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• interfacing: simplified

  - by code wombat

  i've been doing some research on interfaces and a simple layman's explanation for what it truly is. For some reason people love using overly complex explanations and jargon to explain truly simple concepts (guess it makes them feel big) and i have a gut feeling it's the same in this case. so from what i could grasp, it seems like interfaces are nothing more than a way to reserve method names, their return type if any, and the type and amount of arguments they accept. so when a class implements an interface (or interfaces) it is forced to define the body of each method from the interface(s). Am i on the nose with this one or do i need to keep digging? p.s. i know javascript doesn't have support for interfaces, but i still need to understand the concept because there are quite a few places where it's shown how to emulate to an extent.

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• Table not created by Hibernate

  - by User1

  I annotated a bunch of POJO's so JPA can use them to create tables in Hibernate. It appears that all of the tables are created except one very central table called "Revision". The Revision class has an @Entity(name="RevisionT") annotation so it will be renamed to RevisionT so there is not a conflict with any reserved words in MySQL (the target database). I delete the entire database, recreate it and basically open and close a JPA session. All the tables seem to get recreated without a problem. Why would a single table be missing from the created schema? What instrumentation can be used to see what Hibernate is producing and which errors? Thanks. UPDATE: I tried to create as a Derby DB and it was successful. However, one of the fields has a a name of "index". I use @org.hibernate.annotations.IndexColumn to specify the name to something other than a reserved word. However, the column is always called "index" when it is created. Here's a sample of the suspect annotations. @ManyToOne @JoinColumn(name="MasterTopID") @IndexColumn(name="Cx3tHApe") protected MasterTop masterTop; Instead of creating MasterTop.Cx3tHApe as a field, it creates MasterTop.Index. Why is the name ignored?

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• How to discard time intervals with Time Series / XYPlots using JFreeChart?

  - by Alex Arnon

  Hi All, I am building a set of chart displays, one of which is for a month display of daily trading - that is, one point of data per day (closing). Since there is no trade during weekends and holidays, I need to discard these data points. Not only that, but data points should still appear adjacent to each other, regardless of any gaps in time. This can be seen in any such chart e.g. in the 3 month graph for Nasdaq on Yahoo Finance - see how weekends are skipped. My question is: how should one correctly implement this in JFreeChart? Thanks in advance!

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• Is there a version of postActionEvent for KeyEvent (specifically for a JTextArea)?

  - by Brian Pelc

  I'm writing a program that contains multiple JTextFields and 2 JTextAreas within an input panel. I have a submit button on the bottom. I have it set up so when a user types something into each field (including the JTextAreas) and hits the Enter key, it updates a text file, and when they press the submit button it updates the file then outputs a new version of it in the local directory. If the user presses Enter in any of the fields, it validates their input, however, I want to re-validate all fields when they press the submit button. Each field (again, JTextAreas included) has it's own validation check within its ActionListener or KeyListener (for the JTextAreas). It's easy enough to use postActionEvent() for the JTextFields, but is there a similar method for the JTextAreas to force fire a KeyEvent? I don't want to duplicate code and consume memory by re-writing the validation for those 2 Components inside the ActionEvent for the JButton. Unfortunately, I can't provide a sample because I'm writing the program on a classified machine (PC).

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• JPA: what is the proper pattern for iterating over large result sets?

  - by Caffeine Coma

  Let's say I have a table with millions of rows. Using JPA, what's the proper way to iterate over a query against that table, such that I don't have all an in-memory List with millions of objects? I suspect that the following will blow up if the table is large: List<Model> models = entityManager().createQuery("from Model m", Model.class).getResultList(); for (Model model : models) { // do something with model } Is pagination (looping and manually updating setFirstResult()/setMaxResult()) really the best solution?

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• Weather API to mobile platform

  - by Alex

  Hello everybody! I would like to ask from you guys/girls somebody used radar image api in MOBILE PLATFORM? I got some good provider but the user agreement don`t allow to use it in mobile platform. Even some good weather forecast API exists? (with moon phase,5-7 days forecast) and radar images ? Maybe search by US zip code?

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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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• When calling CRUD check if "parent" exists with read or join?

  - by Trick

  All my entities can not be deleted - only deactivated, so they don't appear in any read methods (SELECT ... WHERE active=TRUE). Now I have some 1:M tables on this entities on which all CRUD operations can be executed. What is more efficient or has better performance? My first solution: To add to all CRUD operations: UPDATE ... JOIN entity e ... WHERE e.active=TRUE My second solution: Before all CRUD operations check if entity is active: if (getEntity(someId) != null) { //do some CRUD } In getEntity there's just SELECT * FROM entity WHERE id=? AND active=TRUE. Or any other solution, recommendation,...?

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• Framework Recommendation request: spring, struts, j2ee?

  - by Jack BeNimble

  The last time I looked at web applications, the consensus seemed to be Struts/J2EE. Now, it looks like Spring MVC/J2EE or Struts/J2EE are both viable solutions. Is this generally correct? Or is Spring MVC now the consensus choice over Struts? We have at least one guy who has worked with Struts before and wants to go with that. I'm more familiar with Struts as well, having reviewed in the past. Also, is J2EE still considered the viable solution for handling remote components? Or are there alternatives?

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• DB2 Query to Hibernate Criteria

  - by Fortega

  Hi, I have a specific DB2 query, and I would like to execute this query using criteria. The query: SELECT sum(units) as volume, location_id, aged FROM ( SELECT units, location_id, CASE WHEN daysinstock < 61 THEN 'NOT_AGED' WHEN daysinstock < 91 THEN 'AGED' ELSE 'OVER_AGED' END AS AGED FROM STOCK_TABLE ) x group by location_id, aged the STOCK_TABLE contains the following fields: units, location_id, daysinstock. This table is matched by a StockDataSource object, with the same fields.

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• Overriding a method in statically created objects

  - by I82Much

  All, Due to a bug in a library I'm using, I need to override the dispose() method on all objects extending a certain class and make it a NO-OP. I know that if I'm making new instances of the classes directly, this is easy to do: layerManager = new LayerManagerLayer(wwd) { @Override public void dispose() {} }; The problem is that a lot of the object instances I get are not directly constructed by my client code, but instead are created via static library method calls. // Here I want to override the dispose method, but I cannot. Layer l = ShapefileLoader.makeShapefileLayer(this.getClass().getResource("polylines10.shp")); Is there a way I can inject my dispose method into that statically created object without modifying the original sourcecode?

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• Packages for import android.net.http.RequestQueue;

  - by Saranya.R

  Hi... I have a problem while using the following import functions..Can any1 help me how to solve it import android.net.http.RequestQueue; import org.apache.commons.codec.binary.Base64; My intent is to send a tweet using Android..

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• Generics Type issue

  - by JohnJohnGa

  ArrayList<Integer> arrI = new ArrayList<Integer>(); ArrayList arrO = arrI; // Warning /* It is ok to add a String as it is an ArrayList of Objects but the JVM will know the real type, arrO is an arrayList of Integer... */ arrO.add("Hello"); /* How I can get a String in an ArrayList<Integer> ?? Even if the compiler told me that I will get an Integer! */ System.out.println(arrI.get(0)); Anybody can explain what's happening here?

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• How to display panel which is of Singleton class in two different frames at a time?

  - by Sriku

  I am trying to display a singleton obj on two different Jframe, but it is displayed only in the Jframe in which the object is added at last ( in example Frame2). Other Jframe is empty. This Singleton class is inherited from Panel and contains a label in it. Can anybody please tell me how can i display this singleton object in two different frame ? public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { NewJFrame inst = new NewJFrame(); inst.setTitle("Frame1"); inst.setSize(300, 300); inst.setLocationRelativeTo(null); inst.setVisible(true); singltonpanel _sin = singltonpanel.instance(); inst.add(_sin); inst.repaint(); JFrame frame = new JFrame("Frame2"); frame.setSize(300, 300); frame.setVisible(true); singltonpanel _sin1 = singltonpanel.instance(); frame.add(_sin1); frame.repaint(); } });

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• How to center elements in the BoxLayout using center of the element?

  - by Roman

  I use outputPanel.setLayout(new BoxLayout(outputPanel, BoxLayout.Y_AXIS)); and then I add elements (for example JLabels, JButtons) to the outputPanel. For example: outputPanel.add(submitButton);. I see that all added elements are "centered". It is good, because I do want my elements to be in the center. When I write "center" I mean "equal distance from left and right". But the problem is that the left part of the element is put into the center. And I want to have center of elements to be put into the center. How can I get this behavior?

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• Casting to specific class in HQL

  - by bungrudi

  My situation is like this.. (note: for those who work with JBPM might already familiar with following data structures and HB mapping) Class LongInstance extends from VariableInstance, with the mapping for field "value" overridden in LongInstance. The mapping for VariableInstance is here and for LongInstance here. VariableInstance is polymorphically mapped to a collection in TokenVariableMap, the mapping is here. The question: how can I query the polymorphic collection using specific/overridden property of the member class? I'm looking for something like this "... from TokenVariableMaps tvm left join fetch tvm.variableInstances tvi where cast(tvi as LongInstance).value in(:vars)"

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• How to connect .asmx web services in Eclipse

  - by egebilmuh

  Hi guys i'm trying to connect asmx web services in Eclipse Enterprice Edition. i cant make it .it wants to wsdl. Any help will be appreciated.I just want to be client of the web services.

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• Problem inretrieving the name field in symbian using j2me

  - by learn

  I have added the firstname, middlename, lastname, suffix, prefix in symbian and now i want to retrieve each of this attributes of name. I am getting the firstname and lastname together by if(contactlist.isSupportedField(Contact.FORMATTED_NAME) && contact.countValues(Contact.FORMATTED_NAME)0) { mycontact.setName(contact.getString(Contact.FORMATTED_NAME, 0)); }

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• getResourceAsStream returns HttpInputStream not of the entire file

  - by khue

  Hi, I am having a web application with an applet which will copy a file packed witht the applet to the client machine. When I deploy it to webserver and use: InputStream in = getClass().getResourceAsStream("filename") ; The in.available() always return a size of 8192 bytes for every file I tried, which means the file is corrupted when it is copied to the client computer. The InputStream is of type HttpInputStream (sun.net.protocol.http.HttpUrlConnection$httpInputStream). But while I test applet in applet viewer, the files are copied fine, with the InputStream returned is of type BufferedInputStream, which has the file's byte sizes. I guess that when getResourceStream in file system the BufferedInputStream will be used and when at http protocol, HttpInputStream will be used. How will I copy the file completely, is there a size limited for HttpInputStream? Thanks a lot.

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• Using enums or a set of classes when I know I have a finite set of different options?

  - by devoured elysium

  Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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• How to disable a container and its children in Swing

  - by Fuzzy76

  I cannot figure out a way to disable a container AND its children in Swing. Is Swing really missing this basic feature? If I do setEnabled(false) on a container, its children are still enabled. My GUI structure is pretty complex, and doing a traversion of all elements below the container is not an option. Neither is a GlassPane on top of the container (the container is not the entire window).

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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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• 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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• Encrypt/ Secure communication Android app <-> REST webservice

  - by Ascorbin

  I want to create a backend for my android app with Tapestry5 and this http://code.google.com/p/t5-restful-webservices/ plugin. The app will communicate with the server by calling REST methods both for registered users (that would be easy to secure I guess) as well as unregistered users. Now of course I don't want people to just call that webservice from a browser. How can I make sure that only my app can make calls to this backend?

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• Jsp declaration element

  - by Stardust

  <%! class father { static int s = 0; } %> <% father f1 = new father(); father f2 = new father(); f1.s++; out.println(f2.s); // It must print "1" %> When I run the file, I got this error. Can anybody explain? "The field s cannot be declared static; static fields can only be declared in static or top level types"

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