice component. However I want to show the end user only the name attribute of Group objects, and then get the selected values' id attribute to add database. What to do? private List<Group> groupTypes; DatabaseApp db = new DatabaseApp(); groupTypes = db.getGroups(); groupDropDownChoice = new DropDownChoice("type", groupTypes); ... ... addUserForm.add(new Button("submit"){ @Override public void onSubmit(){ Group group = (Group) groupDropDownChoice.getModelObject(); ... ... db.addUser(group.getId(), den, name, login, email, password1); DatabaseApp.java public List<Group> getGroups() throws SQLException{ List<Group> groups = new ArrayList<Group>(); try { String query = "SELECT * FROM [GROUP]"; Statement statement = db.createStatement(); ResultSet result = statement.executeQuery(query); while(result.next()){ int id = result.getInt("ID"); String name = result.getString("NAME"); groups.add(new Group(id, name)); } result.close(); } catch (SQLException ex) { throw new SQLException(ex.getMessage()); } return groups; }

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  • Dynamic WebService implementation

    - by chardex
    I have a set of different interfaces and I need to give them access via web services. I have implemented this task in .NET as follows: dynamically generated interface implementation on the IL, marked methods with WebMethod annotation, and in *.asmx handler called generated stub. More needs to be able to change the method signatures (eg change the type of certain argument or add new arguments), ie not always explicitly implement an interface, and use it as a decorator pattern. Example: interface ISomeService { void simpleMetod (String arg1); void customMetod (CusomType arg1, Integer arg2); } // Need to dynamically generate such class @WebService class SomeWebService { private ISomeService someService = new SomeServiceImpl (); @WebMethod public void simpleMethod (String arg1) { someService.simpleMethod (arg1); } @WebMethod public void customMethod (String arg1, Integer arg2) { someService.customMethod (CusomType.fromString (arg1), arg2); } } Interfaces such as ISomeService quite a lot. And manually write code like this I don't want. I work with Java recently, what technology/libraries should be used to solve such task. Thanks.

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  • Calling a class method within a method definition in the same class

    - by user1786288
    So I'm writing a program for an intro Java class. I'm defining a method to add two fractions together within the class Fraction. Fraction has 2 variables, numerator and denominator. Each of these variables has a setter and a getter. Anyway, I have a problem with my addition method, which is shown below. I've just sort of tried to implement it in a way that made sense, but I'm sure I did something with calling methods/using objects that doesn't work. public void add(Fraction fraction1, Fraction fraction2) { Fraction fraction3 = new Fraction(); int a = fraction1.getNumerator; int b = fraction1.getDenominator; int c = fraction2.getNumerator; int d = fraction2.getDenominator; fraction3.setNumerator((a * d) + (b * c)); fraction3.setDenominator(b * d); } I don't know if the problem is in the method definition, if I can use the object type that way, or if there's something else wrong. any help would be appreciated, and if I need to provide any information, I'll do so ASAP.

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  • Scraping with multiple IP, in java.

    - by Titi Wangsa bin Damhore
    Well basically I have a scraping application. It scrapes around n items per minute. currently i have only one IP. The site i'm scraping allows me 3 connections per IP. I'm thinking about getting another IP. so i'll be able to get 6 connections. in theory i should be able to get n items in 40 seconds, more or less. currently i'm using java (commons-httpcore) to get the job done. I'm not sure if this is java question or an OS question. my machine has IP 1 and IP 2 how do i connect to, say, www.microsoft.com, using IP 1 and using IP2? how can i specify, which ip i want to use to do a connection?

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  • How do I code a tree of objects in Haskell with pointers to parent and children?

    - by axilmar
    I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

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  • InputStreamBody in HttpMime 4.0.3 settings for content-length

    - by Ram
    I am trying to send a multi part formdata post through my java code. Can someone tell me how to set Content Length in the following?? There seem to be headers involved when we use InputStreamBody which implements the ContentDescriptor interface. Doing a getContentLength on the InputStreamBody gives me -1 after i add the content. I subclassed it to give contentLength the length of my byte array but am not sure if other headers required by ContentDescriptor will be set for a proper POST. HttpClient httpclient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(myURL); ContentBody cb = new InputStreamBody(new ByteArrayInputStream(bytearray), myMimeType, filename); //ContentBody cb = new ByteArrayBody(bytearray, myMimeType, filename); MultipartEntity mpentity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE); mpentity.addPart("key", new StringBody("SOME_KEY")); mpentity.addPart("output", new StringBody("SOME_NAME")); mpentity.addPart("content", cb); httpPost.setEntity(mpentity); HttpResponse response = httpclient.execute(httpPost); HttpEntity resEntity = response.getEntity();

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  • Strange Puzzle - Invalid memory access of location

    - by Rob Graeber
    The error message I'm getting consistently is: Invalid memory access of location 0x8 rip=0x10cf4ab28 What I'm doing is making a basic stock backtesting system, that is iterating huge arrays of stocks/historical data across various algorithms, using java + eclipse on the latest Mac Os X. I tracked down the code that seems to be causing it. A method that is used to get the massive arrays of data and is called thousands of times. Nothing is retained so I don't think there is a memory leak. However there seems to be a set limit of around 7000 times I can iterate over it before I get the memory error. The weird thing is that it works perfectly in debug mode. Does anyone know what debug mode does differently in Eclipse? Giving the jvm more memory doesn't help, and it appears to work fine using -xint. And again it works perfectly in debug mode. public static List<Stock> getStockArray(ExchangeType e){ List<Stock> stockArray = new ArrayList<Stock>(); if(e == ExchangeType.ALL){ stockArray.addAll(getStockArray(ExchangeType.NYSE)); stockArray.addAll(getStockArray(ExchangeType.NASDAQ)); }else if(e == ExchangeType.ETF){ stockArray.addAll(etfStockArray); }else if(e == ExchangeType.NYSE){ stockArray.addAll(nyseStockArray); }else if(e == ExchangeType.NASDAQ){ stockArray.addAll(nasdaqStockArray); } return stockArray; } A simple loop like this, iterated over 1000s of times, will cause the memory error. But not in debug mode. for (Stock stock : StockDatabase.getStockArray(ExchangeType.ETF)) { System.out.println(stock.symbol); }

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  • Singletons and constants

    - by devoured elysium
    I am making a program which makes use of a couple of constants. At first, each time I needed to use a constant, I'd define it as //C# private static readonly int MyConstant = xxx; //Java private static final int MyConstant = xxx; in the class where I'd need it. After some time, I started to realise that some constants would be needed in more than one class. At this time, I had 3 choises: To define them in the different classes that needed it. This leads to repetition. If by some reason later I need to change one of them, I'd have to check in all classes to replace them everywhere. To define a static class/singleton with all the constants as public. If I needed a constant X in ClassA, ClassB and ClassC, I could just define it in ClassA as public, and then have ClassB and ClassC refer to them. This solution doesn't seem that good to me as it introduces even more dependencies as the classes already have between them. I ended up implementing my code with the second option. Is that the best alternative? I feel I am probably missing some other better alternative. What worries me about using the singleton here is that it is nowhere clear to a user of the class that this class is using the singleton. Maybe I could create a ConstantsClass that held all the constants needed and then I'd pass it in the constructor to the classes that'd need it? Thanks

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  • Is it possible to get a truly unique id for a particular JVM instance?

    - by Uri
    I need a way to uniquely and permanently identify an instance of the JVM from within Java code running in that JVM. That is, if I have two JVMs running at the same time on the same machine, each is distinguishable. It is also distinguishable from running JVMs on other machines and from future executions on the same machine even if the process id is reused. I figure I could implement something like this by identifying the start time, the machine MAC, and the process id, and combining them in some way. I'm wondering if there is some standard way to achieve this. Update: I see that everyone recommended a UUID for the entire session. That seems like a good idea though possibly a little too heavyweight. Here is my problem though: I want to use the JVM id to create multiple unique identifiers in each JVM execution that somehow incorporate the JVM instance. My understanding is that you shouldn't really mix other numbers into a UUID because uniqueness is no longer guaranteed. An alternative is to make the UUID into a string and chain it, but then it becomes too long. Any ideas on overcoming this?

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  • Data transformation question

    - by tkm
    I have data composed of a list of employers and a list of workers. Each has a many-to-many relationship with the other (so an employer can have many workers, and a worker can have many employers). The way the data is retrieved (and given to me) is as follows: each employer has an array of workers. In other words: employer n has: worker x, worker y etc. So I have a bunch of employer objects each containing an array of workers. I need to transform this data (and basically invert the relationship). I need to have a bunch of worker objects, each containing and array of employers. In other words: worker x has: employer n1, employer n2 etc. The context is hypothetical so please don't comment on why I need this or why I am doing it this way. I would really just like help on the algorithm to perform this transformation (there isn't that much data so I would prefer readability over complex optimizations which reduce complexity). (Oh and I am using Java, but pseudocode would be fine). Thanks!

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  • What goes into the "Controller" in "MVC"?

    - by P72endragon
    I think I understand the basic concepts of MVC - the Model contains the data and behaviour of the application, the View is responsible for displaying it to the user and the Controller deals with user input. What I'm uncertain about is exactly what goes in the Controller. Lets say for example I have a fairly simple application (I'm specifically thinking Java, but I suppose the same principles apply elsewhere). I organise my code into 3 packages called app.model, app.view and app.controller. Within the app.model package, I have a few classes that reflect the actual behaviour of the application. These extends Observable and use setChanged() and notifyObservers() to trigger the views to update when appropriate. The app.view package has a class (or several classes for different types of display) that uses javax.swing components to handle the display. Some of these components need to feed back into the Model. If I understand correctly, the View shouldn't have anything to do with the feedback - that should be dealt with by the Controller. So what do I actually put in the Controller? Do I put the public void actionPerformed(ActionEvent e) in the View with just a call to a method in the Controller? If so, should any validation etc be done in the Controller? If so, how do I feedback error messages back to the View - should that go through the Model again, or should the Controller just send it straight back to View? If the validation is done in the View, what do I put in the Controller? Sorry for the long question, I just wanted to document my understanding of the process and hopefully someone can clarify this issue for me!

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