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• Best implementation of Java Queue?

  - by Georges Oates Larsen

  I am working (In java) on a recursive image processing algorithm that recursively traverses the pixels of the image, outward from a center point. Unfortunately... That causes stack overflows, so I have decided to switch to a Queue-based algorithm. Now, this is all fine and dandy -- But considering the fact that its queue will be analyzing THOUSANDS of pixels in a very short amount of time, while constantly popping and pushing, WITHOUT maintaining a predictable state (It could be anywhere between length 100, and 20000); The queue implementation needs to have significantly fast popping and pushing abilities. A linked list seems attractive due to its ability to push elements unto its self without rearranging anything else in the list, but in order for it to be fast enough, it would need easy access to both its head, AND its tail (or second-to-last node if it were not doubly-linked). Sadly, though I cannot find any information related to the underlying implementation of linked lists in Java, so it's hard to say if a linked list is really the way to go... This brings me to my question... What would be the best implementation of the Queue interface in Java for what I intend to do? (I do not wish to edit or even access anything other than the head and tail of the queue -- I do not wish to do any sort of rearranging, or anything. On the flip side, I DO intend to do a lot of pushing and popping, and the queue will be changing size quite a bit, so preallocating would be inefficient)

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• PHP Combo Box AJAX Refresh

  - by bhs

  I have a PHP page that currently has 4 years of team positions in columns on the page. The client wants to select the players in positions and have first, second and thrid choices. Currently the page shows 4 columns with sets of combos for each position. Each combo has a full set of players in it and the user chooses the player he wants from the combos. On submit the player positions are stored in the database. However, the client now wants to change the page so that when he selects a player in a year and position then the player is removed from the combo and can no longer be selected for that year. I've used a bit of AJAX but was wondering if anyone had any thoughts/suggestions. The page is currently quite slow so they want it speeded up as well. The page layout is currently like this POISTION YEAR1 YEAR2 YEAR3 YEAR4 1 COMBOC1 COMBOC1 COMBOC1 COMBOC1 COMBOC2 COMBOC2 COMBOC2 COMBOC2 COMBOC3 COMBOC3 COMBOC3 COMBOC3 2 same as above COMBOC1, 2 and 3 all currently have the same players - when a player is selected it needs to be removed for all combos below it. I was thinking of starting by changing the page design and having text boxes for the players and a single player select under each year like this: POISTION YEAR1 YEAR2 YEAR3 YEAR4 1 <PLAYER><POSITION><CHOICE> ... [TEXT BOX CHOICE1] [TEXT BOX CHOICE2] [TEXT BOX CHOICE3] 2 ... Then I only have 1 combo box for each year to worry about - I do however have the same problem of refreshing the combo box and removing the player that has been selected, and I'd prefer to do it withough a page submit. Sorry for the long posting - cheers

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• Solr : how do i index and search several fields?

  - by sbrattla

  Hi, I've set up my first 'installation' of Solr, where each index (document) represents a musical work (with properties like number (int), title (string), version (string), composers (string) and keywords (string)). I've set the field 'title' as the default search field. However, what do I do when I would like to do a query on all fields? I'd like to give users the opportunity to search in all fields, and as far as I've understood there is at least two options for this: (1) Specify which fields the query should be made against. (2) Set up the Solr configuration with copyfields, so that values added to each of the fields will be copied to a 'catch-all'-like field which can be used for searching. However, in this case, i am uncertain how things would turn out when i take into consideration that the data types are not all the same for the various fields (the various fields will to a lesser og greater degree go through filters, but as copyfield values are taken from their original fields before the values have been run through their original fields' filters, i would have to apply one single filter to all values on the copyfield. This, again, would result in integers being 'filtered' just as strings would). Is this a case where i should use copyfields? At first glance, it seems a bit more 'flexible' to rather just search on all fields. However, maybe there's a cost? All feedback appreciated! Thanks!

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• Data historian queries

  - by Scott Dennis

  Hi, I have a table that contains data for electric motors the format is: DATE(DateTime) | TagName(VarChar(50) | Val(Float) | 2009-11-03 17:44:13.000 | Motor_1 | 123.45 2009-11-04 17:44:13.000 | Motor_1 | 124.45 2009-11-05 17:44:13.000 | Motor_1 | 125.45 2009-11-03 17:44:13.000 | Motor_2 | 223.45 2009-11-04 17:44:13.000 | Motor_2 | 224.45 Data for each motor is inserted daily, so there would be 31 Motor_1s and 31 Motor_2s etc. We do this so we can trend it on our control system displays. I am using views to extract last months max val and last months min val. Same for this months data. Then I join the two and calculate the difference to get the actual run hours for that month. The "Val" is a nonresetable Accumulation from a PLC(Controller). This is my query for Last months Max Value: SELECT TagName, Val AS Hours FROM dbo.All_Data_From_Last_Mon AS cur WHERE (NOT EXISTS (SELECT TagName, Val FROM dbo.All_Data_From_Last_Mon AS high WHERE (TagName = cur.TagName) AND (Val > cur.Val))) This is my query for Last months Max Value: SELECT TagName, Val AS Hours FROM dbo.All_Data_From_Last_Mon AS cur WHERE (NOT EXISTS (SELECT TagName, Val FROM dbo.All_Data_From_Last_Mon AS high WHERE (TagName = cur.TagName) AND (Val < cur.Val))) This is the query that calculates the difference and runs a bit slow: SELECT dbo.Motors_Last_Mon_Max.TagName, STR(dbo.Motors_Last_Mon_Max.Hours - dbo.Motors_Last_Mon_Min.Hours, 12, 2) AS Hours FROM dbo.Motors_Last_Mon_Min RIGHT OUTER JOIN dbo.Motors_Last_Mon_Max ON dbo.Motors_Last_Mon_Min.TagName = dbo.Motors_Last_Mon_Max.TagName I know there is a better way. Ultimately I just need last months total and this months total. Any help would be appreciated. Thanks in advance

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• Why am I getting a ClassCastException here?

  - by Holly

  I'm creating an android application and i'm trying to use a PreferenceActivity. I'm getting the java.lang.ClassCastException: java.lang.String error when it gets to this line return PreferenceManager.getDefaultSharedPreferences(context).getInt(USER_TERM, USER_TERM_DEF); I thought it might be because I'm not converting it properly from it's string value in the EditText box to the int I need but I can't figure out how to fix this, or is that even the cause? I'm flummoxed. Here's my preference activity class: public class UserPrefs extends PreferenceActivity { //option names and default vals private static final String USER_TERM = "term_length"; private static final String USER_YEAR = "year_length"; private static final int USER_TERM_DEF = 12; private static final int USER_YEAR_DEF = 34; @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.preferences); } public static int getTermLength(Context context){ try{ return PreferenceManager.getDefaultSharedPreferences(context).getInt(USER_TERM, USER_TERM_DEF); }catch (ClassCastException e){Log.v("getTermLength", "error::: " + e); } //return 1;//temporary, needed to catch the error and couldn't without adding a return outside the block.// } public static int getYearLength(Context context){ return PreferenceManager.getDefaultSharedPreferences(context).getInt(USER_YEAR, USER_YEAR_DEF); } And here's the bit of code where I'm trying to use the the preferences inside another class: public float alterForFrequency(Context keypadContext, float enteredAmount, String spinnerPosition){ int termLength = UserPrefs.getTermLength(keypadContext); int yearLength = UserPrefs.getYearLength(keypadContext); } The complete android logcat, i've uploaded here: http://freetexthost.com/v3t4ta3wbi

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• PHP in_array() can't even match a single character. Strict is set to true.

  - by solefald

  I've seen a million of these threads here already, and read through every single one already. Including some serious time Googling. Nothing complicated. All I have to do is check if a single character in a loop matches my alphabet array. print_r($alphabet); // all 26 letters Array ( [0] => a [1] => b [2] => c ... [23] => x [24] => y [25] => z ) print_r($emptyLetters); // dynamic array. Array ( [0] => b [1] => s ) foreach($alphabet as $letter): { echo $letter . '<br />' // Correctly prints out every letter from $alphabet. if(in_array($letter, $emptyLetters, true)): // $strict is set // do something endif; } What the hell is going on??? I do not understand what i am doing wrong.... I tried every combination and option possible, but for some reason even array_search() is bit working...

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• minifying final html output using regex with codeigniter

  - by Aman

  Google pages suggest you to minify html i.e. remove all the un-necessary spaces. Codeigniter does have feature of giziping output or it can be done via .htaccess. But still I also would like to remove un-necessary spaces from final html output as well. I played a bit with this peace of code to do it, and it seem to work. This does indeed result in html that is without excess spaces and removes other tab formatting. class Welcome extends CI_Controller { function _output() { echo preg_replace('!\s+!', ' ', $output); } function index(){ ... } } Now the problem with this is there may be tag like <pre>,<textarea>, etc.. which may have space in it and regx should remove them. So, how do I remove excess space from final html, without effecting spaces or formatting for these certain tags using regx? Thanks to @Alan Moore got the answer, this worked for me echo preg_replace('#(?ix)(?>[^\S ]\s*|\s{2,})(?=(?:(?:[^<]++|<(?!/?(?:textarea|pre)\b))*+)(?:<(?>textarea|pre)\b|\z))#', ' ', $output); @ridgerunner here did very good job of analyzing this regx, ended up using his solution. Cheers to ridgerunner.

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• Memory management of objects returned by methods (iOS / Objective-C)

  - by iOSNewb

  I am learning Objective-C and iOS programming through the terrific iTunesU course posted by Stanford (http://www.stanford.edu/class/cs193p/cgi-bin/drupal/) Assignment 2 is to create a calculator with variable buttons. The chain of commands (e.g. 3+x-y) is stored in a NSMutableArray as "anExpression", and then we sub in random values for x and y based on an NSDictionary to get a solution. This part of the assignment is tripping me up: The final two [methods] “convert” anExpression to/from a property list: + (id)propertyListForExpression:(id)anExpression; + (id)expressionForPropertyList:(id)propertyList; You’ll remember from lecture that a property list is just any combination of NSArray, NSDictionary, NSString, NSNumber, etc., so why do we even need this method since anExpression is already a property list? (Since the expressions we build are NSMutableArrays that contain only NSString and NSNumber objects, they are, indeed, already property lists.) Well, because the caller of our API has no idea that anExpression is a property list. That’s an internal implementation detail we have chosen not to expose to callers. Even so, you may think, the implementation of these two methods is easy because anExpression is already a property list so we can just return the argument right back, right? Well, yes and no. The memory management on this one is a bit tricky. We’ll leave it up to you to figure out. Give it your best shot. Obviously, I am missing something with respect to memory management because I don't see why I can't just return the passed arguments right back. Thanks in advance for any answers!

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• Open closed prinicple, problem

  - by Marcus

  Hi, I'm trying to apply OCP to a code snippet I have that in it's current state is really smelly, but I feel I'm not getting all the way to the end. Current code: public abstract class SomeObject {} public class SpecificObject1 : SomeObject {} public class SpecificObject2 : SomeObject {} // Smelly code public class Model { public void Store(SomeObject someObject) { if (someObject is SpecificObject1) {} else if (someObject is SpecificObject2) {} } } That is really ugly, my new approach looks like this: // No so smelly code public class Model { public void Store(SomeObject someObject) { throw new Expception("Not allowed!"); } public void Store(SpecificObject1 someObject) {} public void Store(SpecificObject2 someObject) {} } When a new SomeObject type comes along I must implement how that specific object is stored, this will break OCP cause I need to alter the Model-class. To move the store logic to SomeObject also feels wrong cause then I will violate SRP (?), becuase in this case the SomeObject is almost like a DTO, it's resposibility it not how to know to store itself. If a new implementation to SomeObject comes along who's store implementation is missing I will get a runtime error due to exception in Store method in Model class, it also feels like a code smell. This is because calling code will in the form of IEnumerable<SomeObject> sequence; I will not know the specific types of the sequence objects. I can't seem to grasp the OCP-concept. Anyone has any concrete examples or links that is a bit more than just some Car/Fruit example?

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• Weird compile-time behavior when trying to use primitive type in generics

  - by polygenelubricants

  import java.lang.reflect.Array; public class PrimitiveArrayGeneric { static <T> T[] genericArrayNewInstance(Class<T> componentType) { return (T[]) Array.newInstance(componentType, 0); } public static void main(String args[]) { int[] intArray; Integer[] integerArray; intArray = (int[]) Array.newInstance(int.class, 0); // Okay! integerArray = genericArrayNewInstance(Integer.class); // Okay! intArray = genericArrayNewInstance(int.class); // Compile time error: // cannot convert from Integer[] to int[] integerArray = genericArrayNewInstance(int.class); // Run time error: // ClassCastException: [I cannot be cast to [Ljava.lang.Object; } } I'm trying to fully understand how generics works in Java. Things get a bit weird for me in the 3rd assignment in the above snippet: the compiler is complaining that Integer[] cannot be converted to int[]. The statement is 100% true, of course, but I'm wondering WHY the compiler is making this complaint. If you comment that line, and follow the compiler's "suggestion" as in the 4th assignment, the compiler is actually satisfied!!! NOW the code compiles just fine! Which is crazy, of course, since like the run time behavior suggests, int[] cannot be converted to Object[] (which is what T[] is type-erased into at run time). So my question is: why is the compiler "suggesting" that I assign to Integer[] instead for the 3rd assignment? How does the compiler reason to arrive to that (erroneous!) conclusion?

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• JApplet behaving unexpectedly

  - by JohnW

  import java.awt.Graphics; import java.awt.Image; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JApplet; import javax.swing.Timer; public class CountingSheep extends JApplet { private Image sheepImage; private Image backgroundImage; private GameBoard gameBoard; private scoreBoard scoreBoard; public void init() { loadImages(); gameBoard = new GameBoard(sheepImage, backgroundImage); scoreBoard = new scoreBoard(); getContentPane().add(gameBoard); getContentPane().add(scoreBoard); } public void loadImages() { sheepImage = getImage(getDocumentBase(), "sheep.png"); backgroundImage = getImage(getDocumentBase(), "bg.jpg"); } } Update guys: Alright, first of all, thank you very much for all the help you've given so far (specifically creemam and Hovercraft Full of Eels), and your persistence. You've helped me out a lot as this is incredibly important (i.e. me passing my degree). The problem now is: The program works correctly when nothing but the GameBoard class is added to the JApplet, however, when I try to add the ScoreBoard class, both Panel classes do not show on the Applet. I'm guessing this is now down to positioning? Any ideas? EDIT: Gone back to the previously asked question Hovercraft, and found it was due to the layout of the contentPane and the order at with the components were added. Thanks to all of you so much. People like you make the development community a bit of alright.

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• MemoryFailPoint fires to early in WinXP 64

  - by msedi

  Hello, I have created a volume class (called VoxelVolume) with a self-organizing memory management, since the GC in C# didn't provide a good mechanism for managing contents of the volume for mapping, unmapping and remapping. Although I could have used the mechanisms of virtual memory, the problem is that the files are often too large to fit into the page file and I don't want to force the users to increase the pagefile size. Currently this system is working quite well and there is no problem in lacking resources and OutOfMemoryExceptions since the InsufficientMemoryException using the MemoryFailPoint works quite well. This was all testes on a 32bit WinXP system with 2GB of main memory. Running the same mechanism on 64bit system with 32GB of main memory also works well, but when the application runs the MemoryFailPoint suddenly throws an exception although 24GB of main memory are still free. Another point is when the MemoryFailPoint has fired once, it fires everytime and there is no chance to get rid of it. What I have read so far, that there is a small object and a large object heap (SOH and LOH). But only for the SOH the GC takes real care of and I can free the SOH from unused objects by applying GC.Collect() and GC.WaitForPendingFinalizers. The MemoryFailPoint is obviously the only way to get a little bit of control for the LOH, but since there is enough memory left on the system I see no reason why the MemoryFilePoint should fire. Is there any experience around here using the MemoryFailPoint? Thank you for your help Martin

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• How do I stop Chrome from yellowing my site's input boxes?

  - by davebug

  Among other text and visual aids on a form submission, post-validation, I'm coloring my input boxes red to signify the interactive area needing attention. On Chrome (and for Google Toolbar users) the auto-fill feature re-colors my input forms yellow. Here's the complex issue: I want auto-complete allowed on my forms, as it speeds users logging in. I am going to check into the ability to turn the autocomplete attribute to off if/when there's an error triggered, but it is a complex bit of coding to programmatically turn off the auto-complete for the single effected input on a page. This, to put it simply, would be a major headache. So to try to avoid that issue, is there any simpler method of stopping Chrome from re-coloring the input boxes? [edit] I tried the !important suggestion below and it had no effect. I have not yet checked Google Toolbar to see if the !important attribute woudl work for that. As far as I can tell, there isn't any means other than using the autocomplete attribute (which does appear to work).

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• Why are (almost) all the on-line games written in ActionScript (Flash) not Java?

  - by MasterPeter

  I absolutely love good defender games (e.g. Gemcraft, Protector: reclaiming the throne) as they can be intellectually quite challenging; it's like playing chess but a little less thinking a bit more action. Sadly, there are not that many good ones out there and I thought I would create one myself and share it with the rest of the world by making it available on-line. I have never worked with ActionScript but when it comes to on-line games, this is the main choice. I have tried to find a decent 2D game in the form of a Java applet but to no avail. Why is this so? I could write the game, most comfortably, in Delphi for Win32 but then people would need to download the executable, which could deter some form downloading it, and also it would only work on Windows. I am also familiar with Java, having worked with Java for the last four years or so. Although I don't have much experience with games programming. Should I note be deterred by the fact that all online games are written for in Flash and create my defender game as a Java applet, or should I consider learning ActionScript and games development for the ActionScript Virtual Machine (AS3 looks very much like Java... but still, it's an entirely new technology to me and I might never use it professionally.) Could you, please, just answer the the question in the title? Why Flash, not Java applets? Is it only 'politics'?

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• How can I build a wrapper to wait for listening on a port?

  - by BillyBBone

  Hi, I am looking for a way of programmatically testing a script written with the asyncore Python module. My test consists of launching the script in question -- if a TCP listen socket is opened, the test passes. Otherwise, if the script dies before getting to that point, the test fails. The purpose of this is knowing if a nightly build works (at least up to a point) or not. I was thinking the best way to test would be to launch the script in some kind of sandbox wrapper which waits for a socket request. I don't care about actually listening for anything on that port, just intercepting the request and using that as an indication that my test passed. I think it would be preferable to intercept the open socket request, rather than polling at set intervals (I hate polling!). But I'm a bit out of my depths as far as how exactly to do this. Can I do this with a shell script? Or perhaps I need to override the asyncore module at the Python level? Thanks in advance, - B

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• EF4 + STE: Reattaching via a WCF Service? Using a new objectcontext each and every time?

  - by Martin

  Hi there, I am planning to use WCF (not ria) in conjunction with Entity Framework 4 and STE (Self tracking entitites). If i understnad this correctly my WCF should return an entity or collection of entities (using LIST for example and not IQueryable) to the client (in my case silverlight) The client then can change the entity or update it. At this point i believe it is self tracking???? This is where i sort of get a bit confused as there are a lot of reported problems with STEs not tracking.. Anyway... Then to update i just need to send back the entity to my WCF service on another method to do the update. I should be creating a new OBJECTCONTEXT everytime? In every method? If i am creaitng a new objectcontext everytime in everymethod on my WCF then don't i need to re-attach the STE to the objectcontext? So basically this alone wouldn't work?? using(var ctx = new MyContext()) { ctx.Orders.ApplyChanges(order); ctx.SaveChanges(); } Or should i be creating the object context once in the constructor of the WCF service so that 1 call and every additional call using the same wcf instance uses the same objectcontext? I could create and destroy the wcf service in each method call from the client - hence creating in effect a new objectcontext each time. I understand that it isn't a good idea to keep the objectcontext alive for very long. Any insight or information would be gratefully appreciated thanks

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• Get Mail with PHP and IMAP in Gmail just loading

  - by Oscar Godson

  I'm not sure why. Ive tried a bunch of different code. Wrote it myself, and copied other people's tutorials but every bit of code it's loading forever and eventually stops due to script processing times on the server. Does anyone know why? Oh, and IMAP is turned on, i get IMAP / Exchange on my iPhone from this same account fine. And IMAP is turned on in my version of PHP (checked with phpinfo they all say enabled.) <?php /* connect to gmail */ $hostname = '{imap.gmail.com:993/imap/ssl}INBOX'; $username = '[email protected]'; $password = 'xxxxxx'; /* try to connect */ $inbox = imap_open($hostname,$username,$password) or die('Cannot connect to Gmail: ' . imap_last_error()); /* grab emails */ $emails = imap_search($inbox,'ALL'); /* if emails are returned, cycle through each... */ if($emails) { /* begin output var */ $output = ''; /* put the newest emails on top */ rsort($emails); /* for every email... */ foreach($emails as $email_number) { /* get information specific to this email */ $overview = imap_fetch_overview($inbox,$email_number,0); $message = imap_fetchbody($inbox,$email_number,2); /* output the email header information */ $output.= '<div class="toggler '.($overview[0]->seen ? 'read' : 'unread').'">'; $output.= '<span class="subject">'.$overview[0]->subject.'</span> '; $output.= '<span class="from">'.$overview[0]->from.'</span>'; $output.= '<span class="date">on '.$overview[0]->date.'</span>'; $output.= '</div>'; /* output the email body */ $output.= '<div class="body">'.$message.'</div>'; } echo $output; } /* close the connection */ imap_close($inbox); ?

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• Multiple marker icons, how to add to google mashup

  - by user351189

  I have created a Google maps mashup, where with a bit of input, I have managed to have a sidebar that links to a video icon/marker that then opens up an info window showing virtual tours. I would, however, like to put different coloured marker icons on the map depending on the category that the video is in. This would be easy enough to do, but my page is made up of a mixture of J-Query and JavaScript all calling to the individual flash files. Could someone help me with the code for adding extra marker icons for different categories? Here is the code: So, after the intial 'var camera;' point, there comes this: function addMarker(point, title, video, details) { var marker = new GMarker(point, {title: title, icon:camera}); GEvent.addListener(marker, "click", function() { if (details) { marker.openInfoWindowTabsHtml([new GInfoWindowTab("Video", video), new GInfoWindowTab("More", details)]); } else { marker.openInfoWindowHtml(video); } }); Then further down, is the code for calling the individual marker image. I would like to add another image to this list - would I start out by calling the new object 'camera-red.image' or something similar? function initialize() { if (GBrowserIsCompatible()) { map = new GMap2(document.getElementById("mapDiv")); map.setCenter(new GLatLng(51.52484592590448, -0.13345599174499512), 17); map.setUIToDefault(); var uclvtSatMapType = createUclVTSatMapType() map.addMapType(uclvtSatMapType); map.setMapType(uclvtSatMapType); camera = new GIcon(G_DEFAULT_ICON); camera.image = "ucl-video.png"; camera.iconSize = new GSize(32,37); camera.iconAnchor = new GPoint(16,35); camera.infoWindowAnchor = new GPoint(16,2); addMarkersToMap(); } The actual map can be found here: link text Thanks.

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• Building an 'Activation Key' Generator in JAVA

  - by jax

  I want to develop a Key generator for my phone applications. Currently I am using an external service to do the job but I am a little concerned that the service might go offline one day hence I will be in a bit of a pickle. How authentication works now. Public key stored on the phone. When the user requests a key the 'phone ID' is sent to the "Key Generation Service" and the encrypted key key is returned and stored inside a license file. On the phone I can check if the key is for the current phone by using a method getPhoneId() which I can check with the the current phone and grant or not grant access to features. I like this and it works well, however, I want to create my own "Key Generation Service" from my own website. Requirements: Public and Private Key Encryption:(Bouncy Castle) Written in JAVA Must support getApplicationId() (so that many applications can use the same key generator) and getPhoneId() (to get the phone id out of the encrypted license file) I want to be able to send the ApplicationId and PhoneId to the service for license key generation. Can someone give me some pointers on how to accomplish this? I have dabbled around with some java encryption but am definitely no expert and can't find anything that will help me. A list of the Java classes I would need to instantiate would be helpful.

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• IndexOutOfRangeException when a stream is a multiple of the buffer size

  - by dnord

  I don't have a lot of experience with streams and buffers, but I'm having to do it for a project, and I'm stuck on an exception being thrown when the stream I'm reading is a multiple of the buffer size I've chosen. Let me show you: My code starts by reading bufferSize (100, let's say) bytes from the stream: numberOfBytesRead = DataReader.GetBytes(0, index, output, 0, bufferSize); Then, I loop through a while loop: while (numberOfBytesRead == bufferSize) { BufferWriter.Write(output); BufferWriter.Flush(); index += bufferSize; numberOfBytesRead = DataReader.GetBytes(0, index, output, 0, bufferSize); } ... and, once we get to a non-bufferSize read, we know we've hit the end of the stream and can move on. But if the bufferSize is 100, and the stream is 200, we'll read positions 0-99, 100-199, and then the attempt to read 200-299 errors out. I'd like it if it returned 0, but it throws an error. What I'm doing to handle that is, well, a try-catch: catch (System.IndexOutOfRangeException) numberOfBytesRead = 0; ...which ends the loop, and successfully finishes the thing, but we all know I don't want to control code flow with error handling. Is there a better (more standard?) way to handle stream reading when the stream length is unknown? This seems like a small wrinkle in a fairly reasonable strategy for reading streams, but I just don't know if I've got it wrong or what. The specifics of this (which I've cleaned up a little bit for posting) are a MySqlDataReader hitting a LARGEBLOB column. It's working whenever the buffer is larger than the number of returned bytes, or when the number of returned bytes is not a multiple of bufferSize. Because we don't, in that case, throw an IndexOutOfRangeException.

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• Android Layout + Programming

  - by MD

  I'm trying to create a "scrollable" layout in Android. Even using developers.android.com, though, I feel a little bit lost at the moment. I'm somewhat new to Java, but not so much that I feel I should be having these issues--being new to Android is the bigger problem right now. The layout I'm trying to create should scroll in a sort of a "grid". I THINK what I'm looking for is the Gallery view, but I'm really lost as to how to implement it at the moment. I want it to "snap" to center the frame, like in the actual Gallery application. Essentially, if I had a photo gallery of 9 pictures, the idea is to scroll between them up/down AND side to side, in a 3x3 manner. Doesn't need to dynamically adjust, or anything like that, I just want a grid I can scroll through. I'm also not asking for anyone to give me explicit code for it--I'm trying to learn, more than anything. But pointing me in the right direction for helpful layout programming resources would be greatly appreciated, and confirming if it's a Gallery view I'm looking for would also be really helpful. Thanks in advance.

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• C programming - How to print numbers with a decimal component using only loops?

  - by californiagrown

  I'm currently taking a basic intro to C programming class, and for our current assignment I am to write a program to convert the number of kilometers to miles using loops--no if-else, switch statements, or any other construct we haven't learned yet are allowed. So basically we can only use loops and some operators. The program will generate three identical tables (starting from 1 kilometer through the input value) for one number input using the while loop for the first set of calculations, the for loop for the second, and the do loop for the third. I've written the entire program, however I'm having a bit of a problem with getting it to recognize an input with a decimal component. Here is what I have for the while loop conversions: #include <stdio.h> #define KM_TO_MILE .62 main (void) { double km, mi, count; printf ("This program converts kilometers to miles.\n"); do { printf ("\nEnter a positive non-zero number"); printf (" of kilometers of the race: "); scanf ("%lf", &km); getchar(); }while (km <= 1); printf ("\n KILOMETERS MILES (while loop)\n"); printf (" ========== =====\n"); count = 1; while (count <= km) { mi = KM_TO_MILE * count; printf ("%8.3lf %14.3lf\n", count, mi); ++count; } getchar(); } The code reads in and converts integers fine, but because the increment only increases by 1 it won't print a number with a decimal component (e.g. 3.2, 22.6, etc.). Can someone point me in the right direction on this? I'd really appreciate any help! :)

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• C++ STL Map vs Vector speed

  - by sub

  In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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• How strict should I be in the "do the simplest thing that could possible work" while doing TDD

  - by Support - multilanguage SO

  For TDD you have to Create a test that fail Do the simplest thing that could possible work to pass the test Add more variants of the test and repeat Refactor when a pattern emerge With this approach you're supposing to cover all the cases ( that comes to my mind at least) but I'm wonder if am I being too strict here and if it is possible to "think ahead" some scenarios instead of simple discover them. For instance, I'm processing a file and if it doesn't conform to a certain format I am to throw an InvalidFormatException So my first test was: @Test void testFormat(){ // empty doesn't do anything... processor.validate("empty.txt"); try { processor.validate("invalid.txt"); assert false: "Should have thrown InvalidFormatException"; } catch( InvalidFormatException ife ) { assert "Invalid format".equals( ife.getMessage() ); } } I run it and it fails because it doesn't throw an exception. So the next thing that comes to my mind is: "Do the simplest thing that could possible work", so I : public void validate( String fileName ) throws InvalidFormatException { if(fileName.equals("invalid.txt") { throw new InvalidFormatException("Invalid format"); } } Doh!! ( although the real code is a bit more complicated, I found my self doing something like this several times ) I know that I have to eventually add another file name and other test that would make this approach impractical and that would force me to refactor to something that makes sense ( which if I understood correctly is the point of TDD, to discover the patterns the usage unveils ) but: Q: am I taking too literal the "Do the simplest thing..." stuff?

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• Python refuses text.replace() in one environment

  - by gx

  Hi fellow programmers, I've been mocking about with the following bit of dirty support-code for a pylons app, which works fine in a python-shell, a separate python file, or when running in paster. Now, we've put the application on-line through mod_wsgi and apache and this specific piece of code stopped working completely. First off, the code itself: def fixStyle(self, text): t = text.replace('<p>', '<p style="%s">' % (STYLEDEF,)) t = t.replace('class="wide"', 'style="width: 125px; %s"' % (DEFSTYLE,)) t = t.replace('<td>', '<td style="%s">' % (STYLEDEF,)) t = t.replace('<a ', '<a style="%s" ' % (LINKSTYLE,)) return t It seems pretty straightforward, and to be honest, it is. So what happens when I put a piece of text in it, for example: <table><tr><td>Test!</td></tr></table> The output should be: <table><tr><td style="stuff-from-styledef">Test!</td></tr></table> and it is, on most systems. When we put it through the app on Apache/mod_wsgi though, the following happens: <table><tr><td>Test!</td></tr></table> You guessed it. I'm currently at a loss and have no idea where to go next. Googling doesn't really work out, so I'm hoping on you guys to help out and perhaps point out a fundamental issue with using whatever-is-causing-this. If anything is missing I'll edit it in.

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