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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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  • What is design principle behind Servlets being Singleton

    - by Sandeep Jindal
    A servlet container "generally" create one instance of a servlet and different threads of the same instance to serve multiple requests. (I know this can be changed using deprecated SingleThreadModel and other features, but this is the usual way). I thought, the simple reason behind this is performance gain, as creating threads is better than creating instances. But it seems this is not the reason. On the other hand, creating instances have little advantage that developers never have to worry about thread safety. I am trying to understand the reason for this decision over the trade-off of thread-safety.

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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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  • Running server-program from a .jar file

    - by skiwi
    I have created and am working on a server-application that monitors for specific folders and takes appropriate actions whenever files are being added. Now I come to the point where I want to be able to shutdown the program, for example for applying a patch. The server runs simply in a command prompt, how can I signal that I want to perform maintenance on it? I do not think reading System.In is feasible as I am also outputting text in the prompt. Regards.

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  • ResultSet in JTable

    - by Merin Treesa Joseph
    Sir, How display ResultSet in JTable. i using this code /*String [] record= new String[ColCount]; for (i=0; i } cell[i] = rset1.getString("loginname"); cell[i] = rset1.getString( "role"); System.out.println(cell[i][0]); //ItemGroup = rset1.getString( "Status"); } System.out.println(ItemCode); JTable jt = new JTable( cell[i], headers);*/ but i get only one row that lastly inserted to database.

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  • Security when using GWT RPC

    - by gerdemb
    I have an POJO in Google Web Toolkit like this that I can retrieve from the server. class Person implements Serializable { String name; Date creationDate; } When the client makes changes, I save it back to the server using the GWT RemoteServiceServlet like this: rpcService.saveObject(myPerson,...) The problem is that the user shouldn't be able to change the creationDate. Since the RPC method is really just a HTTP POST to the server, it would be possible to modify the creationDate by changing the POST request. A simple solution would be to create a series of RPC functions like changeName(String newName), etc., but with a class with many fields would require many methods for each field, and would be inefficient to change many fields at once. I like the simplicity of having a single POJO that I can use on both the server and GWT client, but need a way to do it securely. Any ideas?

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  • storage service with google app engine.

    - by Bunny Rabbit
    i've been assigned a project to create a filestorage service on google applet engine.but i am really doubtful wheather it's possible or not given the 30 sec limit to process the response and moreover its the bigtable is just a database system not a storage server .am i correct ?

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  • Adding additional components to a web page after rendering by Wicket

    - by Andrew Fielden
    I have a requirement to create a web page using Wicket 1.5, which can present a variable number of panels to capture user input. All the panels have the same structure. The page would start off with one panel, and includes a button to dynamically add more as required. So the number of panels is unknown at the time the page is initially rendered. Effectively I'd be altering the structure of the page dynamically. This is possible in Javascript, using document.addElement() I've done a similar thing in the past by creating all the components on page load, and selectively showing/hiding components. The difference here is that the number of components (panels) is initially unknown. I'm unsure as to how this would be achieved with Wicket.

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  • How to override j_security_check in glassfish?

    - by Alex B
    I'm currently using FORM based authentication in glassfish v2.1 to log users in and it works fine. I want to switch to ProgrammaticLogin and I want to be able to get the initially requested URL (i.e. before redirecting to login page) and use it in my programmatic login code so that the user is redirected back to the requested page after authentication. I've seen the source code for j_security_check - in my case that's FormAuthenticator (catalina codebase) and it saves the initial request in a SavedRequest object in the session but that session is a StandardSession rather than HttpSession so there's no direct way to access it. Or should I change the authentication mechanism from FORM to something else? Thanks!

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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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  • What is the best practice of using return keyword?

    - by Artic
    What is the best practice of using return keyword? If i need to return something from method which pattern is better to use? public boolean method(){ if (case1){ return true; } if (case 2){ return false; } return false; } or public boolean method(){ boolean result = false; if (case1){ result = true; } if (case 2){ result = false; } return result; }

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  • Hibernate -using Table per subclass - how to link an existing superclass object to a sibclass object

    - by Chandni
    Hi, I have a User hibernate class, Clerk class and Consumer class. All these maps to their own tables in database. The User PK also acts as Clerk's and Consumer's PK. So now my problem is that if a user is initially a Clerk, he has a record in Users table and Clerks table. If that user wants to become a consumer, I want to link that User's record to the new Consumer's record. So even if I pass the userId to the consumer's record, it treats it as a new User to be persisted and gives a duplicate_key exception. How do I tell Hiernate to link the same user object with this new Consumer object. Thanks in advance, -Chandni

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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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  • Move 3 rectangles up in their X but keep order of rectangles

    - by Nicolas Martel
    I have 3 rectangles being rendered here. Let's say i wanted to move them all above the line yet keep their order, how would i go about that? I tried subtracting the Y and height rather than adding the Y it but as expected, the lower rectangle goes at the top, middle stays in the middle and top goes to the bottom before: after: So is there any simple solution to render them just above rather than having to change all values ?

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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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  • 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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  • How do I add a library in Eclipse?

    - by jul
    hi, I downloaded the Gson library from http://code.google.com/p/google-gson/. The archive contains the following jar files: google-gson-1.3/gson-1.3-javadoc.jar google-gson-1.3/gson-1.3.jar google-gson-1.3/gson-1.3-sources.jar How do I set my Eclipse to be able to use the package in my projects? Where do I put the documentation? Thanks jul

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  • How to get fan list of Facebook page or can overwrite facebook social plugin css?

    - by Vaibhav Bhalke
    Hi, We are trying it with facebook social plugin. The HTML code for it as follow: <iframe border='0' src='http://www.facebook.com/plugins/likebox.php?id=1185611481&width=243&height=400&connections=15&stream=false&header=false' scrolling='yes' frameborder='0' allowTransparency='false' style='border:0px; overflow:hidden; width:243px; height:300px; background-color: #03869E; color: white;'> <iframe> As it replace inner HTML of frame on load. We want our own CSS to apply to this HTML. But as it replace whole HTML and it have its own CSS we are unable to set our CSS. We are doing this in GWT. Is there any way we can get the list of fans so we can display it as we want and can apply css? Or check given user is fan of page?

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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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  • Websphere 6.1, Datasource, two apps

    - by asrijaal
    Hi, I've got a webapp running on a Websphere 6.1 Server which JNDI lookups for a datasource. This webapp runs fine, the Websphere server recognizes the datasource ref in the web.xml etc.. Now we added a second webapp which should use this datasource with same configuration but I only getting a NULL Object when I invoke my JNDI lookup and a ClassCastException is thrown (which is correct). Maybe one of you has some suggestions?

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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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