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  • How can I find out if two arguments are instances of the same, but unknown class?

    - by Ingmar
    Let us say we have a method which accepts two arguments o1 and o2 of type Object and returns a boolean value. I want this method to return true only when the arguments are instances of the same class, e.g.: foo(new Integer(4),new Integer(5)); Should return true, however: foo(new SomeClass(), new SubtypeSomeClass()); should return false and also: foo(new Integer(3),"zoo"); should return false. I believe one way is to compare the fully qualified class names: public boolean foo(Object o1, Object o2){ Class<? extends Object> c1 = o1.getClass(); Class<? extends Object> c2 = o2.getClass(); if(c1.getName().equals(c2.getName()){ return true;} return false; } An alternative conditional statement would be : if (c1.isAssignableFrom(c2) && c2.isAssignableFrom(c1)){ return true; } The latter alternative is rather slow. Are there other alternatives to this problem?

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  • Modelling a manyToMany relationship with attributes

    - by Javi
    Hello, I have a ManyToMany relationship between two classes, for instance class Customer and class Item. A customer can buy several items and an item can be bought by different customers. I need to store extra information in this relationship, for example the day when the item was bought. I wonder how is this usually modelled in JPA, cause I'm not sure how to express this in code. Do I have to create a new class to model all the attributes of the relationship and make a manyToMany relationship between the other classes or is a better way to do this? Thanks

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  • how to register a selectionProvider for the Viewer from a superclass

    - by Tom
    I have a View which extends a View provided by another plugin like this; public class View2 extends some.other.package.View1 { public void createPartControl(Composite parent) { super.createPartControl(parent); //I want to do this, but I can't because its private //getSite().setSelectionProvider(treeViewer); } } But I can't edit the super class, so I need to access the viewer from the Control. public class some.other.package.View1 extends ViewPart { private TreeViewer treeViewer; public void createPartControl(Composite parent) { treeViewer = new TreeViewer(parent, SWT.V_SCROLL); } } I tried using parent.getChildren(); to get a Tree object, but I can't see that it can be cooerced into an ISElectionProvider as required

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  • Annoying struts 2 problem

    - by Parhs
    Hello... I am using this code to include some menus to my code... <s:action namespace="/" name="get_header" executeResult="true" /> <jsp:include page="/get_menu" > <jsp:param name="menuKey" value="configuration"></jsp:param> <jsp:param name="subMenuKey" value="user.add"></jsp:param> </jsp:include> THe problem is that the menus are generated dynamically... So suppose that we have 2 Actions ActionA and get_menu Action The jsp page for the result of ActionA calls get_menu to generate the menus. So suppose that ActionA sets a variable groups and get_menu also uses a groups variable... ActionA's variable will overtake get_menu's variable. I tried many solutions and even jsp:inculde doesnt help:(...

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  • Why a variable is seen in the loop and is not seen outside the loop?

    - by Roman
    I have the following code: String serviceType; ServiceBrowser tmpBrowser; for (String playerName: players) { serviceType = "_" + playerName + "._tcp"; tmpBrowser = BrowsersGenerator.getBrowser(serviceType); tmpBrowser.browse(); System.out.println(tmpBrowser.getStatus()); } System.out.println(tmpBrowser.getStatus()); The compiler complains about the last line. It writes "variable tmpBrowser might not been initialized". If I comment the last line the compile does not complain.

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  • How To Keep Size Of JTextArea constant?

    - by Supereme
    Hi! I'm using an object of JTextArea in my application which deals with sending sms. I've used a DocumentFilter so as to allow only 160 characters to be typed in the textarea but now, I want the size of the textarea to be constant. it goes on increasing if I keep writing on the same line without pressing 'enter' key or even when I keep on pressing only 'enter' key. I tried once using 'scrollbar' too but the problem remains same. Suggest me something over this.

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  • Variable length Blob in hibernate?

    - by Seth
    I have a byte[] member in one of my persistable classes. Normally, I'd just annotate it with @Lob and @Column(name="foo", size=). In this particular case, however, the length of the byte[] can vary a lot (from ~10KB all the way up to ~100MB). If I annotate the column with a size of 128MB, I feel like I'll be wasting a lot of space for the small and mid-sized objects. Is there a variable length blob type I can use? Will hibernate take care of all of this for me behind the scenes without wasting space? What's the best way to go about this? Thanks!

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  • JAXB unmarshal exclude specific element

    - by zigomir
    Hi everyone! I know for @XmlTransient annotation, but sometimes I need this element and in other use cases I really have to prevent it from unmarshaling, because it contains base64 text. So I need to exclude it because performance problems. Is there any way to dynamicly exclude one element from unmarshaling with JAXB?

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  • check if a tree is a binary search tree

    - by TimeToCodeTheRoad
    I have written the following code to check if a tree is a Binary search tree. Please help me check the code: Pair p{ boolean isTrue; int min; int max; } public boo lean isBst(BNode v){ return isBST1(v).isTrue; } public Pair isBST1(BNode v){ if(v==null) return new Pair(true, INTEGER.MIN,INTEGER.MAX); if(v.left==null && v.right==null) return new Pair(true, v.data, v.data); Pair pLeft=isBST1(v.left); Pair pRight=isBST1(v.right); boolean check=pLeft.max<v.data && v.data<= pRight.min; Pair p=new Pair(); p.isTrue=check&&pLeft.isTrue&&pRight.isTrue; p.min=pLeft.min; p.max=pRight.max; return p; } Note: This function checks if a tree is a binary search tree

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  • Receiving a NullPointerException when calling a cursor in Android

    - by LordSnoutimus
    I am creating an application which tracks the users location using GPS, stores the longitude and latitude in a database using a content provider then output the first long and lat to a mapview. I am able to create the cursor using this line of code: Cursor c = getContentResolver().query(GPSContentProvider.CONTENT_URI, null, null, null, null); startManagingCursor(c); However, when I make a call to move to the first row in the database or even try to close the cursor using c.close(); I receive a NullPointerException.

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  • Using ControllerClassNameHandlerMapping with @Controller and extending AbstractController

    - by whiskerz
    Hey there, actually I thought I was trying something really simple. ControllerClassNameHandlerMapping sounded great to produce a small spring webapp using a very lean configuration. Just annotate the Controller with @Controller, have it extend AbstractController and the configuration shouldn't need more than this <context:component-scan base-package="test.mypackage.controller" /> <bean id="urlMapping" class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" /> to resolve my requests and map them to my controllers. I've mapped the servlet to "*.spring", and calling <approot>/hello.spring All I ever get is an error stating that no mapping was found. If however I extend the MultiActionController, and do something like <approot>/hello/hello.spring it works. Which somehow irritates me, as I would have thought that if that is working, why didn't my first try? Does anyone have any idea? The two controllers I used looked like this @Controller public class HelloController extends AbstractController { @Override protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception { ModelAndView modelAndView = new ModelAndView("hello"); modelAndView.addObject("message", "Hello World!"); return modelAndView; } } and @Controller public class HelloController extends MultiActionController { public ModelAndView hello(HttpServletRequest request, HttpServletResponse response) throws Exception { ModelAndView modelAndView = new ModelAndView("hello"); modelAndView.addObject("message", "Hello World!"); return modelAndView; } }

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  • Hibernate constraint ConstraintViolationException. Is there an easy way to ignore duplicate entries?

    - by vincent
    Basically I've got the below schema and I'm inserting records if they don't exists. However when it comes to inserting a duplicate it throws and error as I would expect. My question is whether there is an easy way to make Hibernate to just ignore inserts which would in effect insert duplicates? CREATE TABLE IF NOT EXISTS `method` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `name` varchar(10) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; SEVERE: Duplicate entry 'GET' for key 'name' Exception in thread "pool-11-thread-4" org.hibernate.exception.ConstraintViolationException: could not insert:

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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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  • Axis2 issue with comment in WSDL

    - by Sirs
    I'm using an Axis2 client to access an external Webservice, whose WSDL starts with the following content: <?xml version="1.0" encoding="UTF-8"?><!--Created by TIBCO WSDL--><wsdl:definitions xmlns:wsdl=... My call to sendReceive crashes with the following error: com.ctc.wstx.exc.WstxUnexpectedCharException: Unexpected character 'C' (code 67) in prolog; expected '<' The 'C' is the first character on the comment in the WSDL. Without that comment everything works fine, but as far as my knowledge of basic XML dictates that comment is correct. My question would be: Is this a bug in Axis2 or is the accessed WSDL malformed? Is there any way to prevent Axis2 from crashing under these circumstances?

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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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  • Call the method of base Class which was over ridden

    - by Abhijith Venkata
    I have illustrated my question in this example class Car { public void start(){ System.out.println("Car Started!!!"); } } class Mercedes extends Car { public void start(){ System.out.println("Mercedes Started!!!"); } } Now, in my main program, I write Mercedes m = new Mercedes(); m.start(); It prints: Mercedes Started!!! How do I call the start() method of Car class using the same object so that the output can be Car Started!!!. Edit: Actually It was asked in an interview I attended. I gave the super keyword answer. But the interviewer denied it. He said he'd give me a hint and said Virtual Function. I have no idea how to use that hint.

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  • Why might RvdProxy.getServices() incorrectly return an empty Array?

    - by butterchicken
    The following code snippet attempts to create a Tib DaemonManager connecting to a particular rvd, and then query for that rvd's services. public static void main(String[] args) throws RuntimeException { DaemonManager daemonManager = new DaemonManager("http://foo.com:7580"); if(daemonManager.getDaemonType() == DaemonManager.RVD) { DaemonProxy daemonProxy = daemonManager.getDaemonProxy(); final RvdProxy rvdProxy = (RvdProxy) daemonProxy; Service[] services = rvdProxy.getServices(); System.out.println(services.length); //prints 0 for (Service service : services) { System.out.println(service.getNetwork()); } } } This prints zero, even though the web interface for this rvd lists multiple available services. Why might this happen? The daemon I am connecting to is running v 7.5.1 of the software, and the rvconfig.jar that I am using is from v 7.5.1 as well. Is there a gotcha when using Tibco's DaemonManager that is causing me to come unstuck?

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  • Hibernate: deletes not cascading for self-referencing entities

    - by jwaddell
    I have the following (simplified) Hibernate entities: @Entity @Table(name = "package") public abstract class Package { protected Content content; @ManyToOne(cascade = {javax.persistence.CascadeType.ALL}) @JoinColumn(name = "content_id") @Fetch(value = FetchMode.JOIN) public Content getContent() { return content; } public void setContent(Content content) { this.content = content; } } @Entity @Table(name = "content") public class Content { private Set<Content> subContents = new HashSet<Content>(); @ManyToMany(fetch = FetchType.EAGER) @JoinTable(name = "subcontents", joinColumns = {@JoinColumn(name = "content_id")}, inverseJoinColumns = {@JoinColumn(name = "elt")}) @Cascade(value = {org.hibernate.annotations.CascadeType.DELETE, org.hibernate.annotations.CascadeType.REPLICATE}) @Fetch(value = FetchMode.SUBSELECT) public Set<Content> getSubContents() { return subContents; } public void setSubContents(Set<Content> subContents) { this.subContents = subContents; } } So a Package has a Content, and a Content is self-referencing in that it has many sub-Contents (which may contain sub-Contents of their own etc). The relationships are required to be ManyToOne (Package to Content) and ManyToMany (Content to sub-Contents) but for the case I am currently testing each sub-Content only relates to one Package or Content. The problem is that when I delete a Package and flush the session, I get a Hibernate error stating that I'm violating a foreign key constraint on table subcontents, with a particular content_id still referenced from table subcontents. I've tried specifically (recursively) deleting the Contents before deleting the Package but I get the same error. Is there a reason why this entity tree is not being deleted properly?

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  • Spring - Redirect after POST (even with validation errors)

    - by Taylor L
    I'm trying to figure out how to "preserve" the BindingResult so it can be used in a subsequent GET via the Spring <form:errors> tag. The reason I want to do this is because of Google App Engine's SSL limitations. I have a form which is displayed via HTTP and the post is to an HTTPS URL. If I only forward rather than redirect then the user would see the https://whatever.appspot.com/my/form URL. I'm trying to avoid this. Any ideas how to approach this? Below is what I'd like to do, but I only see validation errors when I use return "create". @RequestMapping(value = "/submit", method = RequestMethod.POST) public final String submit( @ModelAttribute("register") @Valid final Register register, final BindingResult binding) { if (binding.hasErrors()) { return "redirect:/register/create"; } return "redirect:/register/success"; }

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  • Fill a array with List data with one more element

    - by marionmaiden
    Hello, By a question that I made, I figured out that tho copy elements from one list to an array I just need to use the method toArray() for this. But let's suppose I have a List with n objects. I want to copy then into a array sized n+1 and add into the first position another object and in the other n positions the n data of the list. This is the way I'm doing it for now, but I'm just wondering if there is a better way for do that: Object array[] = new Object[list.size() + 1]; Object chk = new Object(); array[0] = chk; for(int i = 1; i < array.length; i++){ array[i] = list.get(i); }

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  • Best practice for storage and retrieval of error messages.

    - by ferrari fan
    What is a best practice for storing user messages in a configuration file and then retrieving them for certain events throughout an application? I was thinking of having 1 single configuration file with entries such as REQUIRED_FIELD = {0} is a required field INVALID_FORMAT = The format for {0} is {1} etc. and then calling them from a class that would be something like this public class UIMessages { public static final String REQUIRED_FIELD = "REQUIRED_FIELD"; public static final String INVALID_FORMAT = "INVALID_FORMAT"; static { // load configuration file into a "Properties" object } public static String getMessage(String messageKey) { // return properties.getProperty(messageKey); } } Is this the right way to approach this problem or is there some de-facto standard already in place?

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  • Adding and removing elements efficiently from Collection object

    - by user569125
    Hi, Below coding is the working sample,but still i am not happy with this code with related to performancewise.Please have a look and let me know if any better approach is there.Thanks in advance. Adding items to the arraylist object String resultItems[] = paging.getMoveLeftArray().split(","); String fields[]={"id","name","name1"}; leftObj=new ArrayList(); for(int i=0;i<resultItems.length;i++){ //below line mea TestVO bean=new TestVO(); String resultItem = resultItems[i]; String idANDname[] = resultItem.split("@"); String id = idANDname[0]; // name or id should not contain "-" String name[] = idANDname[1].split("-"); //values and fileds are always having same length for(int j=0;j<name.length;j++) { PropertyUtils.setProperty(bean, fields[j], name[j]); } leftObj.add(bean); } Removing items from the arraylist object:availableList contains all the TestVO objects: String []removeArray=paging.getMoveRightArray().split(","); tempList=new CopyOnWriteArrayList(); newTempList=new CopyOnWriteArrayList(); for(int i=0;i<availableList.size();i++){ boolean flag = false; TestVO tempObj = (TestVO )availableList.get(i); int id =(Integer)tempObj.getId(); // System.out.println("id value"+id); // availableList.get(i).getClass().getField(name); for(int j=0;j<removeArray.length;j++){ String resultItem = removeArray[j]; String idandname[] = resultItem.split("@"); for(int k=0;k<idandname.length;k++){ String ids[]=idandname[0].split("-"); if(id==Integer.parseInt(ids[0])){ flag = true; break; } } } if(flag){ tempList.add(tempObj); } else{ newTempList.add(tempObj); }

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