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  • Possible loss of precision / [type] cannot be dereferenced

    - by Samuel
    I have been looking around a lot but i simply can't find a nice solution to this... Point mouse = MouseInfo.getPointerInfo().getLocation(); int dx = (BULLET_SPEED*Math.abs(x - mouse.getX()))/ (Math.abs(y - mouse.getY()) + Math.abs(x - mouse.getX()))* (x - mouse.getX())/Math.abs(x - mouse.getX()); In this constellation i get: Possible loss of precision, when i change e.g (x - mouse.getX()) to (x - mouse.getX()).doubleValue() it says double cannot be dereferenced, when i add intValue() somewhere it says int cannot be dereferenced. What's my mistake? [x, y are integers | BULLET_SPEED is a static final int] Thanks!

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  • Conceptual inheritance implementation

    - by TheSENDER
    Hi there, I'm writing a spatial data structure and I have a doubt about what's the best NODE implementation. According to my design I have an abstract node entity and three classes which inherit from it: EMPTYNODE, FULLNODE, INTERNALNODE. The first one has no particular data. The second one has 1 reference to a generic element. The third one has 2 references to other nodes. I have found several ways to implement this situation (that I have already coded) but I can't decide what's the best. The first solution that I have found is to use a single class Node that potentially performs all the operation in this way: private static class Node { private Elem elem = null; private Node left = null, right = null; public Elem getElem() { assert isFull(); return elem; } public boolean isEmpty() { return elem == null && left == null; } public boolean isFull() { return elem != null; } public boolean isInternal() { return elem == null && left != null; } } The second solution is to write an explicit division by classes where every class offers only its methods. Obviously in this way we are obliged to perform several casts to the node objects. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); } private static class FullNode extends Node{ private ITriangle elem; @Override public boolean isEmpty() { return false; } @Override public final boolean isFull() { return true; } @Override public final boolean isInternal() { return false; } public Elem getElem() { return elem; } } The third one solution is to use the inheritance allowing every classes to offer all the methods, but the object type should by check by "isEmpty()" and similar methods. In case of wrong call we'll throw an exception. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); public abstract Elem getElem(); } private static class Empty extends Node{ @Override public boolean isEmpty() { return true; } @Override public final boolean isFull() { return false; } @Override public final boolean isInternal() { return false; } @Override public Elem getElem() { throw new AssertionError(); } } What do you think about these three solutions? Which one would you use? Any other ideas? Thanks for your help. Every idea will be appreciated.

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  • Maven profile for single module

    - by c0mrade
    I have a multi module maven project, which builds successfully, I'd like to build just one of the modules I have. How would I do that with profiles ? I could do it from console in two ways, one way is go to the child module and mvn package or I could use reactor to build just one module. Can I do the same thing with profiles? By modifying POM? Thank you EDIT If is impossible from POM, can I do it from settings.xml ?

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  • Does GAE/OpenID/OAuth support xmlhttp proxy?

    - by h2g2java
    Currently, my code would construct the GWT form, which user would submit directly to openId (or any authenticaiton service). Such a method works fine. However, what if I had the gwt page server access the OpenID provider, is there a way/strategy for the server to mediate authentication between its client and the auth provider? I wish to know the answers with respect to GAE as the proxy and, regardless if GAE or Tomcat is the intended proxy, answers wrt Google Accounts OpenID OAuth If so, it would be wonderful if someone could describe the installation strategy.

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  • Dynamically add annotation to an existing class

    - by ng
    I have the following class public class Person { ... } I would like to create another class that would look like this. @SomeAnnotation public class Person { ... } Via a simple method like so. public static Class addAnnotation(Class originalType, Class<? extends Annotation> annotation) { // what goes here? } Is there an easy way to do this via ASM for example? What dependencies would I need. I have tried to Google this however the examples I have found are either incomplete or are doing something else. Other frameworks such as javassist would be just as good.

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  • task strategies for handling HardDeadlineExceededError

    - by Stevko
    I've got a number of tasks/servlets that are hitting the HardDeadlineExceededError which is leaving everything hanging in an 'still executing' state. The work being done can easily exceed the 29 second threshold. I try to catch the DeadlineExceededException and base Exception in order to save the exit state but neither of these exception handlers are being caught... Is there a way to determine which tasks are in the queue or currently executing? Are there any other strategies for dealing with this situation?

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  • how to selectively filter items in a collection

    - by Samuel
    I use the following snippet to filter the list of selected users, where isSelected is a boolean variable. Is there a simpler way (helper function) to populate the selectedUsers collection instead of writing the following lines of code. List<User> selectedUsers = new ArrayList<User>(0); for (User user : this.getUsers()) { if (user.isSelected()) { selectedUsers.add(user.getId()); } }

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  • Limiting JMS Destination Instances

    - by jumponadoughnut
    Is it possible to limit the number of JMS receiver instances to a single instance? I.e. only process a single message from a queue at any one time? The reason I ask is because I have a fairly intensive render type process to run for each message (potentially many thousands). I'd like to limit the execution of this code to a single instance at a time. My application server is JBoss AS 6.0 Any help much appreciated

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  • Is there a design pattern to cut down on code duplication when subclassing Activities in Android?

    - by Daniel Lew
    I've got a common task that I do with some Activities - downloading data then displaying it. I've got the downloading part down pat; it is, of course, a little tricky due to the possibility of the user changing the orientation or cancelling the Activity before the download is complete, but the code is there. There is enough code handling these cases such that I don't want to have to copy/paste it to each Activity I have, so I thought to create an abstract subclass Activity itself such that it handles a single background download which then launches a method which fills the page with data. This all works. The issue is that, due to single inheritance, I am forced to recreate the exact same class for any other type of Activity - for example, I use Activity, ListActivity and MapActivity. To use the same technique for all three requires three duplicate classes, except each extends a different Activity. Is there a design pattern that can cut down on the code duplication? As it stands, I have saved much duplication already, but it pains me to see the exact same code in three classes just so that they each subclass a different type of Activity.

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  • Does close ever throw an IOException?

    - by TofuBeer
    After providing some answers here, and reading some comments, it would seem that, in practice IOException is never thrown on close for file I/O. Are there any cases in which calling close on a Stream/Reader/Writer actually throws an IOException? If an exception is actually thrown, how should it be dealt with?

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  • How to find a particular string in a paragraph in android?

    - by user1448108
    In my project the data is stored in html format along with image tag. For example the following data is stored in html format and it contains 2 to 3 images. Mother Teresa as she is commonly known, was born Agnes Gonxha Bojaxhiu. Although born on the 26 August 1910, she considered 27 August, the day she was baptized, to be her "true birthday". “By blood, I am Albanian. By citizenship, an Indian. By faith, I am a Catholic nun. As to my calling, I belong to the world. As to my heart, I belong entirely to the Heart of Jesus." img ----- src="image1.png" ---- Mother Teresa founded the Missionaries of Charity, a Roman Catholic religious congregation, which in 2012 consisted of over 4,500 sisters and is active in 133 countries.img ----- src="image2.png" ----. She was the recipient of numerous honours including the 1979 Nobel Peace Prize. She refused the conventional ceremonial banquet given to laureates, and asked that the $192,000 funds be given to the poor in India. img ----- src="image3.png" ---- Now from the above data I need to find how many images the paragraph has and need to get all the image names along with the extensions and should display them in android. Tried with splitting but did not work. Please help me regarding this. Thanks in advance

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  • What is the correct approach to using GWT with persistent objects?

    - by dankilman
    Hi, I am currently working on a simple web application through Google App engine using GWT. It should be noted that this is my first attempt at such a task. I have run into to following problem/dilema: I have a simple Class (getters/setters and nothing more. For the sake of clarity I will refer to this Class as DataHolder) and I want to make it persistent. To do so I have used JDO which required me to add some annotations and more specifically add a Key field to be used as the primary key. The problem is that using the Key class requires me to import com.google.appengine.api.datastore.Key which is ok on the server side, but then I can't use DataHolder on the client side, because GWT doesn't allow it (as far as I know). So I have created a sister Class ClientDataHolder which is almost identical, though it doesn't have all the JDO annotations nor the Key field. Now this actually works but It feels like I'm doing something wrong. Using this approach would require maintaining to separate classes for each entity I wish to have. So my question is: Is there a better way of doing this? Thank you.

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  • Why do I have to explicitly cast sometimes for varargs?

    - by Daniel Lew
    I've got a Class that uses reflection a lot, so I wrote a method to help out: private <T> T callMethod(String methodName, Class[] parameterTypes, Object[] args) { try { Class c = mVar.getClass(); Method m = c.getMethod(methodName, (Class[]) parameterTypes); return (T) m.invoke(mVar, args); } // Insert exception catching here [...] } This worked well for any method that had parameters, however I had to explicitly cast parameterTypes to Class[] in order for this to work for methods with no parameters (e.g., callMethod('funName', null, null);). I've been trying to figure out why this is the case. It seems to me that if parameterTypes, when null, had no concept of what type it is (Class[]), then I'd need to cast it for getMethod(). But if that's the case, why is getMethod() able to tell the difference between null, and (Class[]) null when the method is invoked?

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  • Dynamically Insert Variables into DB Table using PreparedStatement

    - by gran_profaci
    I was working with PreparedStatement today and noticed that it used setString() setTimestamp() etc. to insert variables into the DB. I basically have 20 tables each with at least 15 columns and it would not be feasible for me to manuallt write down all the setters. Considering that I have an ArrayList "Vals" which contains all the variables to be inputted in String format (obtained by getString() using PreparedStatement itself), is there any way I can do an insert without using expressly using the Setters? That would save me a lot of time.

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  • How to select the specific cell in Jtable?

    - by Nitz
    Hey guys Now in my one jframe i have used two jtables with different data. But now what i want is..as soon as user select one cell on first table, then in second table, the cell next to selected cell of the first table should be selected. means.... if user had selected the cell which is on column - 3 and row - 1 [ first table cell position ] then next table should automatically select the cell at column - 4 and row - 1 [ second table cell position ] i know how to get the selected row and column of jtable but i don't know how to set Select on jtable.

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  • How can I get a project type on Netbeans Platform?

    - by Fabio
    Hi folks, Is there a way to know the type of a selected project? I would like to do some specific actions depending of the project type like a J2SE project. Below is the only way that I found to do that: public final class MyAction extends CookieAction { @Override public boolean isEnabled() { if(this.getActivatedNodes() == null || this.getActivatedNodes().length != 1) { return false; } Lookup lookup = this.getActivatedNodes()[0].getLookup(); // gets the selected project Project currentProject = lookup.lookup(Project.class); // checks if the selected project is a J2SE Project or a Maven Project if(currentProject != null && (currentProject.getClass().getSimpleName().equals("J2SEProject") || currentProject.getClass().getSimpleName().equals("NbMavenProjectImpl"))) { return true; } return false; }}

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  • What is the effect of final variable declaration in methods?

    - by Finbarr
    Classic example of a simple server: class ThreadPerTaskSocketServer { public static void main(String[] args) throws IOException { ServerSocket socket = new ServerSocket(80); while (true) { final Socket connection = socket.accept(); Runnable task = new Runnable() { public void run() { handleRequest(connection); } }; new Thread(task).start(); } } } Why should the Socket be declared as final? Is it because the new Thread that handles the request could refer back to the socket variable in the method and cause some sort of ConcurrentModificationException?

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  • How do I convert jstring to wchar_t *

    - by Obediah Stane
    Let's say that on the C++ side my function takes a variable of type jstring named myString. I can convert it to an ANSI string as follows: const char* ansiString = env-GetStringUTFChars(myString, 0); is there a way of getting const wchar_t* unicodeString = ...

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  • Can you use regular expressions in struts-config.xml?

    - by rquinn
    I'm trying to route these two url's to different Actions. We are using Struts 1.2: /abc-def/products /abc-def I tried putting this action first: <action path="/abc*/products" type="com.business.exampleAction"> <forward name="success" path="/go"/> </action> and then this one after: <action path="/abc*" type="com.business.differentExampleAction"> <forward name="success" path="/goElsewhere"/> </action> but it always goes to the second action (differentExampleAction in this case). I've tried various iterations for the , like . or (.*), but haven't found anything that actually works yet. From what I've read, it seems like the only regular-expression-like characters allowed in struts-config are the wildcard symbols (* and **), but I hope I am wrong.

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  • Prevent duplicate entries in arraylist

    - by timyh
    Say I create some object class like so public class thing { private String name; private Integer num; public oDetails (String a, Integer b) { name = a; num = b; } ...gets/ sets/ etc Now I want to create an arraylist to hold a number of this object class like so. ArrayList<thing> myList = new ArrayList<thing>; thing first = new thing("Star Wars", 3); thing second = new thing("Star Wars", 1); myList.add(first); myList.add(second); I would like to include some sort of logic so that in this case...when we try and add object "second" rather than add a new object to the arrayList, we add second.getNum() to first.getNum(). So if you were to iterate through the ArrayList it would be "Star Wars", 4 I am having trouble coming up with an elegant way of handling this. And as the arraylist grows, searching through it to determine if there are duplicate name items becomes cumbersome. Can anyone provide some guidance on this?

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  • What does assert do?

    - by peiska
    What does assert do? for example in the function? private static int charAt(String s, int d) { assert d >= 0 && d <= s.length(); if (d == s.length()) return -1; return s.charAt(d); }

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