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  • Using XPath on String in Android (JAVA)

    - by Rav
    I am looking for some examples of using xpath in Android? Or if anyone can share their experiences. I have been struggeling to make tail or head of this problem :-( I have a string that contains a standard xml file. I believe I need to convert that into an xml document. I have found this code which I think will do the trick: public static Document stringToDom(String xmlSource) throws SAXException, ParserConfigurationException, IOException { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); return builder.parse(new InputSource(new StringReader(xmlSource))); } Next steps Assuming the code above is OK, I need to apply xpath to get values from cat: "/animal/mammal/feline/cat" I look at the dev doc here: http://developer.android.com/reference/javax/xml/xpath/XPath.html and also look online, but I am not sure where to start! I have tried to use the following code: XPathFactory xPathFactory = XPathFactory.newInstance(); // To get an instance of the XPathFactory object itself. XPath xPath = xPathFactory.newXPath(); // Create an instance of XPath from the factory class. String expression = "SomeXPathExpression"; XPathExpression xPathExpression = xPath.compile(expression); // Compile the expression to get a XPathExpression object. Object result = xPathExpression.evaluate(xmlDocument); // Evaluate the expression against the XML Document to get the result. But I get "Cannot be resolved". Eclipse doesn't seem to be able to fix this import. I tried manually entering: javax.xml.xpath.XPath But this did not work. Does anyone know any good source code that I can utilise, for Android platform? 1.5

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  • Constructor Overloading

    - by Mark Baker
    Normally when I want to create a class constructor that accepts different types of parameters, I'll use a kludgy overloading principle of not defining any args in the constructor definition: e.g. for an ECEF coordinate class constructor, I want it to accept either $x, $y and $z arguments, or to accept a single array argument containg x, y and z values, or to accept a single LatLong object I'd create a constructor looking something like: function __construct() { // Identify if any arguments have been passed to the constructor if (func_num_args() > 0) { $args = func_get_args(); // Identify the overload constructor required, based on the datatype of the first argument $argType = gettype($args[0]); switch($argType) { case 'array' : // Array of Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromArray'; break; case 'object' : // A LatLong object that needs converting to Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromLatLong'; break; default : // Individual Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromXYZ'; break; } // Call the appropriate overload constructor call_user_func_array(array($this,$overloadConstructor),$args); } } // function __construct() I'm looking at an alternative: to provide a straight constructor with $x, $y and $z as defined arguments, and to provide static methods of createECEFfromArray() and createECEFfromLatLong() that handle all the necessary extraction of x, y and z; then create a new ECEF object using the standard constructor, and return that Which option is cleaner from an OO purists perspective?

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  • How to authenticate my own provider( only for testing purposes)

    - by user308806
    Dear all Now, I wrote a new provider (ESMJCE provider), and I also write a simple application to test it, but I have some exceptions like that java.lang.SecurityException: JCE cannot authenticate the provider ESMJCE at javax.crypto.Cipher.getInstance(DashoA13*..) at javax.crypto.Cipher.getInstance(DashoA13*..) at testprovider.main(testprovider.java:27) Caused by: java.util.jar.JarException: Cannot parse file:/C:/Program%20Files/Java/jre1.6.0_02/lib/ext/abc.jar at javax.crypto.SunJCE_c.a(DashoA13*..) at javax.crypto.SunJCE_b.b(DashoA13*..) at javax.crypto.SunJCE_b.a(DashoA13*..) ... 3 more And here is my source code import java.security.Provider; import java.security.Security; import javax.crypto.Cipher; import esm.jce.provider.ESMProvider; public class testprovider { / @param args / public static void main(String[] args) { // TODO Auto-generated method stub ESMProvider esmprovider = new esm.jce.provider.ESMProvider(); Security.insertProviderAt(esmprovider,2); Provider[] temp = Security.getProviders(); for (int i= 0; i<temp.length; i++){ System.out.println("Providers: " temp[i].getName()); } try{ Cipher cipher = Cipher.getInstance("DES", "ESMJCE"); System.out.println("Cipher: " cipher); int blockSize= cipher.getBlockSize(); System.out.println("blockSize= " + blockSize); }catch (Exception e){ e.printStackTrace(); } } } Please help me solve this issue Thanks

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  • Mono WCF NetTcp service takes only one client at a time

    - by vene
    While trying to build a client-server WCF application in Mono we ran into some issues. Reducing it to just a bare example we found that the service only accepts one client at a time. If another client attempts to connect, it hangs until the first one disconnects. Simply changing to BasicHttpBinding fixes it but we need NetTcpBinding for duplex communication. Also the problem does not appear if compiled under MS .NET. EDIT: I doubt (and hope not) that Mono doesn't support what I'm trying to do. Mono code usually throws NotImplementedExceptions in such cases as far as I noticed. I am using Mono v2.6.4 This is how the service is opened in our basic scenario: public static void Main (string[] args) { var binding = new NetTcpBinding (); binding.Security.Mode = SecurityMode.None; var address = new Uri ("net.tcp://localhost:8080"); var host = new ServiceHost (typeof(Hello)); host.AddServiceEndpoint (typeof(IHello), binding, address); ServiceThrottlingBehavior behavior = new ServiceThrottlingBehavior () { MaxConcurrentCalls = 100, MaxConcurrentSessions = 100, MaxConcurrentInstances = 100 }; host.Description.Behaviors.Add (behavior); host.Open (); Console.ReadLine (); host.Close (); } The client channel is obtained like this: var binding = new NetTcpBinding (); binding.Security.Mode = SecurityMode.None; var address = new EndpointAddress ("net.tcp://localhost:8080/"); var client = new ChannelFactory<IHello> (binding, address).CreateChannel (); As far as I know this is a Simplex connection, isn't it? The contract is simply: [ServiceContract] public interface IHello { [OperationContract] string Greet (string name); } Service implementation has no ServiceModel tags or attributes. I'll update with details as required.

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  • TreeMap sort by value

    - by vito huang
    I'm new to java, i want to write an comparator to that will let me sort TreeMap by value instead of the default natural sorting. i tried something like this, but can't find out what went wrong: import java.util.*; class treeMap { public static void main(String[] args) { System.out.println("the main"); byValue cmp = new byValue(); Map<String, Integer> map = new TreeMap<String, Integer>(cmp); map.put("de",10); map.put("ab", 20); map.put("a",5); for (Map.Entry<String,Integer> pair: map.entrySet()) { System.out.println(pair.getKey()+":"+pair.getValue()); } } } class byValue implements Comparator<Map.Entry<String,Integer>> { public int compare(Map.Entry<String,Integer> e1, Map.Entry<String,Integer> e2) { if (e1.getValue() < e2.getValue()){ return 1; } else if (e1.getValue() == e2.getValue()) { return 0; } else { return -1; } } } I guess what am i asking is what controls what get pass to comparator function, can i get an Map.Entry pass to comparator?

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  • What is the space character for the browser?

    - by Hiro Protagonist
    echo "\n\s\s\s\s\s\s" . "<div id='data-load' data-load='" . $load . "'></div>"; \n works for adding a return in...I tried \s logically for space but this does not work. Keep mind, I don't want this rendered in the browser view...but in the source view ( when you click view-source )...I'm trying to put my html in to a readable form. echo "&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp\n" . "<div id='data-path' data-path='" . $path . "'></div>"; This does not work either. I am composing HTML from PHP... echo " \n" . "<div id='data-load' data-load='" . $load . "'></div>"; This does not work either. Actual Code: public static function setUniversals() { $shared_object = new Shared(); if ( $shared_object->getLoadOn() == 1 ) { $load = 'server'; } else { $load = 'client'; } if( getcwd() === '/home/foo/public_html/develop' ) { $path = 'development'; } else { $path = 'production'; } $shared_object = new Shared(); echo "\n"; echo "\n " . "<div id='data-path' data-path='" . $path . "'></div>"; echo "\n " . "<div id='data-load' data-load='" . $load . "'></div>"; }

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  • Pros and cons of each JEE server for developing within Eclipse

    - by Thorbjørn Ravn Andersen
    Eclipse JEE has a lot of server adapters allowing development against many different application servers like JBoss, Glassfish and WebSphere. Frequently you can benefit from using another server for developing new features than for production, simply because it may be able to deploy changes much faster and when the functionality is in place, you can iron out bugs for the production platform. Unfortunately finding that server is a time consuming process, where others experience is invaluable. If you have experience with any server with an Eclipse Server Adapter, please add your findings and your recommendation. I believe that the following is of interest: Does saving a file trigger an update in the server, giving save edit+reload browser functionality? How fast is a deployment? (Saved a JSP? Java class? Static file?) Can the actual server be downloaded by the Server Adapter Wizard allowing for easy installation? Are there known bugs and issues with suitable work-arounds? Is debugging fully supported? Is profiling? Would you recommend this server? Note: Eclipse can also work with Tomcat but that is a web container, which cannot deploy EAR files.

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  • Dynamically added JTable not displaying

    - by Graza
    Java Newbie here. I have a JFrame that I added to my netbeans project, and I've added the following method to it, which creates a JTable. Problem is, for some reason when I call this method, the JTable isn't displayed. Any suggestions? public void showFromVectors(Vector colNames, Vector data) { jt = new javax.swing.JTable(data, colNames); sp = new javax.swing.JScrollPane(jt); //NB: "this" refers to my class DBGridForm, which extends JFrame this.add(sp,java.awt.BorderLayout.CENTER); this.setSize(640,480); } The method is called in the following context: DBGridForm gf = new DBGridForm(); //DBGridForm extends JFrame DBReader.outMatchesTable(gf); gf.setVisible(true); ... where DBReader.outMatchesTable() is defined as static public void outMatchesTable(DBGridForm gf) { DBReader ddb = new DBReader(); ddb.readMatchesTable(null); gf.showFromVectors(ddb.lastRsltColNames, ddb.lastRsltData); } My guess is I'm overlooking something, either about the swing classes I'm using, or about Java. Any ideas?

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  • String operations

    - by NEO
    I am trying to find the most repeated word in a string. My code is as follows: public class Word { private String toWord; private int Count; public Word(int count, String word){ toWord = word; Count = count; } public static void main(String args[]){ String str="my name is neo and my other name is also neo because I am neo"; String []str1=str.split(" "); Word w1=new Word(0,str1[0]); LinkedList<Word> list = new LinkedList<Word>(); list.add(w1); ListIterator itr = list.listIterator(); for(int i=1;i<str1.length;i++){ while(itr.hasNext()){ if(str1[i].equalsTO(????)); else list.add(new Word(0,str1[i])); } How do I compare the string from string array str1 to the string stored in the linked list and then how do i increase the respective count. I will then print the string with the highest count, I dont know how to do that either.

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  • java: can't use constructors in abstract class

    - by ufk
    Hi. I created the following abstract class for job scheduler in red5: package com.demogames.jobs; import com.demogames.demofacebook.MysqlDb; import org.red5.server.api.IClient; import org.red5.server.api.IConnection; import org.red5.server.api.IScope; import org.red5.server.api.scheduling.IScheduledJob; import org.red5.server.api.so.ISharedObject; import org.apache.log4j.Logger; import org.red5.server.api.Red5; /** * * @author ufk */ abstract public class DemoJob implements IScheduledJob { protected IConnection conn; protected IClient client; protected ISharedObject so; protected IScope scope; protected MysqlDb mysqldb; protected static org.apache.log4j.Logger log = Logger .getLogger(DemoJob.class); protected DemoJob (ISharedObject so, MysqlDb mysqldb){ this.conn=Red5.getConnectionLocal(); this.client = conn.getClient(); this.so=so; this.mysqldb=mysqldb; this.scope=conn.getScope(); } protected DemoJob(ISharedObject so) { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.so=so; this.scope=conn.getScope(); } protected DemoJob() { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.scope=conn.getScope(); } } Then i created a simple class that extends the previous one: public class StartChallengeJob extends DemoJob { public void execute(ISchedulingService service) { log.error("test"); } } The problem is that my main application can only see the constructor without any parameters. with means i can do new StartChallengeJob() why doesn't the main application sees all the constructors ? thanks!

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  • implementing gravity to projectile - delta time issue

    - by Murat Nafiz
    I'm trying to implement a simple projectile motion in Android (with openGL). And I want to add gravity to my world to simulate a ball's dropping realistically. I simply update my renderer with a delta time which is calculated by: float deltaTime = (System.nanoTime()-startTime) / 1000000000.0f; startTime = System.nanoTime(); screen.update(deltaTime); In my screen.update(deltaTime) method: if (isballMoving) { golfBall.updateLocationAndVelocity(deltaTime); } And in golfBall.updateLocationAndVelocity(deltaTime) method: public final static double G = -9.81; double vz0 = getVZ0(); // Gets initial velocity(z) double z0 = getZ0(); // Gets initial height double time = getS(); // gets total time from act begin double vz = vz0 + G * deltaTime; // calculate new velocity(z) double z = z0 - vz0 * deltaTime- 0.5 * G * deltaTime* deltaTime; // calculate new position time = time + deltaTime; // Update time setS(time); //set new total time Now here is the problem; If I set deltaTime as 0.07 statically, then the animation runs normally. But since the update() method runs as faster as it can, the length and therefore the speed of the ball varies from device to device. If I don't touch deltaTime and run the program (deltaTime's are between 0.01 - 0.02 with my test devices) animation length and the speed of ball are same at different devices. But the animation is so SLOW! What am I doing wrong?

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  • Using unset member variables within a class or struct

    - by Doug Kavendek
    It's pretty nice to catch some really obvious errors when using unset local variables or when accessing a class or struct's members directly prior to initializing them. In visual studio 2008 you get an "uninitialized local variable used" warning at compile-time and get a run-time check failure at the point of access when debugging. However, if you access an uninitialized struct's member variable through one of its functions, you don't get any warnings or assertions. Obviously the easiest solution is don't do that, but nobody's perfect. For example: struct Test { float GetMember() const { return member; } float member; }; Test test; float f1 = test.member; // Raises warning, asserts in VS debugger at runtime float f2 = test.GetMember(); // No problem, just keeps on going This surprised me, but it makes some sense -- the compiler can't assume calling a function on an unused struct is an error, or how else would you initialize or construct it? And anything fancier just quickly brings up so many other complications that it makes sense that it wouldn't bother classifying which functions are ok to call and when, especially just as a debugging help. I know I can set up my own assertions or error checking within the class itself, but that can complicate some simpler structs. Still, it would seem like within the context of the function call, wouldn't it know insides GetMember() that member wasn't initialized yet? I'm assuming it's not only relying on static compile-time deduction, given the Run-Time Check Failure #3 it raises during execution, so based on my current understanding of it it would seem reasonable for the same checks to apply. Is this just a limitation of this specific compiler/debugger (Visual Studio 2008), or more tied to how C++ works?

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  • Consuming WCF Web Service

    - by Debby
    Hi, I have a simple web service running and I have a console application client consuming the service. I did have issues getting this running and I had been helped by some wonderful people in this community. I have another problem: if I want to call the service from the client in a loop, it doesn't work. It works only for the first time and then it just keeps waiting. Why is this happening and how can I resolve it. The code: namespace WebService { [ServiceContract] public interface IService { [OperationContract(Name="Result")] [WebGet(UriTemplate = "/")] Stream Result(); } public class Service:IService { public Stream Result() { // read a file from the server and return it as stream } } } The client: namespace WebServiceClient { [ServiceContract] public interface IService { [OperationContract(Name="Result")] [WebGet(UriTemplate = "/")] Stream Result(); } } static void Main() { Console.WriteLine("Press enter when the service is available"); Console.ReadLine(); // creating factory HttpChunkingBinding binding = new HttpChunkingBinding(); binding.MaxReceivedMessageSize = 0x7fffffffL; ChannelFactory<WebServiceClient.IService> factory = new ChannelFactory<WebServiceClient.IService> (binding, new EndpointAddress("http://localhost/WebService/Service")); WebServiceClient.IService service = factory.CreateChannel(); for(int i = 0; i < 10; i++) { Stream s = service.Result(); // write this stream to a file and close the stream } //Closing our channel. ((IClientChannel)service).Close(); } Thanks,

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  • Default Button after dispose and setVisible

    - by DaDaDom
    Hi, given the following code: public class DialogTest implements ActionListener { public static void main(String[] args) {DialogTest g = new DialogTest();} public DialogTest() { JButton b1 = new JButton("Button A"); b1.addActionListener(this); JDialog d = new JDialog(); d.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE); JPanel p = new JPanel(); p.add(b1); d.add(p); d.getRootPane().setDefaultButton(b1); d.pack(); d.setVisible(true); d.dispose(); d.pack(); d.setVisible(true); } public void actionPerformed(ActionEvent e) {System.out.println("hello");} } Shouldn't pressing the Enter key write something to the console? According to the docs (http://java.sun.com/javase/7/docs/api/java/awt/Window.html#dispose()): The Window and its subcomponents can be made displayable again by rebuilding the native resources with a subsequent call to pack or show. The states of the recreated Window and its subcomponents will be identical to the states of these objects at the point where the Window was disposed Is this intended behaviour?

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  • C Run-Time library part 2

    - by b-gen-jack-o-neill
    Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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  • 'Bank Switching' Sprites on old NES applications

    - by Jeffrey Kern
    I'm currently writing in C# what could basically be called my own interpretation of the NES hardware for an old-school looking game that I'm developing. I've fired up FCE and have been observing how the NES displayed and rendered graphics. In a nutshell, the NES could hold two bitmaps worth of graphical information, each with the dimensions of 128x128. These are called the PPU tables. One was for BG tiles and the other was for sprites. The data had to be in this memory for it to be drawn on-screen. Now, if a game had more graphical data then these two banks, it could write portions of this new information to these banks -overwriting what was there - at the end of each frame, and use it from the next frame onward. So, in old games how did the programmers 'bank switch'? I mean, within the level design, how did they know which graphic set to load? I've noticed that Mega Man 2 bankswitches when the screen programatically scrolls from one portion of the stage to the next. But how did they store this information in the level - what sprites to copy over into the PPU tables, and where to write them at? Another example would be hitting pause in MM2. BG tiles get over-written during pause, and then get restored when the player unpauses. How did they remember which tiles they replaced and how to restore them? If I was lazy, I could just make one huge static bitmap and just grab values that way. But I'm forcing myself to limit these values to create a more authentic experience. I've read the amazing guide on how M.C. Kids was made, and I'm trying to be barebones about how I program this game. It still just boggles my mind how these programmers accomplisehd what they did with what they had. EDIT: The only solution I can think of would be to hold separate tables that state what tiles should be in the PPU at what time, but I think that would be a huge memory resource that the NES wouldn't be able to handle.

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  • Groovy / Scala / Java under the hood

    - by Jack
    I used Java for like 6-7 years, then some months ago I discovered Groovy and started to save a lot of typing.. then I wondered how certain things worked under the hood (because groovy performance is really poor) and understood that to give you dynamic typing every Groovy object is a MetaClass object that handles all the things that the JVM couldn't handle by itself. Of course this introduces a layer in the middle between what you write and what you execute that slows down everything. Then somedays ago I started getting some infos about Scala. How these two languages compare in their byte code translations? How much things they add to the normal structure that it would be obtained by plain Java code? I mean, Scala is static typed so wrapper of Java classes should be lighter, since many things are checked during compile time but I'm not sure about the real differences of what's going inside. (I'm not talking about the functional aspect of Scala compared to the other ones, that's a different thing) Can someone enlighten me? From WizardOfOdds it seems like that the only way to get less typing and same performance would be to write an intermediate translator that translates something in Java code (letting javac compile it) without alterating how things are executed, just adding synctatic sugar withour caring about other fallbacks of the language itself.

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  • How to get application context path in spring-ws?

    - by Dhaliwal
    I am using Spring-WS to create a webservice. In my project, I have created a Helper class to reads sample response and request xml file which are located in my /src/main/resource folder. When I am unit-testing my webservice application 'locally', I use the System.getProperty("user.dir") to get the application context folder. The following is a method that I created in the Helper class to help me retrieve the file that I am interested in my resource folder. public static File getFileFromResources(String filename) { System.out.println("Getting file from resource folder"); File request = null; String curDir = System.getProperty("user.dir"); String contextpath = "C:\\src\\main\\resources\\"; request = new File(curDir + contextpath + filename); return request; } However, after 'publishing' the compiled WAR file to the ../webapps folder to the Apache Tomcat directory, I realise that System.getProperty("user.dir") no longer returns my application context path. Instead, it is returning the Apache Tomcat root directory as shown C:\Program Files\Apache Software Foundation\Tomcat 6.0\src\main\resources\SampleClientFile I cant seem to find any information about getting the root folder of my webservice. I have seen examples on Spring web application where I can retrieve the context path by using the following : request.getSession().getServletContext().getContextPath() But in this case, I am using a Spring web application where there is a servlet context in the request. But the Spring-WS, my entry point is an endpoint. How can I get the context path of my webservice application. I am expecting a context path of something like C:\Program Files\Apache Software Foundation\Tomcat 6.0\webapps\clientWebService\WEB-INF\classes Could someone suggest a way to achieve this?

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  • Hiding/blocking tabs using windows forms in c#

    - by Audel
    The thing is that i have a 'log in window' and a 'mainwindow' that is called after pressing the log in button or the "VISITANT" button If pressing the log in button, the whole system will come out, and if i press the VISITANT button, one tab should disappear or be blocked or something. private void visitant(object sender, EventArgs e) { mainwindow menu = new mainwindow(); menu.Show(); //mainwindow.tabPage1.Enabled = false; //attempt1 //mainwindow.tabPage1.Visible = false; //attempt1 //System.Windows.Forms.tabPage1.Enabled = false;//attempt2 //System.Windows.Forms.tabPage1.Visible = false;//attempt2 this.Hide(); } the errors i get for using the attempt1 are Error 1 'System.mainwindow.tabPage1' is inaccessible due to its protection level' Error 2 An object reference is required for the non-static field, method, or property 'System.mainwindow.tabPage1' and the one i get for using the attempt2 is Error 1 The type or namespace name 'tabPage1' does not exist in the namespace 'System.Windows.Forms' (are you missing an assembly reference?) as you probably have guessed "tabPage1" is the tab i need to hide when pressing the visitant button. I can't think of any more details, I will be around to provide any extra information Thanks in advance.

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  • Passing IDisposable objects through constructor chains

    - by Matt Enright
    I've got a small hierarchy of objects that in general gets constructed from data in a Stream, but for some particular subclasses, can be synthesized from a simpler argument list. In chaining the constructors from the subclasses, I'm running into an issue with ensuring the disposal of the synthesized stream that the base class constructor needs. Its not escaped me that the use of IDisposable objects this way is possibly just dirty pool (plz advise?) for reasons I've not considered, but, this issue aside, it seems fairly straightforward (and good encapsulation). Codes: abstract class Node { protected Node (Stream raw) { // calculate/generate some base class properties } } class FilesystemNode : Node { public FilesystemNode (FileStream fs) : base (fs) { // all good here; disposing of fs not our responsibility } } class CompositeNode : Node { public CompositeNode (IEnumerable some_stuff) : base (GenerateRaw (some_stuff)) { // rogue stream from GenerateRaw now loose in the wild! } static Stream GenerateRaw (IEnumerable some_stuff) { var content = new MemoryStream (); // molest elements of some_stuff into proper format, write to stream content.Seek (0, SeekOrigin.Begin); return content; } } I realize that not disposing of a MemoryStream is not exactly a world-stopping case of bad CLR citizenship, but it still gives me the heebie-jeebies (not to mention that I may not always be using a MemoryStream for other subtypes). It's not in scope, so I can't explicitly Dispose () it later in the constructor, and adding a using statement in GenerateRaw () is self-defeating since I need the stream returned. Is there a better way to do this? Preemptive strikes: yes, the properties calculated in the Node constructor should be part of the base class, and should not be calculated by (or accessible in) the subclasses I won't require that a stream be passed into CompositeNode (its format should be irrelevant to the caller) The previous iteration had the value calculation in the base class as a separate protected method, which I then just called at the end of each subtype constructor, moved the body of GenerateRaw () into a using statement in the body of the CompositeNode constructor. But the repetition of requiring that call for each constructor and not being able to guarantee that it be run for every subtype ever (a Node is not a Node, semantically, without these properties initialized) gave me heebie-jeebies far worse than the (potential) resource leak here does.

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  • garbage collector Issue

    - by Eslam
    this question is like my previous one Given: 3. interface Animal { void makeNoise(); } 4. class Horse implements Animal { 5. Long weight = 1200L; 6. public void makeNoise() { System.out.println("whinny"); } 7. } 8. public class Icelandic extends Horse { 9. public void makeNoise() { System.out.println("vinny"); } 10. public static void main(String[] args) { 11. Icelandic i1 = new Icelandic(); 12. Icelandic i2 = new Icelandic(); 13. Icelandic i3 = new Icelandic(); 14. i3 = i1; i1 = i2; i2 = null; i3 = i1; 15. } 16. } When line 14 is reached, how many objects are eligible for the garbage collector? A. 0 B. 1 C. 2 D. 3 E. 4 F. 6 i choosed A but the right answer is E, but i don't know Why?

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  • iOS - when to remove subviews from UITableViewCell

    - by Milad Ghattavi
    I have a UITableView which a UIImage is added as a subview to each cell of it. The images are PNG transparent. The problem is when I scroll through the UITableView, the images get overlapped and then I receive the memory warning and stuff. here's the current code for configuring a cell: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; } int cellNumber = indexPath.row + 1; NSString *cellImage1 = [NSString stringWithFormat:@"c%i.png", cellNumber]; UIImage *theImage = [UIImage imageNamed:cellImage1]; UIImageView *cellImage = [[UIImageView alloc] initWithImage:theImage]; [cell.contentView addSubview:cellImage]; return cell; } I know the code for removing the UIImage subview would be like: [cell.imageView removeFromSuperview]; But I don't know where to put it. I've placed it between all the lines; even added an else, in the if statement. didn't seem to work!

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  • java applet stops running on exceptions

    - by Marius
    I've developed a simple applet that imports an image from the clipboard. When i run the class file from NetBeans, everything works fine. But when i try to run it as an applet ... it gives me lots of errors in the java console and does not run ... - The applet is signed - There is a static method in one class, called getImageFromClipboard(). When the applet runs, it calls this method. - getImageFromClipboard() method has a try-catch block and suppresses all errors. It simply returns either a BufferedImage or null. - When applet runs, it does some visual adjustments before calling getImageFromClipboard() Now the scenario is as follows: the class from netbeans runs, fails to import the image and adjusts the interface accordingly (displays an error in a label) But when i run it in a browser, java console is filled with errors and nothing after the getImageFromClipboard() line works. Although the applet itself loads and does everything it's supposed do do before importing the image. So why am i getting errors if i accept the certificate and all of the possible errors are in try-catch blocks? None of this code should throw any exceptions. Any ideas why this is happening? Or do you need to see the errors to tell? UPDATE I've managed to find out the problem myself. The class that i'm using is not in the jar file :( How do i add it in? I'm using "add jar folder" in netbeans on the libraries package to import it but it does not seem to get copied to the jar.

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  • How can I write a unit test to determine whether an object can be garbage collected?

    - by driis
    In relation to my previous question, I need to check whether a component that will be instantiated by Castle Windsor, can be garbage collected after my code has finished using it. I have tried the suggestion in the answers from the previous question, but it does not seem to work as expected, at least for my code. So I would like to write a unit test that tests whether a specific object instance can be garbage collected after some of my code has run. Is that possible to do in a reliable way ? EDIT I currently have the following test based on Paul Stovell's answer, which succeeds: [TestMethod] public void ReleaseTest() { WindsorContainer container = new WindsorContainer(); container.Kernel.ReleasePolicy = new NoTrackingReleasePolicy(); container.AddComponentWithLifestyle<ReleaseTester>(LifestyleType.Transient); Assert.AreEqual(0, ReleaseTester.refCount); var weakRef = new WeakReference(container.Resolve<ReleaseTester>()); Assert.AreEqual(1, ReleaseTester.refCount); GC.Collect(); GC.WaitForPendingFinalizers(); Assert.AreEqual(0, ReleaseTester.refCount, "Component not released"); } private class ReleaseTester { public static int refCount = 0; public ReleaseTester() { refCount++; } ~ReleaseTester() { refCount--; } } Am I right assuming that, based on the test above, I can conclude that Windsor will not leak memory when using the NoTrackingReleasePolicy ?

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  • How do tools like Hiphop for PHP deal with heterogenous arrays?

    - by Derek Thurn
    I think HipHop for PHP is an interesting tool. It essentially converts PHP code into C++ code. Cross compiling in this manner seems like a great idea, but I have to wonder, how do they overcome the fundamental differences between the two type systems? One specific example of my general question is heterogeneous data structures. Statically typed languages don't tend to let you put arbitrary types into an array or other container because they need to be able to figure out the types on the other end. If I have a PHP array like this: $mixedBag = array("cat", 42, 8.5, false); How can this be represented in C++ code? One option would be to use void pointers (or the superior version, boost::any), but then you need to cast when you take stuff back out of the array... and I'm not at all convinced that the type inferencer can always figure out what to cast to at the other end. A better option, perhaps, would be something more like a union (or boost::variant), but then you need to enumerate all possible types at compile time... maybe possible, but certainly messy since arrays can contain arbitrarily complex entities. Does anyone know how HipHop and similar tools which go from a dynamic typing discipline to a static discipline handle these types of problems?

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