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• Speaking at Mix11

  - by Dennis Vroegop

  In April Microsoft will hold the next MIX event. MIX was usually targeted at web designers and developers but has grown over the years to be more a general conference focused on the web and devices. In other words: everything the normal consumer might encounter. It’s not your typical developers conference, although you’ll find many developers there as well. But next to the developers you’ll probably run into designers and user experience specialists as well. This year I am proud to say that I will be one of the people presenting there. Together with all the Surface MVP’s in the world (sounds impressive, but there are only 7 of us) we’ll host a panel discussion on all things Surface, NUI and everything else that matches those subjects. Here’s what the abstract says: The Natural User Interface (NUI) is a hot topic that generates a lot of excitement, but there are only a handful of companies doing real innovation with NUIs and most of the practical experience in the NUI style of design and development is limited to a small number of experts. The Microsoft Surface MVPs are a subset of these experts that have extensive real-world experience with Microsoft Surface and other NUI devices. This session is a panel featuring the Microsoft Surface MVPs and an unfiltered discussion with each other and the audience about the state of the art in NUI design and development. We will share our experiences and ideas, discuss what we think NUI will look like in the near future, and back up our statements with cutting-edge demonstrations prepared by the panelists involving combinations of Microsoft Surface 2.0, Kinect, and Windows Phone 7. We, as Surface MVPs think we are more than just Surface oriented. We like to think we are more NUI MVP’s. But since that’s not a technology with Microsoft you can’t actually become a NUI MVP so Surface is the one that comes the closest. We are currently working on the details of our session but believe me: it will blow you away. Several people we talked to have said this could potentially be the best session of Mix. Quite a challenge, but we’re up for it! Of course I won’t be telling you exactly what we’re going to do in Las Vegas but rest assured that when you visit our session you’ll leave with a lot of new ideas and hopefully be inspired to bring into practice what you’ve seen. Even if the technology we’ll show you isn’t readily available yet. So, if you are in Las Vegas between April 12th and 14th, please join Joshua Blake, Neil Roodyn, Rick Barraza, Bart Roozendaal, Josh Santangelo, Nicolas Calvi and myself for some NUI fun! See you in Vegas! Tags van Technorati: mix11,las vegas,surface,nui,kinecct

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• Python: speed up removal of every n-th element from list.

  - by ChristopheD

  I'm trying to solve this programming riddle and althought the solution (see code below) works correct, it is too slow for succesful submission. Any pointers as how to make this run faster? (removal of every n-th element from a list)? Or suggestions for a better algorithm to calculate the same; seems I can't think of anything else then brute-force for now... Basically the task at hand is: GIVEN: L = [2,3,4,5,6,7,8,9,10,11,........] 1. Take the first remaining item in list L (in the general case 'n'). Move it to the 'lucky number list'. Then drop every 'n-th' item from the list. 2. Repeat 1 TASK: Calculate the n-th number from the 'lucky number list' ( 1 <= n <= 3000) My current code (it calculates the 3000 first lucky numbers in about a second on my machine - but unfortunately too slow): """ SPOJ Problem Set (classical) 1798. Assistance Required URL: http://www.spoj.pl/problems/ASSIST/ """ sieve = range(3, 33900, 2) luckynumbers = [2] while True: wanted_n = input() if wanted_n == 0: break while len(luckynumbers) < wanted_n: item = sieve[0] luckynumbers.append(item) items_to_delete = set(sieve[::item]) sieve = filter(lambda x: x not in items_to_delete, sieve) print luckynumbers[wanted_n-1]

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• Codility-like sites for code golfs

  - by Adam Matan

  Hi, I've run into codility.com new cool service after listening to one of the recent stackoverflow.com podcasts. In short, it presents the user with a programming riddle to solve, within a given time frame. The user writes code in an online editor, and has the ability to run the program and view the standard output. After final submission, the user sees its final score and which tests failed him. Quoting Joel Spolsky: You are given a programming problem, you can do it in Java, C++, C#, C, Pascal, Python and PHP, which is pretty cool, and you have 30 minutes. And it gives you an editor in a webpage. And you've got to just start typing your code. And it's going to time you, basically you have to do it in a certain amount of time. And it actually runs your code and determines the performance characteristics of your code. It is intended for job interview screenings, but the idea seems very cool for code-golfs and for practicing new languages. Do you know if there's any proper open replacement? Adam

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• Is it possible to implement an infinite IEnumerable without using yield with only C# code?

  - by sinelaw

  Edit: Apparently off topic...moving to Programmers.StackExchange.com. This isn't a practical problem, it's more of a riddle. Problem I'm curious to know if there's a way to implement something equivalent to the following, but without using yield: IEnumerable<T> Infinite<T>() { while (true) { yield return default(T); } } Rules You can't use the yield keyword Use only C# itself directly - no IL code, no constructing dynamic assemblies etc. You can only use the basic .NET lib (only mscorlib.dll, System.Core.dll? not sure what else to include). However if you find a solution with some of the other .NET assemblies (WPF?!), I'm also interested. Don't implement IEnumerable or IEnumerator. Notes The closest I've come yet: IEnumerable<int> infinite = null; infinite = new int[1].SelectMany(x => new int[1].Concat(infinite)); This is "correct" but hits a StackOverflowException after 14399 iterations through the enumerable (not quite infinite). I'm thinking there might be no way to do this due to the CLR's lack of tail recursion optimization. A proof would be nice :)

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• Word characteristics tags

  - by theBlinker

  I want to do a riddle AI chatbot for my AI class. So i figgured the input to the chatbot would be : Something like : "It is blue, and it is up, but it is not the ceiling" Translation : <Object X> <blue> <up> <!ceiling> </Object X> (Answer : sky?) So Input is a set of characteristics (existing \ not existing in the object), output is a matched, most likely object. The domain will be limited to a number of objects, i could input all attributes myself, but i was thinking : How could I programatically build a database of characteristics for a word? Is there such a database available? How could i tag a word, how could i programatically find all it's attributes? I was thinking on crawling wikipedia, or some forum, but i can't see it build any reliable word tag database. Any ideas on how i could achieve such a thing? Any ideas on some literature on the subject? Thank you

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• What Counts for A DBA - Logic

  - by drsql

  "There are 10 kinds of people in the world. Those who will always wonder why there are only two items in my list and those who will figured it out the first time they saw this very old joke."  Those readers who will give up immediately and get frustrated with me for not explaining it to them are not likely going to be great technical professionals of any sort, much less a programmer or administrator who will be constantly dealing with the common failures that make up a DBA's day.  Many of these people will stare at this like a dog staring at a traffic signal and still have no more idea of how to decipher the riddle. Without explanation they will give up, call the joke "stupid" and, feeling quite superior, walk away indignantly to their job likely flipping patties of meat-by-product. As a data professional or any programmer who has strayed  to this very data-oriented blog, you would, if you are worth your weight in air, either have recognized immediately what was going on, or felt a bit ignorant.  Your friends are chuckling over the joke, but why is it funny? Unfortunately you left your smartphone at home on the dresser because you were up late last night programming and were running late to work (again), so you will either have to fake a laugh or figure it out.  Digging through the joke, you figure out that the word "two" is the most important part, since initially the joke mentioned 10. Hmm, why did they spell out two, but not ten? Maybe 10 could be interpreted a different way?  As a DBA, this sort of logic comes into play every day, and sometimes it doesn't involve nerdy riddles or Star Wars folklore.  When you turn on your computer and get the dreaded blue screen of death, you don't immediately cry to the help desk and sit on your thumbs and whine about not being able to work. Do that and your co-workers will question your nerd-hood; I know I certainly would. You figure out the problem, and when you have it narrowed down, you call the help desk and tell them what the problem is, usually having to explain that yes, you did in fact try to reboot before calling.  Of course, sometimes humility does come in to play when you reach the end of your abilities, but the ‘end of abilities’ is not something any of us recognize readily. It is handy to have the ability to use logic to solve uncommon problems: It becomes especially useful when you are trying to solve a data-related problem such as a query performance issue, and the way that you approach things will tell your coworkers a great deal about your abilities.  The novice is likely to immediately take the approach of  trying to add more indexes or blaming the hardware. As you become more and more experienced, it becomes increasingly obvious that performance issues are a very complex topic. A query may be slow for a myriad of reasons, from concurrency issues, a poor query plan because of a parameter value (like parameter sniffing,) poor coding standards, or just because it is a complex query that is going to be slow sometimes. Some queries that you will deal with may have twenty joins and hundreds of search criteria, and it can take a lot of thought to determine what is going on.  You can usually figure out the problem to almost any query by using basic knowledge of how joins and queries work, together with the help of such things as the query plan, profiler or monitoring tools.  It is not unlikely that it can take a full day’s work to understand some queries, breaking them down into smaller queries to find a very tiny problem. Not every time will you actually find the problem, and it is part of the process to occasionally admit that the problem is random, and everything works fine now.  Sometimes, it is necessary to realize that a problem is outside of your current knowledge, and admit temporary defeat: You can, at least, narrow down the source of the problem by looking logically at all of the possible solutions. By doing this, you can satisfy your curiosity and learn more about what the actual problem was. For example, in the joke, had you never been exposed to the concept of binary numbers, there is no way you could have known that binary - 10 = decimal - 2, but you could have logically come to the conclusion that 10 must not mean ten in the context of the joke, and at that point you are that much closer to getting the joke and at least won't feel so ignorant.

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• Static factory pattern with EJB3/JBoss

  - by purecharger

  I'm fairly new to EJBs and full blown application servers like JBoss, having written and worked with special purpose standalone Java applications for most of my career, with limited use of JEE. I'm wondering about the best way to adapt a commonly used design pattern to EJB3 and JBoss: the static factory pattern. In fact this is Item #1 in Joshua Bloch's Effective Java book (2nd edition) I'm currently working with the following factory: public class CredentialsProcessorFactory { private static final Log log = LogFactory.getLog(CredentialsProcessorFactory.class); private static Map<CredentialsType, CredentialsProcessor> PROCESSORS = new HashMap<CredentialsType, CredentialsProcessor>(); static { PROCESSORS.put(CredentialsType.CSV, new CSVCredentialsProcessor()); } private CredentialsProcessorFactory() {} public static CredentialsProcessor getProcessor(CredentialsType type) { CredentialsProcessor p = PROCESSORS.get(type); if(p == null) throw new IllegalArgumentException("No CredentialsProcessor registered for type " + type.toString()); return p; } However, in the implementation classes of CredentialsProcessor, I require injected resources such as a PersistenceContext, so I have made the CredentialsProcessor interface a @Local interface, and each of the impl's marked with @Stateless. Now I can look them up in JNDI and use the injected resources. But now I have a disconnect because I am not using the factory anymore. My first thought was to change the getProcessor(CredentialsType) method to do a JNDI lookup and return the SLSB instance that is required, but then I need to configure and pass the proper qualified JNDI name. Before I go down that path, I wanted to do more research on accepted practices. How is this design pattern treated in EJB3 / JEE?

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• Why does using Collections.emptySet() with generics work in assignment but not as a method parameter

  - by Karl von L

  So, I have a class with a constructor like this: public FilterList(Set<Integer> labels) { ... } and I want to construct a new FilterList object with an empty set. Following Joshua Bloch's advice in his book Effective Java, I don't want to create a new object for the empty set; I'll just use Collections.emptySet() instead: FilterList emptyList = new FilterList(Collections.emptySet()); This gives me an error, complaining that java.util.Set<java.lang.Object> is not a java.util.Set<java.lang.Integer>. OK, how about this: FilterList emptyList = new FilterList((Set<Integer>)Collections.emptySet()); This also gives me an error! Ok, how about this: Set<Integer> empty = Collections.emptySet(); FilterList emptyList = new FilterList(empty); Hey, it works! But why? After all, Java doesn't have type inference, which is why you get an unchecked conversion warning if you do Set<Integer> foo = new TreeSet() instead of Set<Integer> foo = new TreeSet<Integer>(). But Set<Integer> empty = Collections.emptySet(); works without even a warning. Why is that?

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• Creation of Objects: Constructors or Static Factory Methods

  - by Rachel

  I am going through Effective Java and some of my things which I consider as standard are not suggested by the book, for instance creation of object, I was under the impression that constructors are the best way of doing it and books says we should make use of static factory methods, I am not able to few some advantages and so disadvantages and so am asking this question, here are the benefits of using it. Advantages: One advantage of static factory methods is that, unlike constructors, they have names. A second advantage of static factory methods is that, unlike constructors, they are not required to create a new object each time they’re invoked. A third advantage of static factory methods is that, unlike constructors, they can return an object of any subtype of their return type. A fourth advantage of static factory methods is that they reduce the verbosity of creating parameterized type instances. I am not able to understand this advantage and would appreciate if someone can explain this point Disadvantages: The main disadvantage of providing only static factory methods is that classes without public or protected constructors cannot be subclassed. A second disadvantage of static factory methods is that they are not readily distinguishable from other static methods.I am not getting this point and so would really appreciate some explanation. Reference: Effective Java, Joshua Bloch, Edition 2, pg: 5-10 Also, How to decide to use whether to go for Constructor or Static Factory Method for Object Creation ?

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• post increment operator java

  - by srandpersonia

  I can't make heads or tails of the following code from "java puzzlers" by joshua bloch. public class Test22{ public static void main(String args[]){ int j=0; for(int i=0;i<100;i++){ j=j++; } System.out.println(j); //prints 0 int a=0,b=0; a=b++; System.out.println(a); System.out.println(b); //prints 1 } } I can't get the part where j prints 0. According to the author, j=j++ is similar to temp=j; j=j+1; j=temp; But a=b++ makes b 1. So it should've evaluated like this, a=b b=b+1 By following the same logic, shouldn't j=j++ be evaluated as, j=j j=j+1 Where does the temp come into picture here? Any explanations would be much appreciated. << I'm breaking my head over this. ;) Thanks in advance.

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• Eclipselink read complex object model in an ordered way

  - by Raven

  Hi, I need to read a complex model in an ordered way with eclipselink. The order is mandantory because it is a huge database and I want to have an output of a small portion of the database in a jface tableview. Trying to reorder it in the loading/quering thread takes too long and ordering it in the LabelProvider blocks the UI thread too much time, so I thought if Eclipselink could be used that way, that the database will order it, it might give me the performance I need. Unfortunately the object model can not be changed :-( The model is something like: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end In the table view the y-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Thing m ORDER BY m.name ASC"); using the "name" attribute from the Thing objects as label. In the table view the x-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Item m ORDER BY m.name ASC"); using the "name" attribute from the Item objects as label. Each cell has the value Things.getProperties().get[x].getValue() Unfortunately the list "properties" is not ordered, so the combination of cell value and x-axis column number (x) is not necessarily correct. Therefore I need to order the list "properties" in the same way as I ordered the labeling of the x-axis. And exactly this is the thing I dont know how it is done. So querying for the Thing objects should return the list "properties" "ORDER BY name ASC" but of the "Item"s objects. My ideas are something like having a query with two JOINs. Joing Things with Property and with Item but somehow I was unable to get it to work yet. Thank you for your help and your ideas to solve this riddle.

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• Eclipselink read complex oject model in an ordered way

  - by Raven

  Hi, I need to read a complex model in an ordered way with eclipselink. The order is mandantory because it is a huge database and I want to have an output of a small portion of the database in a jface tableview. Trying to reorder it in the loading/quering thread takes too long and ordering it in the LabelProvider blocks the UI thread too much time, so I thought if Eclipselink could be used that way, that the database will order it, it might give me the performance I need. Unfortunately the object model can not be changed :-( The model is something like: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end In the table view the y-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Thing m ORDER BY m.name ASC"); using the "name" attribute from the Thing objects as label. In the table view the x-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Item m ORDER BY m.name ASC"); using the "name" attribute from the Item objects as label. Each cell has the value Things.getProperties().get[x].getValue() Unfortunately the list "properties" is not ordered, so the combination of cell value and x-axis column number (x) is not necessarily correct. Therefore I need to order the list "properties" in the same way as I ordered the labeling of the x-axis. And exactly this is the thing I dont know how it is done. So querying for the Thing objects should return the list "properties" "ORDER BY name ASC" but of the "Item"s objects. My ideas are something like having a query with two JOINs. Joing Things with Property and with Item but somehow I was unable to get it to work yet. Thank you for your help and your ideas to solve this riddle.

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• Why is Linux choosing the wrong source ip address

  - by Scheintod

  and what to do to let it choose the right one? This all happens inside an OpenVZ container: The Host is Debian/Wheezy with Redhat/OpenVZ Kernel: root@mycl2:~# uname -a Linux mycl2 2.6.32-openvz-042stab081.5-amd64 #1 SMP Mon Sep 30 16:40:27 MSK 2013 x86_64 GNU/Linux The container has two (virtual) network interfaces. One in public and one in private address-space: root@mycl2:~# ifconfig lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) venet0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:127.0.0.2 P-t-P:127.0.0.2 Bcast:0.0.0.0 Mask:255.255.255.255 UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1 RX packets:475 errors:0 dropped:0 overruns:0 frame:0 TX packets:775 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:32059 (31.3 KiB) TX bytes:56309 (54.9 KiB) venet0:0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:80.123.123.29 P-t-P:80.123.123.29 Bcast:80.123.123.29 Mask:255.255.255.255 UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1 venet0:1 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.0.1.29 P-t-P:10.0.1.29 Bcast:10.0.1.29 Mask:255.255.255.255 UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1 The route to the private network is set manually: root@mycl2:~# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 venet0 0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 0 venet0 Tring to ping others on the private network leads to the wrong source address been choosen: root@mycl2:~# ip route get 10.0.1.26 10.0.1.26 dev venet0 src 80.123.123.29 cache mtu 1500 advmss 1460 hoplimit 64 Why is this and what can I do about it? EDIT: If I create the route with (thanks to Joshua) ip route add 10.0.0.0/8 dev venet0 src 10.0.1.29 it is working. But according to man ip-route the src parameter should only set the source-ip if this route is chosen. But if this route is chosen then the source-ip would be that anyway.

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• How to restart RoR services after server has been rebooted

  - by Alan DeLonga

  Update I have been searching around to see what services would possibly need to be restarted in my project after reboot. One of them was thinking sphinx, which I finally got to the point where it logs: [Fri Nov 16 19:34:29.820 2012] [29623] accepting connections But I still cant run searchd or searchd --stop because there was no generated sphinx.conf file in the etc/sphinxsearch for more info refer to this open thread on thinking_sphinx after reboot I then turned to looking into restarting unicorn or thin based on some insight I got. The issue is when I check my gems I see one for thin AND unicorn. But when I try to start either one of them they have no file residing in etc/init.d/ where the nginx and sphinxsearch files reside... Would rebooting totally erase the files for an app server like thin or unicorn? We are hosted on Rackspace running ruby 1.9.2p290 rails (3.2.8, 3.2.7, 3.2.0) nginx/1.1.19 notice that there are gems for unicorn and thin but there is no unicorn.rb or thin.rb in my config folder for my app... I am still super lost if any one can give me some insight on some steps to take to figure this out I would really appreciate it. Anything would help, thanks for reading. thin 1.4.1 unicorn 4.3.1 When I run unicorn I get the same issue as referenced here : > /usr/local/bin/unicorn start /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/configurator.rb:610:in `parse_rackup_file': rackup file (start) not readable (ArgumentError) from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/configurator.rb:76:in `reload' from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/configurator.rb:67:in `initialize' from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:104:in `new' from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:104:in `initialize' from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/bin/unicorn:121:in `new' from /usr/local/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/bin/unicorn:121:in `<top (required)>' from /usr/local/bin/unicorn:19:in `load' from /usr/local/bin/unicorn:19:in `<main>' When I run thin it just opens a command line prompt... /usr/local/bin/thin start >> Using rack adapter Other gems: * LOCAL GEMS * actionmailer (3.2.8, 3.2.7, 3.2.0) actionpack (3.2.8, 3.2.7, 3.2.0) activemodel (3.2.8, 3.2.7, 3.2.0) activerecord (3.2.8, 3.2.7, 3.2.0) activeresource (3.2.8, 3.2.7, 3.2.0) activesupport (3.2.8, 3.2.7, 3.2.0) arel (3.0.2) builder (3.0.0) bundler (1.1.5) carmen (1.0.0.beta2) carmen-rails (1.0.0.beta3) cocaine (0.2.1) coffee-rails (3.2.2) coffee-script (2.2.0) coffee-script-source (1.3.3) daemons (1.1.9) erubis (2.7.0) eventmachine (0.12.10) execjs (1.4.0) faraday (0.8.4) faraday_middleware (0.8.8) foursquare2 (1.8.2) geokit (1.6.5) hashie (1.2.0) hike (1.2.1) httparty (0.8.3) httpauth (0.1) i18n (0.6.0) journey (1.0.4) jquery-rails (2.0.2) json (1.7.4, 1.7.3) jwt (0.1.5) kgio (2.7.4) lastfm (1.8.0) libv8 (3.3.10.4 x86_64-linux) mail (2.4.4) mime-types (1.19, 1.18) minitest (1.6.0) multi_json (1.3.6) multi_xml (0.5.1) multipart-post (1.1.5) mysql2 (0.3.11) oauth2 (0.8.0) paperclip (3.1.1) polyglot (0.3.3) rack (1.4.1) rack-cache (1.2) rack-ssl (1.3.2) rack-test (0.6.1) rails (3.2.8, 3.2.7, 3.2.0) railties (3.2.8, 3.2.7, 3.2.0) raindrops (0.10.0, 0.9.0) rake (0.9.2.2, 0.8.7) rdoc (3.12, 2.5.8) riddle (1.5.3) sass (3.2.0, 3.1.19) sass-rails (3.2.5) sprockets (2.1.3) sqlite3 (1.3.6) sqlite3-ruby (1.3.3) therubyracer (0.10.2, 0.10.1) thin (1.4.1) thinking-sphinx (2.0.10) thor (0.16.0, 0.15.4, 0.14.6) tilt (1.3.3) treetop (1.4.10) tzinfo (0.3.33) uglifier (1.2.7, 1.2.4) unicorn (4.3.1) xml-simple (1.1.1) I am working on a project that was built by another group. I made some modifications to a constants file in the config folder (changing some values for arrays that populated some drop down fields), but the app had to be rebooted before those changes would be recognized. The hosting is through Rackspace, we rebooted through the option on their site. I contacted them and checked the status of our server, the port is open and operational. The problem is the app is not running when you go to the address for the site. Then when I put in the ip address of the server it just says "Welcome to Nginx". But in a log files I see: [Thu Nov 15 02:34:37.945 2012] [15916] caught SIGTERM, shutting down [Thu Nov 15 02:34:37.996 2012] [15916] shutdown complete I am not very versed in server side set up. I have also never worked on a Rails project that had to have specific services started before the application will start. Any insight as to how to figure out what services need to be restarted and how to go about restarting them would be greatly appreciated. I feel kind of dead in the water at this point... Thanks, Alan

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• Java Builder pattern with Generic type bounds

  - by I82Much

  Hi all, I'm attempting to create a class with many parameters, using a Builder pattern rather than telescoping constructors. I'm doing this in the way described by Joshua Bloch's Effective Java, having private constructor on the enclosing class, and a public static Builder class. The Builder class ensures the object is in a consistent state before calling build(), at which point it delegates the construction of the enclosing object to the private constructor. Thus public class Foo { // Many variables private Foo(Builder b) { // Use all of b's variables to initialize self } public static final class Builder { public Builder(/* required variables */) { } public Builder var1(Var var) { // set it return this; } public Foo build() { return new Foo(this); } } } I then want to add type bounds to some of the variables, and thus need to parametrize the class definition. I want the bounds of the Foo class to be the same as that of the Builder class. public class Foo<Q extends Quantity> { private final Unit<Q> units; // Many variables private Foo(Builder<Q> b) { // Use all of b's variables to initialize self } public static final class Builder<Q extends Quantity> { private Unit<Q> units; public Builder(/* required variables */) { } public Builder units(Unit<Q> units) { this.units = units; return this; } public Foo build() { return new Foo<Q>(this); } } } This compiles fine, but the compiler is allowing me to do things I feel should be compiler errors. E.g. public static final Foo.Builder<Acceleration> x_Body_AccelField = new Foo.Builder<Acceleration>() .units(SI.METER) .build(); Here the units argument is not Unit<Acceleration> but Unit<Length>, but it is still accepted by the compiler. What am I doing wrong here? I want to ensure at compile time that the unit types match up correctly.

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• I am using a constructor for my array but why is it saying i need a return type?

  - by JB

  using System; using System.IO; using System.Data; using System.Text; using System.Drawing; using System.Data.OleDb; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Drawing.Printing; using System.Collections.Generic; namespace Eagle_Eye_Class_Finder { public class GetSchedule { public class IDnumber { public string Name { get; set; } public string ID { get; set; } public string year { get; set; } public string class1 { get; set; } public string class2 { get; set; } public string class3 { get; set; } public string class4 { get; set; } IDnumber[] IDnumbers = new IDnumber[3]; public GetSchedule() //here i get an error saying method must have a return type??? { IDnumbers[0] = new IDnumber() { Name = "Joshua Banks",ID = "900456317", year = "Senior", class1 = "TEET 4090", class2 = "TEET 3020", class3 = "TEET 3090", class4 = "TEET 4290" }; IDnumbers[1] = new IDnumber() { Name = "Sean Ward", ID = "900456318", year = "Junior", class1 = "ENGNR 4090", class2 = "ENGNR 3020", class3 = "ENGNR 3090", class4 = "ENGNR 4290" }; IDnumbers[2] = new IDnumber() { Name = "Terrell Johnson",ID = "900456319",year = "Sophomore", class1 = "BUS 4090", class2 = "BUS 3020", class3 = "BUS 3090", class4 = "BUS 4290" }; } static void ProcessNumber(IDnumber myNum) { StringBuilder myData = new StringBuilder(); myData.AppendLine(IDnumber.Name); myData.AppendLine(": "); myData.AppendLine(IDnumber.ID); myData.AppendLine(IDnumber.year); myData.AppendLine(IDnumber.class1); myData.AppendLine(IDnumber.class2); myData.AppendLine(IDnumber.class3); myData.AppendLine(IDnumber.class4); MessageBox.Show(myData); } public string GetDataFromNumber(string ID) { foreach (IDnumber idCandidateMatch in IDnumbers) { if (IDCandidateMatch.ID == ID) { StringBuilder myData = new StringBuilder(); myData.AppendLine(IDnumber.Name); myData.AppendLine(": "); myData.AppendLine(IDnumber.ID); myData.AppendLine(IDnumber.year); myData.AppendLine(IDnumber.class1); myData.AppendLine(IDnumber.class2); myData.AppendLine(IDnumber.class3); myData.AppendLine(IDnumber.class4); return myData; } } return ""; } } } }

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• Adding a div layer on top of a jquery carousel. Tough one.

  - by wilwaldon

  Hey everyone, I have a tough one, well it's tough for me because I'm kinda new to the whole jQuery carousel thing, never built one before this project. Here's my problem. If you go to the TEST SITE you will see a scroller with a blue background about half way down the page. If you mouse onto the "data analytics" slide you should see a black box fade in. Here is my dilemma. I want that black box to be a menu that's connected to the data analytics slide. I've done a mock up for you so you can see what I'm talking about. Here is my scroller code. I'm using jCarousel. <div class="carousel"> <ul> <li> <div id="homeslide1"> testers sdfasdfasdfas asdftjhs iasndkad kasdnf <a href="#" id="#homeslide1-toggle">Close this</a> </div> <a href="#" id="homeslide1-show"><img src="<?php bloginfo('template_url'); ?>/images/home_data_analytics.jpg" width="200" height="94" /></a> </li> <li><img src="<?php bloginfo('template_url'); ?>/images/home_oem_partnerships.jpg" width="200" height="94" /></li> <li><img src="<?php bloginfo('template_url'); ?>/images/home_reporting.jpg" width="200" height="92" /></li> <li><img src="<?php bloginfo('template_url'); ?>/images/home_returning_lost_customers.jpg" width="200" height="92" /></li> <li><img src="<?php bloginfo('template_url'); ?>/images/home_sales.jpg" width="200" height="92" /></li> <li><img src="<?php bloginfo('template_url'); ?>/images/home_service_retention.jpg" width="200" height="92" /></li> </ul> Here is my scroller css /*HOMEPAGE SCROLLER*/ .carousel {!important padding:10px; width: 890px; margin: 0px 0px 0px 26px;} .carousel ul li element.style{height: 94px;} .carousel ul{width: 200px; padding: 5px;} .carouselitem{height: 94px;} .prev{background: url(images/home_left_scroll.png); height: 94px; width: 16px; text-indent: -999px; outline: none; cursor:pointer; float: left;} .next{background: url(images/home_right_scroll.png); height: 94px; width: 16px; text-indent: -999px; outline: none; cursor:pointer; float: right;} .carousel ul li{ padding: 0px 3px 0px 3px; margin: 0px; height:!important 94px; } .home_right_arrow{ width: 16px; float: right;} .home_left_arrow{ width: 16px; float: left;} .homeslide1{ width: 200px; height: 94px;} I've tried all sorts of z-index tricks but can't seem to figure it out on my own. If you solve this riddle I'll buy you a beer if we ever meet up. I'll also give you a high five through the internet. Is there a simple way to do this via jQuery? If so could you point me in the right direction? Thanks so much.

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• DKIMPROXY signing wrong domain

  - by user64566

  Just.... wont sign a thing... The dkimproxy_out.conf: # specify what address/port DKIMproxy should listen on listen 127.0.0.1:10028 # specify what address/port DKIMproxy forwards mail to relay 127.0.0.1:10029 # specify what domains DKIMproxy can sign for (comma-separated, no spaces) domain tinymagnet.com,hypnoenterprises.com # specify what signatures to add signature dkim(c=relaxed) signature domainkeys(c=nofws) # specify location of the private key keyfile /etc/postfix/dkim/private.key # specify the selector (i.e. the name of the key record put in DNS) selector mail The direct connection straight to the server, making it clear that this is a problem with dkimproxy and not postfix... mmxbass@hypno1:~$ telnet localhost 10028 Trying 127.0.0.1... Connected to localhost.localdomain. Escape character is '^]'. 220 hypno1.hypnoenterprises.com ESMTP Postfix (Debian/GNU) EHLO hypno1.hypnoenterprises.com 250-hypno1.hypnoenterprises.com 250-PIPELINING 250-SIZE 250-ETRN 250-STARTTLS 250-AUTH PLAIN LOGIN 250-AUTH=PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN MAIL FROM:<[email protected]> 250 2.1.0 Ok RCPT TO:<[email protected]> 250 2.1.5 Ok DATA 354 End data with <CR><LF>.<CR><LF> SUBJECT:test . 250 2.0.0 Ok: queued as B62A78D94F QUIT 221 2.0.0 Bye Now lets look at the mail headers as reported by myiptest.com: From [email protected] Thu Dec 23 18:57:14 2010 Return-path: Envelope-to: [email protected] Delivery-date: Thu, 23 Dec 2010 18:57:14 +0000 Received: from [184.82.95.154] (helo=hypno1.hypnoenterprises.com) by myiptest.com with esmtp (Exim 4.69) (envelope-from ) id 1PVqLi-0004YR-5f for [email protected]; Thu, 23 Dec 2010 18:57:14 +0000 Received: from hypno1.hypnoenterprises.com (localhost.localdomain [127.0.0.1]) by hypno1.hypnoenterprises.com (Postfix) with ESMTP id 878418D902 for ; Thu, 23 Dec 2010 13:57:26 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha1; c=simple; d=hypnoenterprises.com; h= from:to:subject:date:mime-version:content-type :content-transfer-encoding:message-id; s=mail; bh=uoq1oCgLlTqpdD X/iUbLy7J1Wic=; b=HxBKTGjzTpZSZU8xkICtARCKxqriqZK+qHkY1U8qQlOw+S S1wlZxzTeDGIOgeiTviGDpcKWkLLTMlUvx8dY4FuT8K1/raO9nMC7xjG2uLayPX0 zLzm4Srs44jlfRQIjrQd9tNnp35Wkry6dHPv1u21WUvnDWaKARzGGHRLfAzW4= Received: from localhost (localhost.localdomain [127.0.0.1]) by hypno1.hypnoenterprises.com (Postfix) with ESMTP id 2A04A8D945 for ; Thu, 23 Dec 2010 13:57:26 -0500 (EST) X-Virus-Scanned: Debian amavisd-new at hypno1.hypnoenterprises.com Received: from hypno1.hypnoenterprises.com ([127.0.0.1]) by localhost (hypno1.hypnoenterprises.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ua7BnnzmIaUO for ; Thu, 23 Dec 2010 13:57:25 -0500 (EST) Received: from phoenix.localnet (c-76-23-245-211.hsd1.ma.comcast.net [76.23.245.211]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hypno1.hypnoenterprises.com (Postfix) with ESMTPSA id 48A0D8D90D for ; Thu, 23 Dec 2010 13:57:25 -0500 (EST) From: Joshua Pech To: [email protected] Subject: test Date: Thu, 23 Dec 2010 13:57:25 -0500 User-Agent: KMail/1.13.5 (Linux/2.6.32-5-amd64; KDE/4.4.5; x86_64; ; ) MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: DomainKey-Status: no signature Received-SPF: pass (myiptest.com: domain of tinymagnet.com designates 184.82.95.154 as permitted sender) Notice how the dkim signature specifies the d=hypnoenterprises.com.... why?

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• CodePlex Daily Summary for Sunday, October 23, 2011

  CodePlex Daily Summary for Sunday, October 23, 2011Popular ReleasesView Layout Replicator for Microsoft Dynamics CRM 2011: View Layout Replicator (1.0.921.51): Added CodePlex and PayPal links New iconSiteMap Editor for Microsoft Dynamics CRM 2011: SiteMap Editor (1.0.921.340): Added CodePlex and PayPal links New iconRibbon Browser for Microsoft Dynamics CRM 2011: Ribbon Browser (1.0.922.41): Added CodePlex and PayPal links New iconMVCQuick: MVCQuick 0.3.1: Features??NHibernate 3.2??Repository（ORuM） ??Spring.Net 1.3.2??Container（IoC） ??Common.Logging 1.2??Logging ASP.NET Security Provider?? ??MVCQuick.Framework??MusicStoreElysium: Elysium Theme 1.1 (CTP 1): === Version history === Elysium Theme: Version 1.1 This is pre-release Community Technology Preview version. We recommended use it only for testing and studying project's possibilities. This version included: styles for: ContextMenu MenuItem (partially) bug fixes for: CommandButton: bug #598 ComboBox: bug #599 Window: bug #605 Elysium Theme: Version 1.0 This version included: classes: ThemeManager (with standart Windows Phone colors) CommandButton, RepeatCommandButton, ToggleC...DotNet.Framework.Common: DotNet.Framework.Common 4.0: ??????????，????????????XML Explorer: XML Explorer 4.0.5: Changes in 4.0.5: Added 'Copy Attribute XPath to Address Bar' feature. Added methods for decoding node text and value from Base64 encoded strings, and copying them to the clipboard. Added 'ChildNodeDefinitions' to the options, which allows for easier navigation of parent-child and ID-IDREF relationships. Discovery happens on-demand, as nodes are expanded and child nodes are added. Nodes can now have 'virtual' child nodes, defined by an xpath to select an identifier (usually relative to ...Media Companion: MC 3.419b Weekly: A couple of minor bug fixes, but the important fix in this release is to tackle the extremely long load times for users with large TV collections (issue #130). A note has been provided by developer Playos: "One final note, you will have to suffer one final long load and then it should be fixed... alternatively you can delete the TvCache.xml and rebuild your library... The fix was to include the file extension so it doesn't have to look for the video file (checking to see if a file exists is a...CODE Framework: 4.0.11021.0: This build adds a lot of our WPF components, including our MVVC and MVC components as well as a "Metro" and "Battleship" style.GridLibre para Visual FoxPro: GridLibre para Visual FoxPro v3.5: GridLibre Para Visual FoxPro: esta herramienta ayudara a los usuarios y programadores en los manejos de los datos, como Filtrar, multiseleccion y el autoformato a las columnas como la asignacion del controlsource.Self-Tracking Entity Generator for WPF and Silverlight: Self-Tracking Entity Generator v 0.9.9: Self-Tracking Entity Generator v 0.9.9 for Entity Framework 4.0Umbraco CMS: Umbraco 5.0 CMS Alpha 3: Umbraco 5 Alpha 3Umbraco 5 (aka Jupiter) will be the next version of everyone's favourite, friendly ASP.NET CMS that already powers over 100,000 websites worldwide. Try out the Alpha of v5 today! If you're new to Umbraco and would like to get a low-down on our popular and easy-to-learn approach to content management, check out our intro video. What's Alpha 3?This is our third Alpha release. It's intended for developers looking to become familiar with the codebase & architecture, or for thos...Vkontakte WP: Vkontakte: source codeWay2Sms Applications for Android, Desktop/Laptop & Java enabled phones: Way2SMS Desktop App v2.0: 1. Fixed issue with sending messages due to changes to Way2Sms site 2. Updated the character limit to 160 from 140GART - Geo Augmented Reality Toolkit: 1.0.1: About Release 1.0.1 Release 1.0.1 is a service release that addresses several issues and improves performance. As always, check the Documentation tab for instructions on how to get started. If you don't have the Windows Phone SDK yet, grab it here. Breaking Change Please note: There is a breaking change in this release. As noted below, the WorldCalculationMode property of ARItem has been replaced by a user-definable function. ARItem is now automatically wired up with a function that perform...Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.32: Fix for issue #16710 - string literals in "constant literal operations" which contain ASP.NET substitutions should not be considered "constant." Move the JS1284 error (Misplaced Function Declaration) so it only fires when in strict mode. I got a couple complaints that people didn't like that error popping up in their existing code when they could verify that the location of that function, although not strict JS, still functions as expected cross-browser.Naked Objects: Naked Objects Release 4.0.110.0: Corresponds to the packaged version 4.0.110.0 available via NuGet. Please note that the easiest way to install and run the Naked Objects Framework is via the NuGet package manager: just search the Official NuGet Package Source for 'nakedobjects'. It is only necessary to download the source code (from here) if you wish to modify or re-build the framework yourself. If you do wish to re-build the framework, consul the file HowToBuild.txt in the release. Documentation Please note that after ...myCollections: Version 1.5: New in this version : Added edit type for selected elements Added clean for selected elements Added Amazon Italia Added Amazon China Added TVDB Italia Added TVDB China Added Turkish language You can now manually add artist Added Order by Rating Improved Add by Media Improved Artist Detail Upgrade Sqlite engine View, Zoom, Grouping, Filter are now saved by category Added group by Artist Added CubeCover View BugFixingIronPython: 2.7.1 RC: This is the first release candidate of IronPython 2.7.1. Like IronPython 54498, this release requires .NET 4 or Silverlight 4. This release will replace any existing IronPython installation. If there are no showstopping issues, this will be the only release candidate for 2.7.1, so please speak up if you run into any roadblocks. The highlights of 2.7.1 are: Updated the standard library to match CPython 2.7.2. Add the ast, csv, and unicodedata modules. Fixed several bugs. IronPython To...Rawr: Rawr 4.2.6: This is the Downloadable WPF version of Rawr!For web-based version see http://elitistjerks.com/rawr.php You can find the version notes at: http://rawr.codeplex.com/wikipage?title=VersionNotes Rawr AddonWe now have a Rawr Official Addon for in-game exporting and importing of character data hosted on Curse. The Addon does not perform calculations like Rawr, it simply shows your exported Rawr data in wow tooltips and lets you export your character to Rawr (including bag and bank items) like Char...New Projects"Cupa Timisului" evaluation app: The application is used for evaluating CABRILLO log file for "Cupa Timisului" HAM contest. You can use this code as a startup for ham contest log evaluating software... It's developed in C#.Afrihost Capped Account Monitoring Gadget: The Afrihost Monitoring Gadget is a Windows gadget to monitor the usage on your Afrihost capped account. This project is independently developed and not associated with Afrihost. It has been developed by an Afrihost client and not Afrihost themselves. Custom ORM for .NET: This project represents tiny "Custom ORM" system written in .NET (3.5 as of now). It has strongly typed mapping like in FluentNH. It allows you to change underlying data access logic on the fly. It is simple enough to grag-&-drop in your project and than change as you like.diagnostic medical system: Medical diagnostic system. Simple academic project using BiztTalk Bussines Rule Engine. DotNetNuke Kitchen Sink: A sample module project for DotNetNuke with a variety of different scenarios covered.ecBlog: ecBlog is a very simple blog application. Just run and use. Technology Choice I developed the site as expected with the MVC and HTML 5. Why MVC? In fact there is no one reason. I developed with one of the many features of MVC . MVC comes with a specific architecture, it also conFastPizza: This is a project to delivery stores, restaurants, and othersGB2312 for Silverlight: This class is for support GB2312 simplified Chinese characters for Silverlight(include Windows Phone 7) Application and inherited from Encoding abstract class. It's developed in CSharp. ?????? Silverlight（?? Windows Phone 7）?????? GB2312 ???????，? Encoding ?????。?? C# ????。Ginnay Distributed Downloader: Distributed Downloader using multiple proxiesIn for Consideration - EGR101 Rocket Launch Sequencer: In for Consideration's EGR101 RLS is an executable version of the simplified launch sequence presented in class materials of "Introduction to Engineering" at Embry-Riddle Aeronautical University in Daytona Beach, FL. Source code is available for those interested (C# only).luminji's core lib: luminji's core lib, provide the common utility of the c#.Muki erp System: MukiERP, features. MukiERP is a free, user-friendly, web-based ERP system. MukiERP is Open Source licensed on GPL. MukiERP is in active development and is constantly improved according to its users needs. MukiERP is written in .Net C# language. MukiERP is running well on a ASP.NET and MSSQL. NameDOB: This is for sharing a specific sample with a specific group.network utility: this is a project for working with network API.PGS: (functional) Program Generator from Spreadsheets: This project allows the generation of a functional program semantically equivalent to a given spreadsheet. Using this system, you can: - solve the calculation expressed by the user using a compiled approach. - use spreadsheets as a tool for programming by example.pkrss: c++ version:pkrss.sf.net csharp version:is here. pkrss.sf.net is c++ version desktop productor written by qt 4.7.3. pkrss.codeplex is csharp version web productor.SharePoint Log Browser: The SharePoint log browser is yet another way to view the log of SharePoint.SharpChip-8: Chip-8 Emulator written in C#SQL Server Stored Procedure best practices: This SQL Server stored procedure best practice guide contains documentations of best practices and helper tools to enhance further match with the best practices. sqlsearch: Hi, Googling gives me many search tools. But all tools are not efficient or not able to search into data. So I thought why developers on codeplex and I will not find out some solution for this same. All of you are invited to contribute in this project. Thank you, Hiren V.Suffix Tree in C# and F#: SuffixTree builds a suffix tree structure. A simple client shows how to find substrings in it, and the visual client shows the actual tree. Implemented in C# and F#.Test11: it is a test projectThe Seal: The Seal is a basic Open Source 2D Fantasy Based RPG(Role Playing Game) for Windows. More info coming soon.Toolpack: Updated and improves version silverlight toolkit and wpf toolkit.Unity Azure Setting Injector: Using Unity in Windows Azure made simple. Ever considered moving to Windows Azure, but didn't know how to inject setting from your Service Configuration file? Just reference this project and you will be able to inject Azure Storage Account Connection Strings & Local Storage Paths

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• Managing highly repetitive code and documentation in Java

  - by polygenelubricants

  Highly repetitive code is generally a bad thing, and there are design patterns that can help minimize this. However, sometimes it's simply inevitable due to the constraints of the language itself. Take the following example from java.util.Arrays: /** * Assigns the specified long value to each element of the specified * range of the specified array of longs. The range to be filled * extends from index <tt>fromIndex</tt>, inclusive, to index * <tt>toIndex</tt>, exclusive. (If <tt>fromIndex==toIndex</tt>, the * range to be filled is empty.) * * @param a the array to be filled * @param fromIndex the index of the first element (inclusive) to be * filled with the specified value * @param toIndex the index of the last element (exclusive) to be * filled with the specified value * @param val the value to be stored in all elements of the array * @throws IllegalArgumentException if <tt>fromIndex &gt; toIndex</tt> * @throws ArrayIndexOutOfBoundsException if <tt>fromIndex &lt; 0</tt> or * <tt>toIndex &gt; a.length</tt> */ public static void fill(long[] a, int fromIndex, int toIndex, long val) { rangeCheck(a.length, fromIndex, toIndex); for (int i=fromIndex; i<toIndex; i++) a[i] = val; } The above snippet appears in the source code 8 times, with very little variation in the documentation/method signature but exactly the same method body, one for each of the root array types int[], short[], char[], byte[], boolean[], double[], float[], and Object[]. I believe that unless one resorts to reflection (which is an entirely different subject in itself), this repetition is inevitable. I understand that as a utility class, such high concentration of repetitive Java code is highly atypical, but even with the best practice, repetition does happen! Refactoring doesn't always work because it's not always possible (the obvious case is when the repetition is in the documentation). Obviously maintaining this source code is a nightmare. A slight typo in the documentation, or a minor bug in the implementation, is multiplied by however many repetitions was made. In fact, the best example happens to involve this exact class: Google Research Blog - Extra, Extra - Read All About It: Nearly All Binary Searches and Mergesorts are Broken (by Joshua Bloch, Software Engineer) The bug is a surprisingly subtle one, occurring in what many thought to be just a simple and straightforward algorithm. // int mid =(low + high) / 2; // the bug int mid = (low + high) >>> 1; // the fix The above line appears 11 times in the source code! So my questions are: How are these kinds of repetitive Java code/documentation handled in practice? How are they developed, maintained, and tested? Do you start with "the original", and make it as mature as possible, and then copy and paste as necessary and hope you didn't make a mistake? And if you did make a mistake in the original, then just fix it everywhere, unless you're comfortable with deleting the copies and repeating the whole replication process? And you apply this same process for the testing code as well? Would Java benefit from some sort of limited-use source code preprocessing for this kind of thing? Perhaps Sun has their own preprocessor to help write, maintain, document and test these kind of repetitive library code? A comment requested another example, so I pulled this one from Google Collections: com.google.common.base.Predicates lines 276-310 (AndPredicate) vs lines 312-346 (OrPredicate). The source for these two classes are identical, except for: AndPredicate vs OrPredicate (each appears 5 times in its class) "And(" vs Or(" (in the respective toString() methods) #and vs #or (in the @see Javadoc comments) true vs false (in apply; ! can be rewritten out of the expression) -1 /* all bits on */ vs 0 /* all bits off */ in hashCode() &= vs |= in hashCode()

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• XSLT Select all nodes containing a specific substing

  - by Mike

  I'm trying to write an XPath that will select certain nodes that contain a specific word. In this case the word is, "Lockwood". The correct answer is 3. Both of these paths give me 3. count(//*[contains(./*,'Lockwood')]) count(BusinessLetter/*[contains(../*,'Lockwood')]) But when I try to output the text of each specific node //*[contains(./*,'Lockwood')][1] //*[contains(./*,'Lockwood')][2] //*[contains(./*,'Lockwood')][3] Node 1 ends up containing all the text and nodes 2 and 3 are blank. Can some one please tell me what's happening or what I'm doing wrong. Thanks. <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="XPathFunctions.xsl"?> <BusinessLetter> <Head> <SendDate>November 29, 2005</SendDate> <Recipient> <Name Title="Mr."> <FirstName>Joshua</FirstName> <LastName>Lockwood</LastName> </Name> <Company>Lockwood &amp; Lockwood</Company> <Address> <Street>291 Broadway Ave.</Street> <City>New York</City> <State>NY</State> <Zip>10007</Zip> <Country>United States</Country> </Address> </Recipient> </Head> <Body> <List> <Heading>Along with this letter, I have enclosed the following items:</Heading> <ListItem>two original, execution copies of the Webucator Master Services Agreement</ListItem> <ListItem>two original, execution copies of the Webucator Premier Support for Developers Services Description between Lockwood &amp; Lockwood and Webucator, Inc.</ListItem> </List> <Para>Please sign and return all four original, execution copies to me at your earliest convenience. Upon receipt of the executed copies, we will immediately return a fully executed, original copy of both agreements to you.</Para> <Para>Please send all four original, execution copies to my attention as follows: <Person> <Name> <FirstName>Bill</FirstName> <LastName>Smith</LastName> </Name> <Address> <Company>Webucator, Inc.</Company> <Street>4933 Jamesville Rd.</Street> <City>Jamesville</City> <State>NY</State> <Zip>13078</Zip> <Country>USA</Country> </Address> </Person> </Para> <Para>If you have any questions, feel free to call me at <Phone>800-555-1000 x123</Phone> or e-mail me at <Email>[email protected]</Email>.</Para> </Body> <Foot> <Closing> <Name> <FirstName>Bill</FirstName> <LastName>Smith</LastName> </Name> <JobTitle>VP of Operations</JobTitle> </Closing> </Foot> </BusinessLetter>

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• Why does one of two identical Javascripts work in Firefox?

  - by Gigpacknaxe

  Hi, I have two image swap functions and one works in Firefox and the other does not. The swap functions are identical and both work fine in IE. Firefox does not even recognize the images as hyperlinks. I am very confused and I hope some one can shed some light on this for me. Thank you very much in advance for any and all help. FYI: the working script swaps by onClick via DIV elements and the non-working script swaps onMouseOver/Out via "a" elements. Remember both of these work just fine in IE. Joshua Working Javascript in FF: <script type="text/javascript"> var aryImages = new Array(); aryImages[1] = "/tires/images/mich_prim_mxv4_profile.jpg"; aryImages[2] = "/tires/images/mich_prim_mxv4_tread.jpg"; aryImages[3] = "/tires/images/mich_prim_mxv4_side.jpg"; for (i=0; i < aryImages.length; i++) { var preload = new Image(); preload.src = aryImages[i]; } function swap(imgIndex, imgTarget) { document[imgTarget].src = aryImages[imgIndex]; } <div id="image-container"> <div style="text-align: right">Click small images below to view larger.</div> <div class="thumb-box" onclick="swap(1, 'imgColor')"><img src="/tires/images/thumbs/mich_prim_mxv4_profile_thumb.jpg" width="75" height="75" /></div> <div class="thumb-box" onclick="swap(2, 'imgColor')"><img src="/tires/images/thumbs/mich_prim_mxv4_tread_thumb.jpg" width="75" height="75" /></div> <div class="thumb-box" onclick="swap(3, 'imgColor')"><img src="/tires/images/thumbs/mich_prim_mxv4_side_thumb.jpg" width="75" height="75" /></div> <div><img alt="" name="imgColor" src="/tires/images/mich_prim_mxv4_profile.jpg" /></div> <div><a href="mich-prim-102-large.php"><img src="/tires/images/super_view.jpg" border="0" /></a></div> Not Working in FF: <script type="text/javascript"> var aryImages = new Array(); aryImages[1] = "/images/home-on.jpg"; aryImages[2] = "/images/home-off.jpg"; aryImages[3] = "/images/services-on.jpg"; aryImages[4] = "/images/services-off.jpg"; aryImages[5] = "/images/contact_us-on.jpg"; aryImages[6] = "/images/contact_us-off.jpg"; aryImages[7] = "/images/about_us-on.jpg"; aryImages[8] = "/images/about_us-off.jpg"; aryImages[9] = "/images/career-on.jpg"; aryImages[10] = "/images/career-off.jpg"; for (i=0; i < aryImages.length; i++) { var preload = new Image(); preload.src = aryImages[i]; } function swap(imgIndex, imgTarget) { document[imgTarget].src = aryImages[imgIndex]; } <td> <a href="home.php" onMouseOver="swap(1, 'home')" onMouseOut="swap(2, 'home')"><img name="home" src="/images/home-off.jpg" alt="Home Button" border="0px" /></a> </td>

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• Looking Back at MIX10

  - by WeigeltRo

  It’s the sad truth of my life that even though I’m fascinated by airplanes and flight in general since my childhood days, my body doesn’t like flying. Even the ridiculously short flights inside Germany are taking their toll on me each time. Now combine this with sitting in the cramped space of economy class for many hours on a transatlantic flight from Germany to Las Vegas and back, and factor in some heavy dose of jet lag (especially on my way eastwards), and you get an idea why after coming back home I had this question on my mind: Was it really worth it to attend MIX10? This of course is a question that will also be asked by my boss at Comma Soft (for other reasons, obviously), who decided to send me and my colleague Jens Schaller, to the MIX10 conference. (A note to my German readers: An dieser Stelle der Hinweis, dass Comma Soft noch Silverlight-Entwickler und/oder UI-Designer für den Standort Bonn sucht – aussagekräftige Bewerbungen bitte an [email protected]) Too keep things short: My answer is yes. Before I’ll go into detail, let me ask the heretical questions whether tech conferences in general still make sense. There was a time, where actually being at a tech conference gave you a head-start in regard to learning about new technologies. Nowadays this is no longer true, where every bit of information and every detail is immediately twittered, blogged and whatevered to death. In the case of MIX10 you even can download the video-taped sessions shortly after. So: Does visiting a conference still make sense? It depends on what you expect from a conference. It should be clear to everybody that you’ll neither get exclusive information, nor receive training in a small group. What a conference does offer that sitting in front of your computer does not can be summarized as follows: Focus Being away from work and home will help you to focus on the presented information. Of course there are always the poor guys who are haunted by their work (with mails and short text messages reporting the latest showstopper problem), but in general being out of your office makes a huge difference. Inspiration With the focus comes the emotional involvement. I find it much easier to absorb information if I feel that certain vibe when sitting in a session. This still means that I have put work into reviewing the information later, but it’s a better starting point. And all the impressions collected at a (good) conference combined lead to a higher motivation – be it by the buzz (“this is gonna be sooo cool!”) or by the fear to fall behind (“man, we’ll have work on this, or else…”). People At a conference it’s pretty easy to get into contact with other people during breakfast, lunch and other breaks. This is a good opportunity to get a feel for what other development teams are doing (on a very general level of course, nobody will tell you about their secret formula) and what they are thinking about specific technologies. So MIX10 did offer focus, inspiration and people, but that would have meant nothing without valuable content. When I (being a frontend developer with a strong interest in UI/UX) planned my visit to MIX10, I made the decision to focus on the "soft" topics of design, interaction and user experience. I figured that I would be bombarded with all the technical details about Silverlight 4 anyway in the weeks and months to come. Actually, I would have liked to catch a few technical sessions, but the agenda wasn’t exactly in favor of people interested in any kind of Silverlight and UI/UX/Design topics. That’s one of my few complaints about the conference – I would have liked one more day and/or more sessions per day. Overall, the quality of the workshops and sessions was pretty high. In fact, looking back at my collection of conferences I’ve visited in the past I’d say that MIX10 ranks somewhere near the top spot. Here’s an overview of the workshops/sessions I attended (I’ll leave out the keynotes): Day 0 (Workshops on Sunday) Design Fundamentals for Developers Robby Ingebretsen is the man! Great workshop in three parts with the perfect mix of examples, well-structured definition of terminology and the right dose of humor. Robby was part of the WPF team before founding his own company so he not only has a strong interest in design (and the skillz!) but also the technical background.   Design Tools and Techniques Originally announced to be held by Arturo Toledo, the Rosso brothers from ArcheType filled in for the first two parts, and Corrina Black had a pretty general part about the Windows Phone UI. The first two thirds were a mixed bag; the two guys definitely knew what they were talking about, and the demos were great, but the talk lacked the preparation and polish of a truly great presentation. Corrina was not allowed to go into too much detail before the keynote on Monday, but the session was still very interesting as it showed how much thought went into the Windows Phone UI (and there’s always a lot to learn when people talk about their thought process). Day 1 (Monday) Designing Rich Experiences for Data-Centric Applications I wonder whether there was ever a test-run for this session, but what Ken Azuma and Yoshihiro Saito delivered in the first 15 minutes of a 30-minutes-session made me walk out. A commercial for a product (just great: a video showing a SharePoint plug-in in an all-Japanese UI) combined with the most generic blah blah one could imagine. EPIC FAIL.   Great User Experiences: Seamlessly Blending Technology & Design I switched to this session from the one above but I guess I missed the interesting part – what I did catch was what looked like a “look at the cool stuff we did” without being helpful. Or maybe I was just in a bad mood after the other session.   The Art, Technology and Science of Reading This talk by Kevin Larson was very interesting, but was more a presentation of what Microsoft is doing in research (pretty impressive) and in the end lacked a bit the helpful advice one could have hoped for.   10 Ways to Attack a Design Problem and Come Out Winning Robby Ingebretsen again, and again a great mix of theory and practice. The clean and simple, yet effective, UI of the reader app resulted in a simultaneous “wow” of Jens and me. If you’d watch only one session video, this should be it. Microsoft has to bring Robby back next year! Day 2 (Tuesday) Touch in Public: Multi-touch Interaction Design for Kiosks & Architectural Experiences Very interesting session by Jason Brush, a great inspiration with many details to look out for in the examples. Exactly what I was hoping for – and then some!   Designing Bing: Heart and Science How hard can it be to design the UI for a search engine? An input field and a list of results, that should be it, right? Well, not so fast! The talk by Paul Ray showed the many iterations to finally get it right (up to the choice of a specific blue for the links). And yes, I want an eye-tracking device to play around with!   The Elephant in the Room When Nishant Kothary presented a long list of what his session was not about, I told to myself (not having the description text present) “Am I in the wrong talk? Should I leave?”. Boy, was I wrong. A great talk about human factors in the process of designing stuff.   An Hour with Bill Buxton Having seen Bill Buxton’s presentation in the keynote, I just had to see this man again – even though I didn’t know what to expect. Being more or less unplanned and intended to be more of a conversation, the session didn’t provide a wealth of immediately useful information. Nevertheless Bill Buxton was impressive with his huge knowledge of seemingly everything. But this could/should have been a session some when in the evening and not in parallel to at least two other interesting talks. Day 3 (Wednesday) Design the Ordinary, Like the Fixie This session by DL Byron and Kevin Tamura started really well and brought across the message to keep things simple. But towards the end the talk lost some of its steam. And, as a member of the audience pointed out, they kind of ignored their own advice when they used a fancy presentation software other then PowerPoint that sometimes got in the way of showing things.   Developing Natural User Interfaces Speaking of alternative presentation software, Joshua Blake definitely had the most remarkable alternative to PowerPoint, a self-written program called NaturalShow that was controlled using multi-touch on a touch screen. Not a PowerPoint-killer, but impressive nevertheless. The (excellent) talk itself was kind of eye-opening in regard to what “multi-touch support” on various platforms (WPF, Silverlight, Windows Phone) actually means.   Treat your Content Right The talk by Tiffani Jones Brown wasn’t even on my planned schedule, but somehow I ended up in that session – and it was great. And even for people who don’t necessarily have to write content for websites, some points made by Tiffani are valid in many places, notably wherever you put texts with more than a single word into your UI. Creating Effective Info Viz in Microsoft Silverlight The last session of MIX10 I attended was kind of disappointing. At first things were very promising, with Matthias Shapiro giving a brief but well-structured introduction to info graphics and interactive visualizations. Then the live-coding began and while the result was interesting, too much time was spend on wrestling to get the code working. Ending earlier than planned, the talk was a bit light on actual content, but at least it included a nice list of resources. Conclusion It could be felt all across MIX10, UIs will take a huge leap forward; in fact, there are enough examples that have already. People who both have the technical know-how and at least a basic understanding of design (“literacy” as Bill Buxton called it) are in high demand. The concept of the MIX conference and initiatives like design.toolbox shows that Microsoft understands very well that frontend developers have to acquire new knowledge besides knowing how to hack code and putting buttons on a form. There are extremely exciting times before us, with lots of opportunity for those who are eager to develop their skills, that is for sure.

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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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