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  • How does ambigous methods are resolved in java ?

    - by Jijoy
    Hi , I do have a question. package org.study.algos; public class Study { public static void main(String[] args) { A a = new A(); a.m1(null); } } class A { public void m1(String s) { System.out.println("String"); System.out.println(s); } public void m1(Object obj) { System.out.println("Object"); System.out.println(obj); } } Here , the output is String null Why JVM resolve the method to one with String arguement ? Thanks in advance J

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  • Does declaring many identical anonymous classes waste memory in java?

    - by depsypher
    I recently ran across the following snippet in an existing codebase I'm working on and added the comment you see there. I know this particular piece of code can be rewritten to be cleaner, but I just wonder if my analysis is correct. Will java create a new class declaration and store it in perm gen space for every call of this method, or will it know to reuse an existing declaration? protected List<Object> extractParams(HibernateObjectColumn column, String stringVal) { // FIXME: could be creating a *lot* of anonymous classes which wastes perm-gen space right? return new ArrayList<Object>() { { add(""); } }; }

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  • In Java, how do I set a return type if an exception occurs?

    - by beagleguy
    hey all, I'm new to Java and was wondering if I define a method to return a database object like import java.sql.*; public class DbConn { public Connection getConn() { Connection conn; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); if(System.getenv("MY_ENVIRONMENT") == "development") { String hostname = "localhost"; String username = "root"; String password = "root"; } conn = DriverManager.getConnection("jdbc:mysql:///mydb", username, password); return conn; } catch(Exception e) { throw new Exception(e.getMessage()); } } } if the connection fails when I try to create it what should I return? eclipse is telling me I have to return a Connection object but if it fails I'm not sure what to do. thanks!

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  • set arraylist element as null

    - by Jessy
    The first index is set to null (empty), but it doesn't print the right output, why? //set the first index as null and the rest as "High" String a []= {null,"High","High","High","High","High"}; //add array to arraylist ArrayList<Object> choice = new ArrayList<Object>(Arrays.asList(a)); for(int i=0; i<choice.size(); i++){ if(i==0){ if(choice.get(0).equals(null)) System.out.println("I am empty"); //it doesn't print this output } }

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  • pass value to servlet from a hidden input type

    - by kawtousse
    I am trying to pass the parameter called value in the hidden input type to my servlet. It is like that: retour.append("<input type=\"hidden\" id=\"id_" + nomTab + "_" + compteur + "\" value=\"" + object.getIdDailyTimeSheet() + "\"/>"); retour.append("<button id=edit name=edit type=submit onClick= editarow()>"); retour.append("<img src=edit.gif />"); retour.append("</button>"); retour.append("</td>"); But the method get parameter recommend a name to be able to get the value here. So how can I deal with it? Here I want to pass to the servlet the value of object.getIdDailyTimeSheet().

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  • how to get a constant in java with class

    - by vincent
    basically I need to get a constant for a class however I have no instance of the object but only its class. In PHP I would do constant(XYZ); Is there a similar way of retrieving a constant in JAVA? I need it to facilitate a dynamic getMethod call Class parameterType = Class.forName(class_name); object.setProperty(field name, field value, parameterType); the set property method would then get the correct method and set the specified property, however I cant get a method which has int as parameter type without using Interger.TYPE

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  • Deferred printing in Java

    - by Bober02
    I have a specific issue with general console printing and I was wondering whether anyone has a solution for it. I am trying to print a dataTable which would look like sth like this: Table ---------------------- Name |Surname | ---------------------- Mike |Mikhailowish| Rafaello|Mirena | and so on. In order to print the border of the bar I need to know what the maximum length of each column value is. I don't want to go through the whole database to find that out and then again to print it. I would rather like to do sth like: System.out.printLater(s); //herejust leave a pointer to a StringBuilder you will build ... s.append("--------"); ... System.out.printAllDeferred(); I understand the above is probably in 99.99999% chances impossible, but perhaps you guys have a clever way of achieving the above?

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  • page_load another handler?

    - by joe doe
    can someone please explain why this code is not working as expected: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class temp : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("foo<br>"); this.Load += new EventHandler(temp_Load); } void temp_Load(object sender, EventArgs e) { Response.Write("bar<br>"); Response.End(); } } trying to add another handler for page Load event so that output would be: foo<br> bar<br>

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  • Entity Framework 4 Hiding Underlying Resolver Tables when model is generated from database

    - by grrrrrrrrrrrrr
    When creating an entity framework model from scratch it is possible to specify a Many to Many relationship in the model. e.g Entity1 * ----- * Entity2 When a database is then generated from this, a resolver table is then created automatically between the two entities, this is hidden in the code model, allowing direct access to each of the entities via properties. e.g. Entity1 ----* ResolverEntity *----- Entity2 My question is, when a model is generated from an existing database, which contains resolver tables, is it possible to create the same effect so the resolver tables do not appear in the generated object model? When I have attempted this, the entity framework appears to create entities in the model for the resolver tables with no obvious way of hiding them in the object model. Thanks.

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  • Inline Zend Navigation links in view content saved to db

    - by takeshin
    I'm storing the page content in the database (both as markup and HTML code) and displaying this content in the view (let's say it's CMS or forum post). The this data have also some links to internal pages existing in sitemap (Zend_Navigation object). It's easy to insert the link in page body just by using <a> tag. But the contents of this inline links does not change when I update the sorce XML for Zend Navigation (url's, attributes, ACL permissions). How do you handle this case? Special markup for the link, converting the link using url view helper? Iterate Zend_Navigation object extracting specific link (one by one)?

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  • Problem using GDI+ with multiple threads (VB.NET)

    - by Joe B
    I think it would be best if I just copy and pasted the code (it's very trivial). Private Sub Main() Handles MyBase.Shown timer.Interval = 10 timer.Enabled = True End Sub Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint e.Graphics.DrawImage(image, 0, 0) End Sub Private Sub tick() Handles timer.Elapsed Using g = Graphics.FromImage(image) g.Clear(Color.Transparent) g.DrawLine(Pens.Red, 0 + i, 0 + i, Me.Width - i, Me.Height - i) End Using Me.Invalidate() End Sub An exception, "The object is currently in use elsewhere", is raised during the tick event. Could someone tell me why this happens and how to solve it? Thanks.

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  • Rails, making certain multiparameter attributes optional?

    - by Joseph Silvashy
    Is there a method already part of Rails for making certain parameters option when part of a multiparameter attribute, for example say I'm prompting a user for their birthday, when saved the has may look like this: "birthday(2i)"=>"8", "birthday(3i)"=>"17", "birthday(1i)"=>"1980"}, ... But the issue arises when say I want to allow the user to just provide their month and day, making the year optional, how would this work being a datetime object, I'm assuming you can't do this as a date object... but any ideas would be helpful. Happy new year.

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  • Accessing a function of an instance which is in an arraylist

    - by fadeir
    I'm tring to access a function of an instance which is in an arraylist. Is there any way to do that without using the class name of the instance? import java.util.ArrayList; import java.util.List; class apple{ int price; public void myFunction(int iPrice) { price=iPrice; } } class orange{ int price; public void myFunction(int iPrice) { price=iPrice; } } public class main { public static void main(String[] args) { List list= new ArrayList(); //create 3 apple object to list list.add( new apple() ); list.add( new apple() ); list.add( new orange() ); list.get(0).myFunction(1); /* Error: The method myFunction(int) is undefined for the type Object*/ } } I know that;((apple) list.get(0)).myFunction(1); is a way but I'dont want to use any class name while calling the function.

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  • Is it guaranteed that new Integer(i) == i in Java?

    - by polygenelubricants
    Consider the following snippet: int i = 99999999; byte b = 99; short s = 9999; Integer ii = Integer.valueOf(9); // should be within cache System.out.println(new Integer(i) == i); // "true" System.out.println(new Integer(b) == b); // "true" System.out.println(new Integer(s) == s); // "true" System.out.println(new Integer(ii) == ii); // "false" It's obvious why the last line will ALWAYS prints "false": we're using == reference identity comparison, and a new object will NEVER be == to an already existing object. The question is about the first 3 lines: are those comparisons guaranteed to be on the primitive int, with the Integer auto-unboxed? Are there cases where the primitive would be auto-boxed instead, and reference identity comparisons are performed? (which would all then be false!)

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  • Why is 1942/4/3 00:00:00 an illegal date in java.util.Calendar?

    - by Aleksi
    Is there something special in the date 3rd of April 1942? For some reason the the hour of day 0 (12:00 am) is illegal for this specific date. The date is accepted when a lenient calendar is used but the hour of day is incremented to 1 (1:00 am). Relevant code java.util.Calendar calendar = java.util.Calendar.getInstance(); calendar.clear(); calendar.setLenient(false); calendar.set(1942, 3, 3, 0, 0, 0); calendar.getTimeInMillis(); Exception java.lang.IllegalArgumentException: HOUR_OF_DAY at java.util.GregorianCalendar.computeTime(Unknown Source) at java.util.Calendar.updateTime(Unknown Source) at java.util.Calendar.getTimeInMillis(Unknown Source) I'd really prefer is the dates were not lenient as I don't want to accept impossible dates.

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  • Why is super.super.method(); not allowed in Java?

    - by Tim Büthe
    I read this question and thought that would easily be solved (not that it isn't solvable without) if one could write: @Override public String toString() { return super.super.toString(); } I'm not sure if it is useful in many cases, but I wonder why it isn't and if something like this exists in other languages. What do you guys think? EDIT: To clarify: yes I know, that's impossible to at to Java and I don't really miss it. This is nothing I expected to work and was surprised getting a compiler error. I just had the idea and like to discuss it.

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  • Is there a name for a pure-data Objective-C class?

    - by BrianEnigma
    This is less of a code-specific question and more of an Objective-C nomenclature question. In C you have struct for pure data. In Enterprise Java, you have "bean" classes that are purely member variables with getters and setters, but no business logic. In Adobe FLEX, you have "Value Objects". In Objective-C, is there a proper name for an object (descended from NSObject, of course) that simply has ivars and getters/setters (or @property/@synthesize, if you want to get fancy) and no real business logic? A more concrete example might be a simple class with getters and setters for filename, file size, description, and assorted other metadata. You could then take a bunch of these and easily throw them into a container (NSDictionary, NSArray) without the need for messy NSValue wrapping of a C struct. It is also a little more structure than putting, say, a bunch of loosely-typed child NSDictionaries into a parent container object.

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  • Constructors with inheritance in c++

    - by Crystal
    If you have 3 classes, with the parent class listed first shape- 2d shapes, 3d shapes - circle, sphere When you write your constructor for the circle class, would you ever just initialize the parent Shape object and then your current object, skipping the middle class. It seems to me you could have x,y coordinates for Shape and initialize those in the constructor, and initialize a radius in the circle or sphere class, but in 2d or 3d shape classes, I wouldn't know what to put in the constructor since it seems like it would be identical to shape. So is something like this valid Circle::Circle(int x, int y, int r) : Shape(x, y), r(r) {} I get a compile error of: illegal member initialization: 'Shape' is not a base or member So I wasn't sure if my code was legal or best practice even. Or if instead you'd have the middle class just do what the top level Shape class does TwoDimensionalShape::TwoDimensionalShape(int x, int y) : Shape (x, y) {} and then in the Circle class Circle::Circle(int x, int y, int r) : TwoDimensionalShape(x, y), r(r) {}

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  • How to crete a Java Iterator that throws IOException

    - by Antonio
    I'd like to implement an iterator that retrieves objects from disk/network. Iterator itr = getRemoteIterator(); while(itr.hasNext()) { Object element = itr.next(); System.out.print(element + " "); } However the problem is that hasNext() and next() methods of the Iterator object does not allow to throw IOException. Is there any other standard interface work around this issue? Desired code is: public interface RemoteIterator<E> { boolean hasNext() throws IOException; E next() throws IOException; void remove(); }

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  • DoWork of BackgroundWorker is called twice when RunWorkerAsync is called once?

    - by Power-Mosfet
    I have create a backgroundworker in an class it works, but if i call and wait until the end run, call it for the second time it will do the same process twice i thinks there is somthing wrong with bw.DoWork += private void button1_Click(object sender, EventArgs e) { nptest.test.start("null", "null"); } namespace nptest { class test { public static void start(string str, string strb) { if (bw.IsBusy != true) { bw.WorkerSupportsCancellation = true; bw.DoWork += (obj, e) => bw_DoWork(str, strb); bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted); bw.RunWorkerAsync(); } } private static BackgroundWorker bw = new BackgroundWorker(); private static void bw_DoWork(string str, string strb) { System.Windows.Forms.MessageBox.Show("initializing BackgroundWorker"); } private static void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { if ((e.Cancelled == true)) { Console.WriteLine("Canceled"); } else if (!(e.Error == null)) { Console.WriteLine("Error: " + e.Error.Message); } bw.Dispose(); } } }

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  • Applying transformations to NSBitmapImageRep

    - by Adam
    So ... I have an image loaded into an NSBitmapImageRep object, so I am able to examine the contents of specific pixels via a two dimensional array. Now I want to apply a couple of "transformations" to the image, in preparation for some additional processing. If I was manipulating the image manually, in Photoshop, I would: Rotate the image Crop a portion of it and discard the rest Apply a "threshold" transformation (which essentially converts the image to black and white, based on the threshold value I provide) Resample the image to shrink it down a bit (which, although losing some image quality, will speed up the subsequent processing) (not necessarily in that order) Are there objective C methods available to facilitate these specific image manipulations, with the data in the NSBitmapImageRep object? If so, can someone point me to some good examples?

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  • How to executing the following command in Android?

    - by Aung Pyae
    I would like to create a new App Linking object for the sharing posts of my android application to facebook sdk. I look around and I found this. My App is "Mobile-Only". So, it seems I supposed to send this command to facebook. How can I send this ? FYI; I have set-up Facebook App and successfully integrated "Sharing Post on Facebook via Android App". Seems I am quite new on Graph API of Facebook SDK. Thanks. curl https://graph.facebook.com/app/app_link_hosts \ -F access_token="APP_ACCESS_TOKEN" \ -F name="Android App Link Object Example" \ -F android=' [ { "url" : "sharesample://story/1234", "package" : "com.facebook.samples.sharesample", "app_name" : "ShareSample", }, ]' \ -F web=' { "should_fallback" : false, }'

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  • Taking 2 attributes from XElement to create a dictionary LINQ

    - by AndyC
    I'm trying to take one attribute to use as the key, and another to use as the value. If I use (xDoc is an XDocument object in the example): Dictionary<string, XElement> test = xDoc.Descendants() .Where<XElement>(t => t.Name == "someelement") .ToDictionary<XElement, string>(t => t.Attribute("myattr").Value.ToString()); I get a dictionary with the myattr value as key (which is what I want) but the entire XElement object as the value. What I want to do, is to select a second attribute to set as the value property on each dictionary item, but can't seem to figure that out. Is it possible to do all of this in 1 Linq statement? Curiousity has caught me! Cheers!

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  • [dynamic] Different behaviours between .NET 4.0 beta 2 and last release of .NET 4.0 !

    - by yogi4ever
    Hi. I've identified a difference of DLR between .NET 4.0 Beta 2 and the last release of .NET 4.0. In .NET 4.0 Beta 2, this code perfectly works at runtime : var dateTimeList = new List(); dynamic myDynamicObject = dateTimeList; object value = DateTime.Now; myDynamicObject.Add(value); Now, with last release of .NET 4.0, I have an exception at run time (to solve myDynamicObject.Add(value);) :-( In my real code, 'myDynamicObject' is a dynamic (but I know that it is always an ObservableCollection where T can be anything). 'value' is an instance which was got by some reflexions. As 'value' can have any type, the type of 'value' is Object. Do you see how can I solve this new limitation of .NET 4.0 ? Thanks

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  • Ruby - Is there a way to overwrite the __FILE__ variable?

    - by Markus Orrelly
    I'm doing some unit testing, and some of the code is checking to see if files exist based on the relative path of the currently-executing script by using the FILE variable. I'm doing something like this: if File.directory?(File.join(File.dirname(__FILE__),'..','..','directory')) blah blah blah ... else raise "Can't find directory" end I'm trying to find a way to make it fail in the unit tests without doing anything drastic. Being able to overwrite the __ FILE __ variable would be easiest, but as far as I can tell, it's impossible. Any tips?

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