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• This Android SDK requires Android Developer Toolkit version 22.0.0 or above. Current version is 21.x.x.

  - by user2626673

  Hi i have a problem with my Eclipse and the SDK (i have download and install the latest ADT Bundle for windows ) when i start my eclipse i get this problem : This Android SDK requires Android Developer Toolkit version 22.0.0 or above. Current version is 20.0.0. please update your SDK tools to the latest version i have tried the option : Help - check for updates But with no new update find then i try this one : How to Update your ADT to Latest Version In Eclipse go to Help Install New Software ---> Add inside Add Repository write the Name: ADT (or whatever you want) and Location: https://dl-ssl.google.com/android/eclipse/ after loading you should get Developer Tools and NDK Plugins check both if you want to use the Native Developer Kit (NDK) in the future or check Developer Tool only click Next Finish But i dont have the option to click next to finish (the back , next and finish options are grey ) Then i try this method : Go here download latest version of ADT-22.0.4.zip (*) At Eclipse > Help > Install new software... > Uncheck Contact all update sites during install to find required software (last bottom preference) that will avoid any unwanted delays during install. then at the same screen (top) Click Add > Archive > select downloaded ADT-X.X.X.zip > follow on screen installation steps But had the same problem when it was to finish the installation.. no option to click ''next'' then i try this one : Help – Install New Software in the ADT menu. Type https://dl-ssl.google.com/android/eclipse/site.xml in “Work with:” and Enter. You can see the “Developer Tools” item. Select it and click Next. Click Next one more. Click Finish accepting the terms of the license agreements. Click OK in the “Security Warning” window. Let the installer restart ADT after installing the tools. But and in this option have the same problem as above.. can click the ''next'' to finish http://i30.photobucket.com/albums/c316/caslor_1978/diafora/atdproblem_zps0d141b7b.jpg i check my version and it is the latest but have the problem http://i30.photobucket.com/albums/c316/caslor_1978/diafora/atdproblem2_zps81de6317.jpg How can i fix this problem ? any suggestion? Win7 / 32bit / java SE Development kit7 update 25

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• Robust way to save/load objects with dependencies?

  - by mrteacup

  I'm writing an Android game in Java and I need a robust way to save and load application state quickly. The question seems to apply to most OO languages. To understand what I need to save: I'm using a Strategy pattern to control my game entities. The idea is I have a very general Entity class which e.g. stores the location of a bullet/player/enemy and I then attach a Behaviour class that tells the entity how to act: class Entiy { float x; float y; Behavior b; } abstract class Behavior { void update(Entity e); {} // Move about at a constant speed class MoveBehavior extends Behavior { float speed; void update ... } // Chase after another entity class ChaseBehavior extends Behavior { Entity target; void update ... } // Perform two behaviours in sequence class CombineBehavior extends Behavior { Behaviour a, b; void update ... } Essentially, Entity objects are easy to save but Behaviour objects can have a semi-complex graph of dependencies between other Entity objects and other Behaviour objects. I also have cases where a Behaviour object is shared between entities. I'm willing to change my design to make saving/loading state easier, but the above design works really well for structuring the game. Anyway, the options I've considered are: Use Java serialization. This is meant to be really slow in Android (I'll profile it sometime). I'm worried about robustness when changes are made between versions however. Use something like JSON or XML. I'm not sure how I would cope with storing the dependencies between objects however. Would I have to give each object a unique ID and then use these IDs on loading to link the right objects together? I thought I could e.g. change the ChaseBehaviour to store a ID to an entity, instead of a reference, that would be used to look up the Entity before performing the behaviour. I'd rather avoid having to write lots of loading/saving code myself as I find it really easy to make mistakes (e.g. forgetting to save something, reading things out in the wrong order). Can anyone give me any tips on good formats to save to or class designs that make saving state easier?

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• Techniques for querying a set of object in-memory in a Java application

  - by Edd Grant

  Hi All, We have a system which performs a 'coarse search' by invoking an interface on another system which returns a set of Java objects. Once we have received the search results I need to be able to further filter the resulting Java objects based on certain criteria describing the state of the attributes (e.g. from the initial objects return all objects where x.y z && a.b == c). The criteria used to filter the set of objects each time is partially user configurable, by this I mean that users will be able to select the values and ranges to match on but the attributes they can pick from will be a fixed set. The data sets are likely to contain <= 10,000 objects for each search. The search will be executed manually by the application user base probably no more than 2000 times a day (approx). It's probably worth mentioning that all the objects in the result set are known domain object classes which have Hibernate and JPA annotations describing their structure and relationship. Off the top of my head I can think of 3 ways of doing this: For each search persist the initial result set objects in our database, then use Hibernate to re-query them using the finer grained criteria. Use an in-memory Database (such as hsqldb?) to query and refine the initial result set. Write some custom code which iterates the initial result set and pulls out the desired records. Option 1 seems to involve a lot of toing and froing across a network to a physical Database (Oracle 10g) which might result in a lot of network and disk activity. It would also require the results from each search to be isolated from other result sets to ensure that different searches don't interfere with each other. Option 2 seems like a good idea in principle as it would allow me to do the finer query in memory and would not require the persistence of result data which would only be discarded after the search was complete. Gut feeling is that this could be pretty performant too but might result in larger memory overheads (which is fine as we can be pretty flexible on the amount of memory our JVM gets). Option 3 could be very performant but is something I would like to avoid as any code we write would require such careful testing that the time taken to acheive something flexible and robust enough would probably be prohibitive. I don't have time to prototype all 3 ideas so I am looking for comments people may have on the 3 options above, plus any further ideas I have not considered, to help me decide which idea might be most suitable. I'm currently leaning toward option 2 (in memory database) so would be keen to hear from people with experience of querying POJOs in memory too. Hopefully I have described the situation in enough detail but don't hesitate to ask if any further information is required to better understand the scenario. Cheers, Edd

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• choosing an image locally from http url and serving that image without a server round trip

  - by serverman

  Hi folks I am a complete novice to Flash (never created anything in flash). I am quite familiar with web applications (J2EE based) and have a reasonable expertise in Javascript. Here is my requirement. I want the user to select (via an html form) an image. Normally in the post, this image would be sent to server and may be stored there to be served later. I do not want that. I want to store this image locally and then serve it via HTTP to the user. So, the flow is: 1. Go to the "select image url":mywebsite.com/selectImage Browse the image and select the image This would transfer control locally to some code running on the client (Javascript or flash), which would then store the image locally at some place on the client machine. Go to the "show image url": mywebsite.com/showImage This would eventually result in some client code running on the browser that retrieves the image and renders it (without any server round trips.) I considered the following options: Use HTML5 local storage. Since I am a complete novice to flash, I looked into this. I found that it is fairly straightforward to store and retrieve images in javascript (only strings are allowed but I am hoping storing base64 encoded strings would work at least for small images). However, how do I serve the image via http url that points to my server without a server round trip? I saw the interesting article at http://hacks.mozilla.org/category/fileapi/ but that would work only in firefox and I need to work on all latest browsers (at least the ones supporting HTML5 local storage) Use flash SharedObjects. OK, this would have been good - the only thing is I am not sure where to start. Snippets of actionscripts to do this are scattered everywhere but I do not know how to use those scripts in an actual html page:) I do not need to create any movies or anything - just need to store an image and serve it locally. If I go this route, I would also use it to store other "strings" locally. If you suggest this, please give me the exact steps (could be pointers to other web sites) on how to do this. I would like to avoid paying for any flash development environment software ideally:) Thank you!

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• How to use XSLT to tag specific nodes with unique, sequential, increasing integer ids?

  - by ~otakuj462

  Hi, I'm trying to use XSLT to transform a document by tagging a group of XML nodes with integer ids, starting at 0, and increasing by one for each node in the group. The XML passed into the stylesheet should be echoed out, but augmented to include this extra information. Just to be clear about what I am talking about, here is how this transformation would be expressed using DOM: states = document.getElementsByTagName("state"); for( i = 0; i < states.length; i++){ states.stateNum = i; } This is very simple with DOM, but I'm having much more trouble doing this with XSLT. The current strategy I've devised has been to start with the identity transformation, then create a global variable which selects and stores all of the nodes that I wish to number. I then create a template that matches that kind of node. The idea, then, is that in the template, I would look up the matched node's position in the global variable nodelist, which would give me a unique number that I could then set as an attribute. The problem with this approach is that the position function can only be used with the context node, so something like the following is illegal: <template match="state"> <variable name="stateId" select="@id"/> <variable name="uniqueStateNum" select="$globalVariable[@id = $stateId]/position()"/> </template> The same is true for the following: <template match="state"> <variable name="stateId" select="@id" <variable name="stateNum" select="position($globalVariable[@id = $stateId])/"/> </template> In order to use position() to look up the position of an element in $globalVariable, the context node must be changed. I have found a solution, but it is highly suboptimal. Basically, in the template, I use for-each to iterate through the global variable. For-each changes the context node, so this allows me to use position() in the way I described. The problem is that this turns what would normally be an O(n) operation into an O(n^2) operation, where n is the length of the nodelist, as this require iterating through the whole list whenever the template is matched. I think that there must be a more elegant solution. Altogether, here is my current (slightly simplified) xslt stylesheet: <?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:s="http://www.w3.org/2005/07/scxml" xmlns="http://www.w3.org/2005/07/scxml" xmlns:c="http://msdl.cs.mcgill.ca/" version="1.0"> <xsl:output method="xml"/> <!-- we copy them, so that we can use their positions as identifiers --> <xsl:variable name="states" select="//s:state" /> <!-- identity transform --> <xsl:template match="@*|node()"> <xsl:copy> <xsl:apply-templates select="@*|node()"/> </xsl:copy> </xsl:template> <xsl:template match="s:state"> <xsl:variable name="stateId"> <xsl:value-of select="@id"/> </xsl:variable> <xsl:copy> <xsl:apply-templates select="@*"/> <xsl:for-each select="$states"> <xsl:if test="@id = $stateId"> <xsl:attribute name="stateNum" namespace="http://msdl.cs.mcgill.ca/"> <xsl:value-of select="position()"/> </xsl:attribute> </xsl:if> </xsl:for-each> <xsl:apply-templates select="node()"/> </xsl:copy> </xsl:template> </xsl:stylesheet> I'd appreciate any advice anyone can offer. Thanks.

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• Use multiple inheritance to discriminate useage roles?

  - by Arne

  Hi fellows, it's my flight simulation application again. I am leaving the mere prototyping phase now and start fleshing out the software design now. At least I try.. Each of the aircraft in the simulation have got a flight plan associated to them, the exact nature of which is of no interest for this question. Sufficient to say that the operator way edit the flight plan while the simulation is running. The aircraft model most of the time only needs to read-acess the flight plan object which at first thought calls for simply passing a const reference. But ocassionally the aircraft will need to call AdvanceActiveWayPoint() to indicate a way point has been reached. This will affect the Iterator returned by function ActiveWayPoint(). This implies that the aircraft model indeed needs a non-const reference which in turn would also expose functions like AppendWayPoint() to the aircraft model. I would like to avoid this because I would like to enforce the useage rule described above at compile time. Note that class WayPointIter is equivalent to a STL const iterator, that is the way point can not be mutated by the iterator. class FlightPlan { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) WayPointIter First() const; WayPointIter Last() const; WayPointIter Active() const; void AdvanceActiveWayPoint() const; (...) }; My idea to overcome the issue is this: define an abstract interface class for each usage role and inherit FlightPlan from both. Each user then only gets passed a reference of the appropriate useage role. class IFlightPlanActiveWayPoint { public: WayPointIter Active() const =0; void AdvanceActiveWayPoint() const =0; }; class IFlightPlanEditable { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) }; Thus the declaration of FlightPlan would only need to be changed to: class FlightPlan : public IFlightPlanActiveWayPoint, IFlightPlanEditable { (...) }; What do you think? Are there any cavecats I might be missing? Is this design clear or should I come up with somethink different for the sake of clarity? Alternatively I could also define a special ActiveWayPoint class which would contain the function AdvanceActiveWayPoint() but feel that this might be unnecessary. Thanks in advance!

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• Twisted + SQLAlchemy and the best way to do it.

  - by Khorkrak

  So I'm writing yet another Twisted based daemon. It'll have an xmlrpc interface as usual so I can easily communicate with it and have other processes interchange data with it as needed. This daemon needs to access a database. We've been using SQL Alchemy in place of hard coding SQL strings for our latest projects - those mostly done for web apps in Pylons. We'd like to do the same for this app and re-use library code that makes use of SQL Alchemy. So what to do? Well of course since that library was written for use in a Pylons app it's all the straight-forward blocking style code that everyone is accustomed to and all of the non-blocking is magically handled by Pylons via threading, thread locals, scoped sessions and so on. So now for Twisted I guess I'm a bit stuck. I could: Just write the sql I need directly if it's minimal and use the dbapi pool in twisted to do runInteractions etc when I need to hit the db. Use the objects and inherently blocking methods in our library and block now and then in my Twisted daemon. Bah. Use sAsync which was last updated in 2008 and kind of reuse the models we have defined already but not really and it does address code that needs to work in Pylons either. Does that even work with the latest version SQL Alchemy? Who knows. That project looked great though - why was it apparently abandoned? Spawn a separate subprocess and have it deal with the library code and all it's blocking, the results being returned back to my daemon when ready as objects marshalled via YAML over xmlrpc. Use deferToThread and then expunge the objects returned having made sure to do eager loads so that I have all my stuff that I might need. Seems kind of ugha to me. I'm also stuck using Python 2.5.4 atm so no 2.6 yet and I don't think I can just do an import from future to get access to the cool new multiprocessing module stuff in there. That's OK though I guess as we've got dealing with interprocess communication down pretty well. So I'm leaning towards option 4 mostly as that would avoid the mortal sin of logic duplication with option 1 while also staying the heck away from threads. Any better ideas?

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• Haskell Monad bind currying

  - by Chime

  I am currently in need of a bit of brain training and I found this article on Haskell and Monads I'm having trouble with exercise 7 re. Randomised function bind. To make the problem even simpler to experiment, I replaced the StdGen type with an unspecified type. So instead of... bind :: (a -> StdGen -> (b,StdGen)) -> (StdGen -> (a,StdGen)) -> (StdGen -> (b,StdGen)) I used... bind :: (a -> c -> (b,c)) -> (c -> (a,c)) -> (c -> (b,c)) and for the actual function impelemtation (just straight from the exercise) bind f x seed = let (x',seed') = x seed in f x' seed' and also 2 randomised functions to trial with: rndf1 :: (Num a, Num b) => a -> b -> (a,b) rndf1 a s = (a+1,s+1) rndf2 :: (Num a, Num b) => a -> b -> (a,b) rndf2 a s = (a+8,s+2) So with this in a Haskell compiler (ghci), I get... :t bind rndf2 bind rndf2 :: (Num a, Num c) => (c -> (a, c)) -> c -> (a, c) This matches the bind curried with rndf2 as the first parameter. But the thing I don't understand is how... :t bind rndf2 . rndf1 Suddenly gives bind rndf2 . rndf1 :: (Num a, Num c) => a -> c -> (a, c) This is the correct type of the composition that we are trying to produce because bind rndf2 . rndf1 Is a function that: takes the same parameter type(s) as rndf1 AND takes the return from rndf1 and pipes it as an input of rndf2 to return the same type as rndf2 rndf1 can take 2 parameters a -> c and rndf2 returns (a, c) so it matches that a composition of these function should have type: bind rndf2 . rndf1 :: (Num a, Num c) => a -> c -> (a, c) This does not match the naive type that I initially came up with for bind bind f :: (a -> b -> (c, d)) -> (c, d) -> (e, f) Here bind mythically takes a function that takes two parameters and produces a function that takes a tuple in order that the output from rndf1 can be fed into rndf2 why the bind function needs to be coded as it is Why the bind function does not have the naive type

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• Error when deploying site of a maven multi module project with FTP

  - by julien

  I have a multi module project. When I launch mvn site:deploy, the deployment of the base module works fine, but it fails to create the directory of the module sites on the FTP server: [INFO] Error uploading site Embedded error: Required directory: '/myremoteftprepository/myproject-mymodule' is missing When I create the missing directory by hand, it works fine, but I would like to avoid that. It is surprising that the deploy command do not create it. Do you how to force this directory creation? Is it a bug in the wagon-ftp plugin? FYI, here is my POM: <build> <extensions> <!-- Enabling the use of FTP --> <extension> <groupId>org.apache.maven.wagon</groupId> <artifactId>wagon-ftp</artifactId> <version>1.0</version> </extension> </extensions> </build> I have chosen to include the javadoc with: <reporting> <plugins> <!-- include javadoc in the site --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-javadoc-plugin</artifactId> <version>2.8</version> <configuration> <show>public</show> </configuration> </plugin> </plugins> </reporting> and <distributionManagement> <site> <id>site</id> <name>maven site</name> <url>ftp://ftp.blabla.org/myremoteftprepository</url> </site> </distributionManagement> and my settings.xml is good.

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• Passing enums to functions in C++

  - by rocknroll

  Hi all, I have a header file with all the enums listed (#ifndef #define #endif construct has been used to avoid multiple inclusion of the file) that I use in multiple cpp files in my application.One of the enums in the files is enum StatusSubsystem {ENABLED,INCORRECT_FRAME,INVALID_DATA,DISABLED}; There are functions in the application delcared as ShowStatus(const StatusSubsystem&); Earlier in the application when I made calls to the above function like ShowStatus(INCORRECT_FRAME); my application used to compile perfectly. But after some code was added The compilation halts giving the following error: File.cpp:71: error: invalid conversion from `int' to `StatusSubsystem' File.cpp:71: error: initializing argument 1 of `void Class::ShowStatus(const StatusSubsystem&) I checked the code for any conflicting enums in the new code and it looked fine. My Question is what is wrong with the function call that compiler shows as erroneous? For your reference the function definition is: void Class::ShowStatus(const StatusSubsystem& eStatus) { QPalette palette; mStatus=eStatus;//store current Communication status of system if(eStatus==DISABLED) { //select red color for label, if it is to be shown disabled palette.setColor(QPalette::Window,QColor(Qt::red)); mLabel->setText("SYSTEM"); } else if(eStatus==ENABLED) { //select green color for label,if it is to be shown enabled palette.setColor(QPalette::Window,QColor(Qt::green)); mLabel->setText("SYSTEM"); } else if(eStatus==INCORRECT_FRAME) { //select yellow color for label,to show that it is sending incorrect frames palette.setColor(QPalette::Window,QColor(Qt::yellow)); mLabel->setText("SYSTEM(I)"); } //Set the color on the Label mLabel->setPalette(palette); } A strange side effect of this situation is it compiles when I cast all the calls to ShowStatus() as ShowStatus((StatusSubsystem)INCORRECT_FRAME); Though this removes any compilation error, but a strange thing happens. Though I make call to INCORRECT_FRAME above but in function definition it matches with ENABLED. How on earth is that possible? Its like while passing INCORRECT_FRAME by reference, it magically converts to ENABLED, which should be impossible. This is driving me nuts. Can you find any flaw in what I am doing? or is it something else? The application is made using C++,Qt-4.2.1 on RHEL4. Thanks.

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• how to invoke an activity of a library project from an android apps

  - by Austin

  I have an open source android code that I need to use in my android apps. It has all the source code as well as resource files, manifest files and class path. It can be compiled as a separate android apps. I have constraints for using the open source. 1. I can't change a single line of code. 2. I can't use it as a separate apps. These constraints are non negotiable. What I have done is I have compiled the open source as class library(in Eclipse: Project Properties-Android- Tick check box Is Library). This has resulted in generation of .class files(in bin) for the java files and resource files. This open source has an android activity that i want to open from my application. So I have linked the directory of these sets of class files in the source section of my java build path( in .classpath). I have declared the activity in my manifest file with proper action intent filters. Now when I am trying to call activity from my code, its not working. Cleaning and rebuilding doesn't help. However, if I build the open source project and my apps in the same workspace of eclipse and link the open source in my apps in exact same manner it works fine. I am not able to identify the difference. All settings seems to be same(all files are identical in both the cases). But only in the second case it works. I have tried it as jar file also. I have build the open source as project library and exported it into a jar file(excluding manifest file). But in that case I am getting the following error UNEXPECTED TOP-LEVEL EXCEPTION: java.lang.IllegalArgumentException: already added: .... Conversion to Dalvik format failed with error 1 This I guess is coming because the android library(2.2) has been included twice in my apps( one for building my apps & another for building the open source). I dont know how to avoid this. Cleaning the project doesn't help. What i require is to use the open source and invoking it's activities in my apps without violating the constraints. If i can use the open source as bunch of .class files then great, or else any other way will do fine. Please look into it and let me know. Thanks

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• OutOfMemoryError loading Bitmap via DefaultHttpClient

  - by Goddchen

  i have a simple problem: Although i'm using sampleSize properly, my code doesn't even reach the BitmapFactorycode, since DefaultHttpClient is already throwing the exception. Here is my code: DefaultHttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(mSongInfo.imageLarge); HttpResponse response = client.execute(request); int sampleSize = 1; while (response.getEntity().getContentLength() / sampleSize / sampleSize > 100 * 1024) { sampleSize *= 2; } BitmapFactory.Options options = new BitmapFactory.Options(); options.inSampleSize = sampleSize; final Bitmap bitmap = BitmapFactory.decodeStream(response .getEntity().getContent(), null, options); And here is the exception: 0 java.lang.OutOfMemoryError: (Heap Size=11463KB, Allocated=7623KB, Bitmap Size=9382KB) 1 at org.apache.http.util.ByteArrayBuffer.<init>(ByteArrayBuffer.java:53) 2 at org.apache.http.impl.io.AbstractSessionInputBuffer.init(AbstractSessionInputBuffer.java:82) 3 at org.apache.http.impl.io.SocketInputBuffer.<init>(SocketInputBuffer.java:98) 4 at org.apache.http.impl.SocketHttpClientConnection.createSessionInputBuffer(SocketHttpClientConnection.java:83) 5 at org.apache.http.impl.conn.DefaultClientConnection.createSessionInputBuffer(DefaultClientConnection.java:170) 6 at org.apache.http.impl.SocketHttpClientConnection.bind(SocketHttpClientConnection.java:106) 7 at org.apache.http.impl.conn.DefaultClientConnection.openCompleted(DefaultClientConnection.java:129) 8 at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:173) 9 at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 10 at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 11 at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359) 12 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 13 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 14 at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 15 at de.goddchen.android.easysongfinder.fragments.SongFragment$1.run(SongFragment.java:79) 16 at java.lang.Thread.run(Thread.java:1027) As you can see, the code doesn't even reach the part where i check the size (Content-Length) of the image and calculate a proper sample size. I wasn't aware that simply calling DefaultHttpClient.execute(...) will already load the complete content into the memory. Am i doing something wrong? What is the right way to first retrieve the content length and then start reading the content from an InputStream? EDIT To avoid common answers that show how to load images from a URL: i already know how to do that, i have also posted the code above, so why do you keep referencing tutorials on that? I explicitly was very clear about the problem: Why is HttpClient.execute(...)already fetching the whole content and storing it in memory instead of providing a proper ÌnputStreamto me? Please don't post any beginner tutorials on how to load aBitmap`from a URL...

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• JavaScript Optimisation

  - by Jayie

  I am using JavaScript to work out all the combinations of badminton doubles matches from a given list of players. Each player teams up with everyone else. EG. If I have the following players a, b, c & d. Their combinations can be: a & b V c & d a & c V b & d a & d V b & c I am using the code below, which I wrote to do the job, but it's a little inefficient. It loops through the PLAYERS array 4 times finding every single combination (including impossible ones). It then sorts the game out into alphabetical order and stores it in the GAMES array if it doesn't already exist. I can then use the first half of the GAMES array to list all game combinations. The trouble is if I have any more than 8 players it runs really slowly because the combination growth is exponential. Does anyone know a better way or algorithm I could use? The more I think about it the more my brain hurts! var PLAYERS = ["a", "b", "c", "d", "e", "f", "g"]; var GAMES = []; var p1, p2, p3, p4, i1, i2, i3, i4, entry, found, i; var pos = 0; var TEAM1 = []; var TEAM2 = []; // loop through players 4 times to get all combinations for (i1 = 0; i1 < PLAYERS.length; i1++) { p1 = PLAYERS[i1]; for (i2 = 0; i2 < PLAYERS.length; i2++) { p2 = PLAYERS[i2]; for (i3 = 0; i3 < PLAYERS.length; i3++) { p3 = PLAYERS[i3]; for (i4 = 0; i4 < PLAYERS.length; i4++) { p4 = PLAYERS[i4]; if ((p1 != p2 && p1 != p3 && p1 != p4) && (p2 != p1 && p2 != p3 && p2 != p4) && (p3 != p1 && p3 != p2 && p3 != p4) && (p4 != p1 && p4 != p2 && p4 != p3)) { // sort teams into alphabetical order (so we can compare them easily later) TEAM1[0] = p1; TEAM1[1] = p2; TEAM2[0] = p3; TEAM2[1] = p4; TEAM1.sort(); TEAM2.sort(); // work out the game and search the array to see if it already exists entry = TEAM1[0] + " & " + TEAM1[1] + " v " + TEAM2[0] + " & " + TEAM2[1]; found = false; for (i=0; i < GAMES.length; i++) { if (entry == GAMES[i]) found = true; } // if the game is unique then store it if (!found) { GAMES[pos] = entry; document.write((pos+1) + ": " + GAMES[pos] + "<br>"); pos++; } } } } } } Thanks in advance. Jason.

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• What is the most idiomatic way to emulating Perl's Test::More::done_testing?

  - by DVK

  I have to build unit tests for in environment with a very old version of Test::More (perl5.8 with $Test::More::VERSION being '0.80') which predates the addition of done_testing(). Upgrading to newer Test::More is out of the question for practical reasons. And I am trying to avoid using no_tests - it's generally a bad idea not catching when your unit test exits prematurely - say due to some logic not executing when you expected it to. What is the most idiomatic way of running a configurable amount of tests, assuming no no_tests or done_testing() is used? Details: My unit tests usually take the form of: use Test::More; my @test_set = ( [ "Test #1", $param1, $param2, ... ] ,[ "Test #1", $param1, $param2, ... ] # ,... ); foreach my $test (@test_set) { run_test($test); } sub run_test { # $expected_tests += count_tests($test); ok(test1($test)) || diag("Test1 failed"); # ... } The standard approach of use Test::More tests => 23; or BEGIN {plan tests => 23} does not work since both are obviously executed before @tests is known. My current approach involves making @tests global and defining it in the BEGIN {} block as follows: use Test::More; BEGIN { our @test_set = (); # Same set of tests as above my $expected_tests = 0; foreach my $test (@tests) { my $expected_tests += count_tests($test); } plan tests = $expected_tests; } our @test_set; # Must do!!! Since first "our" was in BEGIN's scope :( foreach my $test (@test_set) { run_test($test); } # Same sub run_test {} # Same I feel this can be done more idiomatically but not certain how to improve. Chief among the smells is the duplicate our @test_test declarations - in BEGIN{} and after it. Another approach is to emulate done_testing() by calling Test::More->builder->plan(tests=>$total_tests_calculated). I'm not sure if it's any better idiomatically-wise.

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• Java Flow Control Problem

  - by Kyle_Solo

  I am programming a simple 2d game engine. I've decided how I'd like the engine to function: it will be composed of objects containing "events" that my main game loop will trigger when appropriate. A little more about the structure: Every GameObject has an updateEvent method. objectList is a list of all the objects that will receive update events. Only objects on this list have their updateEvent method called by the game loop. I’m trying to implement this method in the GameObject class (This specification is what I’d like the method to achieve): /** * This method removes a GameObject from objectList. The GameObject * should immediately stop executing code, that is, absolutely no more * code inside update events will be executed for the removed game object. * If necessary, control should transfer to the game loop. * @param go The GameObject to be removed */ public void remove(GameObject go) So if an object tries to remove itself inside of an update event, control should transfer back to the game engine: public void updateEvent() { //object's update event remove(this); System.out.println("Should never reach here!"); } Here’s what I have so far. It works, but the more I read about using exceptions for flow control the less I like it, so I want to see if there are alternatives. Remove Method public void remove(GameObject go) { //add to removedList //flag as removed //throw an exception if removing self from inside an updateEvent } Game Loop for(GameObject go : objectList) { try { if (!go.removed) { go.updateEvent(); } else { //object is scheduled to be removed, do nothing } } catch(ObjectRemovedException e) { //control has been transferred back to the game loop //no need to do anything here } } // now remove the objects that are in removedList from objectList 2 questions: Am I correct in assuming that the only way to implement the stop-right-away part of the remove method as described above is by throwing a custom exception and catching it in the game loop? (I know, using exceptions for flow control is like goto, which is bad. I just can’t think of another way to do what I want!) For the removal from the list itself, it is possible for one object to remove one that is farther down on the list. Currently I’m checking a removed flag before executing any code, and at the end of each pass removing the objects to avoid concurrent modification. Is there a better, preferably instant/non-polling way to do this?

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• Please clarify how create/update happens against child entities of an aggregate root

  - by christian

  After much reading and thinking as I begin to get my head wrapped around DDD, I am a bit confused about the best practices for dealing with complex hierarchies under an aggregate root. I think this is a FAQ but after reading countless examples and discussions, no one is quite talking about the issue I'm seeing. If I am aligned with the DDD thinking, entities below the aggregate root should be immutable. This is the crux of my trouble, so if that isn't correct, that is why I'm lost. Here is a fabricated example...hope it holds enough water to discuss. Consider an automobile insurance policy (I'm not in insurance, but this matches the language I hear when on the phone w/ my insurance company). Policy is clearly an entity. Within the policy, let's say we have Auto. Auto, for the sake of this example, only exists within a policy (maybe you could transfer an Auto to another policy, so this is potential for an aggregate as well, which changes Policy...but assume it simpler than that for now). Since an Auto cannot exist without a Policy, I think it should be an Entity but not a root. So Policy in this case is an aggregate root. Now, to create a Policy, let's assume it has to have at least one auto. This is where I get frustrated. Assume Auto is fairly complex, including many fields and maybe a child for where it is garaged (a Location). If I understand correctly, a "create Policy" constructor/factory would have to take as input an Auto or be restricted via a builder to not be created without this Auto. And the Auto's creation, since it is an entity, can't be done beforehand (because it is immutable? maybe this is just an incorrect interpretation). So you don't get to say new Auto and then setX, setY, add(Z). If Auto is more than somewhat trivial, you end up having to build a huge hierarchy of builders and such to try to manage creating an Auto within the context of the Policy. One more twist to this is later, after the Policy is created and one wishes to add another Auto...or update an existing Auto. Clearly, the Policy controls this...fine...but Policy.addAuto() won't quite fly because one can't just pass in a new Auto (right!?). Examples say things like Policy.addAuto(VIN, make, model, etc.) but are all so simple that that looks reasonable. But if this factory method approach falls apart with too many parameters (the entire Auto interface, conceivably) I need a solution. From that point in my thinking, I'm realizing that having a transient reference to an entity is OK. So, maybe it is fine to have a entity created outside of its parent within the aggregate in a transient environment, so maybe it is OK to say something like: auto = AutoFactory.createAuto(); auto.setX auto.setY or if sticking to immutability, AutoBuilder.new().setX().setY().build() and then have it get sorted out when you say Policy.addAuto(auto) This insurance example gets more interesting if you add Events, such as an Accident with its PolicyReports or RepairEstimates...some value objects but most entities that are all really meaningless outside the policy...at least for my simple example. The lifecycle of Policy with its growing hierarchy over time seems the fundamental picture I must draw before really starting to dig in...and it is more the factory concept or how the child entities get built/attached to an aggregate root that I haven't seen a solid example of. I think I'm close. Hope this is clear and not just a repeat FAQ that has answers all over the place.

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• What is the best WebControl to create this

  - by balexandre

  current output wanted output current code public partial class test : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) populateData(); } private void populateData() { List<temp> ls = new List<temp>(); ls.Add(new temp { a = "AAA", b = "aa", c = "a", dt = DateTime.Now }); ls.Add(new temp { a = "BBB", b = "bb", c = "b", dt = DateTime.Now }); ls.Add(new temp { a = "CCC", b = "cc", c = "c", dt = DateTime.Now.AddDays(1) }); ls.Add(new temp { a = "DDD", b = "dd", c = "d", dt = DateTime.Now.AddDays(1) }); ls.Add(new temp { a = "EEE", b = "ee", c = "e", dt = DateTime.Now.AddDays(2) }); ls.Add(new temp { a = "FFF", b = "ff", c = "f", dt = DateTime.Now.AddDays(2) }); TemplateField tc = (TemplateField)gv.Columns[0]; // <-- want to assign here just day gv.Columns.Add(tc); // <-- want to assign here just day + 1 gv.Columns.Add(tc); // <-- want to assign here just day + 2 gv.DataSource = ls; gv.DataBind(); } } public class temp { public temp() { } public string a { get; set; } public string b { get; set; } public string c { get; set; } public DateTime dt { get; set; } } and in HTML <asp:GridView ID="gv" runat="server" AutoGenerateColumns="false"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Eval("a") %>' Font-Bold="true" /><br /> <asp:Label ID="Label2" runat="server" Text='<%# Eval("b") %>' Font-Italic="true" /><br /> <asp:Label ID="Label3" runat="server" Text='<%# Eval("dt") %>' /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> What I'm trying to avoid is repeat code so I can only use one unique TemplateField I can accomplish this with 3 x GridView, one per each day, but I'm really trying to simplify code as the Grid will be exactly the same (as the HTML code goes), just the DataSource changes. Any help is greatly appreciated, Thank you.

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• Is it OK to put a standard, pure C header #include directive inside a namespace?

  - by mic_e

  I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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• TypeError: Object {...} has no method 'find' - when using mongoose with express

  - by sdouble

  I'm having trouble getting data from MongoDB using mongoose schemas with express. I first tested with just mongoose in a single file (mongoosetest.js) and it works fine. But when I start dividing it all up with express routes and config files, things start to break. I'm sure it's something simple, but I've spent the last 3 hours googling and trying to figure out what I'm doing wrong and can't find anything that matches my process enough to compare. mongoosetest.js (this works fine, but not for my application) var mongoose = require('mongoose'); mongoose.connect('mongodb://localhost/meanstack'); var db = mongoose.connection; var userSchema = mongoose.Schema({ name: String }, {collection: 'users'}); var User = mongoose.model('User', userSchema); User.find(function(err, users) { console.log(users); }); These files are where I'm having issues. I'm sure it's something silly, probably a direct result of using external files, exports, and requires. My server.js file just starts up and configures express. I also have a routing file and a db config file. routing file (allRoutes.js) var express = require('express'); var router = express.Router(); var db = require('../config/db'); var User = db.User(); // routes router.get('/user/list', function(req, res) { User.find(function(err, users) { console.log(users); }); }); // catch-all route router.get('*', function(req, res) { res.sendfile('./public/index.html'); }); module.exports = router; dbconfig file (db.js) var mongoose = require('mongoose'); var dbHost = 'localhost'; var dbName = 'meanstack'; var db = mongoose.createConnection(dbHost, dbName); var Schema = mongoose.Schema, ObjectId = Schema.ObjectId; db.once('open', function callback() { console.log('connected'); }); // schemas var User = new Schema({ name : String }, {collection: 'users'}); // models mongoose.model('User', User); var User = mongoose.model('User'); //exports module.exports.User = User; I receive the following error when I browse to localhost:3000/user/list TypeError: Object { _id: 5398bed35473f98c494168a3 } has no method 'find' at Object.module.exports [as handle] (C:\...\routes\allRoutes.js:8:8) at next_layer (C:\...\node_modules\express\lib\router\route.js:103:13) at Route.dispatch (C:\...\node_modules\express\lib\router\route.js:107:5) at C:\...\node_modules\express\lib\router\index.js:213:24 at Function.proto.process_params (C:\...\node_modules\express\lib\router\index.js:284:12) at next (C:\...\node_modules\express\lib\router\index.js:207:19) at Function.proto.handle (C:\...\node_modules\express\lib\router\index.js:154:3) at Layer.router (C:\...\node_modules\express\lib\router\index.js:24:12) at trim_prefix (C:\...\node_modules\express\lib\router\index.js:255:15) at C:\...\node_modules\express\lib\router\index.js:216:9 Like I said, it's probably something silly that I'm messing up with trying to organize my code since my single file (mongoosetest.js) works as expected. Thanks.

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• How to safely operate on parameters in threads, using C++ & Pthreads?

  - by ChrisCphDK

  Hi. I'm having some trouble with a program using pthreads, where occassional crashes occur, that could be related to how the threads operate on data So I have some basic questions about how to program using threads, and memory layout: Assume that a public class function performs some operations on some strings, and returns the result as a string. The prototype of the function could be like this: std::string SomeClass::somefunc(const std::string &strOne, const std::string &strTwo) { //Error checking of strings have been omitted std::string result = strOne.substr(0,5) + strTwo.substr(0,5); return result; } Is it correct to assume that strings, being dynamic, are stored on the heap, but that a reference to the string is allocated on the stack at runtime? Stack: [Some mem addr] pointer address to where the string is on the heap Heap: [Some mem addr] memory allocated for the initial string which may grow or shrink To make the function thread safe, the function is extended with the following mutex (which is declared as private in the "SomeClass") locking: std::string SomeClass::somefunc(const std::string &strOne, const std::string &strTwo) { pthread_mutex_lock(&someclasslock); //Error checking of strings have been omitted std::string result = strOne.substr(0,5) + strTwo.substr(0,5); pthread_mutex_unlock(&someclasslock); return result; } Is this a safe way of locking down the operations being done on the strings (all three), or could a thread be stopped by the scheduler in the following cases, which I'd assume would mess up the intended logic: a. Right after the function is called, and the parameters: strOne & strTwo have been set in the two reference pointers that the function has on the stack, the scheduler takes away processing time for the thread and lets a new thread in, which overwrites the reference pointers to the function, which then again gets stopped by the scheduler, letting the first thread back in? b. Can the same occur with the "result" string: the first string builds the result, unlocks the mutex, but before returning the scheduler lets in another thread which performs all of it's work, overwriting the result etc. Or are the reference parameters / result string being pushed onto the stack while another thread is doing performing it's task? Is the safe / correct way of doing this in threads, and "returning" a result, to pass a reference to a string that will be filled with the result instead: void SomeClass::somefunc(const std::string &strOne, const std::string &strTwo, std::string result) { pthread_mutex_lock(&someclasslock); //Error checking of strings have been omitted result = strOne.substr(0,5) + strTwo.substr(0,5); pthread_mutex_unlock(&someclasslock); } The intended logic is that several objects of the "SomeClass" class creates new threads and passes objects of themselves as parameters, and then calls the function: "someFunc": int SomeClass::startNewThread() { pthread_attr_t attr; pthread_t pThreadID; if(pthread_attr_init(&attr) != 0) return -1; if(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) != 0) return -2; if(pthread_create(&pThreadID, &attr, proxyThreadFunc, this) != 0) return -3; if(pthread_attr_destroy(&attr) != 0) return -4; return 0; } void* proxyThreadFunc(void* someClassObjPtr) { return static_cast<SomeClass*> (someClassObjPtr)->somefunc("long string","long string"); } Sorry for the long description. But I hope the questions and intended purpose is clear, if not let me know and I'll elaborate. Best regards. Chris

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• Solve a maze using multicores?

  - by acidzombie24

  This question is messy, i dont need a working solution, i need some psuedo code. How would i solve this maze? This is a homework question. I have to get from point green to red. At every fork i need to 'spawn a thread' and go that direction. I need to figure out how to get to red but i am unsure how to avoid paths i already have taken (finishing with any path is ok, i am just not allowed to go in circles). Heres an example of my problem, i start by moving down and i see a fork so one goes right and one goes down (or this thread can take it, it doesnt matter). Now lets ignore the rest of the forks and say the one going right hits the wall, goes down, hits the wall and goes left, then goes up. The other thread goes down, hits the wall then goes all the way right. The bottom path has been taken twice, by starting at different sides. How do i mark this path has been taken? Do i need a lock? Is this the only way? Is there a lockless solution? Implementation wise i was thinking i could have the maze something like this. I dont like the solution because there is a LOT of locking (assuming i lock before each read and write of the haveTraverse member). I dont need to use the MazeSegment class below, i just wrote it up as an example. I am allowed to construct the maze however i want. I was thinking maybe the solution requires no connecting paths and thats hassling me. Maybe i could split the map up instead of using the format below (which is easy to read and understand). But if i knew how to split it up i would know how to walk it thus the problem. How do i walk this maze efficiently? The only hint i receive was dont try to conserve memory by reusing it, make copies. However that was related to a problem with ordering a list and i dont think the hint was a hint for this. class MazeSegment { enum Direction { up, down, left, right} List<Pair<Direction, MazeSegment*>> ConnectingPaths; int line_length; bool haveTraverse; } MazeSegment root; class MazeSegment { enum Direction { up, down, left, right} List<Pair<Direction, MazeSegment*>> ConnectingPaths; bool haveTraverse; } void WalkPath(MazeSegment segment) { if(segment.haveTraverse) return; segment.haveTraverse = true; foreach(var v in segment) { if(v.haveTraverse == false) spawn_thread(v); } } WalkPath(root);

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• (iOS) UI Automation AlertPrompt button/textField accessiblity

  - by lipd

  I'm having a bit of trouble with UI Automation (the built in to iOS tool) when it comes to alertView. First off, I'm not sure where I can set the accessibilityLabel and such for the buttons that are on the alertView. Secondly, although I am not getting an error, I can't get my textField to actually set the value of the textField to something. I'll put up my code for the alertView and the javaScript I am using for UI Automation. UIATarget.onAlert = function onAlert(alert) { // Log alerts and bail, unless it's the one we want var title = alert.name(); UIALogger.logMessage("Alert with title '" + title + "' encountered!"); alert.logElementTree(); if (title == "AlertPrompt") { UIALogger.logMessage(alert.textFields().length + ''); target.delay(1); alert.textFields()["AlertText"].setValue("AutoTest"); target.delay(1); return true; // Override default handler } else return false; } var target = UIATarget.localTarget(); var application = target.frontMostApp(); var mainWindow = application.mainWindow(); mainWindow.logElementTree(); //target.delay(1); //mainWindow.logElementTree(); //target.delay(1); var tableView = mainWindow.tableViews()[0]; var button = tableView.buttons(); //UIALogger.logMessage("Num buttons: " + button.length); //UIALogger.logMessage("num Table views: " + mainWindow.tableViews().length); //UIALogger.logMessage("Number of cells: " + tableView.cells().length); /*for (var currentCellIndex = 0; currentCellIndex < tableView.cells().length; currentCellIndex++) { var currentCell = tableView.cells()[currentCellIndex]; UIALogger.logStart("Testing table option: " + currentCell.name()); tableView.scrollToElementWithName(currentCell.name()); target.delay(1); currentCell.tap();// Go down a level target.delay(1); UIATarget.localTarget().captureScreenWithName(currentCell.name()); //mainWindow.navigationBar().leftButton().tap(); // Go back target.delay(1); UIALogger.logPass("Testing table option " + currentCell.name()); }*/ UIALogger.logStart("Testing add item"); target.delay(1); mainWindow.navigationBar().buttons()["addButton"].tap(); target.delay(1); if(tableView.cells().length == 5) UIALogger.logPass("Successfully added item to table"); else UIALogger.logFail("FAIL: didn't add item to table"); Here's what I'm using for the alertView #import "AlertPrompt.h" @implementation AlertPrompt @synthesize textField; @synthesize enteredText; - (id)initWithTitle:(NSString *)title message:(NSString *)message delegate:(id)delegate cancelButtonTitle:(NSString *)cancelButtonTitle okButtonTitle:(NSString *)okayButtonTitle withOrientation:(UIInterfaceOrientation) orientation { if ((self == [super initWithTitle:title message:message delegate:delegate cancelButtonTitle:cancelButtonTitle otherButtonTitles:okayButtonTitle, nil])) { self.isAccessibilityElement = YES; self.accessibilityLabel = @"AlertPrompt"; UITextField *theTextField; if(orientation == UIInterfaceOrientationPortrait) theTextField = [[UITextField alloc] initWithFrame:CGRectMake(12.0, 45.0, 260.0, 25.0)]; else theTextField = [[UITextField alloc] initWithFrame:CGRectMake(12.0, 30.0, 260.0, 25.0)]; [theTextField setBackgroundColor:[UIColor whiteColor]]; [self addSubview:theTextField]; self.textField = theTextField; self.textField.isAccessibilityElement = YES; self.textField.accessibilityLabel = @"AlertText"; [theTextField release]; CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 0.0); [self setTransform:translate]; } return self; } - (void)show { [textField becomeFirstResponder]; [super show]; } - (NSString *)enteredText { return [self.textField text]; } - (void)dealloc { //[textField release]; [super dealloc]; } @end Thanks for any help!

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• How can I obtain the IPv4 address of the client?

  - by Dr Dork

  Hello! I'm prepping for a simple work project and am trying to familiarize myself with the basics of socket programming in a Unix dev environment. At this point, I have some basic server side code setup to listen for incoming TCP connection requests from clients after the parent socket has been created and is set to listen... int sockfd, newfd; unsigned int len; socklen_t sin_size; char msg[]="Test message sent"; char buf[MAXLEN]; int st, rv; struct addrinfo hints, *serverinfo, *p; struct sockaddr_storage client; char ip[INET6_ADDRSTRLEN]; . . //parent socket creation and listen code omitted for simplicity . //wait for connection requests from clients while(1) { //Returns the socketID and address of client connecting to socket if( ( newfd = accept(sockfd, (struct sockaddr *)&client, &len) ) == -1 ){ perror("Accept"); exit(-1); } if( (rv = recv(newfd, buf, MAXLEN-1, 0 )) == -1) { perror("Recv"); exit(-1); } struct sockaddr_in *clientAddr = ( struct sockaddr_in *) get_in_addr((struct sockaddr *)&client); inet_ntop(client.ss_family, clientAddr, ip, sizeof ip); printf("Receive from %s: query type is %s\n", ip, buf); if( ( st = send(newfd, msg, strlen(msg), 0)) == -1 ) { perror("Send"); exit(-1); } //ntohs is used to avoid big-endian and little endian compatibility issues printf("Send %d byte to port %d\n", ntohs(clientAddr->sin_port) ); close(newfd); } } I found the get_in_addr function online and placed it at the top of my code and use it to obtain the IP address of the client connecting... // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } but the function always returns the IPv6 IP address since thats what the sa_family property is set as. My question is, is the IPv4 IP address stored anywhere in the data I'm using and, if so, how can I access it? Thanks so much in advance for all your help!

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• compareTo() method java is acting weird

  - by Ron Paul

  hi im having trouble getting this to work im getting an error here with my object comparison...how could I cast the inches to a string ( i never used compare to with anything other than strings) , or use comparison operators to compare the intigers, Object comparison = this.inches.compareTo(obj.inches); here is my code so far import java.io.*; import java.util.*; import java.lang.Integer; import java.lang.reflect.Array; public class Distance implements Comparable<Distance> { private static final String HashCodeUtil = null; private int feet; private int inches; private final int DEFAULT_FT = 1; private final int DEFAULT_IN = 1; public Distance(){ feet = DEFAULT_FT; inches = DEFAULT_IN; } public Distance(int ft, int in){ feet = ft; inches = in; } public void setFeet(int ft){ try { if(ft<0){ throw new CustomException("Distance is not negative"); } } catch(CustomException c){ System.err.println(c); feet =ft; } } public int getFeet(){ return feet; } public void setInches(int in){ try { if (in<0) throw new CustomException("Distance is not negative"); //inches = in; } catch(CustomException c) { System.err.println(c); inches = in; } } public int getInches(){ return inches; } public String toString (){ return "<" + feet + ":" + inches + ">"; } public Distance add(Distance m){ Distance n = new Distance(); n.inches = this.inches + m.inches; n.feet = this.feet + m.feet; while(n.inches>12){ n.inches = n.inches - 12; n.feet++; } return n; } public Distance subtract(Distance f){ Distance m = new Distance(); m.inches = this.inches - f.inches; m.feet = this.feet - f.feet; while(m.inches<0){ m.inches = m.inches - 12; feet--; } return m; } @Override public int compareTo(Distance obj) { // TODO Auto-generated method stub final int BEFORE = -1; final int EQUAL = 0; final int AFTER = 1; if (this == obj) return EQUAL; if(this.DEFAULT_IN < obj.DEFAULT_FT) return BEFORE; if(this.DEFAULT_IN > obj.DEFAULT_FT) return AFTER; Object comparison = this.inches.compareTo(obj.inches); if (this.inches == obj.inches) return compareTo(null); assert this.equals(obj) : "compareTo inconsistent with equals"; return EQUAL; } @Override public boolean equals( Object obj){ if (obj != null) return false; if (!(obj intanceof Distance)) return false; Distance that = (Distance)obj; ( this.feet == that.feet && this.inches == that.inches); return true; else return false; } @Override public int hashCode(int, int) { int result = HashCodeUtil.inches; result = HashCodeUtil.hash(result, inches ); result = HashCodeUtil.hash(result, feet); ruturn result; }

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• Template class + virtual function = must implement?

  - by sold

  This code: template <typename T> struct A { T t; void DoSomething() { t.SomeFunction(); } }; struct B { }; A<B> a; is easily compiled without any complaints, as long as I never call a.DoSomething(). However, if I define DoSomething as a virtual function, I will get a compile error saying that B doesn't declare SomeFunction. I can somewhat see why it happens (DoSomething should now have an entry in the vtable), but I can't help feeling that it's not really obligated. Plus it sucks. Is there any way to overcome this? EDIT 2: Okay. I hope this time it makes sence: Let's say I am doing intrusive ref count, so all entities must inherit from base class Object. How can I suuport primitive types too? I can define: template <typename T> class Primitive : public Object { T value; public: Primitive(const T &value=T()); operator T() const; Primitive<T> &operator =(const T &value); Primitive<T> &operator +=(const T &value); Primitive<T> &operator %=(const T &value); // And so on... }; so I can use Primitive<int>, Primitive<char>... But how about Primitive<float>? It seems like a problem, because floats don't have a %= operator. But actually, it isn't, since I'll never call operator %= on Primitive<float>. That's one of the deliberate features of templates. If, for some reason, I would define operator %= as virtual. Or, if i'll pre-export Primitive<float> from a dll to avoid link errors, the compiler will complain even if I never call operator %= on a Primitive<float>. If it would just have fill in a dummy value for operator %= in Primitive<float>'s vtable (that raises an exception?), everything would have been fine.

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