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  • Which Queue implementation to use in Java?

    - by devoured elysium
    I need to use a FIFO structure in my application. It needs to have at most 5 elements. I'd like to have something easy to use (I don't care for concurrency) that implements the Collection interface. I've tried the LinkedList, that seems to come from Queue, but it doesn't seem to allow me to set it's maximum capacity. It feels as if I just want at max 5 elements but try to add 20, it will just keep increasing in size to fit it. I'd like something that'd work the following way: XQueue<Integer> queue = new XQueue<Integer>(5); //where 5 is the maximum number of elements I want in my queue. for (int i = 0; i < 10; ++i) { queue.offer(i); } for (int i = 0; i < 5; ++i) { System.out.println(queue.poll()); } That'd print: 5 6 7 8 9 Thanks

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  • Joining remote paths in Java

    - by Mickael Marrache
    I'm using the FTP library provided by Apache (commons-net). I want to check if a file exists on the FTP server so I use the listFiles method of FTPClient: ftpClient.listFiles(remoteFileDir + "\\" + fileName); The current directory is the FTP server root directory. So, the value of remoteFileDir is a path relative to this root directory. My question concerns the merge between the remote directory path and the file name. What is the right way to do it? For a local file, I would do: File file = new File(remoteFileDir,fileName); but here it doesn't work since when I call file.getAbsolutePath(), I get an absolute path for the file in the local current directory which is not what I want. Also, I guess the merging has been done according to my local environment. PS: I looked at How are paths determined on a remote machines? but it doesn't help me. Thanks

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  • Nothing happen when refreshing the main Frame (JAVA)

    - by Ams
    Hello everyone, I try to show a ( Logged in ) message when a user is succefully connected but nothing happen when a do a repaint(). you can take a look to the code : public class MainFrame extends JFrame implements ActionListener{ private static final long serialVersionUID = 1L; private static final int FRAME_HEIGHT = 400; private static final int FRAME_WIDTH = 250; private static final String TITLE = new String("TweeX"); private static String TWITTERID = new String(); private static String TWITTERPW = new String(); private boolean logged = false; private JTextField loginField = new JTextField(10); private JPasswordField passField = new JPasswordField(10); private JButton login = new JButton("Connect"); private GridBagConstraints c = new GridBagConstraints(); private String UserStatus = new String("Please login..."); /* * Constructor ! */ MainFrame() { setSize(FRAME_WIDTH, FRAME_HEIGHT); setTitle(TITLE); setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); setResizable(false); loginUser(); } /* * Login Forms */ protected void loginUser(){ this.setLayout(new GridBagLayout()); //add Login Fiels + Label c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 0; c.insets = new Insets(5,5,5,20); c.gridy = 0; add(new JLabel("Username:"),c); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 0; add(loginField,c); //add Password Fiels + Label c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 0; c.gridy = 1; add(new JLabel("Password:"),c); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 1; add(passField,c); //add Login button c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 2; add(login,c); //add listener to login button login.addActionListener((ActionListener) this); c.fill = GridBagConstraints.HORIZONTAL; c.gridx = 1; c.gridy = 3; add(new JLabel(UserStatus),c); setVisible(true); } @Override public void actionPerformed(ActionEvent e) { TWITTERID = loginField.getText(); TWITTERPW = passField.getText(); Twitter twitter = new TwitterFactory().getInstance(TWITTERID,TWITTERPW); logged = true; try { twitter.verifyCredentials(); } catch (TwitterException e1) { logged = false; } } protected void connect(){ if(logged){ UserStatus = "Loged In :)"; repaint(); } } static public void main(String[] argv) { new MainFrame(); } }

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  • export a JOGL applet and embedd into a html page

    - by nkint
    hi guys it is some time that i'm testing opengl with java and JOGL. now i have good result and i wanto to pubblish it on web. but i have some problem. i'm in eclipse, and i'm testing an Applet with JOGL. first of all i have this run time error (but the program works correctly): java.lang.IllegalArgumentException: adding a window to a container at java.awt.Container.checkNotAWindow(Container.java:431) at java.awt.Container.addImpl(Container.java:1039) at java.awt.Container.add(Container.java:365) at AppletHelloWorld.init(AppletHelloWorld.java:30) at sun.applet.AppletPanel.run(AppletPanel.java:424) at java.lang.Thread.run(Thread.java:619) then i found this incredibly clear page and i do what is said, i open html with the browser, the libs are downloaded but it stops at "Starting applet AppletHelloWorld" that is the name i gave to my applet. mayebe i miss something like main function or exporting well the jar? this is my main code: public class AppletHelloWorld extends Applet { public static void main(String[] args) { JFrame fr=new JFrame(); fr.setBounds(0,0,1015,600); fr.add(new AppletHelloWorld()); fr.setVisible(true); } public void init() { setLayout(null); MyJOGLProject canvas = new MyJOGLProject(); //MyJOGLProject extends JFrame canvas.run(); Container c = new Container(); c.add(canvas); add(c); } //....

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  • How to mix two arrays in Java?

    - by roddik
    Hello. I have some String[] arrays, for example: ['a1', 'a2'] ['b1', 'b2', 'b3', 'b4'] ['c1'] How can I mix them, so that I get ['a1', 'b1', 'c1', 'a2', 'b2', 'b3', 'b4'] (0 element of a, then b, c, 1 element of a, b, c and so on)? Thanks

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  • Java Programming Homework

    - by user1427476
    Write a program to read in a file containing the names of the employ of a company and store them in an array of Strings named Employ []. Read another file containing the Salaries of each employ written in the same order and store them in another array of integers named salary[] (contents of both files are shown below). Finally create a file stating for example. Mr. XYZ receive $75,500.00 per year (Note that salary is stored as integer but displayed here as double with a comma separating thousands. This formatting needs to be done using DecimalFormat Class)

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  • program for calculating metrics in java

    - by senzacionale
    i need to calculate few metrics (CBO, NOC, DAC, LCOM, WMC, RFC and DIT metric). Program is written in jdeveloper and i do not know how to calculate this metrics. Migration to eclipse is not possible becouse code is not compiled. Does anyone know any good program for calculating metrics?

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  • Java M4A atom tagging free space issue

    - by Brett
    Hey, I've been trying to be able to read and write iTunes style M4A atoms and while I've successfully done the reading part, I've come to a bit of a halt in regards to the free space atoms. I figured that I should be able edit and shift the padding around to accommodate writing an atom with more data than it originally had. I've been stuck on this for about a day now, and I've been trying to figure out how to determine the closest free space atom with enough size to accommodate the new data. so far I have: private freeAtom acquireFreeSpaceAtom( long position ) { long atomStart = Long.MAX_VALUE; freeAtom atom = null; for( freeAtom a : freeSpace ) { if( Math.abs( position - atomStart ) > Math.abs( position - a.getAtomStart() ) ) atomStart = ( atom = a ).getAtomStart(); } return atom; } That code only takes into account the closest free space atom and completely disregards the fact that it should be greater than or equal to a certain size, but I can't quite figure out how I should check for both closeness and size efficiently.

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  • Date conversion in Java

    - by llm
    How can I take a string in a format such as: 2008-06-02 00:00:00.0 and convert it to: 02-Jun-2008? Can I somehow take the original string, convert it to a Date object, then use a formatter to get the final output (rather than parsing the string myself)? Thanks!

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  • Java interface design

    - by Nayn
    Hi, I had an interface initially as below. public interface testMe { public Set<String> doSomething(); } public class A implements testMe { public Set<String> doSomething() { return // Set<String> } } I had similar classes implementing testMe. Now I have to add one more class which returns Set<Some Object> public class X implements testMe() { public Set<Some OBject> doSomething() { } } How could i add this mehtod in the interface without breaking existing classes? Thanks Nayn

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  • Java: Ignoring escapes when parsing XML

    - by Personman
    I'm using a DocumentBuilder to parse XML files. However, the specification for the project requires that within text nodes, strings like " and < be returned literally, and not turned into the corresponding ASCII values. A previous similar question, http://stackoverflow.com/questions/1979785/read-escaped-quote-as-escaped-quote-from-xml, received one answer that seems to be specific to Apache, and another that appears to simply not not do what it says it does. I'd love to be proven wrong on either count, however :) For reference, here is some code: file = new File(fileName); DocBderFac = DocumentBuilderFactory.newInstance(); DocBder = DocBderFac.newDocumentBuilder(); doc = DocBder.parse(file); NodeList textElmntLst = doc.getElementsByTagName(text); Element textElmnt = (Element) textElmntLst.item(0); NodeList txts = textElmnt.getChildNodes(); String txt = ((Node) txts.item(0)).getNodeValue(); System.out.println(txt); I would like that println() to produce things like &quot;3&gt;2&quot; instead of "3>2" which is what currently happens. Thanks!

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  • Most Elegant Way to write isPrime in java

    - by Anantha Kumaran
    public class Prime { public static boolean isPrime1(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } for (int i = 2; i <= Math.sqrt(n) + 1; i++) { if (n % i == 0) { return false; } } return true; } public static boolean isPrime2(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } if (n % 2 == 0) { return false; } for (int i = 3; i <= Math.sqrt(n) + 1; i = i + 2) { if (n % i == 0) { return false; } } return true; } } public class PrimeTest { public PrimeTest() { } @Test public void testIsPrime() throws IllegalArgumentException, IllegalAccessException, InvocationTargetException { Prime prime = new Prime(); TreeMap<Long, String> methodMap = new TreeMap<Long, String>(); for (Method method : Prime.class.getDeclaredMethods()) { long startTime = System.currentTimeMillis(); int primeCount = 0; for (int i = 0; i < 1000000; i++) { if ((Boolean) method.invoke(prime, i)) { primeCount++; } } long endTime = System.currentTimeMillis(); Assert.assertEquals(method.getName() + " failed ", 78498, primeCount); methodMap.put(endTime - startTime, method.getName()); } for (Entry<Long, String> entry : methodMap.entrySet()) { System.out.println(entry.getValue() + " " + entry.getKey() + " Milli seconds "); } } } I am trying to find the fastest way to check whether the given number is prime or not. This is what is finally came up with. Is there any better way than the second implementation(isPrime2).

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  • Java FileFilter

    - by Mr CooL
    public class DocFilter extends FileFilter { public boolean accept(File f) { if (f.isDirectory()) { return true; } String extension = Utils.getExtension(f); if (extension != null) { if (extension.equals(Utils.doc) || extension.equals(Utils.docx) ) { return true; } else { return false; } } return false; } //The description of this filter public String getDescription() { return "Just Document Files"; } } Netbeans compiler warned with the error, "No interface expected here" for above code Anyone has idea what was the problem?? I tried changing the 'extends' to 'implements', however, it didn't seem to work that way. and when I changed to implements, the following code cannot work, chooser.addChoosableFileFilter(new DocFilter()); and with this error, "method addChoosableFileFilter in class javax.swing.JFileChooser cannot be applied to given types required: javax.swing.filechooser.FileFilter" Can anyone help on this? Thanks..

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  • Java language convention; getters/setters

    - by Skogen
    Public class Example { private int number; public Example(int number){ this.number = number; } public int getNumber(){ return number; } public void setNumber(int number){ this.number = number; } public static void main(String[] args){ Example e = new Example(5); What is preffered when accessing a variable within its own class; "e.number" or "e.getNumber()" ?

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  • Selenium Webdriver Java - looking for alternatives for Actions and Robot when performing drag-and-drop

    - by Ja-ke Alconcel
    I first tried Actions class and the drag-and-drop does work on different elements, however it was unable to locate the a specific draggable element on it's exact screen/webpage position. Here's the code I've used: Point loc = driver.findElement(By.id("thiselement")).getLocation(); System.out.println(loc); WebElement drag = driver.findElement(By.id("thiselement")); Actions test = new Actions(driver); test.dragAndDropBy(drag, 0, 60).build().perform(); I checked the element with it's pixel location and it prints (837, -52), which was somewhere on top of the webpage and was pixels away from the actual element. Then I tried using the Robot class and works perfectly fine on my script, but can only provide constant successful runs on a single test machine, running it with a different machine with different screen resolution and screen size will render the script to fail due to the dependency of Robot on the pixel location of the element. The sample code of the Robot script I'm using: Robot dragAndDrop = new Robot(); dragAndDrop.mouseMove(945, 166); //actual pixel location of the draggable element dragAndDrop.mousePress(InputEvent.BUTTON1_MASK); sleep(3000); dragAndDrop.mouseMove(945, 226); dragAndDrop.mouseRelease(InputEvent.BUTTON1_MASK); sleep(3000); Is there any alternative for Actions and Robot to automate drag-and-drop? Or maybe a help on working the script to work on Actions as I really can't use Robot. Thanks in advance.

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  • Require a default constructor in java?

    - by jdc0589
    Is there any way to require that a class have a default (no parameter) constructor, aside from using a reflection check like the following? (the following would work, but it's hacky and reflection is slow) boolean valid = false; for(Constructor<?> c : TParse.class.getConstructors()) { if(c.getParameterTypes().length == 0) { valid = true; break; } } if(!valid) throw new MissingDefaultConstructorException(...);

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  • Java hashcode based on identity

    - by hjfreyer
    The default behavior of Object.hashCode() is to return essentially the "address" of the object so that a.hashCode() == b.hashCode() if and only if a == b. How can I get this behavior in a user-defined class if a superclass already defines hashCode()? For instance: class A { public int hashCode() { return 0; } } class B extends A { public int hashCode() { // Now I want to return a unique hashcode for each object. // In pythonic terms, it'd look something like: return Object.hashCode(this); } } Ideas?

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  • HTML-like GUI Framework in Java

    - by wintermute
    I was recently brought onto a project where we are developing a lot GUI elements for BlackBerry devices. The standard RIM APIs are pretty basic, almost never do what is required and are difficult or impossible to extend, so we end up re-implementing chunks of it. Currently the code we have isn't super organized and factored so there are lots of little tricks that get implemented over and over again. I had a thought about how to aid development efforts on this platform and wanted to see if the community could tell me if I'm still sane or if I've gone totally nuts. By far, the biggest organizational problem I've run into is making sure that each screen is laid out properly with proper padding and such. The current approach is to manually keep track of padding like so: protected void sublayout(int width, int height) { final int padding = 5; int y = padding; int x = padding; layoutChild(_someChild, width - padding * 2, height / 3 - padding * 2); setPositionChild(_someChild, x, y); y += _someChild.getHeight() + padding; // Calculate where to start drawing next. /* ... snipped ... */ } As you can see, positioning elements on a screen is a nightmare due to the tedium. I have investigated other GUI frameworks but, for a variety of reasons, it is difficult to find one that suites our purposes. One potential solution that came to me is to create a GUI framework who's API resembles HTML/CSS. This would allow for things like padding, margins, borders and colours to be handled through a sort of CSS API while the content would be organized using the HTML part of the API. It might look something like this: public class OptionsScreen extends Document { public OptionsScreen() { // You would set the style (like CSS style) through the constructor. Div content = new Div(new Style(new Padding(5), Color.BLACK)); // Then build up a tree of elements which can each have their own style's. // Each element knows how to draw itself, but it doesn't have to worry about // manually handling things like padding. // content.addChild(new P("This is a paragraph", new Style(new Padding(), Color.RED))); Ul list = new Ul(); list.addChild(new Li("item 1")); list.addChild(new Li("item 2")); content.addChild(list); addChild(content); } } I can imagine this making it easier to customize the UI of our app (which is very important) with different fonts, colours and layouts. Does this idea belong on The Daily WTF or do you think there is some promise?

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  • Using 'or' in Java Generics declaration

    - by Shervin
    I have a method that returns an instance of Map<String, List<Foo>> x(); and another method that returns an instance of Map<String, Collection<Foo>> y(); Now if I want to dynamically add one of this Maps in my field, how can I write the generics for it to work? ie: public class Bar { private Map<String, ? extends Collection<Foo>> myMap; public void initializer() { if(notImportant) myMap = x(); //OK else myMap = y(); // !OK (Need cast to (Map<String, ? extends Collection<Foo>>) } Now is it ok that I cast to the signature even though the y() is declared as being Collection? } } If it is not ok to cast, can I somehow write this (Collection OR List) I mean, List is a Collection, so it should somehow be possible. private Map<String, Collection<Foo> | List<Foo>>> myMap;

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  • Java - Make an object collection friendly

    - by DutrowLLC
    If an object holds a unique primary key, what interfaces does it need to implement in order to be collection friendly especially in terms of being efficiently sortable, hashable, etc...? If the primary key is a string, how are these interfaces best implemented? Thanks!

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  • Java creation of new set too slow

    - by Mgccl
    I have this program where it have some recursive function similar to this: lambda(HashSet<Integer> s){ for(int i=0;i<w;i++){ HashSet<Integer> p = (HashSet) s.clone(); p.addAll(get_next_set()); lambda(p); } } What I'm doing is union every set with the set s. And run lambda on each one of the union. I run a profiler and found the c.clone() operation took 100% of the time of my code. Are there any way to speed this up considerably?

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  • Are there any libraries for parsing "number expressions" like 1,2-9,33- in Java

    - by mihi
    Hi, I don't think it is hard, just tedious to write: Some small free (as in beer) library where I can put in a String like 1,2-9,33- and it can tell me whether a given number matches that expression. Just like most programs have in their print range dialogs. Special functions for matching odd or even numbers only, or matching every number that is 2 mod 5 (or something like that) would be nice, but not needed. The only operation I have to perform on this list is whether the range contains a given (nonnegative) integer value; more operations like max/min value (if they exist) or an iterator would be nice, of course. What would be needed that it does not occupy lots of RAM if anyone enters 1-10000000 but the only number I will ever query is 12345 :-) (To implement it, I would parse a list into several (min/max/value/mod) pairs, like 1,10,0,1 for 1-10 or 11,33,1,2 for 1-33odd, or 12,62,2,10 for 12-62/10 (i. e. 12, 22, 32, ..., 62) and then check each number for all the intervals. Open intervals by using Integer.MaxValue etc. If there are no libs, any ideas to do it better/more efficient?)

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  • Date Comparison using Java

    - by Lakshman
    I have two dates: toDate (user input in MM/dd/yyyy format) currentDate (obtained by new Date()) I need to compare the currentDate with toDate. I have to display a report only when the toDate is equal to or more than currentDate. How can I do that?

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