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Search found 1178 results on 48 pages for 'roman ivanov'.

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  • What is the event dispatching thread?

    - by Roman
    I know what "thread" means and if I understand the event dispatching thread (EDT) as "just a thread", it explains a lot but, apparently, it does not explain everything. I do not understand what is special about this thread. For example I do not understand why we should start a GUI in a the EDT? Why the "main" thread is bed for GUI? Well, if we just do not want to occupy the main thread why we cannot start GUI just in "another thread" why it should be some "special" thread called EDT? Then I do not understand why we cannot start the EDT like any other thread? Why we should use some special tool (called invokeLater). And why GUI, unlike any other thread, does not start immediately. We should wait until it is ready to accept our job. Is it because EDT can, potentially execute several task simultaneously? If you decide to answer this question, could you pleas use a really simple terminology because otherwise, I am afraid, I will not be able to understand the answer.

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  • How to check if my string is equal to null?

    - by Roman
    I want to perform some action ONLY IF my string has a meaningful value. So, I tried this. if (!myString.eqauls("")) { doSomething } and this if (!myString.eqauls(null)) { doSomething } and this if ( (!myString.eqauls("")) && (!myString.eqauls(null))) { doSomething } and this if ( (!myString.eqauls("")) && (myString!=null)) { doSomething } and this if ( myString.length()>0) { doSomething } And in all cases my program doSomething in spite on the fact that my string IS EMPTY. It equals to null. So, what is wrong with that?

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  • Samples of Scala and Java code where Scala code looks simpler/has less lines?

    - by Roman
    I need some code samples (and I also really curious about them) of Scala and Java code which show that Scala code is more simple and concise then code written in Java (of course both samples should solve the same problem). If there is only Scala sample with comment like "this is abstract factory in Scala, in Java it will look much more cumbersome" then this is also acceptable. Thanks!

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  • Mysterious different conversion to string[] of seemingly same input data

    - by Roman Kuzmin
    During investigation of some problem I found that the reason was unexpected different conversion to string[] of seemingly same input data. Namely, in the code below two commands both return the same two items File1.txt and File2.txt. But conversion to string[] gives different results, see the comments. Any ideas why is it? This might be a bug. If anybody also thinks so, I’ll submit it. But it would nice to understand what’s going on and avoid traps like that. # *** WARNING # *** Make sure you do not have anything in C:\TEMP\Test # *** The code creates C:\TEMP\Test with File1.txt, File2.txt # Make C:\TEMP\Test and two test files $null = mkdir C:\TEMP\Test -Force 1 | Set-Content C:\TEMP\Test\File1.txt 1 | Set-Content C:\TEMP\Test\File2.txt # This gets just file names [string[]](Get-ChildItem C:\TEMP\Test) # This gets full file paths [string[]](Get-ChildItem C:\TEMP\Test -Include *) # Output: # File1.txt # File2.txt # C:\TEMP\Test\File1.txt # C:\TEMP\Test\File2.txt

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  • Can I have a set containing identical elements?

    - by Roman
    It is convenient for me to use a set. I like how I can "add" ("remove") an element to (from) the set. It is also convenient to check if a given element is in the set. The only problem, I found out that I cannot add a new element to a set if the set has already such an element. Is it possible to have "sets" which can contain several identical elements.

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  • How can I see a variable defined in another php-file?

    - by Roman
    I use the same constant in all my php files. I do not want to assign the value of this variable in all my files. So, I wanted to create one "parameters.php" file and to the assignment there. Then in all other files I include the "parameters.php" and use variables defined in the "parameters.php". It was the idea but it does not work. I also tried to make the variable global. It also does not work. Is there a way to do what I want? Or may be there some alternative approach?

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  • How to create two columns on a web page?

    - by Roman
    I want to have two columns on my web page. For me the simples way to do that is to use a table: <table> <tr> <td> Content of the first column. </td> <td> Content of the second column. </td> </tr> </table> I like this solution because, first of all, it works (it gives exactly what I want), it is also really simple and stable (I will always have two columns, no matter how big is my window). It is easy to control the size and position of the table. However, I know that people do not like the table-layout and, as far as I know, they use div and css instead. So, I would like also to try this approach. Can anybody help me with that? I would like to have a simple solution (without tricks) that is easy to remember. It also needs to be stable (so that it will not accidentally happen that one column is under another one or they overlap or something like that).

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  • best way to write a-> ..->[a] recursive functions in haskell

    - by Roman A. Taycher
    So I keep having this small problem where I have something like func :: a -> b -> [a] -- or basically any a-> ...-> [a] where ... is any types -> func x y = func' [x] y -- as long as they are used to generate a list of [a] from x func' :: [a] -> b -> [a] func = undefined --situation dependant generates a list from each element and returns it as one long list should I keep it like this? should I use func' hidden by a where? should I only use the [a] - b - [a] version and leave the responsibility of passing [variable] to the callee? I might well need to compose these functions and might want to mess around with the order so I'm leaning towards option 3. What do you think?

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  • How do I remove an old JPanel and add a new one?

    - by Roman
    I would like to remove an old JPanel from the Window (JFrame) and add a new one. How should I do it? I tried the following: public static void showGUI() { JFrame frame = new JFrame("Colored Trails"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(partnerSelectionPanel); frame.setSize(600,400); frame.setVisible(true); } private static void updateGUI(final int i, final JLabel label, final JPanel partnerSelectionPanel) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText(i + " seconds left."); } partnerSelectionPanel.setVisible(false); \\ <------------ } ); } So, my code update the "old" JPanel and them it makes the whole JPanel invisible. It was the idea. But it does not work. The compiler complains about the line indicated with "<------------". It writes: <identifier> expected, illegal start of type.

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  • What is the common way to program action listeners?

    - by Roman
    I just started to learn how to use action listeners. To my understanding it works in the following way: There are some classes which contains "addActionListener" method by default (for example classes for buttons). Using this method we add an action listener to an object. For example: listenedObject.addActionListener(listeningObject). When an action with the "listenedObject" is performed, the "actionPerformed" method of the "listeningObject" will be called. So, it means that when we program a class for the listeningObject, we need to put there "actionPerformed" method. What is not clear to me, should we create a new class for every object that we want to listen. It does not seem to me as an elegant solution. On the other hand, if we have one action listener class for all (or at least many) object, than we have a problem since a instance of this class will not know which object is calling the "actionPerformed" method (and we need to know that since actions performed by the actionPerformed differs depending on who is called for this method). In my opinion, for every listened object we need to create are "personal" action listener and we can do it by setting a specific value to the corresponding field of the action listener. But I am not sure that it is a standard way to go? How do usually people do it?

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  • Why Timer does not work if we do not generate a window?

    - by Roman
    Here is the code: import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JFrame; import javax.swing.Timer; public class TimerSample { public static void main(String args[]) { new JFrame().setVisible(true); ActionListener actionListener = new ActionListener() { public void actionPerformed(ActionEvent actionEvent) { System.out.println("Hello World Timer"); } }; Timer timer = new Timer(500, actionListener); timer.start(); } } It generates a window and then periodically prints "Hello World Timer" in the terminal (Command Prompt). If I comment this line new JFrame().setVisible(true); the application do not print anything to the command line. Why?

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  • How to enforce jsf to create new instance of bean instead of throwing NullPointerException?

    - by Roman
    I'm almost sure that I do something wrong and thus the question's title is a bit incorrect. I have a form with several fields for creating a new User-objects (fields like login, password, birthday etc). And I have 2 buttons - Cancel and Create. I didn't finish Create yet :) , but when I press Cancel I see NullPointerException. Here is simplified code: <f:view> <h:form> <h:panelGroup layout="block"> <h:inputText id="add_login" value="#{userSupport.user.login}"/> <h:inputSecret id="add_password" value="#{userSupport.user.password}"/> <h:inputText id="add_name" value="#{userSupport.user.name}"/> <h:inputText id="add_surname" value="#{userSupport.user.surname}"/> <h:commandButton value="Cancel" action="cancel"/> </h:panelGroup> </h:form> </f:view> UserSupport class has field user with getter and setter and some other methods. It's a Spring bean with Session scope. When I press cancel, I see NPE because jsf tries to save values from inputs in user-object, but user-object is null. What is the correct way of doing this?

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  • How can I close a JFrame by click on a button?

    - by Roman
    I would like to have a button in my window such that if I click it (button) the window is closed. I found out that I can close a window in the following way: referenceToTheFrame.hide(); //hides the frame from view refToTheFrame.dispose(); //disposes the frame from memory But if I do this way, compiler complains: Note: myProgram.java uses or overrides a deprecated API Note: Recompile with -Xlint:deprication for details. Do I do something unsafe?

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  • How to update JLabel in Swing?

    - by Roman
    I am trying to use Swing Timer and I wanted to start from a very simple program. I have a window with text: "You have n seconds", where n changes from 10 to 0 every second. I know how to generate a window with text. And I understand how Timer works (it starts an action periodically). But I cannot figure out how to combing this two things. Should I use that: JLabel label = new JLabel(myMessage); and then with timer I need to update the "myMessage" variable? But I think I need to "force" my window to "update" itself (to display a new value stored in "myMessage").

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  • What is good about php/what is php good for?

    - by Roman A. Taycher
    I have often seen php bashed around the webs as a loosely typed(loose typing as in a lot of type coercion and/or easy(and perhaps common) to cast object all over not dynamic typing) language without a great compiler/interpreter/vm, with even the standard library using a number of different naming conventions. A lot of people complain about perl but many (including a lot of the complainers) also give it a lot of credit for its regexes and general flexibility and power. Other then legacy code , giant web frameworks that can do tons(drupal,ect.), and easy cheap hosting what is good about php (,also what criticism are unfair, and how is the language evolving to overcome its problems). Why would i want to learn it? why would I want to do an independent project in it? The main thing I have heard is that its php codes simplicity is sometimes easier then the over-engineered complexity you find in certain Java frameworks and applications. I'm not just trolling, i'm genuinly curious what makes php programmers use it. try to convince me to put it on my languages to dabble in and languages to learn more in depth lists.

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  • Getting all inner classes by reflection

    - by Roman
    I have the following problem. I have this pretty class and now I want to get all the classes that extend that class (inner classes ) and fill 'classList' with it. ( in an automatic way of course ) public abstract class CompoundReference { private static List<Class<? extends CompoundReference>> classList = new ArrayList<Class<? extends CompoundReference>>(); @CompoundKey(gsType = User.class, dbType = UserDetailsMappings.class) public static class CUser extends CompoundReference { } @CompoundKey(gsType = Catalog.class, dbType = CatalogDetailsMappings.class) public static class CCatalog extends CompoundReference { } @CompoundKey(gsType = Product.class, dbType = ProductDetailsMappings.class) public static class CProduct extends CompoundReference { } @CompoundKey(gsType = Category.class) public static class CCategory extends CompoundReference { } @CompoundKey(gsType = Poll.class, dbType = PollDetailsMappings.class) public static class CPoll extends CompoundReference { } // much mroe inner classes Some manual solution would be just to main such a static block , that is something that I dont want to do. static { classList.addAll(Arrays.asList(CUser.class, CCatalog.class, CProduct.class, CCategory.class, CPoll.class, CComment.class, CWebPage.class, CReview.class, CPost.class, CMessage.class, CStory.class,CPicture.class)); }

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  • How to draw a filled circle in Java?

    - by Roman
    I have a JPanel with a Grid Layout. In the "cells" of the grid I can put different elements (for example JButtons). There is no problems with that. But now I want to put a filled circle in some of the cells. I also would like to relate an ActionListener with these circles. In more details, if I click the circle it disappears from the current cell and appears in another one. How can I do it in Java? I am using Swing.

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