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• How can I run an appear effect and a fade effect in scriptaculous? I need them to run in tandam so t

  - by LeeRM

  Hi, Ive been fiddling with this for hours and hours and just cant get it right. First off my sites are already using Prototytpe and Scriptaculous, and to change would take a long time. Basically I am after achieving a slideshow effect similar to jQuery Cycle plugin. I have written most of it but cant get over this hurdle: I need the user to be able to press a control button which will skip the slide to which ever one they have picked. My problem is that if a fade / appear effect is running, then it causes an overlap. I am using queues and they are in their own scope. The problem as I see it is that the fade effect on one slide and the appear effect on the next slide are separate functions. Which means that if the user clicks the control button to move to another slide whilst the animation is inbetween fade & appear, then the next cycle will slot itself in the queue between those 2 effects. The default is to append to the end of the existing queue, which should be fine. But if the appear hasnt been added when a new fade is instantiated, then the queue messes up. I can make it so nothing happens if animation is in effect but thats not the effect I am after. I want to be able to click a slide and whatever is happening to effectively stop and the next slide appear. This is an example of what I am after: http://www.zendesk.com/ Im sorry if that doesnt make sense. Its a tough one to explain. Thanks Lee

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• PHP generating csv not sending correct new line feeds

  - by sjw

  I have a script that generates a csv file using the following code: header('Content-type: text/csv'); header('Content-Disposition: attachment; filename="'.date("Ymdhis").'.csv"'); print $content; The $content variable simply contains lines with fields separated by commas and then finalised with ."\n"; to generate a new line. When I open the file in csv it looks fine however, when I try to use the file to import into an external program (MYOB) it does not recognise the End Of Line (\n) character and assumes one long line of text. When I view the contents of the file in notepad, the end of line character (\n) is a small rectangle box which looks like the character code 0x7F. If I open the file and re-save it in excel, it removes this character and replaces it with a proper end of line character and I can import the file. What character do I need to be generating in PHP so that notepad recognises it as a valid End Of Line character? (\n) obviously doesn't do the job.

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• AsyncTask never finishes when other tasks are running

  - by rebeccamaher

  In my app, I show a menu screen immediately to the user and then use an AsyncTask to load some data from disk. Loading takes about 3 seconds if that's all the app had to do. When the user hits a menu option and the data hasn't loaded yet, a "Please wait, loading" screen appears. I have two problems: I recently added ads to my app and have found this is making my app hang sometimes because the AsyncTask never finishes loading. What seems to be happening is that the ad banner (I'm using admob and this happens when adsense ads are shown which admob do occasionally) is using resources by playing a simple animation and the AsyncTask never gets a chance to finish. I want to play a simple looping animation (e.g. making a view rotate) on my menu screen and this makes the AsyncTask take about 5 times longer to finish which renders the background loading pointless. How can I avoid situations where my background data never finishes loading or has such a low priority it takes a long time? I can't seem to find a way to increase the priority of an AsyncTask.

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• Why C++ is (one of) the best language to learn at first [closed]

  - by AlexV

  C++ is one of the most used programming language in the world since like 25+ years. My first job as programmer was in C++ and I coded in C++ everyday for nearly 4 years. Now I do mostly PHP, but I will forever cherish this C++ background. C++ has helped me understand many "under the hood" features/behaviors/restrictions of many other (and different) programming languages like PHP and Delphi. I'm a full time programmer for 6+ years now and since I have a quite varied programming background I often get questions by "newbies" as where to start to become a "good" programmer. I think C++ is one of the best language to start with because it gives you a real usefull experience that will last and will teach you how things work under the hood. It's not the easier one to learn for a newbie, but in my opinion it's the one who will reward the most in long term. I would like to know your opinion on this matter to add to my arguments when I guide "newbies". After this introduction, here's my question : Why C++ is for you (one of) the best language to learn at first. Since it's subjective, I've marked this question as community wiki.

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• What is an appropriate way to separate lifecycle events in the logging system?

  - by Hanno Fietz

  I have an application with many different parts, it runs on OSGi, so there's the bundle lifecycles, there's a number of message processors and plugin components that all can die, can be started and stopped, have their setup changed etc. I want a way to get a good picture of the current system status, what components are up, which have problems, how long they have been running for etc. I think that logging, especially in combination with custom appenders (I'm using log4j), is a good part of the solution and does help ad-hoc analysis as well as live monitoring. Normally, I would classify lifecycle events as INFO level, but what I really want is to have them separate from what else is going on in INFO. I could create my own level, LIFECYCLE. The lifecycle events happen in various different areas and on various levels in the application hierarchy, also they happen in the same areas as other events that I want to separate them from. I could introduce some common lifecycle management and use that to distinguish the events from others. For instance, all components that have a lifecycle could implement a particular interface and I log by its name. Are there good examples of how this is done elsewhere? What are considerations?

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• Adding cancel ability and exception handling to async code.

  - by Rob

  I have this sample code for async operations (copied from the interwebs) public class LongRunningTask { public LongRunningTask() { //do nowt } public int FetchInt() { Thread.Sleep(2000); return 5; } } public delegate TOutput SomeMethod<TOutput>(); public class GoodPerformance { public void BeginFetchInt() { LongRunningTask lr = new LongRunningTask(); SomeMethod<int> method = new SomeMethod<int>(lr.FetchInt); // method is state object used to transfer result //of long running operation method.BeginInvoke(EndFetchInt, method); } public void EndFetchInt(IAsyncResult result) { SomeMethod<int> method = result.AsyncState as SomeMethod<int>; Value = method.EndInvoke(result); } public int Value { get; set; } } Other async approaches I tried required the aysnc page attribute, they also seemed to cancel if other page elements where actioned on (a button clicked), this approach just seemed to work. I’d like to add a cancel ability and exception handling for the longRunningTask class, but don’t erm, really know how.

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• Does Socket open another thread? Does it return something?

  - by Roman

  In the client application I call new Socket(serverIP,serverPort). As a result the client application sends a request to the server application to open a socket. Does it start a new thread? I mean which of the following is true? Client application sends a request and immediately starts to execute following commands (not weighting for the answer). Client sends the request and weights for the answer. As soon as the answer is obtained, the client application continues to execute following commands. The second case seems to be more realistic and logical for me. However, I do not understand what happens if the server does not open a socket and it does not say that it does not "want" to open the second (it can happen if the server does not exist or network is broken). What will happen in this case? Will server weight forever? In general it would be nice for the client to know what is the result of its request for the socket. For example I can imagine the following situations: The socket is opened by the server. The server refuses to open a socket. So, server exists, it got the request from the client but it says "no". There is no response from the server. I know that new Socket(serverIP,serverPort) does not "return" this kind of information. But it throws exceptions. One of them is "UnkownHostException". When it is thrown? When the server is not responding for a while (for how long)? ADDED: I just found out that UnknownHostException is thrown to indicate that the IP address of a host could not be determined. So, it is unrelated with the above described situations (server is not responding, server refuses to open a socket).

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• Cordova polluted logs with persistent.js add()

  - by slaver113

  I am using the latest phonegap/cordova version 2.1. and my log in Eclipse logcat get polluted with code when i do var allItems = Item.all(); allItems.list(null, function (results) { results.forEach(function (r) { console.log(r.id+ " " + r.lat + " " + r.long + " " + r.state); }); }); I get a output like (for 100s of lines) 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } at :1149822901

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• help me to choose between two designs

  - by alex

  // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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• Debugging scripts loaded with GroovyShell (in eclipse)

  - by MSh

  I am working with eclipse and groovy plug in. I am building a test harness to debug and test groovy scripts. The scripts are really simple but long, most of them just if/else/return. I figured out that I can call them using GroovyShell and Bindings to pass in the values. The problem is that, while I can call the script and get the results just fine, I CAN NOT step in there with the debugger. Breakpoints in those scripts are not active. Is there a way to debug the scripts? Maybe I should use something other than GroovyShell? I really don't want to modify the scripts by wrapping them into functions, and then calling those functions from my test classes. That's how I am using Binding and GroovyShell: def binding = new Binding(); binding.lineList = [list1]; binding.count = 5; def shell = new GroovyShell(binding); def result = shell.evaluate(new File("src/Rules/checkLimit.groovy"));

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• Hibernate HQL m:n join problem

  - by smallufo

  I am very unfamiliar with SQL/HQL , and am currently stuck with this 'maybe' simple problem : I have two many-to-many Entities , with a relation table : Car , CarProblem , and Problem . One Car may have many Problems , One Problem may appear in many Cars, CarProblem is the association table with other properties . Now , I want to find Car(s) with specified Problem , how do I write such HQL ? All ids are Long type . I've tried a lot of join / inner-join combinations , but all in vain.. -- updated : Sorry , forget to mention : Car has many CarProblem Problem has many CarProblem Car and Problem are not directly connected in Java Object. -- update , java code below -- @Entity public class Car extends Model{ @OneToMany(mappedBy="car" , cascade=CascadeType.ALL) public Set<CarProblem> carProblems; } @Entity public class CarProblem extends Model{ @ManyToOne public Car car; @ManyToOne public Problem problem; ... other properties } @Entity public class Problem extends Model { other properties ... // not link to CarProblem , It seems not related to this problem // **This is a very stupid query , I want to get rid of it ...** public List<Car> findCars() { List<CarProblem> list = CarProblem.find("from CarProblem as cp where cp.problem.id = ? ", id).fetch(); Set<Car> result = new HashSet<Car>(); for(CarProblem cp : list) result.add(cp.car); return new ArrayList<Car>(result); } } The Model is from Play! framework , so these properties are all public .

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• Any techniques to interrupt, kill, or otherwise unwind (releasing synchronization locks) a single de

  - by gojomo

  I have a long-running process where, due to a bug, a trivial/expendable thread is deadlocked with a thread which I would like to continue, so that it can perform some final reporting that would be hard to reproduce in another way. Of course, fixing the bug for future runs is the proper ultimate resolution. Of course, any such forced interrupt/kill/stop of any thread is inherently unsafe and likely to cause other unpredictable inconsistencies. (I'm familiar with all the standard warnings and the reasons for them.) But still, since the only alternative is to kill the JVM process and go through a more lengthy procedure which would result in a less-complete final report, messy/deprecated/dangerous/risky/one-time techniques are exactly what I'd like to try. The JVM is Sun's 1.6.0_16 64-bit on Ubuntu, and the expendable thread is waiting-to-lock an object monitor. Can an OS signal directed to an exact thread create an InterruptedException in the expendable thread? Could attaching with gdb, and directly tampering with JVM data or calling JVM procedures allow a forced-release of the object monitor held by the expendable thread? Would a Thread.interrupt() from another thread generate a InterruptedException from the waiting-to-lock frame? (With some effort, I can inject an arbitrary beanshell script into the running system.) Can the deprecated Thread.stop() be sent via JMX or any other remote-injection method? Any ideas appreciated, the more 'dangerous', the better! And, if your suggestion has worked in personal experience in a similar situation, the best!

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• Passing C++ object to C++ code through Python?

  - by cornail

  Hi all, I have written some physics simulation code in C++ and parsing the input text files is a bottleneck of it. As one of the input parameters, the user has to specify a math function which will be evaluated many times at run-time. The C++ code has some pre-defined function classes for this (they are actually quite complex on the math side) and some limited parsing capability but I am not satisfied with this construction at all. What I need is that both the algorithm and the function evaluation remain speedy, so it is advantageous to keep them both as compiled code (and preferrably, the math functions as C++ function objects). However I thought of glueing the whole simulation together with Python: the user could specify the input parameters in a Python script, while also implementing storage, visualization of the results (matplotlib) and GUI, too, in Python. I know that most of the time, exposing C++ classes can be done, e.g. with SWIG but I still have a question concerning the parsing of the user defined math function in Python: Is it possible to somehow to construct a C++ function object in Python and pass it to the C++ algorithm? E.g. when I call f = WrappedCPPGaussianFunctionClass(sigma=0.5) WrappedCPPAlgorithm(f) in Python, it would return a pointer to a C++ object which would then be passed to a C++ routine requiring such a pointer, or something similar... (don't ask me about memory management in this case, though :S) The point is that no callback should be made to Python code in the algorithm. Later I would like to extend this example to also do some simple expression parsing on the Python side, such as sum or product of functions, and return some compound, parse-tree like C++ object but let's stay at the basics for now. Sorry for the long post and thx for the suggestions in advance.

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• UIView scaled to thumbprint, what about subviews?

  - by Parad0x13

  I have a UIImageView that I create progmatically right? Works like a charm when I initWithImage and set the parameters for scaling to UIViewContentModeScaleToFill. I can scale all day long and create many different smaller 'thumbprint' sized versions of the UIImageView at whim, HOWEVER when I add subviews to said UIImageView and then try to scale the happy new parent the child subview does not scale! I looked around and found that I should enable the setAutoresizingSubviews boolean of the parentView to true (Which I did) and then call: ChildView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; Which I also did... now when I scale the parent view the child also scales but crazy wacked out like and goes all over the place (Not a very good way of putting it) but my point is that I assumed the child would scale proportionally to the parent and stay in the same place (Which it doesn't) My question is how do I set up my code so that when I scale my parent view by 1/4 or w/e to make a thumbprint of the view the children subviews that the parent view owns will scale accordingly and allow the 1/4 sized thumbprint to look just like the full sized view (Just smaller).

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• Team City + Gallio runs tests, but results are not shown

  - by Twindagger

  We recently updated to Visual Studio 2010, and as part of our upgrade we started using Gallio 3.2 prerelease builds. Everything runs fine in Visual Studio (through resharper) but I'm having problems with TeamCity integration. The tests seem to run during TeamCity builds just fine (our build takes long enough to run all our tests), but the tests are not showing up in TeamCity's test area. Here is the test target from our NANT build file (this hasn't changed in our upgrade at all). Is there a trick to getting the tests to show up in TeamCity or is this something that's broken in the latest builds of Gallio? <target name="runTests"> <gallio result-property="exitCode" failonerror="false"> <runner-extension value="TeamCityExtension,Gallio.TeamCityIntegration" /> <assemblies> <include name="..\Source\Tests\${testProject}\bin\Debug\${testProject}.dll" /> </assemblies> </gallio> </target>

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• efficient thread-safe singleton in C++

  - by user168715

  The usual pattern for a singleton class is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) inst = new Foo(...); return *inst; } However, it's my understanding that this solution is not thread-safe, since 1) Foo's constructor might be called more than once (which may or may not matter) and 2) inst may not be fully constructed before it is returned to a different thread. One solution is to wrap a mutex around the whole method, but then I'm paying for synchronization overhead long after I actually need it. An alternative is something like static Foo &getInst() { static Foo *inst = NULL; if(inst == NULL) { pthread_mutex_lock(&mutex); if(inst == NULL) inst = new Foo(...); pthread_mutex_unlock(&mutex); } return *inst; } Is this the right way to do it, or are there any pitfalls I should be aware of? For instance, are there any static initialization order problems that might occur, i.e. is inst always guaranteed to be NULL the first time getInst is called?

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• Android - save/restore state of custom class

  - by user1209216

  I have some class for ssh support - it uses jsch internally. I use this class on main activity, this way: public class MainActivity extends Activity { SshSupport ssh = new SshSupport(); ..... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Handle events for ssh ssh.eventHandler = new ISshEvents() { @Override public void SshCommandExecuted(SshCommandsEnum commandType, String result) { } //other overrides here } //Ssh operations on gui item click @Override public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) { if (ssh.IsConnected() == false) { try { ssh.ConnectAsync(/*parameters*/); } catch (Exception e) { e.printStackTrace(); } } try { ssh.ExecuteCommandAsync(SshCommandsEnum.values()[position]); } catch (Exception e) { e.printStackTrace(); } } }); } It works very well. My application connects to ssh, performs all needed operation in background thread and results are reported to gui, via events as shown above. But nothing works after user change device orientation. It's clear for me - activity is re-created and all state is lost. Unfortunately, my SshSupport class object is lost as well. It's pretty easy to store gui state for dynamically changed/added objects (using put/get serializable etc methods). But I have no idea how to prevent my ssh object, ssh connected session being lost. Since my class is not serializable, I can't save it to bundle. Also, even if I make my SshSupport class serializable, jsch objects it uses still are not serializable. So what is the best way to solve this?

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• Problems with multi-line comments jquery

  - by c0mrade

  Hello, I'm making a image website with a bunch of images on the website, and below every image there is possibility of commenting the image and after that comments gets displayed without page loading and the comment content, the problem is when I have long comments which break the current line they don't get displayed since my comment box css overflow is hidden. Here is example : This is a comment - This is displayed properly This is a comment This is a comment This is a comment - this is not displayed properly since it break line. Here is the jQuery code for this : $.ajax({ type: "POST", url: "<?=base_url()?>imagesform/post_comment", data: datas, success: function () { $("#image-comments-" + image_id).attr("class", "comments"); $("#image-comments-" + image_id).append("<li id=\"new_append_" + image_id+ "\">" + $("#image").find(".comment").val() + "</li>").children(':last').height($('.comments li:last').height()).hide().slideDown(500, function () { var bodyHeight = $('html').height(); $('.addComment').fadeOut(300, function () { $('html').height(bodyHeight); }); }); alert($("#image").find(".comment").val()); } }); Here the $("#image").find(".comment").val() is the value of the text-area in which comment is inputted, when I alert it the whole multi line input is there put its not being appended to the li properly, that is part when I get confused, any suggestions why only part of the inputted string is appended?

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• Order words by number of letters, then place words neatly

  - by bmaster

  I have a list of words in javascript similar to this: var words = ["mine", "minute", "mist", "mixed", "money", "monkey", "month", "moon", "morning", "mother", "motion", "mountain", "mouth", "move", "much", "muscle", "music", "nail", "name", "narrow", "nation", "natural", "near", "necessary", "neck", "need", "needle", "nerve", "net", "new", "news", "night"]; The words can be 1-25? letters long. I have a div id="words", with a set width of 700px (but I might change it from this). Using css/javascript/jquery, how can I make it: Order the words by number of letters Place the words inside the div tag, left to right, but so that there are no gaps at the right edge of the words div, and there is even spacing between words on a line. Each word should have a border around it and a background. Like this: |reallylongwordssdf shorterwordfdf dfsdfsdfsdf sdfsdfsdf| |sdfsdfsdf sdffsdop sdfjpogs sdfsds dfsdsd dfsdsd dfsdsd| I really have no idea where to begin with this. Perhaps I could manage to write code to order the words by number of letters, but after that, I'd be stuck. Edit: I forgot to add, the words must be links.

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• Reducing Duplicated Code

  - by cam

  I have some code that works on the color structure like this public void ChangeColor() { thisColor.R = thisColor.R + 5; } Now I need to make a method that changes a different variable depending on what it is passed. Here is what the code looks like now. public void ChangeColor(int RGBValue) { switch(RGBValue) { case 1: thisColor.R = thisColor.R + 5; break; case 2: thiscolor.B = thisColor.B + 5; break; } } Now, this is something I would normally never question, I'd just throw a #region statement around it and call it a day, but this is just an example of what I have, the actual function is quite long. I want it to look like this: public void ChangeColor(int RGBValue) { thiscolor.RGBValue = thiscolor.RGBValue; } So essentially the value would refer to the variable being used. Is there a name for this? Is this what Reflection is for? Or something like that... Is there a way to do this?

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• Android ProgressDialog inside another dialog

  - by La bla bla

  I'm working on a game using AndEngine, and I need to show the users the list of his Facebook friends. I've created my custom Adatper and after the loading finishes everything works great. I have a problem with the loading it self. The ListView is inside a custom dialog, since I don't really know how to create one using AndEngine, So inside this dialog, I'm running an AsyncTask to fetch the friends' info, in that AsyncTask I'm have a ProgressDialog. The problem is, the ProgressDialog shows up behind the dialog that contains the to-be list (which while loading, is just the title). I can see the ProgressDialog "peeking" behind that dialog.. Any Ideas? Here's some code: FriendsDialog.java private ProgressDialog dialog; //Constructor of the AsyncTask public FriendsLoader(Context context) { dialog = new ProgressDialog(context); dialog.setMessage("Please wait..\nLoading Friends List."); } @Override protected void onPreExecute() { dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); dialog.setView(inflater.inflate(R.layout.loading, null)); dialog.setMessage("Please wait..\nLoading friends."); dialog.show(); } @Override protected void onPostExecute(ArrayList<HashMap<String, Object>> data) { if (dialog.isShowing()) { dialog.dismiss(); } MyAdapter myAdapter = new MyAdapter(context, data); listView = (ListView) findViewById(R.id.list); listView.setAdapter(myAdapter); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> myAdapter, View myView, int myItemInt, long mylng) { String id = (String) listView.getItemAtPosition(myItemInt); listener.onUserSelected(id); dismiss(); } }); }

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• Determing if an unordered vector<T> has all unique elements

  - by Hooked

  Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) { set<T> Y(X.begin(), X.end()); return X.size() == Y.size(); } The second looping over the elements: template <class T> bool is_unique2(vector<T> X) { typename vector<T>::iterator i,j; for(i=X.begin();i!=X.end();++i) { for(j=i+1;j!=X.end();++j) { if(*i == *j) return 0; } } return 1; } I've tested them the best I can, and from what I can gather from reading the documentation about STL, the answer is (as usual), it depends. I think that in the first case, if all the elements are unique it is very quick, but if there is a large degeneracy the operation seems to take O(N^2) time. For the nested iterator approach the opposite seems to be true, it is lighting fast if X[0]==X[1] but takes (understandably) O(N^2) time if all the elements are unique. Is there a better way to do this, perhaps a STL algorithm built for this very purpose? If not, are there any suggestions eek out a bit more efficiency?

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• Number of characters recommended for a statement

  - by liaK

  Hi, I have been using Qt 4.5 and so do C++. I have been told that it's a standard practice to maintain the length of each statement in the application to 80 characters. Even in Qt creator we can make a right border visible so that we can know whether we are crossing the 80 characters limit. But my question is, Is it really a standard being followed? Because in my application, I use indenting and all, so it's quite common that I cross the boundary. Other cases include, there might be a error statement which will be a bit explanatory one and which is in an inner block of code, so it too will cross the boundary. Usually my variable names look bit lengthier so as to make the names meaningful. When I call the functions of the variable names, again I will cross. Function names will not be in fewer characters either. I agree a horizontal scroll bar shows up and it's quite annoying to move back and forth. So, for function calls including multiple arguments, when the boundary is reached I will make the forth coming arguments in the new line. But besides that, for a single statement (for e.g a very long error message which is in double quotes " " or like longfun1()->longfun2()->...) if I use an \ and split into multiple lines, the readability becomes very poor. So is it a good practice to have those statement length restrictions? If this restriction in statement has to be followed? I don't think it depends on a specific language anyway. I added C++ and Qt tags since if it might. Any pointers regarding this are welcome.

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• Practicing inserting data into an array by using binary search, few problems

  - by HelpNeeder

  I'm trying to create a method which inserts and then sort elements in form of binary form. The problem I am experiencing that my code doesn't insert data correctly which means that output does not appear to be in order at all. The list is not organized, and data is added in order that is being inserted. Now, 2 questions, what am I doing wrong here? And how to fix this? public void insertBinarySearch(long value) // put element into array { int j = 0; int lower = 0; int upper = elems-1; int cur = 0; while (cur < elems) { curIn = (lower + upper ) / 2; if(a[cur] < value) { j = cur + 1; break; } else if(a[cur] > value) { j = cur; break; } else { if(a[cur] < value) lower = cur + 1; else upper = cur - 1; } } for(int k = elems; k > j; k--) a[k] = a[k-1]; a[j] = value; elems++; }

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• Best tree/heap data structure for fixed set of nodes with changing values + need top 20 values?

  - by user350139

  I'm writing something like a game in C++ where I have a database table containing the current score for each user. I want to read that table into memory at the start of the game, quickly change each user's score while the game is being played in response to what each user does, and then when the game ends write the current scores back to the database. I also want to be able to find the 20 or so users with the highest scores. No users will be added or deleted during the short period when the game is being played. I haven't tried it yet, but updating the database might take too much time during the period when the game is being played. Fixed set of users (might be 10,000 to 50,000 users) Will map user IDs to their score and other user-specific information. User IDs will be auto_increment values. If the structure has a high memory overhead that's probably not an issue. If the program crashes during gameplay it can just be re-started. Quickly get a user's current score. Quickly add to a user's current score (and return their current score) Quickly get 20 users with highest score. No deletes. No inserts except when the structure is first created, and how long that takes isn't critical. Getting the top 20 users will only happen every five or ten seconds, but getting/adding will happen much more frequently. If not for the last, I could just create a memory block equal to sizeof(user) * max(user id) and put each user at user id * sizeof(user) for fast access. Should I do that plus some other structure for the Top 20 feature, or is there one structure that will handle all of this together?

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