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  • BufferedImage.getGraphics() resulting in memory leak, is there a fix?

    - by user359202
    Hi friends, I'm having problem with some framework API calling BufferedImage.getGraphics() method and thus causing memory leak. What this method does is that it always calls BufferedImage.createGraphics(). On a windows machine, createGraphics() is handled by Win32GraphicsEnvironment which keeps a listeners list inside its field displayChanger. When I call getGraphics on my BufferedImage someChart, someChart's SurfaceManager(which retains a reference to someChart) is added to the listeners map in Win32GraphicsEnvironment, preventing someChart to be garbage collected. Nothing afterwards removes someChart's SurfaceManager from the listeners map. In general, the summarized path stopping a BufferedImage from being garbage collected, once getGraphics is called, is as follows: GC Root - localGraphicsEnvironment(Win32GraphicsEnvironment) - displayChanger(SunDisplayChanger) - listeners(Map) - key(D3DChachingSurfaceManager) - bImg(BufferedImage) I could have changed the framework's code so that after every called to BufferedImage.getGraphics(), I keep a reference to the BufferedImage's SurfaceManager. Then, I get hold of localGraphicsEnvironment, cast it to Win32GraphicsEnvironment, then call removeDisplayChangedListener() using the reference to the BufferedImage's SurfaceManager. But I don't think this is a proper way to solve the problem. Could someone please help me with this issue? Thanks a lot!

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  • How to fire off a asych thread in a web application, and gaurantee only 1 thread fires?

    - by Blankman
    I want to cache a object in memory. Regenerating the object when the cache expires is fairly expensive, so I want to do the following: When the cache is "about" to expire, I want to fire off a asychronous thread that will go and rebuild the object and then reset the cache. One thing I am worry about is multiple threads firing to fetch the object to cache, I only want a single thread doing this, realizing many people will be hitting the website. This might not be the best use case to do this, but I want to know how to do this sort of thing.

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  • hibernate annotation- extending base class - values are not being set - strange error

    - by gt_ebuddy
    I was following Hibernate: Use a Base Class to Map Common Fields and openjpa inheritance tutorial to put common columns like ID, lastModifiedDate etc in base table. My annotated mappings are as follow : BaseTable : @MappedSuperclass public abstract class BaseTable { @Id @GeneratedValue @Column(name = "id") private int id; @Column(name = "lastmodifieddate") private Date lastModifiedDate; ... Person table - @Entity @Table(name = "Person ") public class Person extends BaseTable implements Serializable{ ... Create statement generated : create table Person (id integer not null auto_increment, lastmodifieddate datetime, name varchar(255), primary key (id)) ; After I save a Person object to db, Person p = new Person(); p.setName("Test"); p.setLastModifiedDate(new Date()); .. getSession().save(p); I am setting the date field but, it is saving the record with generated ID and LastModifiedDate = null, and Name="Test". Insert Statement : insert into Person (lastmodifieddate, name) values (?, ?) binding parameter [1] as [TIMESTAMP] - <null> binding parameter [2] as [VARCHAR] - Test Read by ID query : When I do hibernate query (get By ID) as below, It reads person by given ID. Criteria c = getSession().createCriteria(Person.class); c.add(Restrictions.eq("id", id)); Person person= c.list().get(0); //person has generated ID, LastModifiedDate is null select query select person0_.id as id8_, person0_.lastmodifieddate as lastmodi8_, person0_.name as person8_ from Person person0_ - Found [1] as column [id8_] - Found [null] as column [lastmodi8_] - Found [Test] as column [person8_] ReadAll query : //read all Query query = getSession().createQuery("from " + Person.class.getName()); List allPersons=query.list(); Corresponding SQL for read all select query select person0_.id as id8_, person0_.lastmodifieddate as lastmodi8_, person0_.name as person8_ from Person person0_ - Found [1] as column [id8_] - Found [null] as column [lastmodi8_] - Found [Test] as column [person8_] - Found [2] as column [id8_] - Found [null] as column [lastmodi8_] - Found [Test2] as column [person8_] But when I print out the list in console, its being more weird. it is selecting List of Person object with ID fields = all 0 (why all 0 ?) LastModifiedDate = null Name fields have valid values I don't know whats wrong here. Could you please look at it? FYI, My Hibernate-core version : 4.1.2, MySQL Connector version : 5.1.9 . In summary, There are two issues here Why I am getting All ID Fields =0 when using read all? Why the LastModifiedDate is not being inserted?

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  • Can twitter do callbacks?

    - by RenegadeAndy
    Hi! I am wondering if the twitter API supports the following: Whenever I make a post to my twitter account - it also calls a specific URL which I define so I can do something else? Thanks very much, Andy

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  • Given an array of integers [x0 x1 x2], how do you calculate all possible permutations from [0 0 0] t

    - by user319951
    I am writing a program that takes in an ArrayList and I need to calculate all possible permutations starting with a list of zeroes, up to the value in the corresponding input list. Does anyone know how to iteratively calculate these values? For example, given [ 1 2 ] as input, it should find and store the following lists: [0 0], [1 0], [1 1], [1 2], [0 1], [0 2] Thanks!

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  • JUnit 4 test suite problems

    - by Hypnus
    Hi, i have a problem with some JUnit 4 tests that i run with a test suite. If i run the tests individually they work with no problems but when run in a suite most of them, 90% of the test methods, fail with errors. What i noticed is that always the first tests works fine but the rest are failing. Another thing is that a few of the tests the methods are not executed in the right order (the reflection does not work as aspected - or it does because the retrieval of the methods is not necessarily in the created order). This usually happens if there is more than one test with methods that have the same name. I tried to debug some of the tests and it seems that from a line to the next the value of some attributes gets null. Does anyone know what is the problem, or if the behavior is "normal"? Thanks in advance.

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  • Solr; What does this mean?

    - by Camran
    At the end of the README.txt file which is located in the example directory under solr, I find this line: NOTE: This Solr example server references SolrCell jars outside of the server directory with statements in the solrconfig.xml. If you make a copy of this example server and wish to use the ExtractingRequestHandler (SolrCell), you will need to copy the required jars into solr/lib or update the paths to the jars in your solrconfig.xml What does this mean? Do I have to make some adjustment before uploading solr to my server? Also, if you know, what is Solr-nightly:s difference to regular solr? The tutorial states "solr-nightly.zip" but on their download section I cant find it.

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  • Returnimng collection of interfaces

    - by apoorv020
    I have created the following interface public interface ISolutionSpace { public boolean isFeasible(); public boolean isSolution(); public Set<ISolutionSpace> generateChildren(); } However, in the implementation of ISolutionSpace in a class called EightQueenSolutionSpace, I am going to return a set of EightQueenSolutionSpace instances, like the following stub: @Override public Set<ISolutionSpace> generateChildren() { return new HashSet<EightQueenSolutionSpace>(); } However this stub wont compile. What changes do I need to make? EDIT: I tried 'HashSet' as well and had tried using the extends keyword. However since 'ISolutionSpace' is an interface and EightQueenSolutionSpace is an implementation(and not a subclass) of 'ISolutionSpace', it is still not working.

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  • Mutable objects and hashCode

    - by robert
    Have the following class: public class Member { private int x; private long y; private double d; public Member(int x, long y, double d) { this.x = x; this.y = y; this.d = d; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + x; result = (int) (prime * result + y); result = (int) (prime * result + Double.doubleToLongBits(d)); return result; } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj instanceof Member) { Member other = (Member) obj; return other.x == x && other.y == y && Double.compare(d, other.d) == 0; } return false; } public static void main(String[] args) { Set<Member> test = new HashSet<Member>(); Member b = new Member(1, 2, 3); test.add(b); System.out.println(b.hashCode()); b.x = 0; System.out.println(b.hashCode()); Member first = test.iterator().next(); System.out.println(test.contains(first)); System.out.println(b.equals(first)); System.out.println(test.add(first)); } } It produces the following results: 30814 29853 false true true Because the hashCode depends of the state of the object it can no longer by retrieved properly, so the check for containment fails. The HashSet in no longer working properly. A solution would be to make Member immutable, but is that the only solution? Should all classes added to HashSets be immutable? Is there any other way to handle the situation? Regards.

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  • Getting class Type information for Elements on a collection

    - by DutrowLLC
    I would like to get gain access to the type of Object held in a Collection. Below is a simplified example of when and why I might want to do this. Is this even possible? List<Address> addressList = new LinkedList<Address>(); Main.addElement(addressList); Class Main{ public void addElement(Object inArgument){ List<Object> argument = (List<Object>)inArgument; argument.add( /* WOULD LIKE TO CREATE A NEW OBJECT OF THE APPROPRIATE TYPE HERE, IN THIS CASE, IT WOULD BE OF TYPE: "Address" */ ); } }

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  • JarEntry.getSize() is returning -1 when the jar files is opened as InputStream from URL

    - by Reshma Donthireddy
    I am trying to read file from the JarInputStream and the size of file is returning -1. I am accessing Jar file from the URL as a inputStream. URLConnection con = url.openConnection(); JarInputStream jis = new JarInputStream(con.getInputStream()); JarEntry je = null; while ((je = jis.getNextJarEntry()) != null) { htSizes.put(je.getName(), new Integer((int) je.getSize())); if (je.isDirectory()) { continue; } int size = (int) je.getSize(); // -1 means unknown size. if (size == -1) { size = ((Integer) htSizes.get(je.getName())).intValue(); } byte[] b = new byte[(int) size]; int rb = 0; int chunk = 0; while (((int) size - rb) > 0) { chunk = jis.read(b, rb, (int) size - rb); if (chunk == -1) { break; } rb += chunk; } // add to internal resource hashtable htJarContents.put(je.getName(), baos.toByteArray()); }

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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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  • Any tools or techniques for validating constraints programmatically between databases?

    - by Brandon
    If you had two databases, that had two tables between them that would normally implement a one to one (or many to many) constraint but cannot since they are separate databases, how would you validate this relationship in an application or test? Is there a simple way to do this? For example, a tool or technique that can, given a constraint type, tables and fields, does the validation. I imagine that this isn't the first time this come up so I'm hoping people can share their solution. Thanks.

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  • Where should test classes be stored in the project?

    - by limc
    I build all my web projects at work using RAD/Eclipse, and I'm interested to know where do you guys normally store your test's *.class files. All my web projects have 2 source folders: "src" for source and "test" for testcases. The generated *.class files for both source folders are currently placed under WebContent/WEB-INF/classes folder. I want to separate the test *.class files from the src *.class files for 2 reasons:- There's no point to store them in WebContent/WEB-INF/classes and deploy them in production. Sonar and some other static code analysis tools don't produce an accurate static code analysis because it takes account of my crappy yet correct testcase code. So, right now, I have the following output folders:- "src" source folder compiles to WebContent/WEB-INF/classes folder. "test" source folder compiles to target/test-classes folder. Now, I'm getting this warning from RAD:- Broken single-root rule: A project may not contain more than one output folder. So, it seems like Eclipse-based IDEs prefer one project = one output folder, yet it provides an option for me to set up a custom output folder for my additional source folder from the "build path" dialog, and then it barks at me. I know I can just disable this warning myself, but I want to know how you guys handle this. Thanks.

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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 create a zip file and keep entries for directories?

    - by NathanZ
    I would like to create a zip archive from a folder and keep entries for (non-empty) directories. In the code below, FileInputStream throws a FileNotFoundException when a directory is passed to AddToZip. I have tried to put a condition around the actual writing of bytes but it makes the whole archive invalid. How can I add directory entries to the archive? public static void addToZip(File directoryToZip, File file, ZipOutputStream zos) throws FileNotFoundException, IOException { String zipFilePath = file.getCanonicalPath().substring(directoryToZip.getCanonicalPath().length() + 1,file.getCanonicalPath().length()); System.out.println("Writing '" + zipFilePath + "' to zip file"); ZipEntry zipEntry = new ZipEntry(zipFilePath); zos.putNextEntry(zipEntry); FileInputStream fis = new FileInputStream(file); // Throws a FileNotFoundException when directory byte[] bytes = new byte[1024]; int length; while ((length = fis.read(bytes)) >= 0) { zos.write(bytes, 0, length); } zos.closeEntry(); fis.close(); }

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