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  • Exception handling pattern

    - by treefrog
    It is a common pattern I see where the error codes associated with an exception are stored as Static final ints. when the exception is created to be thrown, it is constructed with one of these codes along with an error message. This results in the method that is going to catch it having to look at the code and then decide on a course of action. The alternative seems to be- declare a class for EVERY exception error case Is there a middle ground ? what is the recommended method ?

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  • freeing a memory twice

    - by benjamin button
    Hi, AFAIAK, freeing a NULL will result in nothing.i mean nothing is being done by the compiler/no functionality is performed. Still i do see some statements where people say that one of the scenario,where a memory corruption can occur is "freeing a memory twice"? Is this still true?

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  • Change the default Open With

    - by emptyheaded
    How can I change the program a file is opened with by default (or at least add that program in the list of programs from Open With... ) using C# or VB.NET ? What I mean is, I would like to have programs with the extension abc open by default by the program abc.exe. Or, have the program abc.exe in the list of programs that will be shown in the context menu on the "Open With" option, for files with extension "xls".

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  • How to write an unit test for WCF behaviors?

    - by katie77
    I am new to unit testing. How do I write a unit test for a method when I am extending a WCF behavior. Since I am not sure of when the class is being instantiated, or I can not change the method signature. In the behavior implementation, I am getting the header and looking up a value in the config. public class IncomingValidator : IDispatchMessageInspector { public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext) { // Grab the header and see if one of the particular values(read from config) is there. } public void BeforeSendReply(ref Message reply, object correlationState) { } }

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  • Detecting if two png images are different

    - by Benjol
    (Context: running autohotkey scripts to try and automate some tests. The plan is to take screenshots and then compare them to 'standard' screenshots to detect if output has changed). Is there a 'clever' way to check if two png images are different? By clever I mean other than comparing them byte by byte? (after having compared their size, obviously)

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  • where can i ask questions where my post will not be deleted

    - by user287745
    http://stackoverflow.com/questions/3028161/project-help-needed-some-basic-concepts-great-confusion-because-of-lack-of-prope where can i ask questions where my post will not be deleted because of "it difficult to say what is being asked" i mean general waste area covering questions like the one i asked in.... and please gve links to help forums where there are experts like you before closing this question thank you

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  • Newbie: understanding main and IO()

    - by user1640285
    While learning Haskell I am wondering when an IO action will be performed. In several places I found descriptions like this: "What’s special about I/O actions is that if they fall into the main function, they are performed." But in the following example, 'greet' never returns and therefore nothing should be printed. import Control.Monad main = greet greet = forever $ putStrLn "Hello World!" Or maybe I should ask: what does it mean to "fall into the main function"?

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  • how does tomcat like web container handle struts 2 variables ?

    - by mobby1982
    i am a newbie . i have a question regarding struts 2 framework and tomcat . i know that each request has it own thread , but my question is are the global variables defined in struts action shared amongst requests. for ex: if i have a global variable named say int pageNo; and i am using in say method called paginationAll() can i use the same variable (pageNo) for another method called say paginatonMaterialAll() in the same action or does each thread has its own set of variables even though globally defined?

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  • Java synchronizing static list ?

    - by JavaUser
    Hi, In a Java class , i am having a static list so this list is shared across all the objects of this class.The business logic in this class will run periodically which is invoked by some method with out passing instance parameters.Now I want to invoke this run method based on the list(I will add some vales into this list based on JMS) ,this list may empty sometimes and after finishing the run , i am emptying this list.Now my question is , whether I need to synchronize this list or not? Also let me know is there any other way to pass value in one object instance(Thread1) to other object instance (Thread2) other than having Static variable(static list)? Thx

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  • How to insert into data base using multi threading programming [closed]

    - by user1196650
    I am having a method and that method needs to do the following thing: It has to insert records into a database. No insert is done for the same table again. All inserts are into different tables. I need a multi threading logic which inserts the details into db using different threads. I am using oracle db and driver configuration and remaining stuff are perfect. Please help me with an efficient answer. Can anyone could provide me with a skeleton logic of the program.

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  • Extendable accessing of sqlite database on android platform

    - by mscriven
    Hi, I am fairly new to the android sdk and databases and have been searching for an answer to this quite some time. I am trying to build an app which has multiple tables within a database. e.g. one for weapons, armours etc. However, my DatabaseManager class which handles all of my table creating, DatabaseHelper inner class and populating of data is creating for an extremely large class requiring high maintenance. Every time I would like to add or remove a table column I need to change quite a few areas of code, - Every reference to the addition of a row in that table with data - The method that the above calls - The method returning all of the database rows - The code in the helper class creating the table - Any specific update methods My question is this: Surely there must be some better way of coding this system, maybe using a database isn't the best way to go, or am i just not used to such large classes having only learned java at university and my largest class consisting of a mere 400-600 lines of code. Thanks for any help!

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  • Is any tool can help create/fix a table into normal form?

    - by WuYi
    Hi,I know the importance of being normal in database design. But many people always lives with broken windows. Is any tool can help create/fix a table to normal form? I mean to force developer create table in normal form, or help to check if the table being normal base on existed data within the table. Thanks……

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  • How to remove strings of certain lengths

    - by Macosx Iam
    So I have this array, and I want to delete strings that are 2 or 4 characters in length (strings that contain 2 or 4 characters). I am doing this method, and it doesn't work, even though logically, it SHOULD work. public static void main(String[] args) { ArrayList<String> list = new ArrayList<String>(); list.add("This"); list.add("is"); list.add("a"); list.add("test"); for (int i=0; i<list.size(); i++) { if(list.get(i).length()==2 || list.get(i).length()==4) { list.remove(i); } } } I'd like to stick to this method of doing it. Can you please give me some suggestions as to how to correct this code? The output of this code when I run it is: [is, a] Even though I want the output to be [a] because "is" is 2 characters long.

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  • Rendering HTML in rails without actually displaying it

    - by Kevin Whitaker
    Hello all, My current project requires me to assemble a .zip file containing HTML and text-only templates for a user to download, for importing into an email marketing program. I've inherited this project, and currently the code uses a "fake" model (that is a model that does not directly correlate to a database table), in which it stores the entire template in a string, using dynamic variables to populate certain areas. The "fake" model then has a method for creating a zip file. It seems to me that there has to be a better way to do this. I was wondering if there was a way to move the template into a .erb/haml file, and then write a method that would populate the file in preparation for being zipped up? Basically, is there a way to render an HTML and text file, without actually having to display them? Thanks for any help.

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  • Just how much do I want to make virtual?

    - by Alex
    I am writing an abstract superclass where literally every method is going to be overridden. There is some default functionality I could implement, but most of the time it's enough to leave the implementation to the subclass writer. Since just about every method is going to be overwritten, how much should I make virtual and how much should I just leave as regular methods? In the current incarnation, everything is virtual, but I still haven't let this loose to anyone to use, so the design is flexible. What advantages/disadvantages are there to virtual functions? Links to good reading material about this would be appreciated.

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  • Backbone.js Model validation fails to prevent Model from saving

    - by Benjen
    I have defined a validate method for a Backbone.js Model. The problem is that even if validation fails (i.e. the Model.validate method returns a value) the post/put request is still sent to the server. This contradicts what is explained in the Backbone.js documentation. I cannot understand what I am doing wrong. The following is the Model definition: /** * Model - Contact */ var Contact = Backbone.Model.extend({ urlRoot: '/contacts.json', idAttribute: '_id', defaults: function() { return { surname: '', given_name: '', org: '', phone: new Array(), email: new Array(), address: new Array({ street: '', district: '', city: '', country: '', postcode: '' }) }; } validate: function(attributes) { if (typeof attributes.validationDisabled === 'undefined') { var errors = new Array(); // Validate surname. if (_.isEmpty(attributes.surname) === true) { errors.push({ type: 'form', attribute: 'surname', message: 'Please enter a surname.' }); } // Validate emails. if (_.isEmpty(attributes.email) === false) { var emailRegex = /^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,6}$/i; // Stores indexes of email values which fail validation. var emailIndex = new Array(); _.each(attributes.email, function(email, index) { if (emailRegex.test(email.value) === false) { emailIndex.push(index); } }); // Create error message. if (emailIndex.length > 0) { errors.push({ type: 'form', attribute: 'email', index: emailIndex, message: 'Please enter valid email address.' }); } } if (errors.length > 0) { console.log('Form validation failed.'); return errors; } } } }); Here is the View which calls the Model.save() method (see: method saveContact() below). Note that other methods belonging to this View have not been included below for reasons of brevity. /** * View - Edit contact form */ var EditContactFormView = Backbone.View.extend({ initialize: function() { _.bindAll(this, 'createDialog', 'formError', 'render', 'saveContact', 'updateContact'); // Add templates. this._editFormTemplate = _.template($('#edit-contact-form-tpl').html()); this._emailFieldTemplate = _.template($('#email-field-tpl').html()); this._phoneFieldTemplate = _.template($('#phone-field-tpl').html()); // Get URI of current page. this.currentPageUri = this.options.currentPageUri; // Create array to hold references to all subviews. this.subViews = new Array(); // Set options for new or existing contact. this.model = this.options.model; // Bind with Model validation error event. this.model.on('error', this.formError); this.render(); } /** * Deals with form validation errors */ formError: function(model, error) { console.log(error); }, saveContact: function(event) { var self = this; // Prevent submit event trigger from firing. event.preventDefault(); // Trigger form submit event. eventAggregator.trigger('submit:contactEditForm'); // Update model with form values. this.updateContact(); // Enable validation for Model. Done by unsetting validationDisabled // attribute. This setting was formerly applied to prevent validation // on Model.fetch() events. See this.model.validate(). this.model.unset('validationDisabled'); // Save contact to database. this.model.save(this.model.attributes, { success: function(model, response) { if (typeof response.flash !== 'undefined') { Messenger.trigger('new:messages', response.flash); } }, error: function(model, response) { console.log(response); throw error = new Error('Error occured while trying to save contact.'); } }, { wait: true }); }, /** * Extract form values and update Contact. */ updateContact: function() { this.model.set('surname', this.$('#surname-field').val()); this.model.set('given_name', this.$('#given-name-field').val()); this.model.set('org', this.$('#org-field').val()); // Extract address form values. var address = new Array({ street: this.$('input[name="street"]').val(), district: this.$('input[name="district"]').val(), city: this.$('input[name="city"]').val(), country: this.$('input[name="country"]').val(), postcode: this.$('input[name="postcode"]').val() }); this.model.set('address', address); } });

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  • question on revrse array

    - by davit-datuashvili
    we know algorithm how reverse array of n integers for (int i=0;i<n/2;i++){ swap(a[i],a[n-1-i]): } is this method better according the speed of algorithm or not because swap using xor is more fast then in other method here is code public class swap{ public static void main(String[]args){ int a[]=new int[]{2,4,5,7,8,11,13,12,14,24}; System.out.println(" array at the begining:"); for (int i=0;i<a.length;i++){ System.out.println(a[i]); } for (int j=0;j<a.length/2;j++){ a[j]^=a[a.length-1-j]; a[a.length-1-j]^=a[j]; a[j]^=a[a.length-1-j]; } System.out.println("reversed array:"); for (int j=0;j<a.length;j++){ System.out.println(a[j]); } } } //result array at the begining: 2 4 5 7 8 11 13 12 14 24 reversed array: 24 14 12 13 11 8 7 5 4 2

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  • Enums in java compile error

    - by London
    Hi, I'm trying to learn java from bottom up, and I got this great book to read http://www.amazon.com/o/ASIN/0071591060/ca0cc-20 . Now I found example in the book about declaring Enums inside a class but outside any methods so I gave it a shot : Enum CoffeeSize { BIG, HUGE, OVERWHELMING }; In the book its spelled enum and I get this compile message Syntax error, insert ";" to complete BlockStatements Are the Enums that important at all?I mean should I skip it or its possible that I will be using those some day?

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  • Find record whose field 'name' not contained within any other record

    - by charlie
    I have a model Foo with a String bar and a String name. Some records' bar contain the name of other records in them. This is intentional. I want to find the "root Foo" records - that is, the ones where their name do not appear in the bar records of any other Foo records. Example: Foo id: 1 name: 'foo1' bar: 'something something' id: 2 name: 'foo2' bar: 'foo1 something' id: 3 name: 'foo3' bar: 'foo1, foo4' My method root_foos would return foo2 and foo3 since their names do not appear in any bar string. edit: I don't want to use a relation or foreign key here - just this method.

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  • From a Java programming perspective, what difference does multicast make to a networking program?

    - by pnut butter
    My manager has asked me to assess what changes would be required to add multicast support to a socket-based TCP/IP networking program that is part of a trading system. As far as I can tell, from the perspective of a Java program, it doesn't seem to matter too much whether the program is unicast or multicast. Doesn't the Java networking API make all of this transparent? By this I mean, wouldn't the change be a simple one of simply adding additional destinations for the outgoing connections?

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  • C++ Inheritance Question

    - by shaz
    I have a base class MessageHandler and 2 derived classes, MessageHandler_CB and MessageHandler_DQ. The derived classes redefine the handleMessage(...) method. MH_DQ processes a message and puts the result in a deque while MH_CB processes the message and then executes a callback function. The base class has a static callback function that I pass along with a this pointer to a library which calls the static callback when a new message is available for processing. My problem comes when I am in the static callback with a void * pointing to either a MH_DQ or a MH_CB. If I cast it to the base class the empty MessageHandler::handleMessage(...) method is called, rather than the version in the appropriate derived class. What is the best way to address this situation from a design perspective and/or what language features might help me to implement a solution to my problem? Thanks in advance!

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  • question on reverse array

    - by davit-datuashvili
    we know algorithm how reverse array of n integers for (int i=0;i<n/2;i++){ swap(a[i],a[n-1-i]): } is this method better according the speed of algorithm or not because swap using xor is more fast then in other method here is code public class swap { public static void main(String[]args){ int a[]=new int[]{2,4,5,7,8,11,13,12,14,24}; System.out.println(" array at the begining:"); for (int i=0;i<a.length;i++){ System.out.println(a[i]); } for (int j=0;j<a.length/2;j++){ a[j]^=a[a.length-1-j]; a[a.length-1-j]^=a[j]; a[j]^=a[a.length-1-j]; } System.out.println("reversed array:"); for (int j=0;j<a.length;j++){ System.out.println(a[j]); } } } Result: array at the begining: 2 4 5 7 8 11 13 12 14 24 reversed array: 24 14 12 13 11 8 7 5 4 2

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