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  • Use continue or Checked Exceptions when checking and processing objects

    - by Johan Pelgrim
    I'm processing, let's say a list of "Document" objects. Before I record the processing of the document successful I first want to check a couple of things. Let's say, the file referring to the document should be present and something in the document should be present. Just two simple checks for the example but think about 8 more checks before I have successfully processed my document. What would have your preference? for (Document document : List<Document> documents) { if (!fileIsPresent(document)) { doSomethingWithThisResult("File is not present"); continue; } if (!isSomethingInTheDocumentPresent(document)) { doSomethingWithThisResult("Something is not in the document"); continue; } doSomethingWithTheSucces(); } Or for (Document document : List<Document> documents) { try { fileIsPresent(document); isSomethingInTheDocumentPresent(document); doSomethingWithTheSucces(); } catch (ProcessingException e) { doSomethingWithTheExceptionalCase(e.getMessage()); } } public boolean fileIsPresent(Document document) throws ProcessingException { ... throw new ProcessingException("File is not present"); } public boolean isSomethingInTheDocumentPresent(Document document) throws ProcessingException { ... throw new ProcessingException("Something is not in the document"); } What is more readable. What is best? Is there even a better approach of doing this (maybe using a design pattern of some sort)? As far as readability goes my preference currently is the Exception variant... What is yours?

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  • Configurable Values in Enum

    - by Omer Akhter
    I often use this design in my code to maintain configurable values. Consider this code: public enum Options { REGEX_STRING("Some Regex"), REGEX_PATTERN(Pattern.compile(REGEX_STRING.getString()), false), THREAD_COUNT(2), OPTIONS_PATH("options.config", false), DEBUG(true), ALWAYS_SAVE_OPTIONS(true), THREAD_WAIT_MILLIS(1000); Object value; boolean saveValue = true; private Options(Object value) { this.value = value; } private Options(Object value, boolean saveValue) { this.value = value; this.saveValue = saveValue; } public void setValue(Object value) { this.value = value; } public Object getValue() { return value; } public String getString() { return value.toString(); } public boolean getBoolean() { Boolean booleanValue = (value instanceof Boolean) ? (Boolean) value : null; if (value == null) { try { booleanValue = Boolean.valueOf(value.toString()); } catch (Throwable t) { } } // We want a NullPointerException here return booleanValue.booleanValue(); } public int getInteger() { Integer integerValue = (value instanceof Number) ? ((Number) value).intValue() : null; if (integerValue == null) { try { integerValue = Integer.valueOf(value.toString()); } catch (Throwable t) { } } return integerValue.intValue(); } public float getFloat() { Float floatValue = (value instanceof Number) ? ((Number) value).floatValue() : null; if (floatValue == null) { try { floatValue = Float.valueOf(value.toString()); } catch (Throwable t) { } } return floatValue.floatValue(); } public static void saveToFile(String path) throws IOException { FileWriter fw = new FileWriter(path); Properties properties = new Properties(); for (Options option : Options.values()) { if (option.saveValue) { properties.setProperty(option.name(), option.getString()); } } if (DEBUG.getBoolean()) { properties.list(System.out); } properties.store(fw, null); } public static void loadFromFile(String path) throws IOException { FileReader fr = new FileReader(path); Properties properties = new Properties(); properties.load(fr); if (DEBUG.getBoolean()) { properties.list(System.out); } Object value = null; for (Options option : Options.values()) { if (option.saveValue) { Class<?> clazz = option.value.getClass(); try { if (String.class.equals(clazz)) { value = properties.getProperty(option.name()); } else { value = clazz.getConstructor(String.class).newInstance(properties.getProperty(option.name())); } } catch (NoSuchMethodException ex) { Debug.log(ex); } catch (InstantiationException ex) { Debug.log(ex); } catch (IllegalAccessException ex) { Debug.log(ex); } catch (IllegalArgumentException ex) { Debug.log(ex); } catch (InvocationTargetException ex) { Debug.log(ex); } if (value != null) { option.setValue(value); } } } } } This way, I can save and retrieve values from files easily. The problem is that I don't want to repeat this code everywhere. Like as we know, enums can't be extended; so wherever I use this, I have to put all these methods there. I want only to declare the values and that if they should be persisted. No method definitions each time; any ideas?

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  • How to force HtmlUnit to save page?

    - by booroondook
    Hello. I'm using HtmlUnit to click on a HtmlElement that triggers Javascript action: currentPage = ((HtmlElement) currentPage.getByXPath("//*[contains(@onclick, 'check();')]").get(0)).click(); The element is: <a href="#" onclick="check(); return false;"> The page returned is quite similar to the page, containing that element: same URL, mostly same HTML, but there are some minor differences in the HTML and HtmlUnit doesn't save the new page. I'm using HttpAnalyzer to sniff the traffic and I see that the Webclient correctly handles JS and send the right request. The response is also correct, but when I dump the contents of the currentPage to a file, I see that the actual page didn't change. How can I fix it?

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  • HIbernate query

    - by sarah
    Hi I want to execute a query using hibernate where the requirment is like select * from user where regionname='' that is select all the users from user where region name is some data How to write this in hibernate The below code is giving result appropraitely Criteria crit= HibernateUtil.getSession().createCriteria(User.class); crit.add(Restrictions.eq("regionName", regionName));

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  • Issue calling superclass method in subclass constructor

    - by stormin986
    I get a NullPointerException calling a Superclass Method in Subclass Inner Class Constructor... What's the Deal? In my application's main class (subclass of Application), I have a public inner class that simply contains 3 public string objects. In the parent class I declare an object of that inner class. public class MainApplication extends Application { public class Data { public String x; public String y; public String z; } private Data data; MainApplication() { data = new Data() data.x = SuperClassMethod(); } } After I instantiate the object in the constructor, I get a runtime error when I try to assign a value in the inner class with a superclass method. Any idea what's up here?? Can you not call superclass methods in the subclass constructor? ** Edit ** Original question was about inner class member assignment in outer class constructor. Turned out the issue was with calling a superclass method in the class's constructor. It was giving me a null pointer exception. Thus, the question has changed.

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  • Need to map classes to different databases at runtime in Hibernate

    - by serg555
    I have MainDB database and unknown number (at compile time) of UserDB_1, ..., UserDB_N databases. MainDB contains names of those UserDB databases in some table (new UserDB can be created at runtime). All UserDB have exactly the same table names and fields. How to handle such situation in Hibernate? (database structure cannot be changed). Currently I am planning to create generic User classes not mapped to anything and just use native SQL for all queries: session.createSQLQuery("select * from " + db + ".user where id=1") .setResultTransformer(Transformers.aliasToBean(User.class)); Is there anything better I can do? Ideally I would want to have mappings for UserDB tables and relations and use HQL on required database.

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  • getting number from console!

    - by Johanna
    Hi this is my method that will be called if I want to get a number from user. but if the user also enter a right number just the "else" part will be run ,why? please help me tahnsk. public static int chooseTheTypeOfSorting() { System.out.println("Enter 0 for merge sorting OR enter 1 for bubble sorting"); int numberFromConsole = 0; try { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); String s = br.readLine(); DecimalFormat df = new DecimalFormat(); Number n = df.parse(s); numberFromConsole = n.intValue(); } catch (ParseException ex) { Logger.getLogger(DoublyLinkedList.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException ex) { Logger.getLogger(DoublyLinkedList.class.getName()).log(Level.SEVERE, null, ex); } return numberFromConsole; } and in my main method: public static void main(String[] args) { int i = 0; i = getRandomNumber(10, 10000); int p = chooseTheTypeOfSorting(); DoublyLinkedList list = new DoublyLinkedList(); for (int j = 0; j < i; j++) { list.add(j, getRandomNumber(10, 10000)); if (p == 0) { //do something.... } if (p == 1) { //do something..... } else { System.out.println("write the correct number "); chooseTheTypeOfSorting(); }

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  • hibernate for dynamic table creation

    - by user369316
    i AM A HIBERNATE BEGINNER ,Since i need to create dynamic tables with dynamic fields in them i chose to use hibernate . As far as my understanding , creating tables requires a class with the fields defined in the class . How do i generate the classes dynamically based on the table with the required fields ?

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  • escaping a dollar in the middle of an ant property

    - by jk
    I have a property whose value contains a $. I'd like to use this property as a regexp in a propertyregexp. Ant appears to resolve the property as a paramater to the propertyregexp, but then the dollar gets interpreted as a regexp symbol. Example: <property name="a" value="abc$" /> <property name="b" value="xyz" /> <path id="paths"> <pathelement location="abc$/def" /> <pathelement location="abc$/ghi" /> </path> <pathconvert property="list" refid="paths" pathsep="${line.separator}" dirsep="/" /> <propertyregex property="list" input="${list}" override="true" regexp="${a}(.*)" replace="${b}\1" /> <echo message="${list}" /> I'd like to the pair xyz/def and xyz/ghi. Is this possible? I'm using Ant 1.8.

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  • How to display the properties of the current selected component in a JPanel using the Netbeans Platf

    - by Burmudar
    I am currently building a small visual designer using the Netbeans Platform. All my components that can be placed on the JPanel show correctly in the Palette Window. What I am struggling to do at the moment, is to let the property window show the properties of the component that was either just dragged and dropped or showing the currently selected component in the JPanel in the Properties window. Any help would be greatly appreciated.

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  • SWT Drag and Drop support for Text widget

    - by bryantsai
    I've written an application recently using SWT. In one of its dialog box, I have a few widgets, one of which is Text, which is designed to support DND with other widgets. I've first added DND support for the 2 Tree widgets on the same dialog box (both drag source and drop target). Before I added DND support for that Text widget, I noticed that on Linux platform (gtk), SWT Text widget automatically get drag and drop support. That is, I can already drag from the other Tree widgets and drop on this Text (at any position to inserted there), as well as selecting and dragging any text from this Text to other Tree or Text widget. However, this is only working on Linux platform but not on Windows. The same program, if running on Windows, will not have any DND support for that Text widget (Tree widgets of course have DND support since I specifically write for them). So here's what I want to achieve on Windows as well: drop text at any position in Text widget. before dropping and while hovering, able to see the caret position clearly where the intended position to drop. caret position should move along with the mouse cursor. support multi-line in Text widget SOLUTION: DropTarget target = new DropTarget(sytledText, DND.DROP_MOVE | DND.DROP_COPY); target.setTransfer(new Transfer[] { TextTransfer.getInstance() }); target.addDropListener(new StyleTextDropTargetEffect(sytledText)); Use StyledText instead of Text widget Use StyledTextDropTargetEffect (or extend it) and add it as dr op listener

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  • @NamedQuery select parameter meaning

    - by sergionni
    Found some examples of @NamedQuery annotations,e.g.: @NamedQuery(name="employeeBySsn" query="select e from Employee e where e.ssn = :ssn") what does parameter e mean? the second usage of it seems like alias name of table and what does "select e" part mean?

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  • JToolbar is hidden by JMenu

    - by pierre
    I'm using Netbeans to add a JToolbar to my window which also has a JMenuBar. Here is the design-time look: .. but during run-time I get this: With the toolbar seemingly partially hidden under the menu names. This is on the Mac, btw. Is there something stupid I've forgotten to do or some layout trick I should be using? EDIT: I'll add that the area below the toolbar is a SplitContainer.

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  • Are memcached entries saved by the Danga client compatible with the Spy client?

    - by jigjig
    After saving a String value into memcached using the Danga client, I attempted to get the entry using the Spy client. The two String values are not the same. The Danga client retrieves a string with an additional empty char prepended to the string, therefore violating the equality condition. Danga: t,e,s,t,s,t,r,i,n,g Spy: ,t,e,s,t,s,t,r,i,n,g I also attempted to save a serialized Map using the Danga client and get the Map using the Spy client. The Spy client is able to only get a String form of the Map. The string contains binary values, as below: sr

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  • Prevent an Activity from being killed by the OS while starting a child activity

    - by Martin Marinov
    I have a main activity which calls a child one via Intent I = new Intent(this, Child.class); startActivityForResult(I, 0); But as soon as Child becomes visible the main activity gets its onStop and immediately after that onDestroy method triggered. And as soon as I call finish() within the Child activity or press the back button, the Child activity closes and the home screen shows (instead of the main activity). How can I prevent the main activity from being destroyed? :\

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  • Facebook Connect for BlackBerry

    - by Gadi
    Hi I'm looking for a solution similar to the iPhone Facebook Connect (http://wiki.developers.facebook.com/index.php/Facebook%5FConnect%5Ffor%5FiPhone) for the BlackBerry platform. Basically, I need my users to authenticate against Facebook from within a native BlackBerry application (so, not a Web based mobile application). Is there a library I could use, and if not, what will be the correct approach to achieve this? Thanks in advance!

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  • What is the relation between ContentPane and JPanel?

    - by Roman
    I found one example in which buttons are added to panels (instances of JPanel) then panels are added to the the containers (instances generated by getContentPane) and then containers are, by the construction, included into the JFrame (the windows). I tried two things: I got rid of the containers. In more details, I added buttons to a panel (instance of JPanel) and then I added the panel to the windows (instance of JFrame). It worked fine. I got rid of the panels. In more details, I added buttons directly to the container and then I added the container to the window (instance of JFrame). So, I do not understand two things. Why do we have two competing mechanism to do the same things. What is the reason to use containers in combination with the panels (JPanel)? (For example, what for we include buttons in JPanels and then we include JPanels in the Containers). Can we include JPanel in JPanel? Can we include a container in container?

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  • Semantic stuff (RDF, OWL) on mobile phones - is it possible?

    - by Brian Schimmel
    I'm thinking about using semantic (web) technogies like RDF and OWL in an application on mobile devices. Currently I'm targeting android, but I'd also be interested in the possibilities on the iPhone and on J2ME. I would like to use a lib instead of implementing everything from scratch. I know that there are some libraries and frameworks like Jena, Redland, Protégé but they don't state on which platforms they are known to work. Having a dynamic object model and parsing from and to XML are must-haves for me. I'd also like to use reasoning, but I've been told it was rather computing-intensive, so that's only a nice-to-have. For all platforms mentioned, the question can be interpreted as Is it possible in theory (especially for J2ME I'm not sure) Are there libs that are known to work on those platforms? Is the performance on a mobile platform good enough for real world usage?

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  • Using collections/containers/catalogs in Domain Models

    - by devoured elysium
    Let's say I want to model a cinema. The cinema will have a couple of rooms(for example, 7), where the movies are being played. I wonder how should I design the domain model for this scenario. Should the Cinema class concept concept have a direct association with the 7 rooms? Should the Cinema class concept have an association with a catalog of the 7 rooms? Why? I am having some trouble understanding why in some places I see the first case and in some others I see something like the second case. If instead of rooms, I wanted to depict the relationship between Cinema and: Tickets to sell (today). Tickets already sold (today) Customers in the Cinema database The set of hours at which there are movies playing in a given room in the cinema. The set of places you can sit at in a room in the cinema. Should I use catalogs, should I connect them directly to the Cinema concept with a multiplicity of * in the target? Thanks

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