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  • Testing harness for online teaching?

    - by candeira
    I have been asked to teach an online programming course, and I am looking for a test harness especially geared to education. Some students will have significant coding experience, but others will be total newbies. The course is an introduction to software development, mostly taught in C with some C++ and Java thrown in. In any case, I would like to read their source code only after a test suite has made sure that it compiles and executes properly. The students will also benefit from having a tool they can check their code against before submitting it. However, the Learning Management System my employer is using doesn't have such a system. Do you know of any LMS software that includes this feature? Which testing harness would you recommend in case I have to roll my own?

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  • How do I open an already opened file with a .net StreamReader?

    - by Jon Cage
    I have some .csv files which I'm using as part of a test bench. I can open them and read them without any problems unless I've already got the file open in Excel in which case I get an IOException: System.IO.IOException : The process cannot access the file 'TestData.csv' because it is being used by another process. This is a snippet from the test bench: using (CsvReader csv = new CsvReader(new StreamReader(new FileStream(fullFilePath, FileMode.Open, FileAccess.Read)), false)) { // Process the file } Is this a limitation of StreamReader? I can open the file in other applications (Notepad++ for example) so it can't be an O/S problem. Maybe I need to use some other class? If anyone knows how I can get round this (aside from closing excel!) I'd be very grateful.

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  • How to get jQuery draggable elements scroll with mb.imageNavigator

    - by bulltorious
    I am using jQuery mb.imageNavigator (1.8) from http://pupunzi.open-lab.com/mb-jquery-components/mb-imagenavigator/ to implements a Risk type game adjucation system. Using the imageNavigator plugin I am able to scroll around a large game map of the world. My issue is when I declare some elements as draggable and drag them onto the map image, their location does not stay relative to where in the picture I put them. They just stay fixed on the screen no matter where I scroll. Does anyone know how to make the the draggable elements scroll with the image? Matteo posts about "you can add an additional content layer that overlay image and moves with it" and posts an example, but I can't make it work. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> ` <head> <script type="text/jscript" src="lib/jquery/jquery-1.3.2.js"> </script> <script type="text/jscript" src="lib/jquery/jquery-ui-1.7.2.custom.min.js"> </script> <script type="text/jscript" src="lib/utilities/mbImgNav.min.js_0.js"> </script> <script type="text/jscript" src="lib/utilities/start.js"> </script> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>New Web Project</title> </head> <body> <div id="AdamsAshTray" style="float:right; background-color:red; z-index:999"> test test test </div> <div id="navArea"> <div imageUrl="someimage" navPosition="BR" navWidth="100" style="display:none;" class="imagesContainer"> <span class="title">zuccheriera</span> <div class="description"> <STRONG>description1</STRONG> </div> </div> </div> </body> $(document).ready(function(){ $("#navArea").imageNavigator({ areaWidth:1820, areaHeight:1000, draggerStyle: "1px dotted red", navOpacity: .8 }) $("#AdamsAshTray").draggable({ grid: [20,20] }); })`

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  • Best practices for file system dependencies in unit/integration tests

    - by Olvagor
    I just started writing tests for a lot of code. There's a bunch of classes with dependencies to the file system, that is they read CSV files, read/write configuration files and so on. Currently the test files are stored in the test directory of the project (it's a Maven2 project) but for several reasons this directory doesn't always exist, so the tests fail. Do you know best practices for coping with file system dependencies in unit/integration tests? Edit: I'm not searching an answer for that specific problem I described above. That was just an example. I'd prefer general recommendations how to handle dependencies to the file system/databases etc.

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  • mutidimensional array from javascript/jquery to ruby/sinatra

    - by user199368
    Hi, how do I pass a 2-dimensional array from javascript to ruby, please? I have this on client side: function send_data() { var testdata = { "1": { "name": "client_1", "note": "bigboy" }, "2": { "name": "client_2", "note": "smallboy" } } console.log(testdata); $.ajax({ type: 'POST', url: 'test', dataType: 'json', data: testdata }); } and this on server side: post '/test' do p params end but I can't get it right. The best I could get on server side is something like {"1"=>"[object Object]", "2"=>"[object Object]"} I tried to add JSON.stringify on client side and JSON.parse on server side, but the first resulted in {"{\"1\":{\"name\":\"client_1\",\"note\":\"bigboy\"},\"2\":{\"name\":\"client_2\",\"note\":\"smallboy\"}}"=>nil} while the latter has thrown a TypeError - can't convert Hash into String. Could anyone help, or maybe post a short snippet of correct code, please? Thank you

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  • Algorithm for parsing a flat tree into a non-flat tree

    - by Chad Johnson
    I have the following flat tree: id name parent_id is_directory =========================================================== 50 app 0 1 31 controllers 50 1 11 application_controller.rb 31 0 46 models 50 1 12 test_controller.rb 31 0 31 test.rb 46 0 and I am trying to figure out an algorithm for getting this into the following tree structuree: [{ id: 50, name: app, is_directory: true children: [{ id: 31, name: controllers, is_directory: true, children: [{ id: 11, name: application_controller.rb is_directory: false },{ id: 12, name: test_controller.rb, is_directory: false }], },{ id: 46, name: models, is_directory: true, children: [{ id: 31, name: test.rb, is_directory: false }] }] }] Can someone point me in the right direction? I'm looking for steps (eg. build an associative array; loop through the array looking for x; etc.).

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  • Can't pass a single parameter to lambda function in MVVM Light Toolkit's RelayCommand

    - by Dave
    I don't know if there's a difference between Josh Smith's and Laurent Bugnion's implementations of RelayCommand or not, but everywhere I've looked, it sounds like the Execute portion of RelayCommand can take 0 or 1 parameters. I've only been able to get it to work with 0. When I try something like: public class Test { public RelayCommand MyCommand { get; set; } public Test() { MyCommand = new RelayCommand((param) => SomeFunc(param)); } private void SomeFunc( object param) { } } I get the error: Delegate 'System.Action' does not take '1' arguments. Just to make sure I am not insane, I went to the definition of RelayCommand to make sure I didn't have some rogue implementation in my solution somewhere, but sure enough, it was just Action, and not Action<. What on earth am I missing here?

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  • jQuery AJAX call undefined error with special characters

    - by David
    Hi, I tried to make an AJAX call using jQuery, the data has special characters, e.g {'data':'<p>test</p>'}. It seems failed to pass this data in the first place. It will work if i just pass {'data':'test'}. encodeURIComponent and JSON.stringify failed here due to the special character < > /. Could anyone please help with it? Thanks. $.ajax({ type: "POST", url: "services.aspx", data: "data=" + encodeURIComponent(JSON.stringify(obj)), dataType: "text", error: function(xhr, textStatus, errorThrown) { alert("ERROR"); }, success: function(data) { } }); Regards, David

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  • XSLT Attribute not being added

    - by shaunhare.co.uk
    Trying to mark radio inputs as selected with XSLT 1.0 using the below xslt code but this does not produced the desired result desrired result <input type="radio" value="available" title="email" selected="selected" /> Actual output <input type="radio" value="available" title="email" selected /> Anyone any ideas why not please? XSLT <xsl:variable name="selected">selected</xsl:variable> <xsl:for-each select="item"> <tr> <td><xsl:value-of select="title" /></td> <td> <input type="radio" value="available" > <xsl:attribute name="name"> <xsl:value-of select="title" /> </xsl:attribute> <xsl:if test="category='available'"> <xsl:attribute name="selected"> <xsl:value-of select="$selected"/> </xsl:attribute> </xsl:if> </input> </td> <td> <input type="radio" value="unavailable" > <xsl:attribute name="name"> <xsl:value-of select="title" /> </xsl:attribute> <xsl:if test="category='unavailable'"> <xsl:attribute name="selected"> <xsl:value-of select="$selected"/> </xsl:attribute> </xsl:if> </input> </td> <td> <input type="radio" value="warning" > <xsl:if test="category='warning'"> <xsl:attribute name="selected"> <xsl:value-of select="$selected"/> </xsl:attribute> <xsl:attribute name="name"> <xsl:value-of select="title" /> </xsl:attribute> </xsl:if> </input> </td> </tr> </xsl:for-each>

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  • Does Extreme Programming Need Diagramming Tools?

    - by Ygam
    I have been experimenting with some concepts from XP, like the following: Pair Programming Test First Programming Incremental Deliveries Ruthless Refactoring So far so good until I had a major stump: How do I design my test cases when there aren't any code yet? From what basis do I have to design them? From simple assumptions? From the initial requirements? Or is this where UML diagrams and the "analysis phase" fits in? Just had to ask because in some XP books I've read, there was little to no discussion of any diagramming tool (there was one which suggested I come up with pseudocodes and some sort of a flowchart...but it did not help me in writing my tests)

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  • Objective C: Create arrays from first array based on value

    - by Nic Hubbard
    I have an array of strings that are comma separated such as: Steve Jobs,12,CA Fake Name,21,CA Test Name,22,CA Bill Gates,44,WA Bill Nye,21,OR I have those values in an NSScanner object so that I can loop through the values and get each comma seperated value using objectAtIndex. So, what I would like to do, is group the array items into new arrays, based on a value, in this case, State. So, from those, I need to loop through, checking which state they are in, and push those into a new array, one array per state. CA Array: Steve Jobs,12,CA Fake Name,21,CA Test Name,22,CA WA Array: Bill Gates,44,WA OR Array: Bill Nye,21,OR So in the end, I would have 3 new arrays, one for each state. Also, if there were additional states used in the first array, those should have new arrays created also. Any help would be appreciated!

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  • Performance analysis strategies

    - by Bernd
    I am assigned to a performance-tuning-debugging-troubleshooting task. Scenario: a multi-application environment running on several networked machines using databases. OS is Unix, DB is Oracle. Business logic is implemented across applications using synchronous/asynchronous communication. Applications are multi-user with several hundred call center users at peak time. User interfaces are web-based. Applications are third party, I can get access to developers and source code. I only have the production system and a functional test environment, no load test environment. Problem: bad performance! I need fast results. Management is going crazy. I got symptom examples like these: user interface actions taking minutes to complete. Seaching for a customer usually takes 6 seconds but an immediate subsequent search with same parameters may take 6 minutes. What would be your strategy for finding root causes?

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  • Printing fails after first print with Centos 6 and HP LaserJet P3015dn printer

    - by Gavin Simpson
    Centos 6 recognises and configures a HP LaserJet P3015dn printer connected via USB. This machine is being configured as a small group file/print server. I can print a test page, which is processed/printed correctly. The next time printing is attempted (say printing a second test page), the page is not printed and the printer is set to disabled. The status of the printer is stated as: Stopped - /usr/lib/cups/backend/hp failed in the printer configuration dialogue. /var/log/cups/error_log contains this information (first two lines were there prior to the failed print job) E [24/Jun/2004:09:12:57 +0100] Returning HTTP Forbidden for Resume-Printer (ipp://localhost/printers/HP-LaserJet-P3010-Series) from localhost E [24/Jun/2004:09:20:59 +0100] Returning HTTP Forbidden for CUPS-Delete-Printer (ipp://localhost/printers/HP-LaserJet-P3010-Series) from localhost D [24/Jun/2004:09:37:28 +0100] [Job 28] The following messages were recorded from 09:36:43 AM to 09:37:28 AM D [24/Jun/2004:09:37:28 +0100] [Job 28] Adding start banner page "none". D [24/Jun/2004:09:37:28 +0100] [Job 28] Adding end banner page "none". D [24/Jun/2004:09:37:28 +0100] [Job 28] File of type application/vnd.cups-banner queued by "gavin". D [24/Jun/2004:09:37:28 +0100] [Job 28] hold_until=0 D [24/Jun/2004:09:37:28 +0100] [Job 28] Queued on "HP-LaserJet-P3010-Series" by "gavin". D [24/Jun/2004:09:37:28 +0100] [Job 28] job-sheets=none,none D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[0]="HP-LaserJet-P3010-Series" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[1]="28" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[2]="gavin" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[3]="Test Page" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[4]="1" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[5]="job-uuid=urn:uuid:b3370a97-4ab6-3451-40a2-6239b13fa3e1 job-originating-host-name=localhost" D [24/Jun/2004:09:37:28 +0100] [Job 28] argv[6]="/var/spool/cups/d00028-001" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[0]="CUPS_CACHEDIR=/var/cache/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[1]="CUPS_DATADIR=/usr/share/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[2]="CUPS_DOCROOT=/usr/share/cups/www" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[3]="CUPS_FONTPATH=/usr/share/cups/fonts" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[4]="CUPS_REQUESTROOT=/var/spool/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[5]="CUPS_SERVERBIN=/usr/lib/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[6]="CUPS_SERVERROOT=/etc/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[7]="CUPS_STATEDIR=/var/run/cups" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[8]="HOME=/var/spool/cups/tmp" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[9]="PATH=/usr/lib/cups/filter:/usr/bin:/usr/sbin:/bin:/usr/bin" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[10]="[email protected]" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[11]="SOFTWARE=CUPS/1.4.2" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[12]="TMPDIR=/var/spool/cups/tmp" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[13]="USER=root" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[14]="CUPS_SERVER=/var/run/cups/cups.sock" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[15]="CUPS_ENCRYPTION=IfRequested" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[16]="IPP_PORT=631" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[17]="CHARSET=utf-8" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[18]="LANG=en_US.UTF-8" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[19]="PPD=/etc/cups/ppd/HP-LaserJet-P3010-Series.ppd" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[20]="RIP_MAX_CACHE=8m" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[21]="CONTENT_TYPE=application/vnd.cups-banner" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[22]="DEVICE_URI=hp:/usb/HP_LaserJet_P3010_Series?serial=VNBV993GM4" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[23]="PRINTER_INFO=Hewlett-Packard HP LaserJet P3010 Series" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[24]="PRINTER_LOCATION=electra.geog.ucl.ac.uk" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[25]="PRINTER=HP-LaserJet-P3010-Series" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[26]="CUPS_FILETYPE=document" D [24/Jun/2004:09:37:28 +0100] [Job 28] envp[27]="FINAL_CONTENT_TYPE=application/vnd.cups-postscript" D [24/Jun/2004:09:37:28 +0100] [Job 28] Started filter /usr/lib/cups/filter/bannertops (PID 2858) D [24/Jun/2004:09:37:28 +0100] [Job 28] Started filter /usr/lib/cups/filter/pstops (PID 2859) D [24/Jun/2004:09:37:28 +0100] [Job 28] Started backend /usr/lib/cups/backend/hp (PID 2860) D [24/Jun/2004:09:37:28 +0100] [Job 28] load_banner(filename="/var/spool/cups/d00028-001") D [24/Jun/2004:09:37:28 +0100] [Job 28] Page = 612x792; 12,12 to 600,780 D [24/Jun/2004:09:37:28 +0100] [Job 28] Page = 612x792; 12,12 to 600,780 D [24/Jun/2004:09:37:28 +0100] [Job 28] slow_collate=0, slow_duplex=0, slow_order=0 D [24/Jun/2004:09:37:28 +0100] [Job 28] Before copy_comments - %!PS-Adobe-3.0 D [24/Jun/2004:09:37:28 +0100] [Job 28] %!PS-Adobe-3.0 D [24/Jun/2004:09:37:28 +0100] [Job 28] %%BoundingBox: 12 12 600 780 D [24/Jun/2004:09:37:28 +0100] [Job 28] %cupsRotation: 0 D [24/Jun/2004:09:37:28 +0100] [Job 28] %%Creator: bannertops/CUPS v1.4.2 D [24/Jun/2004:09:37:28 +0100] [Job 28] %%CreationDate: Thu 24 Jun 2004 09:36:43 AM BST D [24/Jun/2004:09:37:28 +0100] [Job 28] %%LanguageLevel: 2 D [24/Jun/2004:09:37:28 +0100] [Job 28] %%DocumentData: Clean7Bit D [24/Jun/2004:09:37:28 +0100] [Job 28] %%Title: (Test Page) D [24/Jun/2004:09:37:28 +0100] [Job 28] %%For: (gavin) D [24/Jun/2004:09:37:28 +0100] [Job 28] %%Pages: 1 D [24/Jun/2004:09:37:28 +0100] [Job 28] %%DocumentSuppliedResources: font Monospace D [24/Jun/2004:09:37:28 +0100] [Job 28] %%+ font Monospace-Bold D [24/Jun/2004:09:37:28 +0100] [Job 28] %%+ font Monospace-BoldOblique D [24/Jun/2004:09:37:28 +0100] [Job 28] %%+ font Monospace-Oblique D [24/Jun/2004:09:37:28 +0100] [Job 28] %%EndComments D [24/Jun/2004:09:37:28 +0100] [Job 28] Before copy_prolog - %%BeginProlog D [24/Jun/2004:09:37:28 +0100] [Job 28] STATE: +connecting-to-device D [24/Jun/2004:09:37:28 +0100] [Job 28] prnt/backend/hp.c 762: ERROR: cannot open channel PRINT D [24/Jun/2004:09:37:28 +0100] [Job 28] Backend returned status 1 (failed) D [24/Jun/2004:09:37:28 +0100] [Job 28] Printer stopped due to backend errors; please consult the error_log file for details. D [24/Jun/2004:09:37:28 +0100] [Job 28] End of messages D [24/Jun/2004:09:37:28 +0100] [Job 28] printer-state=5(stopped) D [24/Jun/2004:09:37:28 +0100] [Job 28] printer-state-message="/usr/lib/cups/backend/hp failed" D [24/Jun/2004:09:37:28 +0100] [Job 28] printer-state-reasons=paused /var/log/messages contains the following reports associated with the recognition of the printer and the failed print job: Jun 24 09:35:07 electra kernel: usb 1-8: new high speed USB device using ehci_hcd and address 2 Jun 24 09:35:07 electra kernel: usb 1-8: New USB device found, idVendor=03f0, idProduct=8d17 Jun 24 09:35:07 electra kernel: usb 1-8: New USB device strings: Mfr=1, Product=2, SerialNumber=3 Jun 24 09:35:07 electra kernel: usb 1-8: Product: HP LaserJet P3010 Series Jun 24 09:35:07 electra kernel: usb 1-8: Manufacturer: Hewlett-Packard Jun 24 09:35:07 electra kernel: usb 1-8: SerialNumber: VNBV993GM4 Jun 24 09:35:07 electra kernel: usb 1-8: configuration #1 chosen from 1 choice Jun 24 09:35:07 electra kernel: usblp0: USB Bidirectional printer dev 2 if 0 alt 1 proto 2 vid 0x03F0 pid 0x8D17 Jun 24 09:35:07 electra kernel: usbcore: registered new interface driver usblp Jun 24 09:35:07 electra udev-configure-printer: invalid or missing IEEE 1284 Device ID Jun 24 09:35:08 electra hp[1942]: io/hpmud/pp.c 627: unable to read device-id ret=-1 Jun 24 09:35:09 electra python: io/hpmud/pp.c 627: unable to read device-id ret=-1 Jun 24 09:35:51 electra kernel: usblp0: removed Jun 24 09:37:28 electra hp[2860]: io/hpmud/dot4.c 254: unable to read Dot4ReverseReply data: Resource temporarily unavailable exp=2 act=0 Jun 24 09:37:28 electra hp[2860]: io/hpmud/dot4.c 330: invalid DOT4InitReply: cmd=0, result=20#012, revision=0 Jun 24 09:37:28 electra hp[2860]: prnt/backend/hp.c 762: ERROR: cannot open channel PRINT I am now at a loss as to how to proceed to get this printer working on my Centos machine. How can I configure the machine to print more than a single print job without needing to be unplugged/plugged in repeatedly?

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  • Aligning data in a table

    - by Hulk
    In the following table, how do I align the data in td cells such that we do not get a horizontal scroll bar, using CSS? <table> <tr><th>name</th> <th>info</th></tr> <tr><td>Harry</td> <td>suminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfosuminfo<td></tr> <tr><td>test</td><td>test data</td></tr> </table>

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  • System.Security.Cryptography.CryptographicException: Length of the data to decrypt is invalid Error

    - by EdA
    I used the code on http://www.obviex.com/samples/Encryption.aspx for encryption/decryption. I was successful in creating a simple test to functionality encrypt and decrypt data. However, I keep on getting the following error when I test the decrypt function that is used from the Accounts Controller. I am thinking it either has to do with the Machine Code within the Web.config or the the last byte not getting read by the decrypt code. Error: "Length of the data to decrypt is invalid" Note: I tried the padding fix I found on the internet and that did not work. Thanks in advance.

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  • Junit vs TestNG

    - by Sam Merrell
    At work we are currently still using Junit3 to run our tests. We have been considering switching over to Junit4 for new tests being written but I have been keeping an eye on TestNG for a while now. What experiences have you all had with either Junit4 or TestNG and which seems to work better for very large numbers of tests. Having flexibility in writing tests is also important to us since our functional tests cover a wide aspect and need to be written in a variety of ways to get results. Old tests will not be re-written as they do their job just fine. What I would like to see in new tests though is flexibility in the way the test can be written, natural assertions, grouping, and easily distributed test executions.

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  • Sharing A Stage: JDeveloper/ADF & NetBeans/Java EE 6?

    - by Geertjan
    A highlight for me during last week's Oracle Developer Day in Romania (which I blogged about here) was meeting Jernej Kaše (who is from Slovenia, just like my philosopher hero Slavoj Žižek), who is an Oracle Fusion Middleware evangelist. At the conference, while I was presenting NetBeans and Java EE 6 in one room, Jernej was presenting JDeveloper and ADF in another room. The application he created looks as follows, i.e., a realistic CRUD app, with a master/detail view, a search feature, and validation: In a conversation during a break, we started imagining a scenario where the two of us would be on the same stage, taking turns talking about NetBeans/Java EE and JDeveloper/ADF. In that way, attendees at a conference wouldn't need to choose which of the two topics to attend, because they'd be handled in the same session, with the session possibly being longer so that sufficient time could be spent on the respective technologies. (The JDeveloper/ADF session would then not be competing with the NetBeans/Java EE 6 session, since they'd be handled simultaneously.) The session would focus on the similarities/differences between the two respective tools/solutions, which would be extremely interesting and also unique. The crucial question in making this kind of co-presentation possible is whether (and how quickly) an application such as the one created above with JDeveloper/ADF could be created with NetBeans/Java EE 6. The NetBeans/Java EE 6 story is extremely strong on the model and controler levels, but less strong on the view layer. Though there are choices between using PrimeFaces, RichFaces, and IceFaces, that support is quite limited in the absence of a visual designer or of other specific tools (e.g., code generators to generate snippets of PrimeFaces) connected to JSF component libraries. However, it so happens that in recent months we at NetBeans have established really good connections with the PrimeFaces team (more about that another time). So I asked them what it would take to write the above UI in PrimeFaces. The PrimeFaces team were very helpful. They sent me the following screenshot, which is of the UI they created in PrimeFaces, reproducing the ADF screenshot above: Of course, the above is purely the UI layer, there's no EJB and entity classes and data connection hooked into it yet. However, this is the Facelets file that the PrimeFaces team sent me, i.e., using the PrimeFaces component library, that produces the above result: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:p="http://primefaces.org/ui"> <f:view> <h:head> <style type="text/css"> .alignRight { text-align: right; } .alignLeft { text-align: left; } .alignTop { vertical-align: top; } .ui-validation-required { color: red; font-size: 14px; margin-right: 5px; position: relative; vertical-align: top; } .ui-selectonemenu .ui-selectonemenu-trigger .ui-icon { margin-top: 7px !important; } </style> </h:head> <h:body> <h:form prependId="false" id="form"> <p:panel header="Employees"> <h:panelGrid columns="4" id="searchPanel"> Search <p:selectOneMenu> <f:selectItem itemLabel="FirstName" itemValue="FirstName" /> <f:selectItem itemLabel="LastName" itemValue="LastName" /> <f:selectItem itemLabel="Email" itemValue="Email" /> <f:selectItem itemLabel="PhoneNumber" itemValue="PhoneNumber" /> </p:selectOneMenu> <p:inputText /> <p:commandLink process="searchPanel" update="@form"> <h:graphicImage name="next.gif" library="img" /> </p:commandLink> </h:panelGrid> <h:panelGrid columns="3" columnClasses="alignTop,,alignTop" style="width:90%;margin-left:10%"> <h:panelGrid columns="2" columnClasses="alignRight,alignLeft"> <h:outputLabel for="firstName">FirstName</h:outputLabel> <p:inputText id="firstName" /> <h:outputLabel for="lastName"> <sup class="ui-validation-required">*</sup>LastName </h:outputLabel> <p:inputText id="lastName" style="width:250px;" /> <h:outputLabel for="email"> <sup class="ui-validation-required">*</sup>Email </h:outputLabel> <p:inputText id="email" style="width:250px;" /> <h:outputLabel for="phoneNumber" value="PhoneNumber" /> <p:inputMask id="phoneNumber" mask="999.999.9999" /> <h:outputLabel for="hireDate"> <sup class="ui-validation-required">*</sup>HireDate</h:outputLabel> <p:calendar id="hireDate" pattern="MM/dd/yyyy" showOn="button" /> </h:panelGrid> <p:outputPanel style="min-width:40px;" /> <h:panelGrid columns="2" columnClasses="alignRight,alignLeft"> <h:outputLabel for="jobId"> <sup class="ui-validation-required">*</sup>JobId </h:outputLabel> <p:selectOneMenu id="jobId" > <f:selectItem itemLabel="Administration Vice President" itemValue="Administration Vice President" /> <f:selectItem itemLabel="Vice President" itemValue="Vice President" /> </p:selectOneMenu> <h:outputLabel for="salary">Salary</h:outputLabel> <p:inputText id="salary" styleClass="alignRight" /> <h:outputLabel for="commissionPct">CommissionPct</h:outputLabel> <p:inputText id="commissionPct" style="width:30px;" maxlength="3" /> <h:outputLabel for="manager">ManagerId</h:outputLabel> <p:selectOneMenu id="manager"> <f:selectItem itemLabel="Steven King" itemValue="Steven" /> <f:selectItem itemLabel="Michael Cook" itemValue="Michael" /> <f:selectItem itemLabel="John Benjamin" itemValue="John" /> <f:selectItem itemLabel="Dav Glass" itemValue="Dav" /> </p:selectOneMenu> <h:outputLabel for="department">DepartmentId</h:outputLabel> <p:selectOneMenu id="department"> <f:selectItem itemLabel="90" itemValue="90" /> <f:selectItem itemLabel="80" itemValue="80" /> <f:selectItem itemLabel="70" itemValue="70" /> <f:selectItem itemLabel="60" itemValue="60" /> <f:selectItem itemLabel="50" itemValue="50" /> <f:selectItem itemLabel="40" itemValue="40" /> <f:selectItem itemLabel="30" itemValue="30" /> <f:selectItem itemLabel="20" itemValue="20" /> </p:selectOneMenu> </h:panelGrid> </h:panelGrid> <p:outputPanel id="buttonPanel"> <p:commandButton value="First" process="@this" update="@form" /> <p:commandButton value="Previous" process="@this" update="@form" style="margin-left:15px;" /> <p:commandButton value="Next" process="@this" update="@form" style="margin-left:15px;" /> <p:commandButton value="Last" process="@this" update="@form" style="margin-left:15px;" /> </p:outputPanel> <p:tabView style="margin-top:25px"> <p:tab title="Job History"> <p:dataTable var="history"> <p:column headerText="StartDate"> <h:outputText value="#{history.startDate}"> <f:convertDateTime pattern="MM/dd/yyyy" /> </h:outputText> </p:column> <p:column headerText="EndDate"> <h:outputText value="#{history.endDate}"> <f:convertDateTime pattern="MM/dd/yyyy" /> </h:outputText> </p:column> <p:column headerText="JobId"> <h:outputText value="#{history.jobId}" /> </p:column> <p:column headerText="DepartmentId"> <h:outputText value="#{history.departmentIdId}" /> </p:column> </p:dataTable> </p:tab> </p:tabView> </p:panel> </h:form> </h:body> </f:view> </html> Right now, NetBeans IDE only has code completion to create the above. So there's not much help for creating such a UI right now. I don't believe that a visual designer is mandatory to create the above. A few code generators and file templates could do the job too. And I'm looking forward to seeing those kinds of tools for PrimeFaces, as well as other JSF component libraries, appearing in NetBeans IDE in upcoming releases. A related option would be for the NetBeans generated CRUD app to include the option of having a master/detail view, as well as the option of having a search feature, i.e., the application generators would provide the option of having additional features typical in Java enterprise apps. In the absence of such tools, there still is room, I believe, for NetBeans/Java EE and JDeveloper/ADF sharing a stage at a conference. The above file would have been prepared up front and the presenter would state that fact. The UI layer is only one aspect of a Java EE 6 application, so that the presenter would have ample other features to show (i.e., the entity class generation, the tools for working with servlets, with session beans, etc) prior to getting to the point where the statement would be made: "On the UI layer, I have prepared this Facelets file, which I will now show you can be connected to the lower layers of the application as follows." At that point, the session beans could be hooked into the Facelets file, the file would be saved, the browser refreshed, and then the whole application would work exactly as the ADF application does. So, Jernej, let's share a stage soon!

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  • Selenium Grid not always using all of its registered RC's, why?

    - by BenA
    My Selenium Grid setup is as follows (all VMs) VM1 - Windows 7 x64 - Grid Hub + 2 RCs registering the default *firefox environment VM2 - Windows XP x32 - 2 RCs registering the default *firefox environment VM3 - Windows XP x32 - 2 RCs registering the default *firefox environment I'm happily using Mbunit and Gallio to drive the Grid, but my problem is that sometimes the Grid hub will stop passing executions over to 1 or more of the RCs, despite their showing available on the hub console. They seem to be happily maintaining their heartbeat back to the hub, but they're never asked to do any more work. This is after they had been executing tests earlier in the test run. Does anybody have any ideas why this should happen? In every case I've observed this behaviour, the last test an RC executed, before it then seemingly gets ignored by the hub, passed, and the session was successfully closed. Interestingly, whenever it happens to more than 1 of the RCs, its always (so far) been the pair that are running on the same VM. Yet they're managing to maintain their heartbeat, so it isn't a network connectivity problem. Any help would be greatly appreciated!

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  • How to create a custom yaml config file in Symfony

    - by Guillaume Flandre
    What I want to do is quite simple: store data in a custom config file that I want to read later on. I created my file something.yml that I put in the global config directory. It looks like that: prod: test: ok dev: test: ko all: foo: bar john: doe Then I copied the config_handlers.yml and also put it in the config directory and added the following at the top of the file: config/something.yml: class: sfDefineEnvironmentConfigHandler param: prefix: something_ But if I'm calling sfConfig::get("something_foo"); I keep getting NULL. What did I do wrong? I just want to read values, so no need to create a custome config handler, right? I've read the doc here: http://www.symfony-project.org/book/1_2/19-Mastering-Symfony-s-Configuration-Files even though I'm running 1.4 (I don't think that changed since then). Edit: Of course I can use sfYaml::load() but I'd like to do things in a better way.

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  • Intermittent fillMode=kCAFillModeForwards bug using CAKeyframeAnimation with path

    - by Mark24x7
    I'm having an intermittent problem when I move a UIImageView around the screen using CAKeyframeAnimation. I want the position of the UIImageView to remain where the animation ends when it is done. This bug only happens for certain start and end points. When I use random points it works correctly most of the time, but about 5-15% of the time it fails and snaps back to the pre-animation position. The problem only appears when using CAKeyframeAnimation using the path property. If I use the values property the bug does not appear. I am setting removedOnCompletion = NO, and fillMode = kCAFillModeForwards. I have posted a link to a test Xcode below. Here is my code for setting up the animation. I have a property usePath. When this is YES, the bug appears. When I set usePath to NO, the snap back bug does not happen. In this case I am using a path that is a simple line, but once I resolve this bug with a simple path, I will use a more complex path with curves in it. // create the point CAKeyframeAnimation *moveAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; if (self.usePath) { CGMutablePathRef path = CGPathCreateMutable(); CGPathMoveToPoint(path, NULL, startPt.x, startPt.y); CGPathAddLineToPoint(path, NULL, endPt.x, endPt.y); moveAnimation.path = path; CGPathRelease(path); } else { moveAnimation.values = [NSArray arrayWithObjects: [NSValue valueWithCGPoint:startPt], [NSValue valueWithCGPoint:endPt], nil]; } moveAnimation.calculationMode = kCAAnimationPaced; moveAnimation.duration = 0.5f; moveAnimation.removedOnCompletion = NO; // leaves presentation layer in final state; preventing snap-back to original state moveAnimation.fillMode = kCAFillModeForwards; moveAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]; // moveAnimation.delegate = self; // start the animation [ball.layer addAnimation:moveAnimation forKey:@"moveAnimation"]; To dl and view my test project goto test project (http://www.24x7digital.com/downloads/PathFillModeBug.zip) Tap the 'Move Ball' button to start the animation of the ball. I have hard coded a start and end point which causes the bug to happen every time. Use the switch to change usePath to YES or NO. When usePath is YES, you will see the snap back bug. When usePath is NO, you will not see the snap back bug. I'm using SDK 3.1.3, but I have seen this bug using SDK 3.0 as well, and I have seen the bug on the Sim and on my iPhone. Any idea on how to fix this or if I am doing something wrong are appreciated. Thanks, Mark.

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  • serializing data with google charts api

    - by Patrick
    I have the following google chart code that im working with as an example: Type: Line Dimensions: 270x150 283,285,295,204,340,#41C0E4 64,120,130,170,175,180,#3962C2 1,2,5,12,28,34,#005E91 Bottom Label: test The following is the URL which generates the image below http://chart.apis.google.com/chart?chs=270x150&cht=lc&chtt=&chd=s:zz1l9,LWXffg,AABCFG&chco=41C0E4,3962C2,005E91&chxl=0:|test|&chxt=x My question is that i dont see the actual data in the url, but i see this chd=s:zz1l9,LWXffg,AABCFG That looks like serialized data, but im wondering how exactly that works, or how to encode/decode that to make the input of chart data dynamic via php.

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  • Possible to register Selenium RC's with the Hudson Selenium Grid Hub w/o the RC's being slaves in th

    - by Rodreegez
    I am trying to get Hudson to run my ruby based selenium tests. I have installed the Selenium Grid plugin, but I don't want to have the RC's running as slaves in a Hudson cluster. The reason for this is I don't want to waste the next six years of my life trying to configure each of my projects in various Windows environments. Hudson currently pulls each project from Github and builds it just fine. With a regular Selenium Grid setup, I am able to edit the grid_configuration.yml file to represent the various environments I wish to tests against, then pass environment variables to the rake task that runs the test i.e. which browser/platfom to run on and the URL of the application under test -- usually a port on the hub machine running in a specific environment. In this way, the machines on which the RC's run don't need to know anything about the source code of my apps, they just need to have selenium-grid installed and have registered with the hub. Is there a way of elegantly emulating this with Hudson?

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  • The Java Specialist: An Interview with Java Champion Heinz Kabutz

    - by Janice J. Heiss
    Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers. Originally published on blogs.oracle.com/javaone.

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  • The Java Specialist: An Interview with Java Champion Heinz Kabutz

    - by Janice J. Heiss
    Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers.

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  • Wrong IO actions order using putStr and getLine

    - by QWRp
    I have a code : main = do putStr "Test input : " content <- getLine putStrLn content And when I run it (with runhaskell) or compile it (ghc 6.10.4) result is like this: asd Test input : asd I'm new to haskell and in my opinion printing should be first. Am I right? In code sample on http://learnyouahaskell.com/ which used putStr then getLine presented output is different than mine (IMHO correct). When I use putStrLn program works as expected (print then prompt and print). Is it a bug in ghc, or it is the way that it should work?

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