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  • JPanel Appears Behind JMenuBar

    - by Matt H
    import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; @SuppressWarnings("serial") public class Main extends JFrame { final int FRAME_HEIGHT = 400; final int FRAME_WIDTH = 400; public static void main(String args[]) { new Main(); } public Main() { super("Game"); GameCanvas canvas = new GameCanvas(); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenuItem startMenuItem = new JMenuItem("Pause"); menuBar.add(fileMenu); fileMenu.add(startMenuItem); super.setVisible(true); super.setSize(FRAME_WIDTH, FRAME_WIDTH); super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); super.setJMenuBar(menuBar); } } import java.awt.Canvas; import java.awt.Graphics; import javax.swing.JPanel; @SuppressWarnings("serial") public class GameCanvas extends JPanel { public void paint(Graphics g) { g.drawString("hI", 0, 0); } } This code causes the string to appear behind the JMenuBar. To see the string, you must draw it at (0,10). I'm sure this must be something simple, so do you guys have any ideas?

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  • Maintaining a pool of DAO Class instances vs doing new operator

    - by Fazal
    we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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  • Is it allowed to load Swing classes in non-EDT thread?

    - by ddimitrov
    After the introduction of Java Memory Model, the Swing guidelines were changed to state that any Swing components need to be instantiated on the EDT in order to avoid non-published instance state. What I could not find anywhere is whether the classloading is also mandated to be on the EDT or can we pre-load key Swing classes in a background thread? Is there any official statement from Sun/Oracle on this? Are there any classes that are known to hold non-threadsafe static state, hence need to be loaded on EDT?

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  • Why I do not see a static variable in a loop?

    - by Roman
    I have a static method which sets a variable: static String[] playersNames; public static void setParameters(String[] players) { playersNames = players; } Then I have a static block: static { JRadioButton option; ButtonGroup group = new ButtonGroup(); // Wright a short explanation of what the user should do. partnerSelectionPanel.add(new JLabel("Pleas select a partner:")); // Generate radio-buttons corresponding to the options available to the player. // Bellow is the problematic line causing the null pointer exception: for (String playerName: playersNames) { final String pn = playerName; option = new JRadioButton(playerName, false); option.addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent evt) { partner = pn; } }); partnerSelectionPanel.add(option); group.add(option); } partnerSelectionPanel.add(label); // Add the "Submit" button to the end of the "form". JButton submitButton = new JButton("Submit"); submitButton.addActionListener(new ActionListener(){ @Override public void actionPerformed(ActionEvent evt) { partnerSelected(); } }); partnerSelectionPanel.add(submitButton); } Compiler does not complain about anything but when I try to execute the code I get problems. In this place SelectPartnerGUI.setParameters(players); I have: Exception in thread "main" java.lang.ExceptionInitializerError. and it is cause by java.lang.NullpointerException at this place for (String playerName: playersNames). Does my program do not see the palyersNames?

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  • struts2 validate

    - by teehoo
    In Struts2 you can change the method used for execution for an action by changing the method attribute in the following line: <action name="registerVal" class="cz.vutbr.fit.pishotel.model.action.Register" method="execute"> Is it possible to change the validation method used as well, or is the validate method name hardcoded.

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  • How to import a class from default package

    - by mykhaylo
    Hi, I am using Eclipse 3.5 and I have created a project with some package structure along with the default package. I have one class in default package - Calculations.java and I want to make the use of that class in any of the package (for instance in com.company.calc). When I try to make the use of the class which is default package, its giving me compile error. Its not able to recognise the class in default package. Where is a problem? Calculations.java - source code public class Calculations{ native public int Calculate(int contextId); native public double GetProgress(int contextId); static { System.loadLibrary("Calc"); } } I can put my class in any other package. This class has some native method which is implemented in Delphi . If I put that class in any of the folder,I will have to make the change that DLL which I want to avoid(really - I can not). Thats why I put my class in the default package.

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  • How can user change the jre parameter values after the exe is generated in Launch4j?

    - by Wing C. Chen
    Is it possible to change the jre parameter values after the exe file is generated through Launch4j? The ideal scenario is like this: The default parameter values are applied when the program is started. However, when the user wants to change some jre parameter values, he goes to a .ini file, MyProgram.ini for example, changes the values there, and the new values will be applied next time the program is started. I think eclipse uses the same way for its memory and some other parameter settings.

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  • Backreferences syntax in replacement strings (why dollar sign?)

    - by polygenelubricants
    In Java, and it seems in a few other languages, backreferences in the pattern is preceded by a slash (e.g. \1, \2, \3, etc), but in a replacement string it's preceded by a dollar sign (e.g. $1, $2, $3, and also $0). Here's a snippet to illustrate: System.out.println( "left-right".replaceAll("(.*)-(.*)", "\\2-\\1") // WRONG!!! ); // prints "2-1" System.out.println( "left-right".replaceAll("(.*)-(.*)", "$2-$1") // CORRECT! ); // prints "right-left" System.out.println( "You want million dollar?!?".replaceAll("(\\w*) dollar", "US\\$ $1") ); // prints "You want US$ million?!?" System.out.println( "You want million dollar?!?".replaceAll("(\\w*) dollar", "US$ \\1") ); // throws IllegalArgumentException: Illegal group reference Questions: Is the use of $ for backreferences in replacement strings unique to Java? If not, what language started it? What flavors use it and what don't? Why is this a good idea? Why not stick to the same pattern syntax? Wouldn't that lead to a more cohesive and an easier to learn language? Wouldn't the syntax be more streamlined if statements 1 and 4 in the above were the "correct" ones instead of 2 and 3?

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  • Why can't I wrap the ServletRequest when trying to capture JSP Output

    - by Patrick Cornelissen
    I am trying to dispatch in a servlet request handler to the JSP processor and capture the content of it. I am providing wrapper instances for the ServletRequest and ServletResponse, they implement the corresponding HTTPServletRequest/-Response interfaces, so they should be drop-in replacements. All methods are currently passed to the original Servlet Request object (I am planning to modify some of them soon). Additionally I have introduced some new methods. (If you want to see the code: http://code.google.com/p/gloudy/source/browse/trunk/gloudyPortal/src/java/org/gloudy/gloudlet/impl/RenderResponseImpl.java) The HttpServletResponse uses it's own output streams to capture the output. When I try to call request.getRequestDispatcher("/WEB-INF/views/test.jsp").include(request, response); With my request and response wrappers the method returns and no content has been captured. When I tried to pass the original request object it worked! But that's not what I need in the long run... request.getRequestDispatcher("/WEB-INF/views/test.jsp").include(request.getServletRequest(), response); This works. getservletRequest() returns the original Request, given by the servlet container. Does anyone know why this is not working with my wrappers?

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  • servlet resopnse data for autocomplete

    - by shams haque
    Hello experts, Following code is in php. i want to do same in java. Please tell me how do i generate this type of array or collection in java. I need this to response to json autocomplete. <?php $q = strtolower($_GET["q"]); if (!$q) return; $items = array( "Peter Pan"=>"[email protected]", "Molly"=>"[email protected]", "Forneria Marconi"=>"[email protected]", "Master Sync"=>"[email protected]", "Dr. Tech de Log"=>"[email protected]", "Don Corleone"=>"[email protected]", "Mc Chick"=>"[email protected]", "Donnie Darko"=>"[email protected]", "Quake The Net"=>"[email protected]", "Dr. Write"=>"[email protected]" ); $result = array(); foreach ($items as $key=>$value) { if (strpos(strtolower($key), $q) !== false) { array_push($result, array( "name" => $key, "to" => $value )); } } echo json_encode($result); ?>

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  • How to shrink-to-fit an std::vector in a memory-efficient way?

    - by dehmann
    I would like to 'shrink-to-fit' an std::vector, to reduce its capacity to its exact size, so that additional memory is freed. The standard trick seems to be the one described here: template< typename T, class Allocator > void shrink_capacity(std::vector<T,Allocator>& v) { std::vector<T,Allocator>(v.begin(),v.end()).swap(v); } The whole point of shrink-to-fit is to save memory, but doesn't this method first create a deep copy and then swaps the instances? So at some point -- when the copy is constructed -- the memory usage is doubled? If that is the case, is there a more memory-friendly method of shrink-to-fit? (In my case the vector is really big and I cannot afford to have both the original plus a copy of it in memory at any time.)

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  • BigInteger.pow(BigInteger) ?

    - by PeterW
    I'm playing with numbers in Java, and want to see how big a number I can make. It is my understanding that BigInteger can hold a number of infinite size, so long as my computer has enough Memory to hold such a number, correct? My problem is that BigInteger.pow accepts only an int, not another BigInteger, which means I can only use a number up to 2,147,483,647 as the exponent. Is it possible to use the BigInteger class as such? BigInteger.pow(BigInteger) Thanks.

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  • Synchronizing screencasting (ffmpeg) and capturing from the webcam (OpenCV)

    - by lyuba
    As from my previous questions, I am trying to build a simple eye tracker. Decided to start from a Linux version (run Ubuntu). To complete this task one should organize screencasting and webcam capturing in such way that frames from both streams exactly match each other and there is the same number of frames in each of them totally. Screencasting fsp fully depends on the camera's fsp, so each time we get the image from the webcam we can potentially grab a screen frame and stay happy. However, all the tools for the fast screencasting, like ffmpeg, for example, return the .avi file as the result and require the fsp already known to be started. From the other side, tools like Java+Robot or ImageMagick seem to require around 20ms to return the .jpg screenshot, which is pretty slow for the task. But they may be requested right after each time the webcam frame is grabbed and provide the needed synchronization. So the sub-questions are: 1. Does the USD camera's frame rate vary during a single session? 2. Are there any tools which provide fast screencasting frame by frame? 3. Is there any way to make ffmpeg push a new frame to the .avi file only when program initiates this request? For my task I may either use C++ or Java. I am, actually, an interface designer, not the driver programmer, and this task seems to be pretty low-level. I would be grateful for any suggestion and tip!

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  • Why setPreferredSize does not change the size of the button?

    - by Roman
    Here is the code: import javax.swing.*; import java.awt.event.*; import java.awt.*; public class TestGrid { public static void main(String[] args) { JFrame frame = new JFrame("Colored Trails"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel mainPanel = new JPanel(); mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS)); JPanel panel = new JPanel(); panel.setLayout(new GridLayout(4, 9)); panel.setMaximumSize(new Dimension(9*30-20,4*30)); JButton btn; for (int i=1; i<=4; i++) { for (int j=1; j<=4; j++) { btn = new JButton(); btn.setPreferredSize(new Dimension(30, 30)); panel.add(btn); } btn = new JButton(); btn.setPreferredSize(new Dimension(30, 10)); panel.add(btn); for (int j=1; j<=4; j++) { btn = new JButton(); btn.setPreferredSize(new Dimension(30, 30)); panel.add(btn); } } mainPanel.add(panel); frame.add(mainPanel); frame.setSize(450,950); frame.setVisible(true); } } I suppose to have a table of buttons with 4 rows and 9 columns. And the middle column should be narrower that other columns. I tried Dimension(30, 10) and Dimension(30, 10) both have no effect on the width of the middle column. Why?

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  • Raw types and subtyping

    - by Dmitrii
    We have generic class SomeClass<T>{ } We can write the line: SomeClass s= new SomeClass<String>(); It's ok, because raw type is supertype for generic type. But SomeClass<String> s= new SomeClass(); is correct to. Why is it correct? I thought that type erasure was before type checking, but it's wrong. From Hacker's Guide to Javac When the Java compiler is invoked with default compile policy it performs the following passes: parse: Reads a set of *.java source files and maps the resulting token sequence into AST-Nodes. enter: Enters symbols for the definitions into the symbol table. process annotations: If Requested, processes annotations found in the specified compilation units. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding. flow: Performs data ow analysis on the trees from the previous step. This includes checks for assignments and reachability. desugar: Rewrites the AST and translates away some syntactic sugar. generate: Generates Source Files or Class Files. Generic is syntax sugar, hence type erasure invoked at 6 pass, after type checking, which invoked at 4 pass. I'm confused.

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  • TreeMap sort by value

    - by vito huang
    I'm new to java, i want to write an comparator to that will let me sort TreeMap by value instead of the default natural sorting. i tried something like this, but can't find out what went wrong: import java.util.*; class treeMap { public static void main(String[] args) { System.out.println("the main"); byValue cmp = new byValue(); Map<String, Integer> map = new TreeMap<String, Integer>(cmp); map.put("de",10); map.put("ab", 20); map.put("a",5); for (Map.Entry<String,Integer> pair: map.entrySet()) { System.out.println(pair.getKey()+":"+pair.getValue()); } } } class byValue implements Comparator<Map.Entry<String,Integer>> { public int compare(Map.Entry<String,Integer> e1, Map.Entry<String,Integer> e2) { if (e1.getValue() < e2.getValue()){ return 1; } else if (e1.getValue() == e2.getValue()) { return 0; } else { return -1; } } } I guess what am i asking is what controls what get pass to comparator function, can i get an Map.Entry pass to comparator?

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  • Search and replace with sed

    - by Binoy Babu
    Last week I accidently externalized all my strings of my eclipse project. I need to revert this and my only hope is sed. I tried to create scripts but failed pathetically because I'm new with sed and this would be a very complicated operation. What I need to do is this: Strings in class.java file is currently in the following format(method) Messages.getString(<key>). Example : if (new File(DataSource.DEFAULT_VS_PATH).exists()) { for (int i = 1; i <= c; i++) { if (!new File(DataSource.DEFAULT_VS_PATH + Messages.getString("VSDataSource.89") + i).exists()) { //$NON-NLS-1$ getnewvfspath = DataSource.DEFAULT_VS_PATH + Messages.getString("VSDataSource.90") + i; //$NON-NLS-1$ break; } } } The key and matching Strings are in messages.properties file in the following format. VSDataSource.92=No of rows in db = VSDataSource.93=Verifying db entry : VSDataSource.94=DB is open VSDataSource.95=DB is closed VSDataSource.96=Invalid db entry for VSDataSource.97=\ removed. So I need the java file back in this format: if (new File(DataSource.DEFAULT_VS_PATH).exists()) { for (int i = 1; i <= c; i++) { if (!new File(DataSource.DEFAULT_VS_PATH + "String 2" + i).exists()) { //$NON-NLS-1$ getnewvfspath = DataSource.DEFAULT_VS_PATH + "String 1" + i; //$NON-NLS-1$ break; } } } How can I accomplish this with sed? Or is there an easier way?

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  • Apache Tuscany 1.6 How do you set the JMS Binding Delivery Mode to NON_PERSISTENT?

    - by Robert Greiner
    I am using Tuscany 1.6 and am trying to set the Delivery Mode JMS Binding to NON_PERSISTENT. I've tried using uri="jms:MyService?deliveryMode=1" (which is what the spec (PDF) says to do) but, I ended up getting the following exception: Unknown token deliveryMode=1 I also tried <headers JMSDeliveryMode="NON_PERSISTENT"/>, although I did not get an exception the messages still got delivered as PERSISTENT. This is the format for the URI jms:<jms-dest>? connectionFactoryName=<Connection-Factory-Name> & destinationType={queue|topic} deliveryMode=<Delivery-Mode> & timeToLive=<Time-To-Live> & priority=<Priority> & <User-Property>=<User-Property-Value> & … This is the example I am using <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" name="MyValueComposite"> <service name="MyValueService"> <interface.java interface="services.myvalue.MyValueService"/> <binding.jms uri="jms:MyValueServiceQueue?activationSpecName=MyValueServiceAS&... "/> </service> <reference name="StockQuoteService"> <interface.java interface="services.stockquote.StockQuoteService"/> <binding.jms uri="jms:StockQuoteServiceQueue?connectionFactoryName=StockQuoteServiceQCF&deliveryMode=1&... "/> </reference> </composite>

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  • How can I work around WinXP using ports 1025-5000 as ephemeral?

    - by Chris Dolan
    If you create a TCP client socket with port 0 instead of a non-zero port, then the operating system chooses any free ephemeral port for you. Most OSes choose ephemeral ports from the IANA dynamic port range of 49152-65535. However in Windows Server 2003 and earlier (including XP) Microsoft used ports 1025-5000 as the ephemeral range, according to their bind() documentation. I run multiple Java services on the same hardware. On rare occasions, this range collides with well-known ports that I use for other services (e.g. port 4160 for Jini discovery). While rare, this has caused real problems. Is there any easy way to tell Windows or Java to use a different port range for client sockets? Microsoft's docs indicate that I can change the high end of that range via the MaxUserPort TcpIP registry setting, but I see no way to change the low end. Update: I've made some progress on this. It looks like Microsoft has a concept of reserved ports that are exceptions to the ephemeral port range. There's a registry setting that lets you change this permanently and apparently there must be an API to do the same thing because there's a data structure that holds high/low values for reserved port ranges, but I can't find the actual function call anywhere... The registry solution may work, but now I'm fixated on this API.

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  • what is the point of heterogenous arrays?

    - by aharon
    I know that more-dynamic-than-Java languages, like Python and Ruby, often allow you to place objects of mixed types in arrays, like so: ["hello", 120, ["world"]] What I don't understand is why you would ever use a feature like this. If I want to store heterogenous data in Java, I'll usually create an object for it. For example, say a User has int ID and String name. While I see that in Python/Ruby/PHP you could do something like this: [["John Smith", 000], ["Smith John", 001], ...] this seems a bit less safe/OO than creating a class User with attributes ID and name and then having your array: [<User: name="John Smith", id=000>, <User: name="Smith John", id=001>, ...] where those <User ...> things represent User objects. Is there reason to use the former over the latter in languages that support it? Or is there some bigger reason to use heterogenous arrays? N.B. I am not talking about arrays that include different objects that all implement the same interface or inherit from the same parent, e.g.: class Square extends Shape class Triangle extends Shape [new Square(), new Triangle()] because that is, to the programmer at least, still a homogenous array as you'll be doing the same thing with each shape (e.g., calling the draw() method), only the methods commonly defined between the two.

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  • Focus behavior in Applet-Javascript interaction

    - by Dan
    I have a web page with an applet that opens a popup window and also makes Javascript calls. When that Javascript call results in a focus() call on an HTML input, that causes the browser window to push itself in front of the applet window. But only on certain browsers, namely MSIE. On Firefox the applet window remains on top. How can I keep that behavior consistent in MSIE? Note that using the old Microsoft VM for Java also achieves the desired (applet window in front) result. HTML code: <html> <head> <script type="text/javascript"> function focusMe() { document.getElementById('mytext').focus(); } </script> </head> <body> <applet id="myapplet" mayscript code="Popup.class" ></applet> <form> <input type="text" id="mytext"> <input type="button" onclick="document.getElementById('myapplet').showPopup()" value="click"> </form> </body> </html> Java code: public class Popup extends Applet { Frame frame; public void start() { frame = new Frame("Test Frame"); frame.setLayout(new BorderLayout()); Button button = new Button("Push Me"); frame.add("Center", button); button.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { frame.setVisible(false); } }); frame.pack(); } public void showPopup() { frame.setVisible(true); JSObject.getWindow(this).eval("focusMe()"); } }

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  • Why isn't componentHidden called for my JPopupMenu?

    - by heycam
    I want to be notified when my JPopupMenu is hidden — whether because an item was selected, the menu was dismissed, or setVisible(false) was called on it. Here is my test code: import javax.swing.*; import java.awt.*; import java.awt.event.*; public class A extends ComponentAdapter implements Runnable, ActionListener { private JButton b; public static void main(String[] args) { EventQueue.invokeLater(new A()); } public void run() { JFrame f = new JFrame("Test"); b = new JButton("Click me"); b.addActionListener(this); f.add(b); f.pack(); f.setVisible(true); } public void actionPerformed(ActionEvent e) { JPopupMenu pm = new JPopupMenu(); pm.addComponentListener(this); pm.add("Popup..."); pm.add("...menu!"); pm.show(b, 10, 10); } public void componentShown(ComponentEvent e) { System.out.println("componentShown"); } public void componentHidden(ComponentEvent e) { System.out.println("componentHidden"); } } Regardless of how I interact with the menu, neither of the two ComponentListener methods are being called. Why is that? Is there different/better/correct way of finding out when my JPopupMenu is hidden? Thanks, Cameron

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  • Default Button after dispose and setVisible

    - by DaDaDom
    Hi, given the following code: public class DialogTest implements ActionListener { public static void main(String[] args) {DialogTest g = new DialogTest();} public DialogTest() { JButton b1 = new JButton("Button A"); b1.addActionListener(this); JDialog d = new JDialog(); d.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE); JPanel p = new JPanel(); p.add(b1); d.add(p); d.getRootPane().setDefaultButton(b1); d.pack(); d.setVisible(true); d.dispose(); d.pack(); d.setVisible(true); } public void actionPerformed(ActionEvent e) {System.out.println("hello");} } Shouldn't pressing the Enter key write something to the console? According to the docs (http://java.sun.com/javase/7/docs/api/java/awt/Window.html#dispose()): The Window and its subcomponents can be made displayable again by rebuilding the native resources with a subsequent call to pack or show. The states of the recreated Window and its subcomponents will be identical to the states of these objects at the point where the Window was disposed Is this intended behaviour?

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