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  • Android Debugging InetAddress.isReachable

    - by badMonkey
    I am trying to figure out how to tell if a particular ipaddress is available in my android app during debugging ( I haven't tried this on an actual device ). From reading it appears that InetAddress.isReachable should do this for me. Initially I thought that I could code something like: InetAddress address = InetAddress.getByAddress( new byte[] { (byte) 192, (byte) 168, (byte) 254, (byte) 10 ); success = address.isReachable( 3000 ); This returns false even though I am reasonably sure it is a reachable address. I found that if I changed this to 127, 0, 0, 1 it returned success. My next attempt was same code, but I used the address I got from a ping of www.google.com ( 72.167.164.64 as of this writing ). No success. So then I tried a further example: int timeout = 2000; InetAddress[] addresses = InetAddress.getAllByName("www.google.com"); for (InetAddress address : addresses) { if ( address.isReachable(timeout)) { success = true; // just set a break point here } } I am relatively new to Java and Android so I suspect I am missing something, but I can't find anything that would indicate what that is.

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  • compareTo and nested Enums

    - by echox
    Hi, in "A Programmers Guide to Java SCJP Certification" I found an example which I can't follow. This the given enum: enum Scale3 { GOOD(Grade.C), BETTER(Grade.B), BEST(Grade.A); enum Grade {A, B, C} private Grade grade; Scale3(Grade grade) { this.grade = grade; } public Grade getGrade() { return grade; } } This is the given expression: Scale3.GOOD.getGrade().compareTo(Scale3.Grade.A) > 0; I don't understand why this expression will be true? The return value will be 2. compareTo() will return a value 0 if the given object is "less" than the object. Scale3.Grade.A is the "biggest" element of Grades, its ordinal number is 0. Scale3.GOOD is the "biggest" element of Scale3, its ordinal number is also 0. The constructor of Scale3 is called with Scale3.Grade.C, which ordinal number is 2. So the given expression is equal to the following code: Scale3.Grade.C.compareTo(Scale3.Grade.A) > 0; A is "bigger" than C, so shouldn't be the result < 0?

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  • Updating Multiple Drop-Down Lists in AjaxTags

    - by Berin
    I'm using AjaxTags as a defined set of JSP tags to facilitate AJAX programming, saving me from some heavy lifting. The project is in trial mode, so I may not adopt the technology and write my own solution. Here's what I'm running into (code abbreviated) I have a drop-down list that defines an item that populates numerous other drop-down lists. <form> ... <select id="item1" name="item1"> <c:forEach items="${list1}" var="item"> <option value="${item}">${item}</option> </c:forEach> </select> <select id="item2" name="items2"></select> <select id="item3" name="items3"></select> ... </form> <ajax:select source="item1" target="item2" baseUrl="${pageContext.request.contextPath}/doAction.view" parameters="action1 = {item}" /> <ajax:select source="item1" target="item3" baseUrl="${pageContext.request.contextPath}/doAction.view" parameters="action2 = {item}" /> The code above works with my back-end, initiating a call to a servlet class that is listening for calls, parses the parameter and takes action based upon the name of the parameter passed. The problem comes from adding the second ajax:select tag above. An action in drop-down "item 1" only causes "item 3" to be populated with new values. What I want is for an action in "item 1" to populate "item 2" and "item 3" (and 4, 5, 6...). Has anyone else used AjaxTags (ajaxtags.sourceforge.net) and solved a similar solution? Environment Details: Tomcat 5.5.27, Spring 2.0.8, Struts 1.2.9, Java 6

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  • Calling an Oracle PL/SQL procedure with Custom Object return types from 0jdbc6 JDBCthin drivers

    - by Andrew Harmel-Law
    I'm writing some JDBC code which calls a Oracle 11g PL/SQL procdedure which has a Custom Object return type. Whenever I try an register my return types, I get either ORA-03115 or PLS-00306 as an error when the statement is executed depending on the type I set. An example is below: PLSQL Code: Procedure GetDataSummary (p_my_key IN KEYS.MY_KEY%TYPE, p_recordset OUT data_summary_tab, p_status OUT VARCHAR2); Java Code: String query = "beginmanageroleviewdata.getdatasummary(?, ?, ?); end;"); CallableStatement stmt = conn.prepareCall(query); stmt.setInt(1, 83); stmt.registerOutParameter(2, OracleTypes.CURSOR); // Causes error: PLS-00306 stmt.registerOutParameter(3, OracleTypes.VARCHAR); stmt.execute(stmt); // Error mentioned above thrown here. Can anyone provide me with an example showing how I can do this? I guess it's possible. However I can't see a rowset OracleType. CURSOR, REF, DATALINK, and more fail. Apologies if this is a dumb question. I'm not a PL/SQL expert and may have used the wrong terminology in some areas of my question. (If so, please edit me). Thanks in advance. Regs, Andrew

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  • Distributed Lock Service over MySql/GigaSpaces/Netapp

    - by ripper234
    Disclaimer: I already asked this question, but without the deployment requirement. I got an answer that got 3 upvotes, and when I edited the question to include the deployment requirement the answer then became irrelevant. The reason I'm resubmitting is because SO considers the original question 'answered', even though I got no meaningful upvoted answer. I opened a uservoice submission about this problem. The reason I reposted is so StackOverflow consider the original question answered, so it doesn't show up on the 'unanswered questions' tab. Which distributed lock service would you use? Requirements are: A mutual exclusion (lock) that can be seen from different processes/machines lock...release semantics Automatic lock release after a certain timeout - if lock holder dies, it will automatically be freed after X seconds Java implementation Easy deployment - must not require complicated deployment beyond either Netapp, MySql or GigaSpaces. Must play well with those products (especially GigaSpaces - this is why TerraCotta was ruled out). Nice to have: .Net implementation If it's free: Deadlock detection / mitigation I'm not interested in answers like "it can be done over a database", or "it can be done over JavaSpaces" - I know. Relevant answers should only contain a ready, out-of-the-box, proven implementation.

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  • Correct Interactive Website System Design Concepts / Methods?

    - by Xandel
    Hi all, I hope this question isn't too open ended, but a nudge in the right direction is all I need! I am currently building an online accounting system - the idea is that users can register, log in, and then create customers, generate invoices and other documents and eventually print / email those documents out. I am a Java programmer but unfortunately haven't had too much experience in web projects and their design concepts... This is what I have got thus far - A Tomcat web server which loads Spring. Spring handles my DAO's and required classes for the business logic. Tomcat serves JSP's containing the pages which make up the website. To make it interactive I have used JavaScript in the pages (jQuery and its AJAX calls) to send and receive JSON data (this is done by posting to a page which calls a handleAction() method in one of my classes). My question is, am I tackling this project in the right way? Am I using the right tools and methods? I understand there are literally countless ways of tackling any project but I would really love to get feedback with regards to tried and tested methods, general practices etc. Thanks in advance! Xandel

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  • resource-ref at application scope in EJB 2.1 Project

    - by Mike Deck
    Is it possible to define resource references that are applicable to all EJBs in an application? Currently I have an ejb-jar.xml that looks something like this: <ejb-jar> <enterprise-beans> <session id="foo"> <!-- snip --> <resource-ref> <res-ref-name>jdbc/myDatasource</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref> </session> <session id="bar"> <!-- snip --> <resource-ref> <res-ref-name>jdbc/myDatasource</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref> </session> </enterprise-beans> </ejb-jar> You'll notice that both EJBs have the same resource-ref defined for both of them. Is there a way to factor this duplication out within a J2EE 1.4 application? Ideally I should be able to define the jdbc/myDatasource resource once within the application and have anything running inside that container be able to access it by doing a JNDI lookup for "java:comp/env/jdbc/myDatasource". Is there any way to accomplish this?

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  • Dymanic if statement evaluation problem with string comparison

    - by Mani
    I tried the example given in http://forums.sun.com/thread.jspa?threadID=780576&tstart=67605 to create if statement dynamically. But it is not working fine. Instead of using "age" variable as integer, i have used string in the below example. I am getting "fail" as answer instead of "success". Can anyone help me? / To change this template, choose Tools | Templates and open the template in the editor. / import java.lang.reflect.*; import bsh.Interpreter; public class Main { public static String d; public static void main(String args[]) { try { String age = "30"; String cond = "age==30"; Interpreter i = new Interpreter(); i.set("age", age); System.out.println(" sss" + i.get("age")); if((Boolean)i.eval(cond)) { System.out.println("success"); } else { System.out.println("fail"); } } catch (Throwable e) { System.err.println(e); } } } Thanks, Mani

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  • org.hibernate.NonUniqueObjectException Within GWT application using hibernate through gilead

    - by molleman
    Hello Guys, i am working on a project for college that uses GWT,Hibernate and Gilead. Basically for the moment users should be able to add friends and remove them. also a user can see if his or her friends are online or not. my trouble is that when i add a friend that is already related to another friend i get this error org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.example.client.YFUser#4] i have a service class public class TestServiceImpl extends PersistentRemoteService implements TestService { this is my service class for my gwt application. my toruble is here with my implmentation class of my serivce in this method that is called when a user presses add friend button on the client-side public void addYFUserFriend(String userName){ //this retrieves the current user YFUser user = (YFUser)getSession().getAttribute(SESSION_USER); Session session = com.example.server.HibernateUtil.getSessionFactory().getCurrentSession(); session.beginTransaction(); YFUser friend = (YFUser) session.createQuery("select u FROM YFUser u where u.username = :username").setParameter("username", userName).uniqueResult(); System.out.println("user " + friend.getUsername() + " Found"); user.getFriends().add(friend); friend.getBefriended().add(user); session.update(user); session.update(friend); session.getTransaction().commit(); } a scenerio : user1 adds user2 as a friend. this works fine. then user3 adds user2 and the exeception is thrown. any ideas why and where my logic is going wrong Ok so i have changed my code, and i have removed all the getCurrentASession() calls and replaced with openSession() call which are closed at the appropiate point, now the error i am getting is com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract void com.example.client.TestService.addYFUserFriend(java.lang.String)' threw an unexpected exception: org.hibernate.NonUniqueResultException: query did not return a unique result: 3

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  • What is the correct way to handle object which is instance of class in apache.xerces?

    - by Roman
    Preface: I'm working on docx parser for java. docx format is based on xml. When I read document its parts are being unmarshalled (with JAXB). And I get a tree of certain elements based on xml markup. Almost problem: But some elements (which are at very deep xml level) returned not as certain class from docx spec (i.e. CTStyle, CTDrawing, CTInline etc) but as Object. Those objects are indeed instances of xerces classes, e.g. ElementNSImpl. Problem: How should I handle these objects. The simplest approach is: CTGraphicData gData = getGraphicData (); Object obj = gData.getAny().get(0); ElementNSImpl element = (ElementNSImpl)obj; But it doesn't seem to be a good solution. I've never worked with xerces directly. What is the better way to do this casting? (If anyone also give me a tip about right way to iterate through nodes it would be great).

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  • Google Web Toolkit Asynchronous Call from a Service Implementation

    - by Thor Thurn
    I'm writing a simple Google Web Toolkit service which acts as a proxy, which will basically exist to allow the client to make a POST to a different server. The client essentially uses this service to request an HTTP call. The service has only one asynchronous method call, called ajax(), which should just forward the server response. My code for implementing the call looks like this: class ProxyServiceImpl extends RemoteServiceServlet implements ProxyService { @Override public Response ajax(String data) { RequestBuilder rb = /*make a request builder*/ RequestCallback rc = new RequestCallback() { @Override public void onResponseReceived(Response response) { /* Forward this response back to the client as the return value of the ajax method... somehow... */ } }; rb.sendRequest(data, requestCallback); return /* The response above... except I can't */; } } You can see the basic form of my problem, of course. The ajax() method is used asynchronously, but GWT decides to be smart and hide that from the dumb old developer, so they can just write normal Java code without callbacks. GWT services basically just do magic instead of accepting a callback parameter. The trouble arises, then, because GWT is hiding the callback object from me. I'm trying to make my own asynchronous call from the service implementation, but I can't, because GWT services assume that you behave synchronously in service implementations. How can I work around this and make an asynchronous call from my service method implementation?

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  • facebook: can't send email from app to user

    - by flybywire
    I can't send email to my app users, even though I have the permissions. I am working with the java library, although I don't think it is related to that. long uid = ...; Collection<Long> uids = new ArrayList<Long>(); uids.add(uid); FacebookXmlRestClient client = new FacebookXmlRestClient(api, secret); boolean sendEmailPerm = client.users_hasAppPermission(Permission.EMAIL,uid); System.out.println("Can send email: "+ sendEmailPerm); Collection<String> sent = client.notifications_sendTextEmail(uids, "subject", "body"); System.out.println("Succesfully sent email to: "+sent); sent = client.notifications_sendFbmlEmail(uids, "subject", "body"); System.out.println("Succesfully sent email to: "+sent); I am trying both with fbml and text email. I can also obtain the user's proxied_email property but when I send email to that address with my regular mail client is doesn't arrive. The output is: Can send email: true Succesfully sent email to: [] Succesfully sent email to: []

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  • Looking for a good dev environment for OSGi bundles

    - by Riduidel
    Hi, I'm currently investigating in the field of dev environment for OSGi bundles. My goal is to find a way to develop, test and debug with ease the bundles I'll be coding. Besides, I have some "cultural" requirements. I want to be able to use java continuous integration servers (typically, Hudson) As a consequence of that first requirement, I want to have a repeatable, one-click build process. My typical tool for that is maven. And finally, being long-term Eclipse user, and having the m2eclipse at hand to merge my eclipse env with my maven one, I obviously want to be able to test and debug with that IDE. So far, here are the infos I know I can use (and have already tested) maven-bundle-plugin, maven-ipojo-plugin which both offer clean packaging facilities I have tested maven pax (and eclipse pax) and am not really satisfied with both : maven pax generates a very heavy project, where adding dependencies is very error-prone (the maven pax:import-bundle command line, with all its arguments, is a hell per se) I have taken a look at Karaf, which seems to have some nice direct maven provisionning, but I don't know how to integrate it with my Eclipse, besides using the traditionnal JPDA bridge. However, it seems to be more production-oriented than dev-oriented, and as such may require heavy configuration to fit my need (although the reading of its user manual doesn't revedal that). Have you got any ideas ? Some maven/eclipse plugins ?

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  • Handling Special char such as ^ÛY, ^ÛR in java

    - by RJ
    Hi, Has anybody encountered special char such as ^ÛY, ^ÛR ? Q1. How do I do an ftp of the files containing these chars? The chars are not seen once I do a ftp on AIX (bi or ascii) and hence I am unable to see my program to replace these, working. Q2. My java program doesn't seem to recognise these or replace these if I search for these explicitly (^ÛY, ^ÛR ) in the file however a replace using regular expression seems to work (I could only see the difference in the length of the string). My program is executed on AIX. Any insights why java cannot recognise these? Q3. Does the Oracle database recognise these chars? An update is failing where my program indicates the string to be of lesser length and without these characters but the db complains "value too large for column" as the string to be updated contains these chars and hence longer. thanks in advance, RJ

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  • GUI for generating XML

    - by Kenston
    Hello. Does anybody know of GUIs for generating XMLs? This means the user will not be presented with an IDE with support for XML for him to type XML codes. This would be helpful for non-technical people using the system. I know this sounds easy, given many libraries that can help in generating XMLs. The issue here is that the schema is really that flexible rather than being straightforward like representing books in a library with their properties. Imagine HTML, where we can create font tags inside a body, a table, a div, or nested even within itself. The solution is a WYSIWYG application that allows user to generate html codes (XML). However, that is good for XML applied in webpages since they involve visual aspect and design. My application of XML would focus on representing some conceptual and computational definitions, much like sql-like syntax, but more than that. I'm actually after the approach or previous works done or tried, although having a library/working framework for that would be better. Btw, I'm using Java for this project. Currently, I'm just thinking of presenting element tags where user will be able to drag and drop them and nest them with each other. And perhaps, assist them through a forms in inputing values for XML attributes. I'm still hoping if there are better ideas from the community. Thank you.

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  • Why this method does not use any properties of the object?

    - by Roman
    Here I found this code: import java.awt.*; import javax.swing.*; public class FunWithPanels extends JFrame { public static void main(String[] args) { FunWithPanels frame = new FunWithPanels(); frame.doSomething(); } void doSomething() { Container c = getContentPane(); JPanel p1 = new JPanel(); p1.setLayout(new BorderLayout()); p1.add(new JButton("A"), BorderLayout.NORTH); p1.add(new JButton("B"), BorderLayout.WEST); JPanel p2 = new JPanel(); p2.setLayout(new GridLayout(3, 2)); p2.add(new JButton("F")); p2.add(new JButton("G")); p2.add(new JButton("H")); p2.add(new JButton("I")); p2.add(new JButton("J")); p2.add(new JButton("K")); JPanel p3 = new JPanel(); p3.setLayout(new BoxLayout(p3, BoxLayout.Y_AXIS)); p3.add(new JButton("L")); p3.add(new JButton("M")); p3.add(new JButton("N")); p3.add(new JButton("O")); p3.add(new JButton("P")); c.setLayout(new BorderLayout()); c.add(p1, BorderLayout.CENTER); c.add(p2, BorderLayout.SOUTH); c.add(p3, BorderLayout.EAST); pack(); setVisible(true); } } I do not understand how "doSomething" use the fact that "frame" is an instance of the class JFrame. It is not clear to me because there is no reference to "this" in the code for the method "doSomething".

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  • Xpath: Selecting all of an element type?

    - by Johannes
    I'm just starting to learn Xpath, I'm trying to write a line of code that will select all of the actors in EACH movie parent (through Java!). Below, I have an example of one movie, but there are multiple <Movie> elements, each with <Actor> elements. <Movie Genre = 'Other'> <Title>Requiem For A Dream</Title> <ReleaseYear>2000</ReleaseYear> <Director>Darren Aronofsky</Director> <Actor Character = 'Sara Goldfarb'>Ellen Burstyn</Actor> <Actor Character = 'Harry Goldfarb'>Jared Leto</Actor> <Actor Character = 'Marion Silver'>Jennifer Connelly</Actor> <Actor Character = 'Tyrone C. Love'>Marlon Wayans</Actor> </Movie> Currently, I can only select the first <Actor> element of each <Movie> element -- is it possible to select all of them without using a for loop? Here is my current line of code that displays the first <Actor> element of every <Movie> element: System.out.println("Starring: " + xpath.evaluate("Actor", movieNode) + " as " + xpath.evaluate("Actor/@Character", movieNode) + "\n"); Any and all help if much appreciated!

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  • Scala wont pattern match with java.lang.String and Case Class

    - by Stefan
    Hello fellow Scala Programmers I have been working with Scala for some month now, however I have a problem with some properly basic stuff, I am hoping you will help my out with it. case class PersonClass(name: String, age: Int) object CaseTester { def main(args:Array[String]) { val string = "hej" string match { case e:String => println(string) case PersonClass => println(string) } } } When I am doing like this I get error: pattern type is incompatible with expected type; found : object PersonClass required: java.lang.String case PersonClass = println(string) And if I then change the second line in the pattern matching to the following: case e:PersonClass => println(string) I then get the error: error: scrutinee is incompatible with pattern type; found : PersonClass required: java.lang.String case e:PersonClass = println(string) However if I change the string definition to the following it compiles fine in both cases. val string:AnyRef = "hej"

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  • GC output clarification

    - by elec
    I'm running a java application with the following settings: -XX:+CMSParallelRemarkEnabled -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution I'm not sure how to interpret the related gc logs(below). In particular: Heap after GC invocations=31 (full 3): does this mean there were 31 minor GCs, and 3 full GCs ? What triggers the several consecutive lines of Total time for which the application threads were stopped and Application Time ? Is it possible to get the time stamps associated with each of these lines ? GC logs: Total time for which application threads were stopped: 0.0046910 seconds Application time: 0.7946670 seconds Total time for which application threads were stopped: 0.0002900 seconds Application time: 1.0153640 seconds Total time for which application threads were stopped: 0.0002780 seconds Application time: 1.0161890 seconds Total time for which application threads were stopped: 0.0002760 seconds Application time: 1.0145990 seconds Total time for which application threads were stopped: 0.0002950 seconds Application time: 0.9999800 seconds Total time for which application threads were stopped: 0.0002770 seconds Application time: 1.0151640 seconds Total time for which application threads were stopped: 0.0002730 seconds Application time: 0.9996590 seconds Total time for which application threads were stopped: 0.0002880 seconds Application time: 0.9624290 seconds {Heap before GC invocations=30 (full 3): par new generation total 131008K, used 130944K [0x00000000eac00000, 0x00000000f2c00000, 0x00000000f2c00000) eden space 130944K, 100% used [0x00000000eac00000, 0x00000000f2be0000, 0x00000000f2be0000) from space 64K, 0% used [0x00000000f2bf0000, 0x00000000f2bf0000, 0x00000000f2c00000) to space 64K, 0% used [0x00000000f2be0000, 0x00000000f2be0000, 0x00000000f2bf0000) concurrent mark-sweep generation total 131072K, used 48348K [0x00000000f2c00000, 0x00000000fac00000, 0x00000000fac00000) concurrent-mark-sweep perm gen total 30000K, used 19518K [0x00000000fac00000, 0x00000000fc94c000, 0x0000000100000000) 2010-05-11T09:30:13.888+0100: 384.955: [GC 384.955: [ParNew Desired survivor size 32768 bytes, new threshold 0 (max 0) : 130944K-0K(131008K), 0.0052470 secs] 179292K-48549K(262080K), 0.0053030 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] Heap after GC invocations=31 (full 3): par new generation total 131008K, used 0K [0x00000000eac00000, 0x00000000f2c00000, 0x00000000f2c00000) eden space 130944K, 0% used [0x00000000eac00000, 0x00000000eac00000, 0x00000000f2be0000) from space 64K, 0% used [0x00000000f2be0000, 0x00000000f2be0000, 0x00000000f2bf0000) to space 64K, 0% used [0x00000000f2bf0000, 0x00000000f2bf0000, 0x00000000f2c00000) concurrent mark-sweep generation total 131072K, used 48549K [0x00000000f2c00000, 0x00000000fac00000, 0x00000000fac00000) concurrent-mark-sweep perm gen total 30000K, used 19518K [0x00000000fac00000, 0x00000000fc94c000, 0x0000000100000000) } Total time for which application threads were stopped: 0.0056410 seconds Application time: 0.0475220 seconds Total time for which application threads were stopped: 0.0001800 seconds Application time: 1.0174830 seconds Total time for which application threads were stopped: 0.0003820 seconds Application time: 1.0126350 seconds Total time for which application threads were stopped: 0.0002750 seconds Application time: 1.0155910 seconds Total time for which application threads were stopped: 0.0002680 seconds Application time: 1.0155580 seconds Total time for which application threads were stopped: 0.0002880 seconds Application time: 1.0155480 seconds Total time for which application threads were stopped: 0.0002970 seconds Application time: 0.9896810 seconds

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  • Lazy non-modifiable list

    - by mindas
    I was looking for a decent implementation of a generic lazy non-modifiable list implementation to wrap my search result entries. The unmodifiable part of the task is easy as it can be achieved by Collections.unmodifiableList() so I only need to sort out the the lazy part. Surprisingly, google-collections doesn't have anything to offer; while LazyList from Apache Commons Collections does not support generics. I have found an attempt to build something on top of google-collections but it seems to be incomplete (e.g. does not support size()), outdated (does not compile with 1.0 final) and requiring some external classes, but could be used as a good starting point to build my own class. Is anybody aware of any good implementation of a LazyList? If not, which option do you think is better: write my own implementation, based on google-collections ForwardingList, similar to what Peter Maas did; write my own wrapper around Commons Collections LazyList (the wrapper would only add generics so I don't have to cast everywhere but only in the wrapper itself); just write something on top of java.util.AbstractList; Any other suggestions are welcome.

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  • Detecting Singularities in a Graph

    - by nasufara
    I am creating a graphing calculator in Java as a project for my programming class. There are two main components to this calculator: the graph itself, which draws the line(s), and the equation evaluator, which takes in an equation as a String and... well, evaluates it. To create the line, I create a Path2D.Double instance, and loop through the points on the line. To do this, I calculate as many points as the graph is wide (e.g. if the graph itself is 500px wide, I calculate 500 points), and then scale it to the window of the graph. Now, this works perfectly for most any line. However, it does not when dealing with singularities. If, when calculating points, the graph encounters a domain error (such as 1/0), the graph closes the shape in the Path2D.Double instance and starts a new line, so that the line looks mathematically correct. Example: However, because of the way it scales, sometimes it is rendered correctly, sometimes it isn't. When it isn't, the actual asymptotic line is shown, because within those 500 points, it skipped over x = 2.0 in the equation 1 / (x-2), and only did x = 1.98 and x = 2.04, which are perfectly valid in that equation. Example: In that case, I increased the window on the left and right one unit each. My question is: Is there a way to deal with singularities using this method of scaling so that the resulting line looks mathematically correct? I myself have thought of implementing a binary search-esque method, where, if it finds that it calculates one point, and then the next point is wildly far away from the last point, it searches in between those points for a domain error. I had trouble figuring out how to make it work in practice, however. Thank you for any help you may give!

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  • java.util.Map with HtmlDataTable

    - by gerry
    Hi, I'm developing an application on GlassFish v3 which uses Suns-RI of JavaEE6 and JSF2.0, etc. And the bad thing is, that no changes/switches away from Suns RI can be made (to use MyFaces or something like that). Now, the problem is, that I want to build HtmlDatatable by hand ( in Java code). The datatable should represent a java.util.Map where the first column should display the key and the second the values of the map. I've build successfully a PanelGrid from a java.util.List and used every time the "setExpressionValue" methods of UIComponent to bind the UI to the underlying List. But now, this doesn't work with the Map. Here is a snippet of my code: public HtmlDataTable getEntityDetailsDataTable() { ... Application app = FacesContext.getCurrentInstance().getApplication(); HtmlDataTable component = (HtmlDataTable)app.createComponent(HtmlDataTable.COMPONENT_TYPE); component.setValueExpression("value", ExpressionUtil.createValueExpression("#{entityTree.entity."+fieldName+".entrySet()}", Map.class)); component.setVar("param"); UIColumn column = new UIColumn(); UIOutput label1 = DynamicHtmlComponentCreator.createHtmlOutputText("#{param[key]}", String.class); column.getChildren().add(label1); UIOutput label2 = DynamicHtmlComponentCreator.createHtmlOutputText("#{param[value]}", String.class); column.getChildren().add(label2); component.getChildren().add(column); ... return component; } component.getChildren().add(column); ... return component; } So, further the problem is, that this code only prints out the content of the Map, on another page I need the values displayed in HtmlInputText elements and the whole map updated if the user clicks a i.e. "Save" button. So, further the problem is, that this code only prints out the content of the Map, on another page I need the values displayed in HtmlInputText elements and the whole map updated if the user clicks a i.e. "Save" button. If there is a workaround, to represent the Map as to Lists...please help me, because for this (map as 2 lists) I've no idea how the underlying map/database model can be updated again. Hopefully, someone can help me....

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  • XMLStreamReader and a real stream

    - by Yuri Ushakov
    Update There is no ready XML parser in Java community which can do NIO and XML parsing. This is the closest I found, and it's incomplete: http://wiki.fasterxml.com/AaltoHome I have the following code: InputStream input = ...; XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance(); XMLStreamReader streamReader = xmlInputFactory.createXMLStreamReader(input, "UTF-8"); Question is, why does the method #createXMLStreamReader() expects to have an entire XML document in the input stream? Why is it called a "stream reader", if it can't seem to process a portion of XML data? For example, if I feed: <root> <child> to it, it would tell me I'm missing the closing tags. Even before I begin iterating the stream reader itself. I suspect that I just don't know how to use a XMLStreamReader properly. I should be able to supply it with data by pieces, right? I need it because I'm processing a XML stream coming in from network socket, and don't want to load the whole source text into memory. Thank you for help, Yuri.

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  • Hibernate and parent/child relations

    - by Marco
    Hi to all, I'm using Hibernate in a Java application, and i feel that something could be done better for the management of parent/child relationships. I've a complex set of entities, that have some kind of relationships between them (one-to-many, many-to-many, one-to-one, both unidirectional and bidirectional). Every time an entity is saved and it has a parent, to estabilish the relationship the parent has to add the child to its collection (considering a one-to-may relationship). For example: Parent p = (Parent) session.load(Parent.class, pid); Child c = new Child(); c.setParent(p); p.getChildren().add(c); session.save(c); session.flush(); In the same way, if i remove a child then i have to explicitly remove it from the parent collection too. Child c = (Child) session.load(Child.class, cid); session.delete(c); Parent p = (Parent) session.load(Parent.class, pid); p.getChildren().remove(c); session.flush(); I was wondering if there are some best practices out there to do this jobs in a different way: when i save a child entity, automatically add it to the parent collection. If i remove a child, automatically update the parent collection by removing the child, etc. For example, Child c = new Child(); c.setParent(p); session.save(c); // Automatically update the parent collection session.flush(); or Child c = (Child) session.load(Child.class, cid); session.delete(c); // Automatically updates its parents (could be more than one) session.flush(); Anyway, it would not be difficult to implement this behaviour, but i was wondering if exist some standard tools or well known libraries that deals with this issue. And, if not, what are the reasons? Thanks

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