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  • Is there any appreciable difference between if and if-else?

    - by Drew
    Given the following code snippets, is there any appreciable difference? public boolean foo(int input) { if(input > 10) { doStuff(); return true; } if(input == 0) { doOtherStuff(); return true; } return false; } vs. public boolean foo(int input) { if(input > 10) { doStuff(); return true; } else if(input == 0) { doOtherStuff(); return true; } else { return false; } } Or would the single exit principle be better here with this piece of code... public boolean foo(int input) { boolean toBeReturned = false; if(input > 10) { doStuff(); toBeReturned = true; } else if(input == 0) { doOtherStuff(); toBeReturned = true; } return toBeReturned; } Is there any perceptible performance difference? Do you feel one is more or less maintainable/readable than the others?

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  • Listener to prevent System.out display on the screen.

    - by harshit
    Hi, I was doing my academic project and while building and testing i have put many println() statements. But when I had to submit all prints should not be displayed. Can i implement something like listener which will be invoked when System.out is tried to be executed and prevents it from displaying. I dont know how feasible this idea is but just want to know whether its possible or not. I know i could have used a log file or write into a file but again its just a thought came into my mind if I have to disable SOP how can i do it .. thanks

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  • How do I change content of ComboFieldEditor?

    - by fastcodejava
    I want to change the values on one ComboFieldEditor depending on another ComboFieldEditor in an eclipse plugin. E.g. if the user changes the package, different classes need to be populated in the second ComboFieldEditor. The ComboFieldEditor class does not seem to to have a way to change the items on the fly.

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  • GF 3.0.1 + Virtual Server: www.myhost.com:8080/projectname-war => www.myhost.com. How?

    - by Harry Pham
    EDIT I need to change www.myhost.com:8080/myproject-war to www.myhost.com. Here is what I've been trying: I configurate the Virtual Server: server. I have still have default Network Listeners to be http-listener-1 and http-listner-2. I change the Default Web Module to ScholarActive#ScholarActive-war.war (The only option in the drop down list, since I only deploy 1 application). For the docroot, I try this ${com.sun.aas.instanceRoot}/applications/ScholarActive/ScholarActive-war_war or this ${com.sun.aas.instanceRoot}/applications/ScholarActive/ Both does not work. What does docroot need to point to, for this to work? what I try to do is: when I type localhost:8080/ScholarActive-war, then my application load, I want to make so that if I type locahost:8080, it will load the app as well, then what left is changed the port to 80. But no luck. Any Idea?

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  • Reporting on release changes when using JIRA, Ivy and SVN

    - by HaveAGuess
    Hey guys, We have an Ivy release procedure where resolve our dependancies using Ivy pre-tagging which means that we can pull in changes for releases by other members of the team that we are not expecting We want to generate reports and track changes to dependancies between releases but there doesn't seem to be an easy way of doing this without a significant effort. We also want to generate a JIRA list of all changes not only in the main project but in dependancies that we own. This is an extension of the problem above. Otherwise we simply don't know what we are releasing - any ideas?!

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  • OPTICS Clustering algorithm. How to get the best epsilon

    - by Marco Galassi
    I am implementing a project which needs to cluster geographical points. OPTICS algorithm seems to be a very nice solution. It needs just 2 parameters as input(MinPts and Epsilon), which are, respectively, the minimum number of points needed to consider them as a cluster, and the distance value used to compare if two points are in can be placed in same cluster. My problem is that, due to the extreme variety of the points, I can't set a fixed epsilon. Just look at the image below. The same points structure but in a different scale would result very different. Suppose to set MinPts=2 and epsilon = 1Km. On the left, the algorithm would create 2 clusters(red and blue), but on the right it would create one single cluster containing all of the points(red), but I would like to obtain 2 clusters even on the right. So my question is: is there any kind of way to calculate dynamically the epsilon value to get this result? Thank you very much and excuse my for my poor english. Marco

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  • Which text margin does SWT Table use when drawing text?

    - by Zordid
    I got a relatively easy question - but I cannot find anything anywhere to answer it. I use a simple SWT table widget in my application that displays only text in the cells. I got an incremental search feature and want to highlight text snippets in all cells if they match. So when typing "a", all "a"s should be highlighted. To get this, I add an SWT.EraseItem listener to interfere with the background drawing. If the current cell's text contains the search string, I find the positions and calculate relative x-coordinates within the text using event.gc.stringExtent - easy. With that I just draw rectangles "behind" the occurrences. Now, there's a flaw in this. The table does not draw the text without a margin, so my x coordinate does not really match - it is slightly off by a few pixels! But how many?? Where do I retrieve the cell's text margins that table's own drawing will use? No clue. Cannot find anything. :-( Bonus question: the table's draw method also shortens text and adds "..." if it does not fit into the cell. Hmm. My occurrence finder takes the TableItem's text and thus also tries to mark occurrences that are actually not visible because they are consumed by the "...". How do I get the shortened text and not the "real" text within the EraseItem draw handler? Thanks!

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  • Make process run on non EDT (event dispatch thread) thread from EDT

    - by Aly
    I have a method running on the EDT and within that I want to make it execute something on a new (non EDT) thread. My current code is follows: @Override public void actionPerformed(ActionEvent arg0) { //gathering parameters from GUI //below code I want to run in new Thread and then kill this thread/(close the JFrame) new GameInitializer(userName, player, Constants.BLIND_STRUCTURE_FILES.get(blindStructure), handState); }

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  • How to figure out which key was pressed on a BlackBerry

    - by Skrud
    What I want: To know when the user has pressed the button that has the number '2' on it, for example. I don't care whether "Alt" or "Shift" has been pressed. The user has pressed a button, and I want to evaluate whether this button has '2' printed on it. Naturally, if I switch devices this key will change. On a Bold 9700/9500 this is the 'E' key. On a Pearl, this is the 'T'/'Y' key. I've managed to get this working in what appears to be a roundabout way, by looking up the keycode of the '2' character with the ALT button enabled and using Keypad.key() to get the actual button: // figure out which key the '2' is on: final int BUTTON_2_KEY = Keypad.key(KeypadUtil.getKeyCode('2', KeypadListener.STATUS_ALT, KeypadUtil.MODE_EN_LOCALE)); protected boolean keyDown(int keycode, int time) { int key = Keypad.key(keycode); if ( key == BUTTON_2_KEY ) { // do something return true; } return super.keyDown(keycode,time); } I can't help but wonder if there is a better way to do this. I've looked at the constants defined in KeypadListener and Keypad but I can't find any constants mapped to the actual buttons on the device. Would any more experienced BlackBerry devs care to lend a helping hand? Thanks!

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  • Maven: add a dependency to a jar by relative path

    - by flybywire
    I have a proprietary jar that I want to add to my pom as a dependency. But I don't want to add it to a repository. The reason is that I want my usual maven commands such as mvn compile, etc, to work out of the box. (Without demanding from the developers a to add it to some repository by themselves). I want the jar to be in a 3rdparty lib in source control, and link to it by relative path from the pom.xml file. Can this be done? How?

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  • Need help make these classes use Visitor Pattern and generics

    - by Shervin
    Hi. I need help to generify and implement the visitor pattern. We are using tons of instanceof and it is a pain. I am sure it can be modified, but I am not sure how to do it. Basically we have an interface ProcessData public interface ProcessData { public setDelegate(Object delegate); public Object getDelegate(); //I am sure these delegate methods can use generics somehow } Now we have a class ProcessDataGeneric that implements ProcessData public class ProcessDataGeneric implements ProcessData { private Object delegate; public ProcessDataGeneric(Object delegate) { this.delegate = delegate; } } Now a new interface that retrieves the ProcessData interface ProcessDataWrapper { public ProcessData unwrap(); } Now a common abstract class that implements the wrapper so ProcessData can be retrieved @XmlSeeAlso( { ProcessDataMotorferdsel.class,ProcessDataTilskudd.class }) public abstract class ProcessDataCommon implements ProcessDataWrapper { protected ProcessData unwrapped; public ProcessData unwrap() { return unwrapped; } } Now the implementation public class ProcessDataMotorferdsel extends ProcessDataCommon { public ProcessDataMotorferdsel() { unwrapped = new ProcessDataGeneric(this); } } similarly public class ProcessDataTilskudd extends ProcessDataCommon { public ProcessDataTilskudd() { unwrapped = new ProcessDataGeneric(this); } } Now when I use these classes, I always need to do instanceof ProcessDataCommon pdc = null; if(processData.getDelegate() instanceof ProcessDataMotorferdsel) { pdc = (ProcessDataMotorferdsel) processData.getDelegate(); } else if(processData.getDelegate() instanceof ProcessDataTilskudd) { pdc = (ProcessDataTilskudd) processData.getDelegate(); } I know there is a better way to do this, but I have no idea how I can utilize Generics and the Visitor Pattern. Any help is GREATLY appreciated.

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  • I have to select the checkbox two times to check/uncheck in jTable

    - by 117526709403775781607
    I have a jTable code i intend to use, but the problem with it is that when i click on the checkbox once it doesn't select/deselect it, instead i have to click twice. But if i select any other cell in the row except the one containing the checkbox the purpose is solved. HERE IS MY CODE : public class TableSelectionTest extends JFrame implements ListSelectionListener { private final int COLUMN_COUNT = 5; private TblModel model; public TableSelectionTest() { initialize(); setDefaultCloseOperation(EXIT_ON_CLOSE); pack(); } private void initialize() { List data = new ArrayList(); for (int i = 0; i < 10; i++) { Object record[] = new Object[COLUMN_COUNT]; record[0] = Boolean.FALSE; for (int j = 1; j < COLUMN_COUNT; j++) { record[j] = new Integer(j); } data.add(record); } model = new TblModel(data); JTable table = new JTable(model); table.getSelectionModel().setSelectionMode(ListSelectionModel.SINGLE_SELECTION); table.getSelectionModel().addListSelectionListener (this); JScrollPane scroll = new JScrollPane(table); getContentPane().add(scroll, BorderLayout.CENTER); } public static void main(String[] args) { TableSelectionTest f = new TableSelectionTest(); f.show(); } class TblModel extends AbstractTableModel { private List data; public TblModel(List data) { this.data = data; } public int getColumnCount() { return COLUMN_COUNT; } public int getRowCount() { return data == null ? 0 : data.size(); } public void setValueAt(Object value, int rowIndex, int columnIndex) { getRecord(rowIndex)[columnIndex] = value; super.fireTableCellUpdated(rowIndex, columnIndex); } public Object getValueAt(int rowIndex, int columnIndex) { return getRecord(rowIndex)[columnIndex]; } public boolean isCellEditable(int rowIndex, int columnIndex) { if(columnIndex == 0) return true; else return false; } public Class getColumnClass(int columnIndex) { if (data == null || data.size() == 0) { return Object.class; } Object o = getValueAt(0, columnIndex); return o == null ? Object.class : o.getClass(); } private Object[] getRecord(int rowIndex) { return (Object[]) data.get(rowIndex); } } public void valueChanged(ListSelectionEvent e) { if (!e.getValueIsAdjusting()) { ListSelectionModel lsm = (ListSelectionModel) e.getSource(); int index = lsm.getMinSelectionIndex(); if(model.getRecord(index)[0] == Boolean.FALSE) model.setValueAt(Boolean.TRUE, index, 0); else if(model.getRecord(index)[0] == Boolean.TRUE) model.setValueAt(Boolean.FALSE, index, 0); } } } Please reply soon as it is bugging me a lot Thank you in advance :)

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  • What is Problem in Runtime.getruntime which does not open notepad.exe

    - by magh
    when try to execute the servlet containing following code Runtime rt = Runtime.getRuntime(); Process p = rt.exec("notepad.exe"); It doesn't launch the application in the environment windows server 2003 and Tomcat 5 but a process is being created as notepad.exe in the windows task manager. In windows xp and tomcat 6 environment launches the notepad i need to work on the windows server 2003 and tomcat 5 Thanks in advance

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  • Why do InterruptedExceptions clear a thread's interrupted status?

    - by Hanno Fietz
    If a thread is interrupted while inside Object.wait() or Thread.join(), it throws an InterruptedException, which resets the thread's interrupted status. I. e., if I have a loop like this inside a Runnable.run(): while (!this._workerThread.isInterrupted()) { // do something try { synchronized (this) { this.wait(this._waitPeriod); } } catch (InterruptedException e) { if (!this._isStopping()) { this._handleFault(e); } } } the thread will continue to run after calling interrupt(). This means I have to explicitly break out of the loop by checking for my own stop flag in the loop condition, rethrow the exception, or add a break. Now, this is not exactly a problem, since this behaviour is well documented and doesn't prevent me from doing anything the way I want. However, I don't seem to understand the concept behind it: Why is a thread not considered interrupted anymore once the exception has been thrown? A similar behaviour also occurs if you get the interrupted status with interrupted() instead of isInterrupted(), then, too, the thread will only appear interrupted once. Am I doing something unusual here? For example, is it more common to catch the InterruptedException outside the loop? (Even though I'm not exactly a beginner, I tagged this "beginner", because it seems like a very basic question to me, looking at it.)

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  • Enums and Annotations

    - by PeterMmm
    I want to use an Annotation in compile-safe form. To pass the value() to the Annotation i want to use the String representation of an enum. Is there a way to use @A with a value from enum E ? public class T { public enum E { a,b; } // C1: i want this, but it won't compile @A(E.a) void bar() { // C2: no chance, it won't compile @A(E.a.toString()) void bar2() { } // C3: this is ok @A("a"+"b") void bar3() { } // C4: is constant like C3, is'nt it ? @A(""+E.a) void bar4() { } } @interface A { String value(); }

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  • Need help with writing test

    - by London
    I'm trying to write a test for this class its called Receiver : public void get(People person) { if(null != person) { LOG.info("Person with ID " + person.getId() + " received"); processor.process(person); }else{ LOG.info("Person not received abort!"); } } Here is the test : @Test public void testReceivePerson(){ context.checking(new Expectations() {{ receiver.get(person); atLeast(1).of(person).getId(); will(returnValue(String.class)); }}); } Note: receiver is the instance of Receiver class(real not mock), processor is the instance of Processor class(real not mock) which processes the person(mock object of People class). GetId is a String not int method that is not mistake. Test fails : unexpected invocation of person.getId() I'm using jMock any help would be appreciated. As I understood when I call this get method to execute it properly I need to mock person.getId() , and I've been sniping around in circles for a while now any help would be appreciated.

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  • Bytecode and Objects

    - by HH
    Hey everyone, I am working on a bytecode instrumentation project. Currently when handling objects, the verifier throws an error most of the time. So I would like to get things clear concerning rules with objects (I read the JVMS but couldn't find the answer I was looking for): I am instrumenting the NEW instruction: original bytecode NEW <MyClass> DUP INVOKESPECIAL <MyClass.<init>> after instrumentation NEW <MyClass> DUP INVOKESTATIC <Profiler.handleNEW> DUP INVOKESPECIAL <MyClass.<init>> Note that I added a call to Profiler.handleNEW() which takes as argument an object reference (the newly created object). The piece of code above throws a VerificationError. While if I don't add the INVOKESTATIC (leaving only the DUP), it doesn't. So what is the rule that I'm violating? I can duplicate an uninitialized reference but I can't pass it as parameter? I would appreciate any help. Thank you

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  • Why is JavaMail Transport.send() a static method?

    - by skiphoppy
    I'm revising code I did not write that uses JavaMail, and having a little trouble understanding why the JavaMail API is designed the way it is. I have the feeling that if I understood, I could be doing a better job. We call: transport = session.getTransport("smtp"); transport.connect(hostName, port, user, password); So why is Eclipse warning me that this: transport.send(message, message.getAllRecipients()); is a call to a static method? Why am I getting a Transport object and providing settings that are specific to it if I can't use that object to send the message? How does the Transport class even know what server and other settings to use to send the message? It's working fine, which is hard to believe. What if I had instantiated Transport objects for two different servers; how would it know which one to use? In the course of writing this question, I've discovered that I should really be calling: transport.sendMessage(message, message.getAllRecipients()); So what is the purpose of the static Transport.send() method? Is this just poor design, or is there a reason it is this way?

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  • Call the method of base Class which was over ridden

    - by Abhijith Venkata
    I have illustrated my question in this example class Car { public void start(){ System.out.println("Car Started!!!"); } } class Mercedes extends Car { public void start(){ System.out.println("Mercedes Started!!!"); } } Now, in my main program, I write Mercedes m = new Mercedes(); m.start(); It prints: Mercedes Started!!! How do I call the start() method of Car class using the same object so that the output can be Car Started!!!. Edit: Actually It was asked in an interview I attended. I gave the super keyword answer. But the interviewer denied it. He said he'd give me a hint and said Virtual Function. I have no idea how to use that hint.

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  • Unique prime factors using HashSet

    - by theGreenCabbage
    I wrote a method that recursively finds prime factors. Originally, the method simply printed values. I am currently trying to add them to a HashSet to find the unique prime factors. In each of my original print statements, I added a primes.add() in order to add that particular integer into my set. My printed output remains the same, for example, if I put in the integer 24, I get 2*2*2*3. However, as soon as I print the HashSet, the output is simply [2]. public static Set<Integer> primeFactors(int n) { Set<Integer> primes = new HashSet<Integer>(); if(n <= 1) { System.out.print(n); primes.add(n); } else { for(int factor = 2; factor <= n; factor++) { if(n % factor == 0) { System.out.print(factor); primes.add(factor); if(factor < n) { System.out.print('*'); primeFactors(n/factor); } return primes; } } } return primes; } I have tried debugging via putting print statements around every line, but was unable to figure out why my .add() was not adding some values into my HashSet.

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  • Maven - 'all' or 'parent' project for aggregation?

    - by disown
    For educational purposes I have set up a project layout like so (flat in order to suite eclipse better): -product | |-parent |-core |-opt |-all Parent contains an aggregate project with core, opt and all. Core implements the mandatory part of the application. Opt is an optional part. All is supposed to combine core with opt, and has these two modules listed as dependencies. I am now trying to make the following artifacts: product-core.jar product-core-src.jar product-core-with-dependencies.jar product-opt.jar product-opt-src.jar product-opt-with-dependencies.jar product-all.jar product-all-src.jar product-all-with-dependencies.jar Most of them are fairly straightforward to produce. I do have some problem with the aggregating artifacts though. I have managed to make the product-all-src.jar with a custom assembly descriptor in the 'all' module which downloads the sources for all non-transitive deps, and this works fine. This technique also allows me to make the product-all-with-dependencies.jar. I however recently found out that you can use the source:aggregate goal in the source plugin to aggregate sources of the entire aggregate project. This is also true for the javadoc plugin, which also aggregates through the usage of the parent project. So I am torn between my 'all' module approach and ditching the 'all' module and just use the 'parent' module for all aggregation. It feels unclean to have some aggregate artifacts produced in 'parent', and others produced in 'all'. Is there a way of making an 'product-all' jar in the parent project, or to aggregate javadoc in the 'all' project? Or should I just keep both? Thanks

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  • Request attributes in jsf / icefaces behaves strange (survive request end)

    - by hubertg
    I have the following code in a listener method: FacesContext.getCurrentInstance().getExternalContext().getRequestMap().put("time", new Date()); When a button is clicked the following code is executed System.out.println(FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get("time")); One could except that "time" is null when the listener was not executed while processing the current request, but: it seems like the "time" object survives the request processing. So when "time" has been set sometimes in the past it stays there... can anybody explain this? Thanks.

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  • Restore previously serialized JFrame-object, how?

    - by elementz
    Hi all. I have managed to serialize my very basic GUI-object containing a JTextArea and a few buttons to a file 'test.ser'. Now, I would like to completely restore the previously saved state from 'test.ser', but seem to have a misconception of how to properly deserialize an objects state. The class MyFrame creates the JFrame and serializes it. public class MyFrame extends JFrame implements ActionListener { // Fields JTextArea textArea; String title; static MyFrame gui = new MyFrame(); private static final long serialVersionUID = 1125762532137824262L; /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub gui.run(); } // parameterless default contructor public MyFrame() { } // constructor with title public MyFrame(String title) { } // creates Frame and its Layout public void run() { JFrame frame = new JFrame(title); JPanel panel_01 = new JPanel(); JPanel panel_02 = new JPanel(); JTextArea textArea = new JTextArea(20, 22); textArea.setLineWrap(true); JScrollPane scrollPane = new JScrollPane(textArea); scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED); panel_01.add(scrollPane); // Buttons JButton saveButton = new JButton("Save"); saveButton.addActionListener(this); JButton loadButton = new JButton("Load"); loadButton.addActionListener(this); panel_02.add(loadButton); panel_02.add(saveButton); // Layout frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(BorderLayout.CENTER, panel_01); frame.getContentPane().add(BorderLayout.SOUTH, panel_02); frame.setSize(300, 400); frame.setVisible(true); } /* * */ public void serialize() { try { ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("test.ser")); oos.writeObject(gui); oos.close(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } public void actionPerformed(ActionEvent ev) { System.out.println("Action received!"); gui.serialize(); } } Here I try to do the deserialization: public class Deserialize { static Deserialize ds; static MyFrame frame; public static void main(String[] args) { try { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.ser")); frame = (MyFrame) ois.readObject(); ois.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

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  • How do you determine an acceptable response time for App Engine DB requests?

    - by qiq
    According to this discussion of Google App Engine on Hacker News, A DB (read) request takes over 100ms on the datastore. That's insane and unusable for about 90% of applications. How do you determine what is an acceptable response time for a DB read request? I have been using App Engine without noticing any issues with DB responsiveness. But, on the other hand, I'm not sure I would even know what to look for in that regard :)

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