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  • Hibernate custom join clause on association

    - by myso
    I would like to associate 2 entities using hibernate annotations with a custom join clause. The clause is on the usual FK/PK equality, but also where the FK is null. In SQL this would be something like: join b on a.id = b.a_id or b.a_id is null From what I have read I should use the @WhereJoinTable annotation on the owner entity, but I'm puzzled about how I specify this condition...especially the first part of it - referring to the joining entity's id. Does anyone have an example?

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  • Check if table exists

    - by Dmitry
    I have a desktop application with a database embedded in it. When I execute my program I need to check that specific table exists, or create it if not. Given a Connection object named conn for my database, how could I check this?

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  • Does a HashSet make an internal copy of added Objects?

    - by praks5432
    Let's say I have a function that is recursive and is like this public void someRecur(List<Integer>someList){ if(someBreakCondition) Set.add(someList); for(int i = 0; i < someLen ; i++){ someList.add(someInt); someRecur(someList); someList.remove(someInt); } } Does the remove affect the list that has been put into the set? What should I do to give the set an actual copy of the list?

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  • How to lowercase every element of a collection efficiently?

    - by Chris
    Whats the most efficient way to lower case every element of a list or set? My idea for a List: final List<String> strings = new ArrayList<String>(); strings.add("HELLO"); strings.add("WORLD"); for(int i=0,l=strings.size();i<l;++i) { strings.add(strings.remove(0).toLowerCase()); } is there a better, faster way? How would this exmaple look like for a set? As there is currently no method for applying an operation to each element of a set (or list) can it be done without creating an additional temporary set? Something like this would be nice: Set<String> strings = new HashSet<String>(); strings.apply( function (element) { this.replace(element, element.toLowerCase();) } ); Thanks,

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  • When I try to redefine a variable, I get an index out of bounds error

    - by user2770254
    I'm building a program to act as a calculator with memory, so you can give variables and their values. Whenever I'm trying to redefine a variable, a = 5, to a = 6, I get an index out of bounds error. public static void main(String args[]) { LinkedHashMap<String,Integer> map = new LinkedHashMap<String,Integer>(); Scanner scan = new Scanner(System.in); ArrayList<Integer> values = new ArrayList<>(); ArrayList<String> variables = new ArrayList<>(); while(scan.hasNextLine()) { String line = scan.nextLine(); String[] tokens = line.split(" "); if(!Character.isDigit(tokens[0].charAt(0)) && !line.equals("clear") && !line.equals("var")) { int value = 0; for(int i=0; i<tokens.length; i++) { if(tokens.length==3) { value = Integer.parseInt(tokens[2]); System.out.printf("%5d\n",value); if(map.containsKey(tokens[0])) { values.set(values.indexOf(tokens[0]), value); variables.set(variables.indexOf(tokens[0]), tokens[0]); } else { values.add(value); } break; } else if(tokens[i].charAt(0) == '+') { value = addition(tokens, value); System.out.printf("%5d\n",value); variables.add(tokens[0]); if(map.containsKey(tokens[0])) { values.set(values.indexOf(tokens[0]), value); variables.set(variables.indexOf(tokens[0]), tokens[0]); } else { values.add(value); } break; } else if(i==tokens.length-1 && tokens.length != 3) { System.out.println("No operation"); break; } } map.put(tokens[0], value); } if(Character.isDigit(tokens[0].charAt(0))) { int value = 0; if(tokens.length==1) { System.out.printf("%5s\n", tokens[0]); } else { value = addition(tokens, value); System.out.printf("%5d\n", value); } } if(line.equals("clear")) { clear(map); } if(line.equals("var")) { variableList(variables, values); } } } public static int addition(String[] a, int b) { for(String item : a) { if(Character.isDigit(item.charAt(0))) { int add = Integer.parseInt(item); b = b + add; } } return b; } public static void clear(LinkedHashMap<String,Integer> b) { b.clear(); } public static void variableList(ArrayList<String> a, ArrayList<Integer> b) { for(int i=0; i<a.size(); i++) { System.out.printf("%5s: %d\n", a.get(i), b.get(i)); } } I included the whole code because I'm not sure where the error is arising from.

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  • about Sorting Algorithms

    - by matin1234
    Hi I want to know that we always use Sorting algorithm like (Insertion Sort or Merge Sort,...) just for lists and arrays?? and we do not use these algorithms for stack or queue ??? thanks

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  • Can getAttribute() method of Tomcat ServletContext implementation be called without synchronization?

    - by oo_olo_oo
    I would like to read some parameters during servlet initializtion (in init() method), and store them among servlet context attributes (using getServletContext().setAttribute()). I would like to read these parameters later - during some request processing (using getServletContext().getAttribute()). So, the multiple threads could do this simultaneously. My question is if such an attempt is safe? Could I be sure that multi threaded calls to the getAttribute() don't mess up any internal state of the servlet context? Please take into account that I'm not going to call the setAttribute() anywhere besides the initialization. So, only calls to the getAttribute() are going to be done from multiple threads. But depending on the internal implementation, this also could be dangerous. So, any information about Tomcat's implementation would be appreciated.

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  • How to solve following issues?

    - by lakshmi
    hi im using postgresql database, I want to insert my datas into database,but whenever i run the server,it was display the following Error. Error:org.postgresql.util.PSQLException: FATAL: sorry, too many clients already How to solve this problem.My server.properties file is following. Sever.properties File: serverPortData=9042 serverPortCommand=9078 simocoConnectionURL=jdbc:postgresql://127.0.0.1:5432/vTrack?user=postgres&password=postgres dst=1 DatabaseName=vTrack ServerName=127.0.0.1 User=postgres Password=admin MaxConnections=90 InitialConnections=80 PoolSize=100 MaxPoolSize=100 KeepAliveTime=100 SimocoPoolSize=120 SimocoMaxPoolSize=120 SimocoKeepAliveTime=100 PortNumber=5432 Logging=1 Thanks.

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  • How to read log4j output to a web page?

    - by Ran
    I have a web page, used for admin purposes, which runs a task (image fetching from a remote site). In order to be able to debug the task using the browser only, no ssh etc, I'd like to be able to read all log output from the executing thread and spit it out to the web page. The task boils down to: Changing log level for current thread at the beginning of the call and restore when the call is done. Reading all log output by current thread and storing it in a string. So in pseudocode my execute() method would look like this: (I'm using struts2) public String execute() throws Exception { turnLoggingLevelToDebugOnlyForThisThread() ... do stuff... restoreLoggingLevelForThisThread() String logs = readAllLogsByThisThread(); } Can this be done with log4j? I'm using tomcat, struts2, log4j and slf4j.

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  • regular expression and escaping

    - by pstanton
    Sorry if this has been asked, my search brought up many off topic posts. I'm trying to convert wildcards from a user defined search string (wildcard is "*") to postgresql like wildcard "%". I'd like to handle escaping so that "%" => "\%" and "\*" => "*" I know i could replace \* with something else prior to replacing * and then swap it back, but i'd prefer not to and instead only convert * using a pattern that selects it when not proceeded by \. String convertWildcard(String like) { like = like.replaceAll("%", "\\%"); like = like.replaceAll("\\*", "%"); return like; } Assert.assertEquals("%", convertWildcard("*")); Assert.assertEquals("\%", convertWildcard("%")); Assert.assertEquals("*", convertWildcard("\*")); // FAIL Assert.assertEquals("a%b", convertWildcard("a*b")); Assert.assertEquals("a\%b", convertWildcard("a%b")); Assert.assertEquals("a*b", convertWildcard("a\*b")); // FAIL ideas welcome.

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  • How can I get jcifs to play nicely with apache axis

    - by Ben Hammond
    I need to connect Apache Axis 1.4 to a Webservice that uses NTLM authentication to restrict access to its operations. I'm expecting to use Samba Jcifs to handle the NTLM handshake. I found http://hc.apache.org/httpcomponents-client/ntlm.html which gives me fantastic directions for how to wire up HttpClient 4.0 with jcifs. Trouble is, Axis wants to use Http Client 3.0 and the two apis look very different. There are 2 possibilities that I can see Write an object for Axis that lets it plug into HttpClient 4. Figure out how to wire HttpClient 3.0 up with Samba Jcifs. Number 1. looks non-trivial, but possible Number 2. I cannot find any encouraging messages on the web describing how to do this. My question is: has anyone successfully connected samba jcifs with HttpClient 3.0 ? Has anyone already created an Axis HttpSender object that works with HttpClient 4 ? Is there some better alternative that I have not considered?

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  • In ArrayBlockingQueue, why copy into ReentrantLock field into local final variable?

    - by mjlee
    In ArrayBlockingQueue, any method that requires lock will get set 'final' local variable before calling 'lock()'. public boolean offer(E e) { if (e == null) throw new NullPointerException(); final ReentrantLock lock = this.lock; lock.lock(); try { if (count == items.length) return false; else { insert(e); return true; } } finally { lock.unlock(); } } Is there any reason to set a local variable 'lock' from 'this.lock' when field 'this.lock' is final also. Additionally, it also set local variable of E[] before acting on. private E extract() { final E[] items = this.items; E x = items[takeIndex]; items[takeIndex] = null; takeIndex = inc(takeIndex); --count; notFull.signal(); return x; } Is there any reason for copying to local final variable?

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  • How do I prevent JDialog from showing in gnome-panel(Linux)?

    - by aeter
    I have a class: public class ANote extends JDialog{...} In GNOME(Linux) it shows an entry in the gnome-panel. I want it to show nothing (the same way it does in the taskbar in Windows), because there may be present several instances of the class simultaneously, and this overcrowds the gnome-panel. How do I prevent it from showing an instance in the gnome-panel? EDIT: So far I have tried playing with the modality, which hides it from the gnome-panel, but blocks the main frame of the application behind the ANote instances.

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  • Exception handling in Iterable

    - by Maas
    Is there any way of handling -- and continuing from -- an exception in an iterator while maintaining the foreach syntactic sugar? I've got a parser that iterates over lines in a file, handing back a class-per-line. Occasionally lines will be syntactically bogus, but that doesn't necessarily mean that we shouldn't keep reading the file. My parser implements Iterable, but dealing with the potential exceptions means writing for (Iterator iter = myParser.iterator(); iter.hasNext(); ) { try { MyClass myClass = iter.next(); // .. do stuff .. } catch (Exception e) { // .. do exception stuff .. } } .. nothing wrong with that, but is there any way of getting exception handling on the implicit individual iter.next() calls in the foreach construct?

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  • hibernate search

    - by Odelya
    Hi! I am using Hibernate. I am looking for a free text engine. Before I investigate into it I need your experience. I have in my applications user, role and object table. Where a user is connected to one or more roles, and a role is connected to one or more objects. In my free text search, the user can reach only data that he is allowed to watch by object table. Can Hibernate search help me with it?

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  • How to detect column conflicts with Hibernate?

    - by Slim
    So let's say I have an ArrayList full of Products that need to be committed to the database via Hibernate. There are already a large number of Products in the database. Each product has an ID. Note this is NOT the PK that is autogenerated by Hibernate. My questions is: what is the best way to detect conflicts with this ID? I am looking for a relatively efficient method of obtaining, from the the database, a List of Products that share an ID with any of the Products in my ArrayList. This is all in a single table called Products and the ID attribute is in column ProductID. The way I've done it is grabbing a list of all Products in the database, and compared each one with each entry in my ArrayList - but that is seriously inefficient and I don't think it would work well with a larger database. How should it be done? Thanks. I say "relatively" efficient because efficiency is not the primary concern, but it shouldn't take noticeably long to test against a table of ~1000-5000 rows. Help? EDIT* I'm very new to hibernate and below is the best I've come up with. How does this look? for(long id : idList){ //idList just holds the IDs of each Product in my ArrayList Query query = session.createQuery("select product from Product product where product.id = :id"); query.setLong("id", id); for(int i = 0; i < query.list().size(); i++){ listOfConflictingProducts.add((Product) query.list().get(i)); } }

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  • PDFBox: Problem with converting pdf page into image

    - by user552910
    My mission is pretty simple: converting every single page of a pdf file into images. I tried using icepdf open source version to generate the images but they don't generate the image with the correct font. So I start using PDFBox instead. The code is the following: PDDocument document = PDDocument.load(new File("testing.pdf")); List<PDPage> pages = document.getDocumentCatalog().getAllPages(); for (int i = 0; i < pages.size(); i++) { PDPage singlePage = pages.get(i); BufferedImage buffImage = convertToImage(singlePage, 8, 12); ImageIO.write(buffImage, "png", new File(PdfUtil.DATA_OUTPUT_DIR+(count++)+".png")); } The font looks good, but the pictures within the pdf file look fainted out (See the attachment). I look into the source code but I still have no clue how to fix it. Do you guys have any idea what's going on? Please help. Thanks!!

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  • How to deploy a single webapp with multiple web-modules that may be removed or added individually

    - by Daniel Bleisteiner
    We currently run two separate webapps (WARs) deployed in one single EAR containing additional JARs and settings. To improve our deployment I want to split one of these webapps into different modules that may be build and packaged individually. But I've currently no clue on how to package these modules so that I'm able to add or remove them as desired - at best during runtime. The webapp is getting more and more complex and I'd like to separate some of the functionality into modules. These modules should be packaged as single archives. As long as they contain only classes and resources loaded through code I know how to do this (simple JARs). But how about JSPs? Normally a WAR file contains JSPs or HTML files. I my case it are JSF pages utilizing JBoss Seam and RichFaces. These modules will add classes, resources and JSF pages and other includes to the running webapplication. Is it somehow possible to deploy them as individual archives to serve the same running webapp? We are using Maven for our build and packaging and deploy into JBoss v4.

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  • Return type value if RunTimeException has been thrown and not catched.

    - by Alfred
    I am using Gson to parse Json. What I don't understand what the return type will be if you don't catch the Runtime Exception. I was expecting it to be null, but it is not null when evaluating with a simple if statement. My code looks something like this: public X x() { return gson.fromJson(jsonString, X.class); } then from another function I call the function: public void y() { final X x = x(); if (x == null) { System.out.println("x == null") } } I was expecting x to be null, but it isn't because the print statement is not called? What is the value of x? How can if them. I have my problem by using a catch block in the x() function and returning null. But I am just wondering what the value of function x() is(if any?)? Hopefully I make any sense at all.

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  • JAXWS and sessions

    - by Pace
    I'm fairly new to writing web services. I'm working on a SOAP service using JAXWS. I'd like to be able to have users log-in and in my service know which user is issuing a command. In other words, have some session handling. One way I've seen to do this is to use cookies and access the HTTP layer from my web service. However, this puts a dependency on using HTTP as the transport layer (I'm aware HTTP is almost always the transport layer but I'm a purist). Is there a better approach which keeps the service layer unaware of the transport layer? Is there some way I can accomplish this with servlet filters? I'd like the answer to be as framework agnostic as possible.

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