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  • Measuring the time to create and destroy a simple object

    - by portoalet
    From Effective Java 2nd Edition Item 7: Avoid Finalizers "Oh, and one more thing: there is a severe performance penalty for using finalizers. On my machine, the time to create and destroy a simple object is about 5.6 ns. Adding a finalizer increases the time to 2,400 ns. In other words, it is about 430 times slower to create and destroy objects with finalizers." How can one measure the time to create and destroy an object? Do you just do: long start = System.nanoTime(); SimpleObject simpleObj = new SimpleObject(); simpleObj.finalize(); long end = System.nanoTime(); long time = end - start;

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  • Diamonds Are Forever. Services Are Not.

    - by rayman
    Hi, ive read this article by Mark Murphy, while i was looking for a solution to my case. I have a Listener in my system, which suppose to get a UDP trigger times to times from an outside server, ive done this listener as a service. how could i prevent it being shut off by the user? (SDK 1.5), i`am working for a company which create cell phones, and we spread the device with this Listener. as soon as the listener goes off our systems will be terminated any idea for this scenario? *i`am already aware to the face, that the system could also take it off, but this case will be easier to handle and avoid. thanks, ray.

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  • Trouble creating a makefile

    - by catia
    Hi everyone! I'm having some trouble making a Makefile. Write now I just compile everything every time. Although, the professor is ok with that, I do want to get it working faster and to avoid unnecessary compiling. Here's what I have. FILES= p6.cpp SetIter.cpp Node.cpp Set.cpp CFLAGS= -ansi -pendantic -Wall -Wextra CC= g++ MakePg6: p6.cpp SetIter.cpp Node.cpp Set.cpp $(CC) $(CFLAGS) $(FILES) -o pg6 Node.cpp - node class Set.cpp - uses nodes. Friend of Node. SetIter.cpp - gets a set and uses a pointer to iterator through I'm confused with some of the depencies arising from the friends thing and the point of lib.o being included in the Makefile as some sites have. Any help is greatly appreciated. Thanks in advance.

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  • How does compiling circular dependencies work?

    - by Fabio F.
    I've made the example in Java but I think (not tested) that it works in other (all?) languages. You have 2 files. First, M.java: public class MType { XType x; MType() {x = null;} } Second, another file (in the same directory), XType.java: public class XType { MType m; public XType(MType m) {this.m = m;} } Ok it's bad programming, but if you run javac XType it compiles: compiles even MType because XType needs it. But ... MType needs XType ... how does that work? How does the compiler know what is happening? Probably this is a stupid question, but I would like to know how the compiler (javac or any other compilers you know) manages that situation, not how to avoid it. I'm asking because i'm writing a precompiler and I would like to manage that situation.

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  • The C vs. C++ way

    - by amc
    Hi, So I have to write a program that will iterate through an image and record the pixel locations corresponding to each color pixel that appears in it. For example, given http://www.socuteurl.com/fishywishykissy I need to find the coordinates of all yellow, purple, dark pink, etc pixels. In C++ I would use a hash table to do this. I would iterate through the image, check each pixel's value, look up that value and either add to a vector of pixel coordinates if it were found or add a new entry to the table if the value were not already there. The problem is that I may need to write this program in pure C instead of C++. How would I go about doing this in C? I feel like implementing a hash table would be pretty obnoxious and error-prone: should I avoid doing that? I'm pretty inexperienced with C and have a fair amount of C++ experience, if that matters. Thanks.

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  • Does ASP.NET Make Request Scheduling Decisions Based Upon SessionID?

    - by Mike Murphy
    I know that a properly implemented SessionStateStoreProvider maintains an exclusive lock on session data for the duration of a request. However, considering that multiple requests could arrive simultaneously (e.g. via IFRAMEs) all but one would be able to make forward progress. All the other requests would block for a bit and reduce the number of worker threads available during that time. It seems if ASP.NET "peeked" at the session IDs on the requests early on, it could avoid running requests simultaneously that were on the same session. This would improve throughput under load for pages that didn't want to give up using IFRAMEs. This seems plausible enough that it might be true.

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  • What's the easiest way to implement background downloading in Wicket?

    - by David Moles
    I've got a simple Wicket form that lets users select some data and then download a ZIP file (generated on the fly) containing what they asked for. Currently the form button's onSubmit() method looks something like this: public void onSubmit() { IResourceStream stream = /* assemble the data they asked for ... */ ; ResourceStreamRequestTarget target = new ResourceStreamRequestTarget(stream); target.setFileName("download.zip"); RequestCycle.get().setRequestTarget(target); } This works, but of course the request stops there and it's impossible to display any other feedback to the user. What I'd like to have is something like the typical "Your requested download [NAME] should begin automatically. If not, click this link." Ideally, still displaying the same page, so the user can immediately select some different data and download that as well. I imagine it's possible to do this using Wicket's Ajax classes, but I've managed to avoid having to use them so far, and it's not immediately obvious to me how. What's my quickest way out, here?

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  • How do you compose DataTemplates / link to a child datatemplate in WPF?

    - by Gishu
    Here's the problem. Given a large/intricate datatemplate A, which has 3 sections - General, Properties, Misc. Imagine 3 grids for each. Now I need to reuse the Properties section of the above Datatemplate in another place. Reasons: To avoid redundancy + ensure that further updates to the datatemplate are applied identically to all usages. So I guess what I am asking for is an ability to slot in a link to a child DataTemplate in a parent Datatemplate. What's the best way to go about this ? I found one way to do this.. but I'm not sure if its the right way or the best.. Posting it as an answer below so that it can be rated.

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  • Is there any way to store full size image returned from camera activity in internal memory ?

    - by SimpleGuy
    I am using Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT,Uri.fromFile(externalFileObj)); intent to call default camera activity. To get full image you need to specify intent.putExtra(). But this always requires URI that works only for external storage files. I tried to create a temp.jpg image in internal memory and pass its URI Uri.fromFile(new File(getFilesDir() + "/temp.jpg")); but the camera activity won't return back after the image is captured. So there is no way to get Full size image from default camera application in our activity without using any external storage ? Assuming that the device do not have SD card or currently in use is there no way I can avoid using it ? Yes I know we can create our own camerapreview surface but I want to use the default camera application as it is natural with many more options. Thanks.

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  • Dynamic proxies to auto-save models

    - by atomman
    I'm trying to make some auto-magic happen in java using proxies to track objects and saving them when a set* method is called. I started of using java's built in Proxy, and everything works just fine, but from what I can understand I need a interface for every model, which is something that I'm trying to avoid. This is where CGLIB comes in, it allows me to create proxies of my models without the use of interfaces. BUT, how can I now retrieve the original object, the one I am trying to save? The optimal solution to be would be something like the EntityManager interface used by hibernate, where you keep your original object, but it is still tracked.

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  • How to enforce lazy loading of entities on certain conditions

    - by Samuel
    We have an JPA @Entity class (say User) which has a @ManyToOne reference (say Address) loaded using the EAGER option which in turn loads it's own @ManyToOne fields (say Country) in a EAGER fashion. We use the EntityQuery interface to count the list of User's based on a search criteria, during such a load all the @ManyToOne fields which have been marked as EAGER get loaded. But in order to perform a EntityQuery.resultCount(), I actually don't need to load the @ManyToOne fields. Is there a way to prevent loading of the EAGER fields in such cases so that we can avoid the unnecessary joins?

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  • sqrt(int_value + 0.0) ? The point?

    - by Earlz
    Hello, while doing some homework in my very strange C++ book, which I've been told before to throw away, had a very peculiar code segment. I know homework stuff always throws in extra "mystery" to try to confuse you like indenting 2 lines after a single-statement for-loop. But this one I'm confused on because it seems to serve some real-purpose. basically it is like this: int counter=10; ... if(pow(floor(sqrt(counter+0.0)),2) == counter) ... I'm interested in this part especially: sqrt(counter+0.0) Is there some purpose to the +0.0? Is this the poormans way of doing a static cast to a double? Does this avoid some compiler warning on some compiler I do not use? The entire program printed the exact same thing and compiled without warnings on g++ whenever I left out the +0.0 part. Maybe I'm not using a weird enough compiler?

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  • How to match the word in jquery

    - by Mirage
    I have the image and i am fade in and fade out the image on click. But i want that if the same is present then it should not fadein/fadeout. My jquery code is switch(current_id) { case 'l1': $("#left_img img").fadeOut(500, function() { $(this).attr("src","rrr.gif").load( function() { $(this).fadeIn(500); }); }); break; case 'l3': $("#left_img img").fadeOut(500, function() { $(this).attr("src","cc1.gif").load( function() { $(this).fadeIn(500); }); }); break; If i click on link 1 then image A appears with fade effect. but if i click again link 1 agan , then again i see fade effect . Is there any way i can avoid that if same link is clicked again

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  • Fusion Table Layer Caching issue

    - by user1854791
    I have created a series of fusion table layers and apply filtering to one of the layers in response to checkbox click events. The base layer of the map contains a gradient applied over county boundaries. When the base layer is unchecked, the filtered layer loses it's styling. I have added unique timestamps to all queries to avoid caching, however I get the feeling that these image tiles are still be cached for this situation. Is there any way to force the google fusion tables api to invalidate a cached image? Test site here: http://map.inquestmarketing.com/new.html Unchecking the Other - Consumer Prospects checkbox reproduces the issue. This is a pure client app, all of the source is in the single page.

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  • Import data from an SSRS report via SSIS package

    - by Chris
    First, I ask that you not ask 'why.' In the famous words of Tennyson "Ours is not to reason why. Ours is but to do and die." It's one of those, "This is what you have, deal with it." situations. The source data comes from SSRS report. The goal is to load the data into a database via SSIS. The hopeful goal is to avoid human intervention in having to download the SSRS report into Excel or CSV. There will be complex SSIS processing from there on out. Any suggestions are humbly appreciated.

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  • MVC best practice when adding functions to controller?

    - by Patrick
    Hi I'm writing a function in my controller; this is supposed to take in a form, process it, register the user in DB, send a confirmation email etc etc. to avoid this function to be too cluttered, I was thinking of calling some sub-functions (eg: function registration() { //process form.. _insertInDb($formdata) _send_mail($address); //load confirmation view.. } function _send_mail($to) { //code here } function _insertInDb($formdata) { //other code here... } I'm not sure whether writing all the functions in the controller would be best practice -maybe I should insert all 'supporting' function (eg send_mail and insertInDb in this example) in another file and then import them? This would probably make the controller much more readable.. what's your view?

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  • The underlying connection was closed when using a WSDL web service

    - by joshlrogers
    I am trying to consume this WSDL service: Transit Time Service I successfully connect and get a response the first time but on subsequent calls I receive the exception: The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. I overrode the GetWebRequest in the reference.cs file as such: protected override System.Net.WebRequest GetWebRequest(Uri uri) { HttpWebRequest webRequest = (HttpWebRequest)base.GetWebRequest(uri); webRequest.KeepAlive = false; return webRequest; } This hasn't yielded any improvement. I am at a loss as to what options I have now, does anyone have any other ideas that I could try so that I may avoid this error? Thanks in advance! Josh

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  • C# - Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new { _t = new T(); private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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  • Optimal way to store and pass a date to Javascript

    - by user1493115
    I need to store a date-time value in MySQL and subsequently display it on a webpage. Due to its flexibility I usually chose to store a Unix timestamp in the database and convert it with PHP's date() to the desired format. This time however I would like to use MySQL's datetime field (mostly due to 2038) and apply the browser's timezone (hence I cannot simply format it on the server and pass the string to the client). I thought of storing the date as UTC datetime in the database and send it as well-defined format to the client, where it will be further processed. Here I would like to avoid a Unix timestamp but everything else might add additional overhead in processing. Is there any best practice as far as date processing is concerned in a MySQL, PHP, JQuery environment? Thanks.

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  • Calling a function in a JavaScript file with Selenium IDE

    - by user1059903
    So, I'm running these Selenium IDE tests against a site I'm working on. Everything about the tests themselves is running fine, except I would like to do a bit of clean-up once I'm done. In my MVC3 Razor based site, I have a JavaScript file with a function that gets a JsonResult from a Controller of mine. That Controller handles the database clean-up that Selenium IDE otherwise couldn't handle. However, I'm having a hard time finding any sort of documentation on how to do this. I know I can do JavaScript{ myJavascriptGoesHere } as one of the Values for a line in the test, but I can't seem to find a way to tell it to go find my clean-up function. Is it even possible for Selenium IDE to do this sort of thing? If it comes down to it, I can just make a separate View to handle the clean-up, but I'd really like to avoid that if possible. Thanks!

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  • Is there any tips for minimising access to a public page without login?

    - by alex
    I have a page that is just a non interactive display for a shop window. Obviously, I don't link to it, and I'd also like to avoid people stumbling across it (by Google etc). It will always be powered by Chrome. I have thought of... Checking User Agent for Chrome Ensuring resolution is 1920 x 1080 (not that useful as it is a client side check) Banning under robots.txt to keep Google out of it Do you have any more suggestions? Should I not really worry about it?

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  • GUID.TryParse() ?

    - by Jack Marchetti
    Obviously there is no public GUID.TryParse() in .NET CLR 2.0. So, I was looking into regular expressions [aka googling around to find one] and each time I found one there was a heated argument in the comments section about RegEx A doesn't work, use RegEx B. Then someone would write Regex C yadda yadda So anyway, What I decided to do was this, but I feel bad about it. public static bool IsGuid (string possibleGuid) { try { Guid gid = new Guid(possibleGuid); return true; } catch (Exception ex) { return false; } } Obviously I don't really like this since it's been drilled into me since day one to avoid throwing exceptions if you can defensibly code around it. Does anyonek now why there is no public Guid.TryParse() in the .NET Framework? Does anyone have a real Regular Expression that will work for all GUIDs?

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  • Linq to SQL inheritance and Table per Class - approach needed for multiple roles

    - by Ash Machine
    I am using L2S and an inheritance model for mapping Persons against certain roles. Guy Burstein's excellent blog post explains how to accomplish this: http://blogs.microsoft.co.il/blogs/bursteg/archive/2007/10/01/linq-to-sql-inheritance.aspx However, I have a specific case where a Person has multiple roles. For example 'Jane Doe' is a Contact and a Programmer. In this model, she would need two rows in the People table, one as Contact (PersonType = 1) and one as Programmer (PersonType = 3). If she changes her last name, and that update happens in her role as Contact, I would need to change all instances of 'Jane Doe' to reflect the name change everywhere. What sort of best approach (improved data structure) could be used to change last name within all roles? Finally, I am hoping to avoid overriding each general form update events to include all instances, but that may be the only way. Any suggestions or approaches appreciated.

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  • NoneType has no attribute Append

    - by Rosarch
    I'm new to Python. I can't understand why a variable is None at a certain point in my code: class UsersInRoom(webapp.RequestHandler): def get(self): room_id = self.request.get("room_id") username = self.request.get("username") UserInRoom_entities = UserInRoom.gql("WHERE room = :1", room_id).get() if UserInRoom_entities: for user_in_room in UserInRoom_entities: if user_in_room.username == username: user_in_room.put() # last_poll auto updates to now whenenever user_in_room is saved else: user_in_room = UserInRoom() user_in_room.username = username user_in_room.put() UserInRoom_entities = [] UserInRoom_entities.append(user_in_room) // error here # name is `user_at_room` intead of `user_in_room` to avoid confusion usernames = [user_at_room.username for user_at_room in UserInRoom_entities] self.response.out.write(json.dumps(usernames)) The error is: Traceback (most recent call last): File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 507, in __call__ handler.get(*groups) File "path\to\chat.py", line 160, in get AttributeError: 'NoneType' object has no attribute 'append' How is this possible? I'm setting UserInRoom_entities = [] immediately before that call. Or is something else the None in question?

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  • jQuery UI: moving items from one list to another

    - by AnC
    While this should be relatively straightforward, I can't figure out how to move (rather than copy) LI elements between ULs. All I want is to drag any item from list foo to list bar (or vice versa) without duplicating the element. While connectToSortable does almost exactly what I want (though I'd prefer to avoid sortable), it clones the element - and manually removing the original element by reacting to the stop event turns out to be not so easy (e.g. ensuring that a valid drop actually happened). A simple "hello world" example would help me greatly.

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