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  • Use PermGen space or roll-my-own intern method?

    - by Adamski
    I am writing a Codec to process messages sent over TCP using a bespoke wire protocol. During the decode process I create a number of Strings, BigDecimals and dates. The client-server access patterns mean that it is common for the client to issue a request and then decode thousands of response messages, which results in a large number of duplicate Strings, BigDecimals, etc. Therefore I have created an InternPool<T> class allowing me to intern each class of object. Internally, the pool uses a WeakHashMap<T, WeakReferemce<T>>. For example: InternPool<BigDecimal> pool = new InternPool<BigDecimal>(); ... // Read BigDecimal from in buffer and then intern. BigDecimal quantity = pool.intern(readBigDecimal(in)); My question: I am using InternPool for BigDecimal but should I consider also using it for String instead of String's intern() method, which I believe uses PermGen space? What is the advantage of using PermGen space?

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  • Pass Alot of Parameters on a Form to Action Struts2

    - by Neeraj
    I have been working on migrating a web application from Struts1 to Struts2. I have a simple Form with around 45 Fields (basically a grid with data). I have to capture all those in Struts2 Action.I noticed that in struts2 we have OGNL through which we just write getters setters in action itself by declaring fields locally to get those variables flowing in the request. I cannot write 45 getters/setters in my action, there must be a way to pass whole object(a POJO) from jsp to Action layer. In Struts 1, we normally get a ActionForm Object and/or get request parameters in a map and then populate. Any help or suggestions will be appreciated.

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  • Duplicate Prefix Error in Jsp page with Struts

    - by Cricandcric.com
    Hi, i am creating and Configuring the Struts for the first time, when I place the following Code in my jsp page <%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%> <%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%> <%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%> <%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles"%> I am getting the error when i move the mouse over the 1st Line "Duplicate Prefix "html" When I move the mouse over the 2nd Line, I am getting as "Duplicate Prefix "html" Similarly for 3rd and 4th Line, Can any one tell me why is this error all about Thanks in advance

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  • regex for matching strings that have illegal filename characters.

    - by cchampion
    I been trying to figure out how this blasted regex for two hours!!! It's midnight I gotta figure this out and go to bed!!! String str = new String("filename\\"); if(str.matches(".*[?/<>|*:\"{\\}].*")) { System.out.println("match"); }else { System.out.println("no match"); } ".*[?/<>|*:\"{\\}].*" is my regex expression. It catches everything correctly except the backslash!!! I need to know how to make it catch the backslash correctly please help! FYI, the illegal characters i'm trying to catch are ? \ / < | * : " I've got it working exception for the backslash

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  • Enum exeeding the 65535 bytes limit of static initializer... what's best to do?

    - by Daniel Bleisteiner
    I've started a rather large Enum of so called Descriptors that I've wanted to use as a reference list in my model. But now I've come across a compiler/VM limit the first time and so I'm looking for the best solution to handle this. Here is my error : The code for the static initializer is exceeding the 65535 bytes limit It is clear where this comes from - my Enum simply has far to much elements. But I need those elements - there is no way to reduce that set. Initialy I've planed to use a single Enum because I want to make sure that all elements within the Enum are unique. It is used in a Hibernate persistence context where the reference to the Enum is stored as String value in the database. So this must be unique! The content of my Enum can be devided into several groups of elements belonging together. But splitting the Enum would remove the unique safety I get during compile time. Or can this be achieved with multiple Enums in some way? My only current idea is to define some Interface called Descriptor and code several Enums implementing it. This way I hope to be able to use the Hibernate Enum mapping as if it were a single Enum. But I'm not even sure if this will work. And I loose unique safety. Any ideas how to handle that case?

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  • correct way of initializing variables

    - by OVERTONE
    ok this is just a shot in the dark but it may be the cause of most of the errors ive gotten. when your initializing something. lets say a smal swing program. would it go liek this variables here { private Jlist contactList; String [] contactArray; ArrayList <String> contactArrayList; ResultSet namesList constructor here public whatever() { GridLayout aGrid = new GridLayout(2,2,10,10); contact1 = new String(); contact2 = new String(); contact3 = new String(); contactArrayList = new ArrayList<String>(); // is something supposed too go in the () of this JList? contactList = new JList(); contactArray = new String[5]; from1 =new JLabel ("From: " + contactArray[1]); gridlayout.add(components)// theres too many components to write onto SO. } // methods here public void fillContactsGui() { createConnection(); ArrayList<String> contactsArrayList = new ArrayList<String>(); while (namesList.next()) { contactArrayList.add(namesList.getString(1)); ContactArray[1] = namesList[1]; } } i know this is probably a huge beginner question but this is the code ive gotten used too. im initializing thigns three and fours times without meaning too because im not sure where they gp. can anyone shed some light on this? p.s. sorry for the messy sample code. i done my best.

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  • android.R.layout.simple_list_item_checked not toggling in ListView

    - by Mohit Deshpande
    Here is my custom adapter: ... @Override public View newView(Context context, Cursor cursor, ViewGroup parent) { LayoutInflater inflater = LayoutInflater.from(context); View v = inflater.inflate(android.R.layout.simple_list_item_checked, parent, false); return v; } ... Now this visually appears to be exactly what I needed. The problem is that I can't get toggle the checked state when I click on the listview item. Any solutions?

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  • paintComponent on JPanel, image flashes and then disappears

    - by mark
    I have a JApplet (MainClass extends JApplet), a JPanel (ChartWindow extends JPanel) and a Grafico class. The problem is that the Grafico class instance has 2 JPanel that should show 2 images (1 for each panel) but the images are shown and after a little while they disappears: instead of them i get a gray background (like an empty JPanel). This happens for every repaint() call (that are made in the ChartWindow class) the MainClass init() contains chartwindow=new ChartWindow(); add(chartwindow) chartwindow has a Grafico instance. it's the ChartWindow's paintComponent (override) paintComponent(Graphics g) { super.paintComponent(g); Image immagineGrafico=createImage(grafico.pannelloGrafico.getWidth() ,grafico.pannelloGrafico.getHeight()); Image immagineVolumi=createImage(grafico.pannelloVolumi.getWidth() ,grafico.pannelloVolumi.getHeight()); Graphics2D imgGrafico=(Graphics2D)immagineGrafico.getGraphics(); Graphics2D imgVolumi=(Graphics2D)immagineVolumi.getGraphics(); grafico.draw(imgGrafico,imgVolumi,mouseX,mouseY); ((Graphics2D)grafico.pannelloGrafico.getGraphics()).drawImage(immagineGrafico,0,0,this); ((Graphics2D)grafico.pannelloVolumi.getGraphics()).drawImage(immagineVolumi,0,0,this); } grafico's JPanels are added this way in the ChartWindow's constructor grafico=new Grafico() ................ add(grafico.pannelloGrafico); add(grafico.pannelloVolumi); Tell me if you need more information, thank you very much :-)

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  • JSP template inheritance

    - by Ryan
    Coming from a background in Django, I often use "template inheritance", where multiple templates inherit from a common base. Is there an easy way to do this in JSP? If not, is there an alternative to JSP that does this (besides Django on Jython that is :) base template <html> <body> {% block content %} {% endblock %} </body> <html> basic content {% extends "base template" %} {% block content %} <h1>{{ content.title }} <-- Fills in a variable</h1> {{ content.body }} <-- Fills in another variable {% endblock %} Will render as follows (assuming that conten.title is "Insert Title Here", and content.body is "Insert Body Here") <html> <body> <h1>Insert title Here <-- Fills in a variable</h1> Insert Body Here <-- Fills in another variable </body> <html>

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  • Count Occurence of Needle String in Haystack String, most optimally?

    - by Taranfx
    The Problem is simple Find "ABC" in "ABCDSGDABCSAGAABCCCCAAABAABC" Here is the solution I propose, I'm looking for any solutions that might be better than this one. public static void main(String[] args) { String haystack = "ABCDSGDABCSAGAABCCCCAAABAABC"; String needle = "ABC"; char [] needl = needle.toCharArray(); int needleLen = needle.length(); int found=0; char hay[] = haystack.toCharArray(); int index =0; int chMatched =0; for (int i=0; i<hay.length; i++){ if (index >= needleLen || chMatched==0) index=0; System.out.print("\nchar-->"+hay[i] + ", with->"+needl[index]); if(hay[i] == needl[index]){ chMatched++; System.out.println(", matched"); }else { chMatched=0; index=0; if(hay[i] == needl[index]){ chMatched++; System.out.print("\nchar->"+hay[i] + ", with->"+needl[index]); System.out.print(", matched"); }else continue; } if(chMatched == needleLen){ found++; System.out.println("found. Total ->"+found); } index++; } System.out.println("Result Found-->"+found); } It took me a while creating this one. Can someone suggest a better solution (if any) P.S. Drop the sysouts if they look messy to you.

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  • JAXB Marshalling supply name space for root element dynamically

    - by Venkat
    I have to pass the namespace for root element dynamically while marshalling using jaxb (JAXB 2.1.10 - JDK 6). i will be using the genrated xml to call different webservices which is qualified with different namespaces but same input xml. here is my sample jaxb annotated class .....guide me with your valuable inputs. @XmlAccessorType(XmlAccessType.FIELD) @XmlType(name = "", propOrder = { "taskName", "taskType" }) @XmlRootElement(name = "TaskRequest") public class TaskRequest { @XmlElement(name = "TaskName", required = true) protected String taskName; @XmlElement(name = "TaskType", required = true) protected String taskType; public String getTaskName() { return taskName; } public void setTaskName(String value) { this.taskName = value; } public String getTaskType() { return taskType; } public void setTaskType(String value) { this.taskType = value; } }

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  • URL of the website calling Restlet API

    - by Christopher McCann
    I have a Restlet API and the methods exposed on it are called by a PHP web app. This web app is accessible by several domain names and depending on the domain certain aspects of the app are changed (look and feel, content etc). Is there a way for Restlet to determine the URL of the calling web app? I have used getReference() but all I can get is the (internal) IP address of the calling web server (not the domain name). My only other alternative is to pass the URL of the web app with every request to the API but it would be cleaner if Restlet already knew. Thanks

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  • JList with custom renderer

    - by AhmadAssaf
    Hello, I have a JList that shows multiple JPanels on them , i have created a custom renderer that returns a new JPanel. The JPanels are displayed in the JList but they are not accessible, i cant select them and if i have a button or a text area in it i can not press it. I want to try if this works in a JList because i want to do further pagination. I managed to get it work by adding panels to a Jscroll pane, but would love to make the JList thing work. Thanks

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  • Encountering NullPointerException when trying to add polynoms

    - by Ayler Cruz
    I need to add two polynomials, which is composed of two ints. For example, the coefficient and the exponent 3x^2 would be constructed using 3 and 2 as parameters. I am getting a NullPointerException but I can't figure out why. Any help would be appreciated! public class Polynomial { private Node poly; public Polynomial() { } private Polynomial(Node p) { poly = p; } private class Term { int coefficient; int exponent; private Term(int coefficient, int exponent) { this.coefficient = coefficient; this.exponent = exponent; } } private class Node { private Term data; private Node next; private Node(Term data, Node next) { this.data = data; this.next = next; } } public void addTerm(int coeff, int exp) { Node pointer = poly; if (pointer.next == null) { poly.next = new Node(new Term(coeff, exp), null); } else { while (pointer.next != null) { if (pointer.next.data.exponent < exp) { Node temp = new Node(new Term(coeff, exp), pointer.next.next); pointer.next = temp; return; } pointer = pointer.next; } pointer.next = new Node(new Term(coeff, exp), null); } } public Polynomial polyAdd(Polynomial p) { return new Polynomial(polyAdd(this.poly, p.poly)); } private Node polyAdd(Node p1, Node p2) { if (p1 == p2) { Term adding = new Term(p1.data.coefficient + p2.data.coefficient, p1.data.exponent); p1 = p1.next; p2 = p2.next; return new Node(adding, null); } if (p1.data.exponent > p2.data.exponent) { p2 = p2.next; } if (p1.data.exponent < p2.data.exponent) { p1 = p1.next; } if (p1.next != null && p2.next != null) { return polyAdd(p1, p2); } return new Node(null, null); } }

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  • Is it possible to have Ant print out the classpath for a particular target? If so, how?

    - by Daryl Spitzer
    I'm trying to get a target to build that has quite a long list of <pathelement location="${xxx}"/> and <path refid="foo.class.path"/> elements in its <path id="bar.class.path"> element (in the build.xml file). I keep getting "package com.somecompany.somepackage does not exist" errors, and I'm having a hard time chasing down these packages and making sure I've synced them from our repository. I'm new to this team so I'm unfamiliar with the build, but I would prefer to figure this out myself if possible (so I don't bother the other very busy team members). I have very limited experience with Ant. I think it would save me quite a bit of time if I could have Ant print out the classpath for the target I'm trying to build.

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  • Can you return an array from a JAX-WS @WebMethod?

    - by LES2
    I'm pretty sure you can, but in addition to answering the question in the title, could you also explain the pros, cons, caveats, if any, to doing so? I know that you can't return a List, Set, Collection, Map, or any interface, from a WebMethod (which is stupid, IMO, but I don't know what the design reasons were should I should probably withhold judgment). Thanks for any advice. -- LES

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  • Does Hibernate support one-to-one associations as pkeys?

    - by Andrzej Doyle
    Hi all, Can anyone tell me whether Hibernate supports associations as the pkey of an entity? I thought that this would be supported but I am having a lot of trouble getting any kind of mapping that represents this to work. In particular, with the straight mapping below: @Entity public class EntityBar { @Id @OneToOne(optional = false, mappedBy = "bar") EntityFoo foo // other stuff } I get an org.hibernate.MappingException: "Could not determine type for: EntityFoo, at table: ENTITY_BAR, for columns: [org.hibernate.mapping.Column(foo)]" Diving into the code it seems the ID is always considered a Value type; i.e. "anything that is persisted by value, instead of by reference. It is essentially a Hibernate Type, together with zero or more columns." I could make my EntityFoo a value type by declaring it serializable, but I wouldn't expect this would lead to the right outcome either. I would have thought that Hibernate would consider the type of the column to be integer (or whatever the actual type of the parent's ID is), just like it would with a normal one-to-one link, but this doesn't appear to kick in when I also declare it an ID. Am I going beyond what is possible by trying to combine @OneToOne with @Id? And if so, how could one model this relationship sensibly?

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  • Android return to the original position of the view after MotionEvent

    - by Kurty
    My application currently changes to another random int (View) when I let go of it (ACTION_UP) but the view stays in the same spot where I dropped it. I want it to return to the original location (the middle of the screen) when I drop it so I can repeat the process. // OnTouch and MotionEvent OnTouchListener dragt = new OnTouchListener() { public boolean onTouch(View v, MotionEvent me) { FrameLayout.LayoutParams par = (FrameLayout.LayoutParams) v.getLayoutParams(); switch (v.getId()) { case R.id.randomView: } switch(me.getAction()) { case MotionEvent.ACTION_MOVE: par.gravity = 0; par.setMargins((int)me.getRawX() - (v.getWidth())/2, (int)me.getRawY() - (v.getHeight())/2, 0, 0); v.setLayoutParams(par); break; case MotionEvent.ACTION_UP: // tallies score. score++; textScore.setText(String.valueOf(score)); // this generates the new view but the location is still the same color.setImageResource(mImageIds[rgenerator.nextInt(mImageIds.length)]); break; } return true; } };

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  • static variable lose its value

    - by user542719
    I have helper class with this static variable that is used for passing data between two classes. public class Helper{ public static String paramDriveMod;//this is the static variable in first calss } this variable is used in following second class mathod public void USB_HandleMessage(char []USB_RXBuffer){ int type=USB_RXBuffer[2]; MESSAGES ms=MESSAGES.values()[type]; switch(ms) { case READ_PARAMETER_VALUE: // read parameter values switch(prm){ case PARAMETER_DRIVE_MODE: // paramet drive mode Helper.paramDriveMod =(Integer.toString(((USB_RXBuffer[4]<< 8)&0xff00))); System.out.println(Helper.paramDriveMod+"drive mode is selectd ");//here it shows the value that I need. ..........}}//let say end switch and method and the following is an third class method use the above class method public void buttonSwitch(int value) throws InterruptedException{ boolean bool=true; int c=0; int delay=(int) Math.random(); while(bool){ int param=3; PARAMETERS prm=PARAMETERS.values()[param]; switch(value){ case 0: value=1; while(c<5){ Thread.sleep(delay); protocol.onSending(3,prm.PARAMETER_DRIVE_MODE.ordinal(),dataToRead,dataToRead.length);//read drive mode System.out.println(Helper.paramDriveMod+" drive mode is ..........in wile loop");//here it shows null value }}//let say end switch and method what is the reason that this variable lose its value?

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  • hibernate versioning parent entity

    - by Priit
    Consider two entities Parent and Child. Child is part of Parent's transient collection Child has a ManyToOne mapping to parent with FetchType.LAZY Both are displayed on the same form to a user. When user saves the data we first update Parent instance and then Child collection (both using merge). Now comes the tricky part. When user modifies only Child property on the form then hibernate dirty checking does not update Parent instance and thus does not increase optimistic locking version number for that entity. I would like to see situation where only Parent is versioned and every time I call merge for Parent then version is always updated even if actual update is not executed in db.

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  • Thread used for ServiceConnection callback (Android)

    - by Jannick
    Hi I'm developing an activity that binds to a local service (in onCreate of the activity): bindService(new Intent(this, CommandService.class), svcConn, BIND_AUTO_CREATE); I would like to be able to call methods through the IBinder in my lifecycle methods, but can not be sure that onServiceConnected have been called prior to these. I'm thinking of handling this by adding a queue of sorts in the ServiceConnection implementation, so that the method calls (Command pattern) will be executed once the connection is established. My questions are then: Is this stupid, any better ways? :) Are there any specification for which thread will be used to execute the ServiceConnection callbacks? More to the point, do I need to worry about synchronizing a queue datastructure? Edit - something like: public void onServiceConnected(ComponentName name, IBinder service) { dispatchService = (DispatchAsync)service; for(ExecutionTask task : queue){ dispatchService.execute(task.getCommand(), task); } }

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  • Redirected wikipedia request

    - by Le_Coeur
    Hi people, i need to write a program, that can redirect's http://localhost:8080 to en.wikipedia.org, it seems to be easy, but i have some problems(only with wikipedia with another sites works good). I make url to wikipedia: URL url = new URL("http", "en.wikipedia.org", 80, "/wiki"); than URLConnection, extract headers, and when i want connection.getInputStream(), i received message 404 Not Found. So i have tried some hack for host header, because in this way host header is localhost:8080, therefor i have tried to change host header to wikipedia, and it works, but after request in browser http://localhost:8080 wikipedia opens, but url in browser changes to en.wikipedia.org, but i want proceed with localhost :)

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