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  • Java inheritance and super() isn't working as expected

    - by dwwilson66
    For a homework assignment, I'm working with the following. It's an assigned class structure, I know it's not the best design by a long shot. Class | Extends | Variables -------------------------------------------------------- Person | None | firstName, lastName, streetAddress, zipCode, phone CollegeEmployee | Person | ssn, salary,deptName Faculty | CollegeEmployee | tenure(boolean) Student | person | GPA,major So in the Faculty class... public class Faculty extends CollegeEmployee { protected String booleanFlag; protected boolean tenured; public Faculty(String firstName, String lastName, String streetAddress, String zipCode, String phoneNumber,String ssn, String department,double salary) { super(firstName,lastName,streetAddress,zipCode,phoneNumber, ssn,department,salary); String booleanFlag = JOptionPane.showInputDialog (null, "Tenured (Y/N)?"); if(booleanFlag.equals("Y")) tenured = true; else tenured = false; } } It was my understanding that super() in Faculty would allow access to the variables in CollegeEmployee as well as Person. With the code above, it compiles fine when I ONLY include the Person variables. As soon as I try to use ssn, department, or salary I get the following compile errors. Faculty.java:15: error: constructor CollegeEmployee in class CollegeEmployee can not be applied to the given types: super(firstName,lastName,streetAddress,zipCode,phoneNumber,ssn,department,salary); ^ Required: String,String,String,String,String Found: String,String,String,String,String,String,String,String reason: actual and formal argument lists differ in length I'm completely confused by this error...which is the actual and formal? Person has five arguments, CollegeEmployee has 3, so my guess is that something's funky with how the parameters are being passed...but I'm not quite sure where to begin fixing it. What am I missing?

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  • Handling selection and deselection of objects in a user interface

    - by Dennis
    I'm writing a small audio application (in Silverlight, but that's not really relevant I suppose), and I'm a struggling with a problem I've faced before and never solved properly. This time I want to get it right. In the application there is one Arrangement control, which contains several Track controls, and every Track can contain AudioObject controls (these are all custom user controls). The user needs to be able to select audio objects, and when these objects are selected they are rendered differently. I can make this happen by hooking into the MouseDown event of the AudioObject control and setting state accordingly. So far so good, but when an audio object is selected, all other audio objects need to be deselected (well, unless the user holds the shift key). Audio objects don't know about other audio objects though, so they have no way to tell the rest to deselect themselves. Now if I would approach this problem like I did the last time I would pass a reference to the Arrangement control in the constructor of the AudioObject control and give the Arrangement control a DeselectAll() method or something like that, which would tell all Track controls to deselect all their AudioObject controls. This feels wrong, and if I apply this strategy to similar issues I'm afraid I will soon end up with every object having a reference to every other object, creating one big tightly coupled mess. It feels like opening the floodgates for poorly designed code. Is there a better way to handle this?

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  • .NET Splash screen issues

    - by CODe
    I have a splash screen for my C# database application that is called via the Shown event. The splash screen contains some information that is preprocessed when the main form's constructor is called, hence why I'm using the Shown event, because that information should be available. However, when the splash screen is shown, the main form is whited out, and the menu bar, bottom menu bar, and even the gray background are all white and invisible. It looks like the program is hanging, but after the 5 second delay I have built in, the banner goes away and the program is shown normally. Also, on the banner, I have labels that are not shown when the splash screen displays... Here is my code, some reasoning behind why it isn't working would help greatly. SPLASH SCREEN CODE : public partial class StartupBanner : Form { public StartupBanner(int missingNum, int expiredNum) { InitializeComponent(); missingLabel.Text = missingNum.ToString() + " MISSING POLICIES"; expiredLabel.Text = expiredNum.ToString() + " EXPIRED POLICIES"; } } CALLING CODE : private void MainForm_Shown(object sender, EventArgs e) { StartupBanner startup = new StartupBanner(missingPoliciesNum, expiredPoliciesNum); startup.MdiParent = this; startup.Show(); Thread.Sleep(5000); startup.Close(); } Using startup.ShowDialog() shows the correct label information on the splash screen, but that locks up the application, and I need the splash to go away after about 5 seconds, which is why it's a splash. ;)

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  • SL3 Nav framework + MVVM ligh

    - by Murari
    Hi All, Thanks for taking time to read through my question. Any guidance is really appreciated. I am using SL3 Navigation framework in my LOB application. I m currently using MVVM Light as the framework guidance. I have a datagrid consisting of employees and when the "user" clicks on "employee id link" in the datagrid, i am transferring the user to "Edit Page". I would like to transfer the "employee id" as query parameter to "edit page". The issue here is: I can access the query parameter in the EditStaffView.xaml.cs - which i don't want to do. protected override void OnNavigatedTo(NavigationEventArgs e) { if (this.NavigationContext.QueryString.ContainsKey("staffcode")) { string title = this.NavigationContext.QueryString["staffcode"]; } } I would like to retrieve the query parameter in my viewmodel and based on the query parameter, i will perform certain operations. When the constructor is called I would like the "view" to pass the staffid as shown below public EditStaffViewModel(int staffId) { LoadData(staffId); } I am constructing my hyperlink buttons in the datagrid dyanmically as shown below: staffListingModel.HyperlinkNavigationUri = string.Format("{0}{1}", NavigationUri.DataEntryEditStaff,"?staffcode={" + staffListingModel.StaffCode + "}"); and XAML looks HyperlinkButton Content="{Binding StaffCode,Mode=TwoWay}" NavigateUri="{Binding HyperlinkNavigationUri}" HyperlinkButton Any idea how to do this ?? Thanks for the help. Murari

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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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  • [JAX-B] How can I ignore a superclass?

    - by MrSpandex
    I'm trying to write a web service for the java.util.logging api. So I wrote a class MyLogRecord that inherits from LogRecord. I annotated this class with JAX-B annotations, including @XmlAccessorType(XmlAccessType.NONE) so it would ignore non-annotated fields and properties. When I start up tomcat, I get errors that java.util.logging.Level and other java.util.logging classes do not have a default constructor, but none of my annotated methods make any reference to the Level class or any of the other java.util.logging classes. These are referenced by the parent class. My sub-class has everything it needs defined. How can I get JAX-B to ignore the parent class completely? Update: I found another post on this, which suggests modifying the parent class. This is obviously not possible because I am extending a java.util class. IS there any way to do this without modifying the superclass? Update2: I found a thread on java.net for a similar problem. That thread resulted in an enhancement request, which was marked as a duplicate of another issue, which resulted in the @XmlTransient annotation. The comments on these bug reports lead me to believe this is impossible in the current spec.

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  • Java swing app can't find image

    - by KáGé
    Hello, I'm making a torpedo game for school in java with swing gui, please see the zipped source HERE. I use custom button icons and mouse cursors of images stored in the /bin/resource/graphics/default folder's subfolders, where the root folder is the program's root folder (it will be the root in the final .jar as well I suppose) which apart from "bin" contains a "main" folder with all the classes. The relative path of the resources is stored in MapStruct.java's shipPath and mapPath variables. Now Battlefield.java's PutPanel class finds them all right and sets up its buttons' icons fine, but every other class fail to get their icons, e.g. Table.java's setCursor, which should set the mouse cursor for all its elements for the selected ship's image or Field.java's this.button.setIcon(icon); in the constructor, which should set the icon for the buttons of the "water". I watched with debug what happens, and the images stay null after loading, though the paths seem to be correct. I've also tried to write a test file in the image folder but the method returns a filenotfound exception. I've tried to get the path of the class to see if it runs from the supposed place and it seems it does, so I really can't find the problem now. Could anyone please help me? Thank you.

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  • Java KeyListener in separate class

    - by Chris
    So I have my main class here, where basically creates a new jframe and adds a world object to it. The world object is basically where all drawing and keylistening would take place... public class Blobs extends JFrame{ public Blobs() { super("Blobs :) - By Chris Tanaka"); setVisible(true); setResizable(false); setSize(1000, 1000); setIgnoreRepaint(true); setDefaultCloseOperation(EXIT_ON_CLOSE); add(new World()); } public static void main(String[] args) { new Blobs(); } } How exactly would you get key input from the world class? (So far I have my world class extending a jpanel and implementing a keylistener. In the constructor i addKeyListener(this). I also have these methods since they are auto implemented: public void keyPressed(KeyEvent e) { if (e.getKeyCode() == KeyEvent.VK_W) System.out.println("Hi"); } public void keyReleased(KeyEvent e) {} public void keyTyped(KeyEvent e) {} However this does not seem to work?

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  • Windsor IHandlerSelector in RIA Services Visual Studio 2010 Beta2

    - by Savvas Sopiadis
    Hi everybody! I want to implement multi tenancy using Windsor and i don't know how to handle this situation: i succesfully used this technique in plain ASP.NET MVC projects and thought incorporating in a RIA Services project would be similar. So i used IHandlerSelector, registered some components and wrote an ASP.NET MVC view to verify it works in a plain ASP.NET MVC environment. And it did! Next step was to create a DomainService which got an IRepository injected in the constructor. This service is hosted in the ASP.NET MVC application. And it actually ... works:i can get data out of it to a Silverlight application. Sample snippet: public OrganizationDomainService(IRepository<Culture> cultureRepository) { this.cultureRepository = cultureRepository; } Last step is to see if it works multi-tenant-like: it does not! The weird thing is this: using some line of code and writing debug messages in a log file i verified that the correct handler is selected! BUT this handler seems not to be injected in the DomainService. I ALWAYS get the first handler (that's the logic in my SelectHandler) Can anybody verify this behavior? Is injection not working in RIA Services? Or am i missing something basic?? Development environment: Visual Studio 2010 Beta2 Thanks in advance

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  • Accessing Web.config directly in ASP.NET MVC 1

    - by Neil T.
    I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve?

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  • What happens when we combine RAII and GOTO ?

    - by Robert Gould
    I'm wondering, for no other purpose than pure curiosity (because no one SHOULD EVER write code like this!) about how the behavior of RAII meshes with the use of Goto (lovely idea isn't it). class Two { public: ~Two() { printf("2,"); } }; class Ghost { public: ~Ghost() { printf(" BOO! "); } }; void foo() { { Two t; printf("1,"); goto JUMP; } Ghost g; JUMP: printf("3"); } int main() { foo(); } When running the following code in VS2005 I get the following output: 1,2,3 BOO! However I imagined, guessed, hoped that 'BOO!' wouldn't actually appear as the Ghost should have never been instantiated (IMHO, because I don't know the actual expected behavior of this code). Any Guru out there knows what's up? Just realized that if I instantiate an explicit constructor for Ghost the code doesn't compile... class Ghost { public: Ghost() { printf(" HAHAHA! "); } ~Ghost() { printf(" BOO! "); } }; Ah, the mystery ...

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  • Returning object from function

    - by brainydexter
    I am really confused now on how and which method to use to return object from a function. I want some feedback on the solutions for the given requirements. Scenario A: The returned object is to be stored in a variable which need not be modified during its lifetime. Thus, const Foo SomeClass::GetFoo() { return Foo(); } invoked as: someMethod() { const Foo& l_Foo = someClassPInstance->GetFoo(); //... } Scneraio B: The returned object is to be stored in a variable which will be modified during its lifetime. Thus, void SomeClass::GetFoo(Foo& a_Foo_ref) { a_Foo_ref = Foo(); } invoked as: someMethod() { Foo l_Foo; someClassPInstance-GetFoo(l_Foo); //... } I have one question here: Lets say that Foo cannot have a default constructor. Then how would you deal with that in this situation, since we cant write this anymore: Foo l_Foo Scenario C: Foo SomeClass::GetFoo() { return Foo(); } invoked as: someMethod() { Foo l_Foo = someClassPInstance->GetFoo(); //... } I think this is not the recommended approach since it would incur constructing extra temporaries. What do you think ? Also, do you recommend a better way to handle this instead ?

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  • Initializing objects on the fly

    - by pocoa
    I have a vector called players and a class called Player. And what I'm trying to do is to write: players.push_back(Player(name, Weapon(bullets))); So I want to be able to create players in a loop. But I see an error message says "no matching function for call Player::Player..." Then I've changed that to: Weapon w(bullets); Player p(name, w); players.push_back(p); Here is my Player definition: class Player { public: Player(string &name, Weapon &weapon); private string name; Weapon weapon; } I'm just trying to learn what is the difference between these definitions. And is this the right way to pass an object to an object constructor. Note: These are not my actual class definitions. I'm just trying to learn something about object oriented programming in C++ with coding it. I mean I know that Weapon should be initialized in Player :)

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  • Live wallpaper settings not applying

    - by Steve
    I have added settings to my live wallpaper but they are not being applied when changed. I would greatly appreciate it if someone could tell me why my settings are not being applied when changed. Here is my code: settings.xml <PreferenceCategory android:title="@string/more"> <PreferenceScreen android:title="@string/more"> <intent android:action="android.intent.action.VIEW" android:data="market://search?q=pub:PSP Demo Center" /> </PreferenceScreen> <ListPreference android:persistent="true" android:enabled="true" android:entries="@array/settings_light_number_options" android:title="@string/settings_light_number" android:key="light_power" android:summary="@string/settings_light_number_summary" android:defaultValue="3" android:entryValues="@array/settings_light_number_optionvalues" /> <ListPreference android:persistent="true" android:enabled="false" android:entries="@array/settings_speed_number_options" android:title="@string/settings_speed_number" android:key="speed" android:summary="@string/settings_speed_number_summary" android:defaultValue="10" android:entryValues="@array/settings_speed_number_optionvalues" /> <ListPreference android:persistent="true" android:enabled="false" android:entries="@array/settings_rotate_number_options" android:title="@string/settings_rotate_number" android:key="rotate" android:summary="@string/settings_rotate_number_summary" android:defaultValue="8000" android:entryValues="@array/settings_rotate_number_optionvalues" /> </PreferenceCategory> </PreferenceScreen> Settings.java public class GraffitiLWPSettings extends PreferenceActivity implements SharedPreferences .OnSharedPreferenceChangeListener { public static final String SHARED_PREFS_NAME = "wallpaper_settings"; protected void onCreate(Bundle icicle) { super.onCreate(icicle); getPreferenceManager(). setSharedPreferencesName(GraffitiLWP.SHARED_PREFS_NAME); addPreferencesFromResource(R.xml.settings); getPreferenceManager().getSharedPreferences(). registerOnSharedPreferenceChangeListener(this); } protected void onResume() { super.onResume(); } protected void onDestroy() { getPreferenceManager().getSharedPreferences() .unregisterOnSharedPreferenceChangeListener(this); super.onDestroy(); } public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) { } } wallpaper.java public class GraffitiLWP extends Wallpaper { private GraffitiLWPRenderer mRenderer; public static final String SHARED_PREFS_NAME = "wallpaper_settings"; public Engine onCreateEngine() { mRenderer = new GraffitiLWPRenderer(this); return new WallpaperEngine( this.getSharedPreferences(SHARED_PREFS_NAME, Context.MODE_PRIVATE), getBaseContext(), mRenderer); } } renderer.java public class GraffitiLWPRenderer extends RajawaliRenderer { private Animation3D mAnim; private BaseObject3D mCan; private SettingsUpdater settingsUpdater; //private SharedPreferences preferences; public GraffitiLWPRenderer(Context context) { super(context); setFrameRate(20); } public class SettingsUpdater implements SharedPreferences .OnSharedPreferenceChangeListener { private GraffitiLWPRenderer renderer; public SettingsUpdater(GraffitiLWPRenderer renderer) { this.renderer = renderer; } public void onSharedPreferenceChanged( SharedPreferences sharedPreferences, String key) { preferences.getInt("wallpaper_settings", 0); renderer.setSharedPreferences(preferences); } } public void initScene() { System.gc(); ALight light = new DirectionalLight(); light.setPower(this.preferences.getLong("light_power", 3)); light.setPosition(0, 0, -10); mCamera.setPosition(0, -1, -7); mCamera.setLookAt(0, 2, 0); mCamera.setFarPlane(1000); ObjParser parser = new ObjParser(mContext .getResources(), mTextureManager, R.raw.spraycan_obj); parser.parse(); mCan = parser.getParsedObject(); mCan.addLight(light); mCan.setScale(1.2f); addChild(mCan); Number3D axis = new Number3D(0, this.preferences.getLong("speed", 10), 0); axis.normalize(); mAnim = new RotateAnimation3D(axis, 360); mAnim.setDuration(this.preferences.getLong("rotate", 8000)); mAnim.setRepeatCount(Animation3D.INFINITE); mAnim.setInterpolator(new AccelerateDecelerateInterpolator()); mAnim.setTransformable3D(mCan); setSkybox(R.drawable.posz, R.drawable.posx, R.drawable.negz, R.drawable.negx, R.drawable.posy, R.drawable.negy); } public void onSurfaceCreated(GL10 gl, EGLConfig config) { settingsUpdater = new SettingsUpdater(this); this.preferences.registerOnSharedPreferenceChangeListener( settingsUpdater); settingsUpdater.onSharedPreferenceChanged(preferences, null); super.onSurfaceCreated(gl, config); mAnim.start(); } public void onDrawFrame(GL10 glUnused) { super.onDrawFrame(glUnused); mSkybox.setRotY(mSkybox.getRotY() + .5f); } } I know the code is long but I would greatly appreciate any help that someone could give me. Thank you.

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  • Zend framework controller action helper

    - by guptanikhilchandra
    I am getting fatal error after adding the action helper class. I am trying to load layout corresponding to called layout. Following is my code snippet: First of all i added a helper class under application/controller/helpers: class Zend_Controller_Action_Helper_Layout extends Zend_Controller_Action_Helper_Abstract { public $pluginLoader; public function __construct() { // TODO Auto-generated Constructor $this->pluginLoader = new Zend_Loader_PluginLoader (); } public function preDispatch() { $bootstrap = $this->getActionController()->getInvokeArg('bootstrap'); $config = $bootstrap->getOptions(); $module = $this->getRequest()->getModuleName(); if (isset($config[$module]['resources']['layout']['layout'])) { $layoutScript = $config[$module]['resources']['layout']['layout']; $this->getActionController()->getHelper('layout')->setLayout($layoutScript); } } } Then i added a loader in bootstrap.php: protected function _initLayoutHelper() { $this->bootstrap('frontController'); Zend_Controller_Action_HelperBroker::addPath(APPLICATION_PATH .'/controllers/helpers'); $layout = Zend_Controller_Action_HelperBroker::addHelper(new Zend_Controller_Action_Helper_Layout()); } Following is my application.ini: [production] autoloaderNamespaces.tree = "Tree_" phpSettings.display_startup_errors = 0 phpSettings.display_errors = 0 includePaths.library = APPLICATION_PATH "/../library" bootstrap.path = APPLICATION_PATH "/Bootstrap.php" bootstrap.class = "Bootstrap" resources.frontController.controllerDirectory = APPLICATION_PATH "/controllers" resources.frontController.moduleDirectory = APPLICATION_PATH "/modules" resources.frontController.helperDirectory = APPLICATION_PATH "/controllers/helpers" resources.modules[] = "" contact.resources.frontController.defaultControllerName = "index" resources.layout.layoutPath = APPLICATION_PATH "/layouts/scripts" resources.layout.layout = layout admin.resources.layout.layout = admin admin.resources.layout.layoutPath = APPLICATION_PATH "/layouts/scripts" resources.view[] = [staging : production] [testing : production] phpSettings.display_startup_errors = 1 phpSettings.display_errors = 1 [development : production] phpSettings.display_startup_errors = 1 phpSettings.display_errors = 1 While running this code i am getting following errors: Warning: include(Zend\Controller\Action\Helper\LayoutLoader.php) [function.include]: failed to open stream: No such file or directory in D:\personal\proj\renovate\library\Zend\Loader.php on line 83 Warning: include() [function.include]: Failed opening 'Zend\Controller\Action\Helper\LayoutLoader.php' for inclusion (include_path='D:\personal\proj\renovate\application/../library;D:\personal\proj\renovate\library;.;C:\php5\pear') in D:\personal\proj\renovate\library\Zend\Loader.php on line 83 Fatal error: Class 'Zend_Controller_Action_Helper_LayoutLoader' not found in D:\personal\proj\renovate\application\Bootstrap.php on line 33 Kindly let me know, how can i come out from this issue. I am beginner in Zend Framework. Thanks Nikhil

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  • Fastest Java way to remove the first/top line of a file (like a stack)

    - by christangrant
    I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

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  • How is a functional programming-based javascript app laid out?

    - by user321521
    I've been working with node.js for awhile on a chat app (I know, very original, but I figured it'd be a good learning project). Underscore.js provides a lot of functional programming concepts which look interesting, so I'd like to understand how a functional program in javascript would be setup. From my understanding of functional programming (which may be wrong), the whole idea is to avoid side effects, which are basically having a function which updates another variable outside of the function so something like var external; function foo() { external = 'bar'; } foo(); would be creating a side effect, correct? So as a general rule, you want to avoid disturbing variables in the global scope. Ok, so how does that work when you're dealing with objects and what not? For example, a lot of times, I'll have a constructor and an init method that initializes the object, like so: var Foo = function(initVars) { this.init(initVars); } Foo.prototype.init = function(initVars) { this.bar1 = initVars['bar1']; this.bar2 = initVars['bar2']; //.... } var myFoo = new Foo({'bar1': '1', 'bar2': '2'}); So my init method is intentionally causing side effects, but what would be a functional way to handle the same sort of situation? Also, if anyone could point me to either a python or javascript source code of a program that tries to be as functional as possible, that would also be much appreciated. I feel like I'm close to "getting it", but I'm just not quite there. Mainly I'm interested in how functional programming works with traditional OOP classes concept (or does away with it for something different if that's the case).

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  • Java Inheritance - Getting a Parameter from Parent Class

    - by Aaron
    I'm trying to take one parameter from the parent class of Car and add it to my array (carsParked), how can i do this? Parent Class public class Car { protected String regNo; //Car registration number protected String owner; //Name of the owner protected String carColor; /** Creates a Car object * @param rNo - registration number * @param own - name of the owner **/ public Car (String rNo, String own, String carColour) { regNo = rNo; owner = own; carColor = carColour; } /** @return The car registration number **/ public String getRegNo() { return regNo; } /** @return A String representation of the car details **/ public String getAsString() { return "Car: " + regNo + "\nColor: " + carColor; } public String getColor() { return carColor; } } Child Class public class Carpark extends Car { private String location; // Location of the Car Park private int capacity; // Capacity of the Car Park - how many cars it can hold private int carsIn; // Number of cars currently in the Car Park private String[] carsParked; /** Constructor for Carparks * @param loc - the Location of the Carpark * @param cap - the Capacity of the Carpark */ public Carpark (String locations, int room) { location = locations; capacity = room; } /** Records entry of a car into the car park */ public void driveIn() { carsIn = carsIn + 1; } /** Records the departure of a car from the car park */ public void driveOut() { carsIn = carsIn - 1; } /** Returns a String representation of information about the carpark */ public String getAsString() { return location + "\nCapacity: " + capacity + " Currently parked: " + carsIn + "\n*************************\n"; } }

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  • Remove pointer object whose reference is mantained in three different lists

    - by brainydexter
    I am not sure how to approach this problem: 'Player' class mantains a list of Bullet* objects: class Player { protected: std::list< Bullet* > m_pBullet_list; } When the player fires a Bullet, it is added to this list. Also, inside the constructor of bullet, a reference of the same object is updated in CollisionMgr, where CollisionMgr also mantains a list of Bullet*. Bullet::Bullet(GameGL*a_pGameGL, Player*a_pPlayer) : GameObject( a_pGameGL ) { m_pPlayer = a_pPlayer; m_pGameGL->GetCollisionMgr()->AddBullet(this); } class CollisionMgr { void AddBullet(Bullet* a_pBullet); protected: std::list< Bullet*> m_BulletPList; } In CollisionMgr.Update(); based on some conditions, I populate class Cell which again contain a list of Bullet*. Finally, certain conditions qualify a Bullet to be deleted. Now, these conditions are tested upon while iterating through a Cell's list. So, if I have to delete the Bullet object, from all these places, how should I do it so that there are no more dangling references to it? std::list< Bullet*>::iterator bullet_it; for( bullet_it = (a_pCell->m_BulletPList).begin(); bullet_it != (a_pCell->m_BulletPList).end(); bullet_it++) { bool l_Bullet_trash = false; Bullet* bullet1 = *bullet_it; // conditions would set this to true if ( l_Bullet_Trash ) // TrashBullet( bullet1 ); continue; } Also, I was reading about list::remove, and it mentions that it calls the destructor of the object we are trying to delete. Given this info, if I delete from one list, the object does not exist, but the list would still contain a reference to it..How do I handle all these problems ? Can someone please help me here ? Thanks PS: If you want me to post more code or provide explanation, please do let me know.

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  • How do I mock a method with an open array parameter in PascalMock?

    - by Oliver Giesen
    I'm currently in the process of getting started with unit testing and mocking for good and I stumbled over the following method that I can't seem to fabricate a working mock implementation for: function GetInstance(const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID = CID_DEFAULT): Boolean; (TImplContextID is just an alias for Integer) I thought it would have to look something like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; begin Result := AddCall('GetInstance') .WithParams([@AIID, AContextID]) .ReturnsOutParams([AInstance]) .ReturnValue; end; But the compiler complains about the .ReturnsOutParams([AInstance]) saying "Bad argument type in variable type array constructor.". Also I haven't found a way to specify the open array parameter AArgs at all. Also, is using the @-notation for the TGUID-typed parameter the right way to go? Is it possible to mock this method with the current version of PascalMock at all? Update: I now realize I got the purpose of ReturnsOutParams completely wrong: It's intended to be used for populating the values to be returned when defining the expectations rather than for mocking the call itself. I now think the correct syntax for mocking the out parameter would probably have to look more like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; var lCall: TMockMethod; begin lCall := AddCall('GetInstance').WithParams([@AIID, AContextID]); Pointer(AInstance) := lCall.OutParams[0]; Result := lCall.ReturnValue; end; The questions that remain are how to mock the open array parameter AArgs and whether passing the TGUID argument (i.e. a value type) by address will work out...

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  • How to process events chain.

    - by theblackcascade
    I need to process this chain using one LoadXML method and one urlLoader object: ResourceLoader.Instance.LoadXML("Config.xml"); ResourceLoader.Instance.LoadXML("GraphicsSet.xml"); Loader starts loading after first frameFunc iteration (why?) I want it to start immediatly.(optional) And it starts loading only "GraphicsSet.xml" Loader class LoadXml method: public function LoadXML(URL:String):XML { urlLoader.addEventListener(Event.COMPLETE,XmlLoadCompleteListener); urlLoader.load(new URLRequest(URL)); return xml; } private function XmlLoadCompleteListener(e:Event):void { var xml:XML = new XML(e.target.data); trace(xml); trace(xml.name()); if(xml.name() == "Config") XMLParser.Instance.GameSetup(xml); else if(xml.name() == "GraphicsSet") XMLParser.Instance.GraphicsPoolSetup(xml); } Here is main: public function Main() { Mouse.hide(); this.addChild(Game.Instance); this.addEventListener(Event.ENTER_FRAME,Game.Instance.Loop); } And on adding a Game.Instance to the rendering queue in game constuctor i start initialize method: public function Game():void { trace("Constructor"); if(_instance) throw new Error("Use Instance Field"); Initialize(); } its code is: private function Initialize():void { trace("initialization"); ResourceLoader.Instance.LoadXML("Config.xml"); ResourceLoader.Instance.LoadXML("GraphicsSet.xml"); } Thanks.

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  • Simple Detached pThread does not cancel! (cout blocks and interleaves even if mutexed)

    - by Gabriel
    I have a hard problem here, which I can not solve and do not find the right answer on the net: I have created a detached thread with a clean up routing, the problem is that on my Imac and Ubuntu 9.1 (Dual Core). I am not able to correctly cancel the detached thread in the fallowing code: #include <iostream> #include <pthread.h> #include <sched.h> #include <signal.h> #include <time.h> pthread_mutex_t mutex_t; using namespace std; static void cleanup(void *arg){ pthread_mutex_lock(&mutex_t); cout << " doing clean up"<<endl; pthread_mutex_unlock(&mutex_t); } static void *thread(void *aArgument) { pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL); pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,NULL); pthread_cleanup_push(&cleanup,NULL); int n=0; while(1){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 2: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_cleanup_pop(0); return NULL; } int main() { pthread_t thread_id; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED); int error; if (pthread_mutex_init(&mutex_t,NULL) != 0) return 1; if (pthread_create(&thread_id, &attr, &(thread) , NULL) != 0) return 1; pthread_mutex_lock(&mutex_t); cout << "waiting 1s for thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); int n =0; while(n<1E3){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 1: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "canceling thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); if (pthread_cancel(thread_id) == 0) { //This doesn't wait for the thread to exit pthread_mutex_lock(&mutex_t); cout << "detaching thread...\n"<<endl; pthread_mutex_unlock(&mutex_t); pthread_detach(thread_id); while (pthread_kill(thread_id,0)==0) { sched_yield(); } pthread_mutex_lock(&mutex_t); cout << "thread is canceled"; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "exit"<<endl; pthread_mutex_unlock(&mutex_t); return 0; } When I replace the Cout with printf() i workes to the end "exit" , but with the cout (even locked) the executable hangs after outputting "detaching thread... It would be very cool to know from a Pro, what the problem here is?. Why does this not work even when cout is locked by a mutex!? Thanks a lot for your support!!

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  • Android inserting into SQLite JSON object

    - by Nizmon
    I'm trying to insert the below json response from a server into my sqlite DB and then read from the DB. The problem I am getting is that when I run my code it compiles fine and runs with no errors. But when trying to read from the DB I just get back what seems like an empty string so I know that the table is being created. I have the correct permissions within the manifest. I have also reference all my classes within there. {"locations": [{"locations":"Newcastle","location_id":"1"},{"locations":"London","location_id":"2"},{"locations":"Sunderland","location_id":"3"}]} Below where I use: Log.v("one", one); Log.v("two", two); below It only prints out the first set within the JSON object so Newcastle and 1. I don't get any errors at all which is stumping me. When I call the method getName within the Location class I just seem to get a blank string back! // This class creates the table as well as inserts and returns data from the sqlite DB public class Location { private DatabaseHelper mDbHelper; private SQLiteDatabase mDb; private final Context mCtx; private static final String vd_location = ("CREATE TABLE " + TABLE_VD_LOCATION + " (" + LOCATION + " TEXT," + LOCATION_ID + " TEXT " +");"); private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(vd_location); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } } public Location(Context ctx) { this.mCtx = ctx; } public Location open() throws SQLException { this.mDbHelper = new DatabaseHelper(this.mCtx); this.mDb = this.mDbHelper.getWritableDatabase(); return this; } public void close() { this.mDbHelper.close(); } public void addOffer (JSONObject json){ try{ JSONArray earthquakes = json.getJSONArray("offers"); for(int i=0;i<earthquakes.length();i++){ open(); JSONObject e = earthquakes.getJSONObject(i); String one = e.getString("locations"); String two = e.getString("location_id"); Log.v("one", one); Log.v("two", two); mDb.execSQL("INSERT INTO " + TABLE_VD_LOCATION + " ( locations, location_id ) " + "VALUES (?, ?)", new Object [] { e.getString("locations"), e.getString("location_id")}); close(); } }catch(Exception e){ }finally{ close(); } } public String getName(long l) throws SQLException{ String[] columns = new String[]{ LOCATION, LOCATION_ID}; Cursor c = mDb.query(TABLE_VD_LOCATION, columns, null, null, null, null, null); String result = ""; int iRow = c.getColumnIndex(LOCATION); int iName = c.getColumnIndex(LOCATION_ID); for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){ result = result + c.getString(iRow) + " " + c.getString(iName) + " " + "\n"; } return result; } } // This code reads from the DB, this is just some very hacked together code so excuse it, it also works when used on other tables public void getData(){ boolean didItWork = true; try { Location loc = new Location(this); loc.open(); String data = loc.getName(0); loc.close(); Dialog t = new Dialog(this); t.setTitle("get" + data); t.show(); } catch (Exception e) { didItWork = false; String error = e.toString(); Dialog d = new Dialog(this); d.setTitle("Dang it!"); TextView tv = new TextView(this); tv.setText(error); d.setContentView(tv); d.show(); } finally { if (didItWork) { Dialog d = new Dialog(this); d.setTitle("Heck Yea!"); TextView tv = new TextView(this); tv.setText("Success"); d.setContentView(tv); d.show(); //entry.close(); } } }

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  • Adding an ASP.NET Web User Control to a Control Dynamically

    - by RandomBen
    I have a simple ASP.NET Web User Control. It looks like this: <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="NewsArticle.ascx.cs" Inherits="Website.Controls.NewsArticle" %> <div> <asp:Literal ID="ltlBody" runat="server" /> </div> My code behind looks like this: namespace Website.Controls { public partial class NewsArticle : System.Web.UI.UserControl { public String bodyText { //get { return ltlBody.Text; } set { ltlBody.Text = value; } } } } On a .aspx page I have <asp:Panel ID="pNews" runat="server" /> In the code behind I have: foreach (vwNews news in newsQuery) { NewsArticle article = new NewsArticle(); aticle.bodyText = news.Body; pNews.Controls.Add(article); } Every time I run this code the newsQuery is populated correctly and I get to the line aticle.bodyText = news.Body; and then I received the error article.bodyText threw an exception of type 'System.NullReferenceException' I am not sure what is causing this error message or how to fix it. I would think that there should not be an issue. I tried creating a constructor for my Web User Control so that it would give default values to my properties but that didn't work. Any idea how to make this work? It doesn't seem like it should be that

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  • Intermittent Issue Writing to Google Appengine Datastore

    - by user242153
    Hi, I have a functioning app and recently have had intermittent problems writing to the datastore. I did not make any relevant code changes, however in the last few days my attempts to write to the datastore sometimes work and sometimes don't. I am trying to save an object that is in a many to one relationship with an existing persisted parent. So, the logic works like this: 1) Parent pulled from the datastore 2) Child created / instantiated using constructor 3) Parent.addSingleChild(child); // the "addSingleChild" method just adds the object argument to the collection of children 4) child.setParent(Parent); // sets the Parent object to the parent field I am using transactions as explained in the documentation ending with "finally {if (tx.isActive()) {tx.rollback(); } }" When the servlet is called, the parent is called from the datastore and the child object is created and added to the many to one mapping to the pre-existing parent. The child should automatically be persisted, since the parent is already persistent, and the child is added to the collection of children that map to the parent. And it worked this way in the past. However, to be sure, i did add a pm.makePersistent(child). Doesn't seem to help, still have the intermittent problem. Any suggestions would be appreciated, and if you need to see the actual code I can post. Thanks

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