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  • Why am I having this InstantiationException in Java when accessing final local variables?

    - by Oscar Reyes
    I was playing with some code to make a "closure like" construct ( not working btw ) Everything looked fine but when I tried to access a final local variable in the code, the exception InstantiationException is thrown. If I remove the access to the local variable either by removing it altogether or by making it class attribute instead, no exception happens. The doc says: InstantiationException Thrown when an application tries to create an instance of a class using the newInstance method in class Class, but the specified class object cannot be instantiated. The instantiation can fail for a variety of reasons including but not limited to: - the class object represents an abstract class, an interface, an array class, a primitive type, or void - the class has no nullary constructor What other reason could have caused this problem? Here's the code. comment/uncomment the class attribute / local variable to see the effect (lines:5 and 10 ). import javax.swing.*; import java.awt.event.*; import java.awt.*; class InstantiationExceptionDemo { //static JTextField field = new JTextField();// works if uncommented public static void main( String [] args ) { JFrame frame = new JFrame(); JButton button = new JButton("Click"); final JTextField field = new JTextField();// fails if uncommented button.addActionListener( new _(){{ System.out.println("click " + field.getText()); }}); frame.add( field ); frame.add( button, BorderLayout.SOUTH ); frame.pack();frame.setVisible( true ); } } class _ implements ActionListener { public void actionPerformed( ActionEvent e ){ try { this.getClass().newInstance(); } catch( InstantiationException ie ){ throw new RuntimeException( ie ); } catch( IllegalAccessException ie ){ throw new RuntimeException( ie ); } } } Is this a bug in Java? edit Oh, I forgot, the stacktrace ( when thrown ) is: Caused by: java.lang.InstantiationException: InstantiationExceptionDemo$1 at java.lang.Class.newInstance0(Class.java:340) at java.lang.Class.newInstance(Class.java:308) at _.actionPerformed(InstantiationExceptionDemo.java:25)

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  • Why is one Func valid and the other (almost identical) not.

    - by runrunraygun
    private static Dictionary<Type, Func<string, object>> _parseActions = new Dictionary<Type, Func<string, object>> { { typeof(bool), value => {Convert.ToBoolean(value) ;}} }; The above gives an error Error 14 Not all code paths return a value in lambda expression of type 'System.Func<string,object>' However this below is ok. private static Dictionary<Type, Func<string, object>> _parseActions = new Dictionary<Type, Func<string, object>> { { typeof(bool), value => Convert.ToBoolean(value) } }; I don't understand the difference between the two. I thought the extra braces in example1 are to allow us to use multiple lines in the anon function so why have they affected the meaning of the code?

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  • Pass Linq Expression to a function

    - by Kushan Hasithe Fernando
    I want to pass a property list of a class to a function. with in the function based on property list I'm going to generate a query. As exactly same functionality in Linq Select method. Here I'm gonna implement this for Ingress Database. As an example, in front end I wanna run a select as this, My Entity Class is like this public class Customer { [System.Data.Linq.Mapping.ColumnAttribute(Name="Id",IsPrimaryKey=true)] public string Id { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Name")] public string Name { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Address")] public string Address { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Email")] public string Email { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Mobile")] public string Mobile { get; set; } } I wanna call a Select function like this, var result = dataAccessService.Select<Customer>(C=>C.Name,C.Address); then,using result I can get the Name and Address properties' values. I think my Select function should looks like this, ( *I think this should done using Linq Expression. But im not sure what are the input parameter and return type. * ) Class DataAccessService { // I'm not sure about this return type and input types, generic types. public TResult Select<TSource,TResult>(Expression<Func<TSource,TResult>> selector) { // Here using the property list, // I can get the ColumnAttribute name value and I can generate a select query. } } This is a attempt to create a functionality like in Linq. But im not an expert in Linq Expressions. There is a project call DbLinq from MIT, but its a big project and still i couldn't grab anything helpful from that. Can someone please help me to start this, or can someone link me some useful resources to read about this.

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  • C# 4.0 dynamics

    - by mehanik
    Hi. Code bellow is working well until I have class ClassSameAssembly in same assembly as class Program. But when I move class ClassSameAssembly to separate assembly I have runtime error. Is it posible to resolve it? using System; namespace ConsoleApplication2 { public static class ClassSameAssembly { public static dynamic GetValues() { return new { Name = "Michael", Age = 20 }; } } internal class Program { private static void Main(string[] args) { var d = ClassSameAssembly.GetValues(); Console.WriteLine("{0} is {1} years old", d.Name, d.Age); } } }

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  • jQuery plugin call internal function

    - by pbcoder
    I want to call removeSomething() (see in line 9) internally: JS-Code is: (function($){ $.fn.extend({ Engine: function(options) { var defaults = { ... }; var options = $.extend(defaults, options); removeSomething(); //----------------------------------------------------------------------- //Public Functions ------------------------------------------------------ //----------------------------------------------------------------------- this.removeSomething = function() { ... }; } }); })(jQuery); But if I call removeSomething console outputs that removeSomething is not a function, how do I have to call this function? The function should be available internally and externally. Thanks for help!

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  • Fire Box doesnot support program based calling function

    - by manish
    on clicking any row of the following program... i am firinf on function mail file click....function just having alert message that shoes deffrent file name on the bases of clicking... *its working properly in IE .....FireBox N other browser function doesnot call on clicking on any row.. whats problem..please help me......i am writing code for your better awareness* For Each info In fsi Response.Write("<span id=" & " 'userijd'" & " onmouseup=" & "mailfileclick('" & info.Name & "')" & ";>") Response.Write("<td width=" & "16%" & " bgcolor=" & "#FFFFFF" & " style=" & "border-bottom-style:&nbsp;solid;&nbsp;border-bottom-width:&nbsp;1px" & " bordercolor=" & "#C0C0C0" & " nowrap" & ">") Response.Write("<font face=" & "Arial" & "style=" & "font-size:&nbsp;9pt" & " color=" & "#000000" & ">" & Mid(contents, InStr(contents, "Date: ") + Len("Date:"), 17) & "</font></td>") Response.Write("</span>") Next

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  • Token based Authentication for WCF HTTP/REST Services: Authorization

    - by Your DisplayName here!
    In the previous post I showed how token based authentication can be implemented for WCF HTTP based services. Authentication is the process of finding out who the user is – this includes anonymous users. Then it is up to the service to decide under which circumstances the client has access to the service as a whole or individual operations. This is called authorization. By default – my framework does not allow anonymous users and will deny access right in the service authorization manager. You can however turn anonymous access on – that means technically, that instead of denying access, an anonymous principal is placed on Thread.CurrentPrincipal. You can flip that switch in the configuration class that you can pass into the service host/factory. var configuration = new WebTokenWebServiceHostConfiguration {     AllowAnonymousAccess = true }; But this is not enough, in addition you also need to decorate the individual operations to allow anonymous access as well, e.g.: [AllowAnonymousAccess] public string GetInfo() {     ... } Inside these operations you might have an authenticated or an anonymous principal on Thread.CurrentPrincipal, and it is up to your code to decide what to do. Side note: Being a security guy, I like this opt-in approach to anonymous access much better that all those opt-out approaches out there (like the Authorize attribute – or this.). Claims-based Authorization Since there is a ClaimsPrincipal available, you can use the standard WIF claims authorization manager infrastructure – either declaratively via ClaimsPrincipalPermission or programmatically (see also here). [ClaimsPrincipalPermission(SecurityAction.Demand,     Resource = "Claims",     Operation = "View")] public ViewClaims GetClientIdentity() {     return new ServiceLogic().GetClaims(); }   In addition you can also turn off per-request authorization (see here for background) via the config and just use the “domain specific” instrumentation. While the code is not 100% done – you can download the current solution here. HTH (Wanna learn more about federation, WIF, claims, tokens etc.? Click here.)

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  • Canonical representation of a class object containing a list element in XML

    - by dendini
    I see that most implementations of JAX-RS represent a class object containing a list of elements as follows (assume a class House containing a list of People) <houses> <house> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </house> <house> </house> </houses> The result above is obtained for instance from Jersey 2 JAX-RS implementation, notice Jersey creates a wrapper class "houses" around each house, however strangely it doesn't create a wrapper class around each person! I don't feel this is a correct mapping of a list, in other words I'd feel more confortable with something like this: <houses> <house> <persons> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </persons> </house> <house> </house> </houses> Is there any document explaining how an object should be correctly mapped apart from any opninion?

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  • How can I enable anonymous access to a Samba share under ADS security mode?

    - by hemp
    I'm trying to enable anonymous access to a single service in my Samba config. Authorized user access is working perfectly, but when I attempt a no-password connection, I get this message: Anonymous login successful Domain=[...] OS=[Unix] Server=[Samba 3.3.8-0.51.el5] tree connect failed: NT_STATUS_LOGON_FAILURE The message log shows this error: ... smbd[21262]: [2010/05/24 21:26:39, 0] smbd/service.c:make_connection_snum(1004) ... smbd[21262]: Can't become connected user! The smb.conf is configured thusly: [global] security = ads obey pam restrictions = Yes winbind enum users = Yes winbind enum groups = Yes winbind use default domain = true valid users = "@domain admins", "@domain users" guest account = nobody map to guest = Bad User [evilshare] path = /evil/share guest ok = yes read only = No browseable = No Given that I have 'map to guest = Bad User' and 'guest ok' specified, I don't understand why it is trying to "become connected user". Should it not be trying to "become guest user"?

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  • Outlook 2010: When sending message on behalf of someone else, store that message in the other person's Sent Items folder

    - by Helge Klein
    We have an e-mail account for support purposes which is tended to by multiple members of the team. When answering a support e-mail we obviously choose the support account as sender. Still, the answer is not stored in the support account's Sent Items folder, but in the Sent Items of the person actually answering. This behavior, which seems to be by design, prevents others from gaining access to the entire conversation and potentially causes multiple answers. I am looking for an automated way of moving e-mails sent on behalf of someone else to that person's Sent Items folder. I tried to create a rule for this but could not find the right setting.

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  • Table sorting & pagination with jQuery and Razor in ASP.NET MVC

    - by hajan
    Introduction jQuery enjoys living inside pages which are built on top of ASP.NET MVC Framework. The ASP.NET MVC is a place where things are organized very well and it is quite hard to make them dirty, especially because the pattern enforces you on purity (you can still make it dirty if you want so ;) ). We all know how easy is to build a HTML table with a header row, footer row and table rows showing some data. With ASP.NET MVC we can do this pretty easy, but, the result will be pure HTML table which only shows data, but does not includes sorting, pagination or some other advanced features that we were used to have in the ASP.NET WebForms GridView. Ok, there is the WebGrid MVC Helper, but what if we want to make something from pure table in our own clean style? In one of my recent projects, I’ve been using the jQuery tablesorter and tablesorter.pager plugins that go along. You don’t need to know jQuery to make this work… You need to know little CSS to create nice design for your table, but of course you can use mine from the demo… So, what you will see in this blog is how to attach this plugin to your pure html table and a div for pagination and make your table with advanced sorting and pagination features.   Demo Project Resources The resources I’m using for this demo project are shown in the following solution explorer window print screen: Content/images – folder that contains all the up/down arrow images, pagination buttons etc. You can freely replace them with your own, but keep the names the same if you don’t want to change anything in the CSS we will built later. Content/Site.css – The main css theme, where we will add the theme for our table too Controllers/HomeController.cs – The controller I’m using for this project Models/Person.cs – For this demo, I’m using Person.cs class Scripts – jquery-1.4.4.min.js, jquery.tablesorter.js, jquery.tablesorter.pager.js – required script to make the magic happens Views/Home/Index.cshtml – Index view (razor view engine) the other items are not important for the demo. ASP.NET MVC 1. Model In this demo I use only one Person class which defines Person entity with several properties. You can use your own model, maybe one which will access data from database or any other resource. Person.cs public class Person {     public string Name { get; set; }     public string Surname { get; set; }     public string Email { get; set; }     public int? Phone { get; set; }     public DateTime? DateAdded { get; set; }     public int? Age { get; set; }     public Person(string name, string surname, string email,         int? phone, DateTime? dateadded, int? age)     {         Name = name;         Surname = surname;         Email = email;         Phone = phone;         DateAdded = dateadded;         Age = age;     } } 2. View In our example, we have only one Index.chtml page where Razor View engine is used. Razor view engine is my favorite for ASP.NET MVC because it’s very intuitive, fluid and keeps your code clean. 3. Controller Since this is simple example with one page, we use one HomeController.cs where we have two methods, one of ActionResult type (Index) and another GetPeople() used to create and return list of people. HomeController.cs public class HomeController : Controller {     //     // GET: /Home/     public ActionResult Index()     {         ViewBag.People = GetPeople();         return View();     }     public List<Person> GetPeople()     {         List<Person> listPeople = new List<Person>();                  listPeople.Add(new Person("Hajan", "Selmani", "[email protected]", 070070070,DateTime.Now, 25));                     listPeople.Add(new Person("Straight", "Dean", "[email protected]", 123456789, DateTime.Now.AddDays(-5), 35));         listPeople.Add(new Person("Karsen", "Livia", "[email protected]", 46874651, DateTime.Now.AddDays(-2), 31));         listPeople.Add(new Person("Ringer", "Anne", "[email protected]", null, DateTime.Now, null));         listPeople.Add(new Person("O'Leary", "Michael", "[email protected]", 32424344, DateTime.Now, 44));         listPeople.Add(new Person("Gringlesby", "Anne", "[email protected]", null, DateTime.Now.AddDays(-9), 18));         listPeople.Add(new Person("Locksley", "Stearns", "[email protected]", 2135345, DateTime.Now, null));         listPeople.Add(new Person("DeFrance", "Michel", "[email protected]", 235325352, DateTime.Now.AddDays(-18), null));         listPeople.Add(new Person("White", "Johnson", null, null, DateTime.Now.AddDays(-22), 55));         listPeople.Add(new Person("Panteley", "Sylvia", null, 23233223, DateTime.Now.AddDays(-1), 32));         listPeople.Add(new Person("Blotchet-Halls", "Reginald", null, 323243423, DateTime.Now, 26));         listPeople.Add(new Person("Merr", "South", "[email protected]", 3232442, DateTime.Now.AddDays(-5), 85));         listPeople.Add(new Person("MacFeather", "Stearns", "[email protected]", null, DateTime.Now, null));         return listPeople;     } }   TABLE CSS/HTML DESIGN Now, lets start with the implementation. First of all, lets create the table structure and the main CSS. 1. HTML Structure @{     Layout = null;     } <!DOCTYPE html> <html> <head>     <title>ASP.NET & jQuery</title>     <!-- referencing styles, scripts and writing custom js scripts will go here --> </head> <body>     <div>         <table class="tablesorter">             <thead>                 <tr>                     <th> value </th>                 </tr>             </thead>             <tbody>                 <tr>                     <td>value</td>                 </tr>             </tbody>             <tfoot>                 <tr>                     <th> value </th>                 </tr>             </tfoot>         </table>         <div id="pager">                      </div>     </div> </body> </html> So, this is the main structure you need to create for each of your tables where you want to apply the functionality we will create. Of course the scripts are referenced once ;). As you see, our table has class tablesorter and also we have a div with id pager. In the next steps we will use both these to create the needed functionalities. The complete Index.cshtml coded to get the data from controller and display in the page is: <body>     <div>         <table class="tablesorter">             <thead>                 <tr>                     <th>Name</th>                     <th>Surname</th>                     <th>Email</th>                     <th>Phone</th>                     <th>Date Added</th>                 </tr>             </thead>             <tbody>                 @{                     foreach (var p in ViewBag.People)                     {                                 <tr>                         <td>@p.Name</td>                         <td>@p.Surname</td>                         <td>@p.Email</td>                         <td>@p.Phone</td>                         <td>@p.DateAdded</td>                     </tr>                     }                 }             </tbody>             <tfoot>                 <tr>                     <th>Name</th>                     <th>Surname</th>                     <th>Email</th>                     <th>Phone</th>                     <th>Date Added</th>                 </tr>             </tfoot>         </table>         <div id="pager" style="position: none;">             <form>             <img src="@Url.Content("~/Content/images/first.png")" class="first" />             <img src="@Url.Content("~/Content/images/prev.png")" class="prev" />             <input type="text" class="pagedisplay" />             <img src="@Url.Content("~/Content/images/next.png")" class="next" />             <img src="@Url.Content("~/Content/images/last.png")" class="last" />             <select class="pagesize">                 <option selected="selected" value="5">5</option>                 <option value="10">10</option>                 <option value="20">20</option>                 <option value="30">30</option>                 <option value="40">40</option>             </select>             </form>         </div>     </div> </body> So, mainly the structure is the same. I have added @Razor code to create table with data retrieved from the ViewBag.People which has been filled with data in the home controller. 2. CSS Design The CSS code I’ve created is: /* DEMO TABLE */ body {     font-size: 75%;     font-family: Verdana, Tahoma, Arial, "Helvetica Neue", Helvetica, Sans-Serif;     color: #232323;     background-color: #fff; } table { border-spacing:0; border:1px solid gray;} table.tablesorter thead tr .header {     background-image: url(images/bg.png);     background-repeat: no-repeat;     background-position: center right;     cursor: pointer; } table.tablesorter tbody td {     color: #3D3D3D;     padding: 4px;     background-color: #FFF;     vertical-align: top; } table.tablesorter tbody tr.odd td {     background-color:#F0F0F6; } table.tablesorter thead tr .headerSortUp {     background-image: url(images/asc.png); } table.tablesorter thead tr .headerSortDown {     background-image: url(images/desc.png); } table th { width:150px;            border:1px outset gray;            background-color:#3C78B5;            color:White;            cursor:pointer; } table thead th:hover { background-color:Yellow; color:Black;} table td { width:150px; border:1px solid gray;} PAGINATION AND SORTING Now, when everything is ready and we have the data, lets make pagination and sorting functionalities 1. jQuery Scripts referencing <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" /> <script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.tablesorter.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.tablesorter.pager.js")" type="text/javascript"></script> 2. jQuery Sorting and Pagination script   <script type="text/javascript">     $(function () {         $("table.tablesorter").tablesorter({ widthFixed: true, sortList: [[0, 0]] })         .tablesorterPager({ container: $("#pager"), size: $(".pagesize option:selected").val() });     }); </script> So, with only two lines of code, I’m using both tablesorter and tablesorterPager plugins, giving some options to both these. Options added: tablesorter - widthFixed: true – gives fixed width of the columns tablesorter - sortList[[0,0]] – An array of instructions for per-column sorting and direction in the format: [[columnIndex, sortDirection], ... ] where columnIndex is a zero-based index for your columns left-to-right and sortDirection is 0 for Ascending and 1 for Descending. A valid argument that sorts ascending first by column 1 and then column 2 looks like: [[0,0],[1,0]] (source: http://tablesorter.com/docs/) tablesorterPager – container: $(“#pager”) – tells the pager container, the div with id pager in our case. tablesorterPager – size: the default size of each page, where I get the default value selected, so if you put selected to any other of the options in your select list, you will have this number of rows as default per page for the table too. END RESULTS 1. Table once the page is loaded (default results per page is 5 and is automatically sorted by 1st column as sortList is specified) 2. Sorted by Phone Descending 3. Changed pagination to 10 items per page 4. Sorted by Phone and Name (use SHIFT to sort on multiple columns) 5. Sorted by Date Added 6. Page 3, 5 items per page   ADDITIONAL ENHANCEMENTS We can do additional enhancements to the table. We can make search for each column. I will cover this in one of my next blogs. Stay tuned. DEMO PROJECT You can download demo project source code from HERE.CONCLUSION Once you finish with the demo, run your page and open the source code. You will be amazed of the purity of your code.Working with pagination in client side can be very useful. One of the benefits is performance, but if you have thousands of rows in your tables, you will get opposite result when talking about performance. Hence, sometimes it is nice idea to make pagination on back-end. So, the compromise between both approaches would be best to combine both of them. I use at most up to 500 rows on client-side and once the user reach the last page, we can trigger ajax postback which can get the next 500 rows using server-side pagination of the same data. I would like to recommend the following blog post http://weblogs.asp.net/gunnarpeipman/archive/2010/09/14/returning-paged-results-from-repositories-using-pagedresult-lt-t-gt.aspx, which will help you understand how to return page results from repository. I hope this was helpful post for you. Wait for my next posts ;). Please do let me know your feedback. Best Regards, Hajan

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  • JPA - insert and retrieve clob and blob types

    - by pachunoori.vinay.kumar(at)oracle.com
    This article describes about the JPA feature for handling clob and blob data types.You will learn the following in this article. @Lob annotation Client code to insert and retrieve the clob/blob types End to End ADFaces application to retrieve the image from database table and display it in web page. Use Case Description Persisting and reading the image from database using JPA clob/blob type. @Lob annotation By default, TopLink JPA assumes that all persistent data can be represented as typical database data types. Use the @Lob annotation with a basic mapping to specify that a persistent property or field should be persisted as a large object to a database-supported large object type. A Lob may be either a binary or character type. TopLink JPA infers the Lob type from the type of the persistent field or property. For string and character-based types, the default is Clob. In all other cases, the default is Blob. Example Below code shows how to use this annotation to specify that persistent field picture should be persisted as a Blob. public class Person implements Serializable {    @Id    @Column(nullable = false, length = 20)    private String name;    @Column(nullable = false)    @Lob    private byte[] picture;    @Column(nullable = false, length = 20) } Client code to insert and retrieve the clob/blob types Reading a image file and inserting to Database table Below client code will read the image from a file and persist to Person table in database.                       Person p=new Person();                      p.setName("Tom");                      p.setSex("male");                      p.setPicture(writtingImage("Image location"));// - c:\images\test.jpg                       sessionEJB.persistPerson(p); //Retrieving the image from Database table and writing to a file                       List<Person> plist=sessionEJB.getPersonFindAll();//                      Person person=(Person)plist.get(0);//get a person object                      retrieveImage(person.getPicture());   //get picture retrieved from Table //Private method to create byte[] from image file  private static byte[] writtingImage(String fileLocation) {      System.out.println("file lication is"+fileLocation);     IOManager manager=new IOManager();        try {           return manager.getBytesFromFile(fileLocation);                    } catch (IOException e) {        }        return null;    } //Private method to read byte[] from database and write to a image file    private static void retrieveImage(byte[] b) {    IOManager manager=new IOManager();        try {            manager.putBytesInFile("c:\\webtest.jpg",b);        } catch (IOException e) {        }    } End to End ADFaces application to retrieve the image from database table and display it in web page. Please find the application in this link. Following are the j2ee components used in the sample application. ADFFaces(jspx page) HttpServlet Class - Will make a call to EJB and retrieve the person object from person table.Read the byte[] and write to response using Outputstream. SessionEJBBean - This is a session facade to make a local call to JPA entities JPA Entity(Person.java) - Person java class with setter and getter method annotated with @Lob representing the clob/blob types for picture field.

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  • JavaScript Class Patterns

    - by Liam McLennan
    To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var john = new Person("John Galt", 50); console.log(john.toString()); var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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  • Can you pass by reference in Java?

    - by dbones
    Hi. Sorry if this sounds like a newbie question, but the other day a Java developer mentioned about passing a paramter by reference (by which it was ment just pass a Reference object) From a C# perspective I can pass a reference type by value or by reference, this is also true to value types I have written a noddie console application to show what i mean.. can i do this in Java? namespace ByRefByVal { class Program { static void Main(string[] args) { //Creating of the object Person p1 = new Person(); p1.Name = "Dave"; PrintIfObjectIsNull(p1); //should not be null //A copy of the Reference is made and sent to the method PrintUserNameByValue(p1); PrintIfObjectIsNull(p1); //the actual reference is passed to the method PrintUserNameByRef(ref p1); //<-- I know im passing the Reference PrintIfObjectIsNull(p1); Console.ReadLine(); } private static void PrintIfObjectIsNull(Object o) { if (o == null) { Console.WriteLine("object is null"); } else { Console.WriteLine("object still references something"); } } /// <summary> /// this takes in a Reference type of Person, by value /// </summary> /// <param name="person"></param> private static void PrintUserNameByValue(Person person) { Console.WriteLine(person.Name); person = null; //<- this cannot affect the orginal reference, as it was passed in by value. } /// <summary> /// this takes in a Reference type of Person, by reference /// </summary> /// <param name="person"></param> private static void PrintUserNameByRef(ref Person person) { Console.WriteLine(person.Name); person = null; //this has access to the orginonal reference, allowing us to alter it, either make it point to a different object or to nothing. } } class Person { public string Name { get; set; } } } If it java cannot do this, then its just passing a reference type by value? (is that fair to say) Many thanks Bones

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  • MySQL port forwarding

    - by Eduard Luca
    I am trying to help a colleague to connect to my MySQL server. However the situation is a bit special, and here's why (let's call him person A and me, person B): Person A has a PC, on which he has a virtual machine, which is in the same network as the actual PC he's running. However person A is also in the same network with person B (a different network). I want the site that lives on A's VM to be able to connect to the MySQL server on B's PC. For this I've thought a port forwarding would be appropriate: from ip-of-person-A:3306 to ip-of-person-B:3306. This way the site would connect to the IP of the PC it's living on (not the VM), which would forward to A's MySQL. I've seen several examples of port forwarding, but I don't think it's what I need, from what I've seen, it's kind of the opposite. So would something like this be achievable?

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  • Get the first and second objects from a list using LINQ

    - by Vahid
    I have a list of Person objects. How can I get the first and second Person objects that meet a certain criteria from List<Person> People using LINQ? Let's say here is the list I've got. How can I get the first and second persons that are over 18 that is James and Jodie. public class Person { public string Name; public int age; } var People = new List<Person> { new Person {Name = "Jack", Age = 15}, new Person {Name = "James" , Age = 19}, new Person {Name = "John" , Age = 14}, new Person {Name = "Jodie" , Age = 21}, new Person {Name = "Jessie" , Age = 19} }

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  • Use HTTP PUT to create new cache (ehCache) running on the same Tomcat?

    - by socal_javaguy
    I am trying to send a HTTP PUT (in order to create a new cache and populate it with my generated JSON) to ehCache using my webservice which is on the same local tomcat instance. Am new to RESTful Web Services and am using JDK 1.6, Tomcat 7, ehCache, and JSON. I have my POJOs defined like this: Person POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Person { private String firstName; private String lastName; private List<House> houses; // Getters & Setters } House POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class House { private String address; private String city; private String state; // Getters & Setters } Using a PersonUtil class, I hardcoded the POJOs as follows: public class PersonUtil { public static Person getPerson() { Person person = new Person(); person.setFirstName("John"); person.setLastName("Doe"); List<House> houses = new ArrayList<House>(); House house = new House(); house.setAddress("1234 Elm Street"); house.setCity("Anytown"); house.setState("Maine"); houses.add(house); person.setHouses(houses); return person; } } Am able to create a JSON response per a GET request: @Path("") public class MyWebService{ @GET @Produces(MediaType.APPLICATION_JSON) public Person getPerson() { return PersonUtil.getPerson(); } } When deploying the war to tomcat and pointing the browser to http://localhost:8080/personservice/ Generated JSON: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So far, so good, however, I have a different app which is running on the same tomcat instance (and has support for REST): http://localhost:8080/ehcache/rest/ While tomcat is running, I can issue a PUT like this: echo "Hello World" | curl -S -T - http://localhost:8080/ehcache/rest/hello/1 When I "GET" it like this: curl http://localhost:8080/ehcache/rest/hello/1 Will yield: Hello World What I need to do is create a POST which will put my entire Person generated JSON and create a new cache: http://localhost:8080/ehcache/rest/person And when I do a "GET" on this previous URL, it should look like this: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So, far, this is what my PUT looks like: @PUT @Path("/ehcache/rest/person") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response createCache() { ResponseBuilder response = Response.ok(PersonUtil.getPerson(), MediaType.APPLICATION_JSON); return response.build(); } Question(s): (1) Is this the correct way to write the PUT? (2) What should I write inside the createCache() method to have it PUT my generated JSON into: http://localhost:8080/ehcache/rest/person (3) What would the command line CURL comment look like to use the PUT? Thanks for taking the time to read this...

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  • I have Person.Surname field implemented as a string if I change the implementation of the field to a

    - by AndyM
    This is me going right back to basics with TDD for learning purposes. I originally implemented Person.Surname as field of type object (the simplest possible way of passing the test. I then added a test setting Person.Surname stating that the return value should be a string and set Person.Surname=20. I 'fixed' the test by changing the implementation to use string rather than object. The test now long compiles due to static type checking, so I commented it out. So I'm left with no way of leaving my intention in the test. Is there a way of having a failing test in this circumstance?

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  • How to fix issue with my 3D first person camera?

    - by dxCUDA
    My camera moves and rotates, but relative to the worlds origin, instead of the players. I am having difficulty rotating the camera and then translating the camera in the direction relative to the camera facing angle. I have been able to translate the camera and rotate relative to the players origin, but not then rotate and translate in the direction relative to the cameras facing direction. My goal is to have a standard FPS-style camera. float yaw, pitch, roll; D3DXMATRIX rotationMatrix; D3DXVECTOR3 Direction; D3DXMATRIX matRotAxis,matRotZ; D3DXVECTOR3 RotAxis; // Set the yaw (Y axis), pitch (X axis), and roll (Z axis) rotations in radians. pitch = m_rotationX * 0.0174532925f; yaw = m_rotationY * 0.0174532925f; roll = m_rotationZ * 0.0174532925f; up = D3DXVECTOR3(0.0f, 1.0f, 0.0f);//Create the up vector //Build eye ,lookat and rotation vectors from player input data eye = D3DXVECTOR3(m_fCameraX, m_fCameraY, m_fCameraZ); lookat = D3DXVECTOR3(m_fLookatX, m_fLookatY, m_fLookatZ); rotation = D3DXVECTOR3(m_rotationX, m_rotationY, m_rotationZ); D3DXVECTOR3 camera[3] = {eye,//Eye lookat,//LookAt up };//Up RotAxis.x = pitch; RotAxis.y = yaw; RotAxis.z = roll; D3DXVec3Normalize(&Direction, &(camera[1] - camera[0]));//Direction vector D3DXVec3Cross(&RotAxis, &Direction, &camera[2]);//Strafe vector D3DXVec3Normalize(&RotAxis, &RotAxis); // Create the rotation matrix from the yaw, pitch, and roll values. D3DXMatrixRotationYawPitchRoll(&matRotAxis, pitch,yaw, roll); //rotate direction D3DXVec3TransformCoord(&Direction,&Direction,&matRotAxis); //Translate up vector D3DXVec3TransformCoord(&camera[2], &camera[2], &matRotAxis); //Translate in the direction of player rotation D3DXVec3TransformCoord(&camera[0], &camera[0], &matRotAxis); camera[1] = Direction + camera[0];//Avoid gimble locking D3DXMatrixLookAtLH(&in_viewMatrix, &camera[0], &camera[1], &camera[2]);

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  • Any good tutorials all this web programming stuff for a GUI person? [closed]

    - by supercheetah
    For some reason, I am having a hard time understanding all this web programming stuff--from AJAX to JSON, etc. I've got plenty of experience programming GUIs. I'm currently working on a project in Python, and I thought that maybe I could just use PyJS (since it's GWT for Python, it uses an API that's very familiar to experienced GUI programmers like myself) to compile it with a Javascript interface on top, but alas, the compiler gave me a spectacular failure. It's obviously not meant to handle much of any Python beyond itself, and some of the core Python library. It would have been nice if it could, but I will admit, it would have been the lazy way to do it. I tried to learn Django, but for some reason, I'm just having a hard time understanding the tutorial on their website, and what it's all doing. Maybe it's not the best framework to learn, perhaps? Anyway, does anyone have a good primer/tutorial explaining all this stuff, especially for Python, and especially for someone coming from a GUI background?

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  • As a person getting into mobile development, what's the best mobile platform in terms of profitability? [closed]

    - by Kyle Loman
    I realize this question can range very far so would love to hear any and all opinions on this. However, I'll be honest and say that I have been thinking of this in terms of most profitable. I know how this may sound either way but this is one of my main sticking points. I realize that I'm not guaranteed a single cent and success is never guaranteed but I'm going into this with the thought of making something out of it both financially and also for my own interest. I know that iOS gets a lot of attention on this front but Android commands a lot more market share. However, I know there are drawbacks to Android too, whether it's in the actual development process and programming (though I've heard conflicting reports on this, such as how easy/difficult it is for to address screen res in different devices) or the app ecosystem being flooded. But iOS's app ecosystem has been described as too saturated and harder to compete in for that reason. Since Windows Phone has fewer apps than both of those two, that might be the best place to start in order to be closer to the ground floor of the store and be noticed more? Less saturation = better chances of sales or differentiating? Something like the gold rush during the first years of the iOS App Store (not exactly but at least in concept)? Would it be that despite fewer users on the platform, there's more exposure due to less competition so that may translate to better success at sales? Plus, I know MS is in it for the long haul so I'm not too fearful of something like WebOS going away. Obviously RIM isn't very popular nowadays but I read a recent article that says Blackberry actually has the apps that make the most money, any thoughts on that: http://gigaom.com/mobile/which-mobile-oss-apps-make-most-money-surprise-its-blackberry/ Again, this is all I've heard or known about so if there's anything to add or correct here, please do. In addition, this has actually affected my next personal phone upgrade. I'm eligible for a carrier discount now and I've had my eye on the iPhone 5. However, the Lumia 920 is the one I'm holding out for and I'm open to trying an Android but I'm not sure I can wait that long for any new Nexus or even the Razr HD. Even the new Lumia in November is making me antsy, I'm so close to just getting an iPhone 5. But when I say this has affected my phone choice, I'd want to be able to carry the apps I write with me so that I'm able to pull my phone out to show people without having to carry around a second device to do so. So that's why I'd like to make my personal phone match the main platform I'm developing for. Of course, I will likely expand to other platforms if I gain any decent success but the one I target now would serve well as my personal phone I carry around so that I can use it as a marketing tool, in a sense, showing people my apps if the opportunity presents itself. So what's the best mobile platform to choose, and especially in regards to most lucrative? As said previously, this would influence my personal phone choice greatly. Thanks in advance and I hope this isn't taken the wrong way - I understand there are trade-offs and other factors that may balance this out but making some revenue is key among that. For some background, I have done software development and know programming language concepts so I'm not entirely new to it and I do get the notion of being familiar with these things so that I can translate this skill among a variety of languages but I'm currently just having difficulty choosing my first main mobile platform based on the criteria I've outlined above.

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