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• Advice for someone moving from Windows / Coldfusion / Java to Linux / Ruby / Rails

  - by Ciaran Archer

  Hi all I am thinking of undertaking a serious career move. Currently I work day to day with ColdFusion 9+, and some Java in a Windows environment. My background is Java/JSP etc prior to ColdFusion. I'm considering a move towards Ruby / Rails on Linux as I think it would be a real challenge, keep things fresh and would stand me in good stead for the next few years. There are also more jobs in this area. I would consider myself an experienced web professional. I do TDD and I understand good OO design concepts. I have worked for the past few years on a busy transactional gaming website with all the security and performance challenges that entails. I have also contributed to an open source ColdFusion project recently and I am a active member of the CF community on StackOverflow . In order to maintain my current remuneration (!) etc. I would like to get up to speed on Ruby / Rails and Linux before I go job hunting. The idea is that I can demonstrate enough proficiency in these new skills and combined with my other language / programming / architectural and performance experience I have I'll be a good candidate. I am building a personal website in Rails 3.0 on Ubuntu which I hope will expose me to lots of Rails/Ruby and I am reading a few books. What else can I do? Has anyone made this type of move, and if so would they have any tips apart from what I've mentioned? Is there any areas around Rails/Ruby/Linux that I have to get up to speed with? Any and all tips are appreciated.

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• Java - Resize images upon class instantiation

  - by Tyler J Fisher

  Hey StackExchange GameDev community, I'm attempting to: Resize series of sprites upon instantiation of the class they're located in (x2) I've attempted to use the following code to resize the images, however my attempts have been unsuccessful. I have been unable to write an implementation that is even compilable, so no error codes yet. wLeft.getScaledInstance(wLeft.getWidth()*2, wLeft.getHeight()*2, Image.SCALE_FAST); I've heard that Graphics2D is the best option. Any suggestions? I think I'm probably best off loading the images into a Java project, resizing the images then outputting them to a new directory so as not to have to resize each sprite upon class instantiation. What do you think? Photoshopping each individual sprite is out of the question, unless I used a macro. Code: package game; //Import import java.awt.Image; import javax.swing.ImageIcon; public class Mario extends Human { Image wLeft = new ImageIcon("sprites\\mario\\wLeft.PNG").getImage(); //Constructor public Mario(){ super("Mario", 50); wLeft.getScaledInstance(wLeft.getWidth()*2, wLeft.getHeight()*2, Image.SCALE_FAST); } Thanks! Note: not homework, just thought Mario would be a good, overused starting point in game dev.

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• Record management system java web framework

  - by Kamil Tomšík

  We're currently reconsidering technologies and frameworks to get more agile with "simple" RMS CRUD-based projects. In short, short-living things like this Right now we have a custom extension on top of SmartGWT but after some time it has proven not to be flexible enough. I also personally dislike the java-js compilation process and the whole GWT codebase. Not only is the design ugly, it also makes certain low-level js things very complicated if not completely impossible. So what I'm looking for is: closest to web as possible, like JSF or possibly Tapestry, it is very important to be able get "low" and weave framework if necessary. Happens more often than we thought. datagrid capable - Ext.js & PrimeFaces looks pretty good, Vaadin does too. db-schema generators (optional, no matter in which way) If it were only on me, I'd probably stick to Ext.js + custom rest-based java solution, possibly generated from database schema (not sure about concrete tooling yet). I only have experience with vanilla Ext.js, vanilla GWT and JSF 2.0 / Seam, so it hard for me to judge or even propose other frameworks. What would be your proposition? What are the problems you've faced? What was your solution and how hard do you think it was to deal with them in "big picture"?

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• Did the developers of Java conciously abandon RAII?

  - by JoelFan

  As a long-time C# programmer, I have recently come to learn more about the advantages of Resource Acquisition Is Initialization (RAII). In particular, I have discovered that the C# idiom: using (my dbConn = new DbConnection(connStr) { // do stuff with dbConn } has the C++ equivalent: { DbConnection dbConn(connStr); // do stuff with dbConn } meaning that remembering to enclose the use of resources like DbConnection in a using block is unnecessary in C++ ! This seems to a major advantage of C++. This is even more convincing when you consider a class that has an instance member of type DbConnection, for example class Foo { DbConnection dbConn; // ... } In C# I would need to have Foo implement IDisposable as such: class Foo : IDisposable { DbConnection dbConn; public void Dispose() { dbConn.Dispose(); } } and what's worse, every user of Foo would need to remember to enclose Foo in a using block, like: using (var foo = new Foo()) { // do stuff with "foo" } Now looking at C# and its Java roots I am wondering... did the developers of Java fully appreciate what they were giving up when they abandoned the stack in favor of the heap, thus abandoning RAII? (Similarly, did Stroustrup fully appreciate the significance of RAII?)

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• How to explain pointers to a Java/VB programmer

  - by Skeith

  I am writing a game and my friend has offered to help me as it is a RPG and will take a long time to do the "scripting" bit of the game. The problem is IMO he's not that good a programmer :( (add flame war here). He has only programmed in Java and VB and keeps saying really stupid things to me like "Why don't you drag and drop an onClick event" to design my UI when I'm using DirectX. I tried explaining pointers to him but his response was, if it's just a variable that holds a memory address, why don't you just use an int? I create an instance of an attack class and give the creature a pointer to it so if several creatures use the same attack there is only one instance of it. He keeps saying why not put if statements in the creature class for every attack class and set true for the ones that are there. He has programmed mainly in VB and a little in Java just to learn OOP. How can I explain advanced C++ concepts like pointers and memory management to him? He just doesn't understand there are no super functions like form.show in C++.

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• RMS java web framework

  - by Kamil Tomšík

  We're currently reconsidering technologies and frameworks to get more agile with "simple" RMS CRUD-based projects. In short, short-living things like this Right now we have custom extension on top of SmartGWT but after some time it has proven not to be enough flexible. I also personally dislike that java-js compilation process and the whole GWT codebase. Not only its ugly designed, it also makes certain low-level js things very complicated if not completely impossible. So what I'm looking for is: closest to web as possible, like JSF or possibly Tapestry, it is very important to be able get "low" and weave framework if necessary. Happens more often than we thought. datagrid capable - Ext.js & PrimeFaces looks pretty good, Vaadin does too. db-schema generators (optional, no matter in which way) If it were only on me, I'd probably stick to Ext.js + custom rest-based java solution, possibly generated from database schema (not sure about concrete tooling yet) I only does have experience with vanilla Ext.js, vanilla GWT and JSF 2.0 / Seam, so it kinda hard for me to judge or even propose other frameworks. What would be your proposition? What are the problems you've faced, what was your solution and how hard do you think it was to deal with them in "big picture"?

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• From physics to Java programmer?

  - by inovaovao

  I'm a physics phd with little actual programming experience. I've always liked programming and played around with Basic and Pascal (also VB and Delphi) as a teen, but the largest actual project I completed was an assignement for the introductory computer science class in university where I wrote a nice little program (about 1500 lines of pascal) to display functions of 2 variables in 3D. I've had also a couple other projects of a few hundred lines range, but during my phd I didn't have (or take) the time to program more (string theory is hard guys!), beside playing around with ruby. Now I've decided that I'm more interested in programming than in physics and started to learn Java (hoping to pass the certification exam next week) and OO design. Still, I have trouble deciding on what to focus next (Java EE? Web development? algorithms and C programming?) in order to maximize my employement chances. Bear in mind that I'm aiming (mostly) at the swedish job market and that I'm 30 years old. So for the questions: Do you think that I have any chances to start and make a career in IT and programming coming from physics? What would be the best strategy to maximize my value in the field? Do you have suggestions as to where my physics background might be useful?

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• Dalvik + Java licensing question

  - by Andrew Bate

  This is a licensing question about the Dalvik and J2SE core libraries. In particular the license governing java.util.concurrent.SynchronousQueue. The license header of the class in the JDK source states that it is GPLv2 only (see grepcode). However, the same file in the Dalvik core libraries seems to be governed by the Apache 2 license only (see android source). How is this possible? I didn't think you could take GPLv2 source and re-license it as Apache 2. (It's obvious they did: a comment above the Java Doc even says "removed link to collections framework docs"!) I'm asking because I have a GPLv3 project and would like to include a derivative work of some source from the core libraries (either Dalvik or J2SE) but publish it under GPLv3. I thought I could do this with Apache 2, but not GPLv2. I know that the J2SE class source is itself derivative work from public domain source, but the changes from the original are substantial. (The original is available at gee.cs.oswego.edu if you are interested.) Therefore the android source really is just a copy of the J2SE source, but published under Apache 2 instead of GPLv2. Is Google really allowed to do this?

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• Java JRE 1.7.0_60 Certified with Oracle E-Business Suite

  - by Steven Chan (Oracle Development)

  Java Runtime Environment 7u60 (a.k.a. JRE 7u60-b19) and later updates on the JRE 7 codeline are now certified with Oracle E-Business Suite Release 11i and 12.0, 12.1, and 12.2 for Windows-based desktop clients. Effects of new support dates on Java upgrades for EBS environments Support dates for the E-Business Suite and Java have changed.  Please review the sections below for more details: What does this mean for Oracle E-Business Suite users? Will EBS users be forced to upgrade to JRE 7 for Windows desktop clients? Will EBS users be forced to upgrade to JDK 7 for EBS application tier servers? All JRE 6 and 7 releases are certified with EBS upon release Our standard policy is that all E-Business Suite customers can apply all JRE updates to end-user desktops from JRE 1.6.0_03 and later updates on the 1.6 codeline, and from JRE 7u10 and later updates on the JRE 7 codeline.  We test all new JRE 1.6 and JRE 7 releases in parallel with the JRE development process, so all new JRE 1.6 and 7 releases are considered certified with the E-Business Suite on the same day that they're released by our Java team.  You do not need to wait for a certification announcement before applying new JRE 1.6 or JRE 7 releases to your EBS users' desktops. What's new in JRE 1.7.0_60? JDK 7u60 contains IANA time zone data version 2014b. For more information, refer to Timezone Data Versions in the JRE Software. It is strongly recommended that all customers upgrade to this release.  Details about update in this release are listed in the release notes. 32-bit and 64-bit versions certified This certification includes both the 32-bit and 64-bit JRE versions for various Windows operating systems. See the respective Recommended Browser documentation for your EBS release for details. Where are the official patch requirements documented? All patches required for ensuring full compatibility of the E-Business Suite with JRE 7 are documented in these Notes: For EBS 11i: Deploying Sun JRE (Native Plug-in) for Windows Clients in Oracle E-Business Suite Release 11i (Note 290807.1) Upgrading Developer 6i with Oracle E-Business Suite 11i (Note 125767.1) For EBS 12.0, 12.1, 12.2 Deploying Sun JRE (Native Plug-in) for Windows Clients in Oracle E-Business Suite Release 12 (Note 393931.1) Upgrading OracleAS 10g Forms and Reports in Oracle E-Business Suite Release 12 (Note 437878.1) EBS + Discoverer 11g Users JRE 1.7.0_60 is certified for Discoverer 11g in E-Business Suite environments with the following minimum requirements: Discoverer (11g) 11.1.1.6 plus Patch 13877486 and later  Reference: How To Find Oracle BI Discoverer 10g and 11g Certification Information (Document 233047.1) Worried about the 'mismanaged session cookie' issue? No need to worry -- it's fixed.  To recap: JRE releases 1.6.0_18 through 1.6.0_22 had issues with mismanaging session cookies that affected some users in some circumstances. The fix for those issues was first included in JRE 1.6.0_23. These fixes will carry forward and continue to be fixed in all future JRE releases on the JRE 6 and 7 codelines.  In other words, if you wish to avoid the mismanaged session cookie issue, you should apply any release after JRE 1.6.0_22 on the JRE 6 codeline, and JRE 7u10 and later JRE 7 codeline updates. Implications of Java 6 End of Public Updates for EBS Users The Support Roadmap for Oracle Java is published here: Oracle Java SE Support Roadmap The latest updates to that page (as of Sept. 19, 2012) state (emphasis added): Java SE 6 End of Public Updates Notice After February 2013, Oracle will no longer post updates of Java SE 6 to its public download sites. Existing Java SE 6 downloads already posted as of February 2013 will remain accessible in the Java Archive on Oracle Technology Network. Developers and end-users are encouraged to update to more recent Java SE versions that remain available for public download. For enterprise customers, who need continued access to critical bug fixes and security fixes as well as general maintenance for Java SE 6 or older versions, long term support is available through Oracle Java SE Support . What does this mean for Oracle E-Business Suite users? EBS users fall under the category of "enterprise users" above.  Java is an integral part of the Oracle E-Business Suite technology stack, so EBS users will continue to receive Java SE 6 updates from February 2013 to the end of Java SE 6 Extended Support in June 2017. In other words, nothing changes for EBS users after February 2013.  EBS users will continue to receive critical bug fixes and security fixes as well as general maintenance for Java SE 6 until the end of Java SE 6 Extended Support in June 2017. How can EBS customers obtain Java 6 updates after the public end-of-life? EBS customers can download Java 6 patches from My Oracle Support.  For a complete list of all Java SE patch numbers, see: All Java SE Downloads on MOS (Note 1439822.1) Both JDK and JRE packages are contained in a single combined download after 6u45.  Download the "JDK" package for both the desktop client JRE and the server-side JDK package.  Will EBS users be forced to upgrade to JRE 7 for Windows desktop clients? This upgrade is highly recommended but remains optional while Java 6 is covered by Extended Support. Updates will be delivered via My Oracle Support, where you can continue to receive critical bug fixes and security fixes as well as general maintenance for JRE 6 desktop clients.  Java 6 is covered by Extended Support until June 2017.  All E-Business Suite customers must upgrade to JRE 7 by June 2017. Coexistence of JRE 6 and JRE 7 on Windows desktops The upgrade to JRE 7 is highly recommended for EBS users, but some users may need to run both JRE 6 and 7 on their Windows desktops for reasons unrelated to the E-Business Suite. Most EBS configurations with IE and Firefox use non-static versioning by default. JRE 7 will be invoked instead of JRE 6 if both are installed on a Windows desktop. For more details, see "Appendix B: Static vs. Non-static Versioning and Set Up Options" in Notes 290807.1 and 393931.1. Applying Updates to JRE 6 and JRE 7 to Windows desktops Auto-update will keep JRE 7 up-to-date for Windows users with JRE 7 installed. Auto-update will only keep JRE 7 up-to-date for Windows users with both JRE 6 and 7 installed.  JRE 6 users are strongly encouraged to apply the latest Critical Patch Updates as soon as possible after each release. The Jave SE CPUs will be available via My Oracle Support.  EBS users can find more information about JRE 6 and 7 updates here: Information Center: Installation & Configuration for Oracle Java SE (Note 1412103.2) The dates for future Java SE CPUs can be found on the Critical Patch Updates, Security Alerts and Third Party Bulletin.  An RSS feed is available on that site for those who would like to be kept up-to-date. What do Mac users need? Mac users running Mac OS X 10.9 can run JRE 7 plug-ins.  See this article: EBS Release 12 Certified with Mac OS X 10.9 with Safari 7 and JRE 7 Will EBS users be forced to upgrade to JDK 7 for EBS application tier servers? JRE is used for desktop clients.  JDK is used for application tier servers JDK upgrades for E-Business Suite application tier servers are highly recommended but currently remain optional while Java 6 is covered by Extended Support. Updates will be delivered via My Oracle Support, where you can continue to receive critical bug fixes and security fixes as well as general maintenance for JDK 6 for application tier servers.  Java SE 6 is covered by Extended Support until June 2017.  All EBS customers with application tier servers on Windows, Solaris, and Linux must upgrade to JDK 7 by June 2017. EBS customers running their application tier servers on other operating systems should check with their respective vendors for the support dates for those platforms. JDK 7 is certified with E-Business Suite 12.  See: Java (JDK) 7 Certified for E-Business Suite 12.0 and 12.1 Servers Java (JDK) 7 Certified with E-Business Suite 12.2 Servers References Recommended Browsers for Oracle Applications 11i (Metalink Note 285218.1) Upgrading Sun JRE (Native Plug-in) with Oracle Applications 11i for Windows Clients (Metalink Note 290807.1) Recommended Browsers for Oracle Applications 12 (MetaLink Note 389422.1) Upgrading JRE Plugin with Oracle Applications R12 (MetaLink Note 393931.1) Related Articles Mismanaged Session Cookie Issue Fixed for EBS in JRE 1.6.0_23 Roundup: Oracle JInitiator 1.3 Desupported for EBS Customers in July 2009

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• What packages are neccessary to have sound output from java applets?

  - by MvG

  I've got a very minimalistic setup of ubuntu precise, created using debootstrap. So please don't assume that any packages are installed just because they usually are. On that system, I'd like to play some sounds from a java applet. However, this always fails with the following error message: javax.sound.midi.MidiUnavailableException: Can not open line at com.sun.media.sound.SoftSynthesizer.open(SoftSynthesizer.java:1132) at com.sun.media.sound.SoftSynthesizer.open(SoftSynthesizer.java:1036) ... Caused by: java.lang.IllegalArgumentException: No line matching interface SourceDataLine supporting format PCM_SIGNED 44100.0 Hz, 16 bit, stereo, 4 bytes/frame, little-endian is supported. at javax.sound.sampled.AudioSystem.getLine(AudioSystem.java:476) at javax.sound.sampled.AudioSystem.getSourceDataLine(AudioSystem.java:604) at com.sun.media.sound.SoftSynthesizer.open(SoftSynthesizer.java:1066) ... 35 more As the messages mention a soft synthesizer, and pcm lines, I expect that the lack of some midi daemon is not the issue here. As far as I can tell, the alsa kernel modules are loaded, including snd_hda_intel, snd_pcm, snd_seq_midi among others. I've also included the alsa-base and alsa-utils packages in my installation. alsa-mixer looks good, using “HDA Intel PCH” as its default device. What other packages, configuration settings or daemon startups does java require to make its sound output work?

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• Java Applet or Unity3D for Cross-Platform 3D Surveying App

  - by Jake M

  Do you think a Java Applet or Unity3D Application is the best option to make a cross-browser 3d web-app? I intend to make a web application that displays 3d environments that can be navigated by dragging(with a finger or mouse depending on the platform). The web app will render 3d environments of development sites including contours, water pipeline locations, buildings etc. The application must work on Windows Desktop, Android, iOS and Windows Phone. So this is why I am tending towards a web-app as opposed to cross-platform smart phone library(like Mosync or Marmalade). The 3d environments will be navigable(by dragging around) and contain simple(not detailed) 3d objects like buildings, mountains, pipelines, etc. One thing I know is that WebGL is out because it doesn't work on IE and has limited support on Smart Phones(am I correct to completely disregard WebGL?). Will future Smart Phone browsers continue to support Java Applets? Also is it really true I can write ONE Application/Game in Unity3D and simply compile it to run on Windows Windows, Mac, Xbox 360, PlayStation 3, Wii, iPad, iPhone and Android? Would you suggest the Unity3D application path or the Unity3D Web Player path? Concerning Unity3D, there's one thing I am unsure about: do all Unity3D features work on iOS and Android?

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• Removed Java replaced with newest "Sun Java", disc won't boot, and won't let me re-install grub using boot repair disc

  - by Al Rowe

  Had a minor problem with my Stock market platform. Set-up screen would freeze program. Called their tech support, got their "Linux guy", who advised remove all Java and replace, not with synaptic version, but newest Sun Java. After removing, computer auto rebooted, and went to blue mem-test screen. Showed no errors, but couldn't get back in. Tried two versions of boot repair disc from iso (checked md5sum, showed good.), but fix aborted, giving apt-error detected. Opened a terminal and typed (or copy/paste): sudo chroot "/mnt/boot-sav/sda1" apt-get -f install. My system is Ubuntu 12.04. Had a few very minor issues from install, all fixed. Also added some of my favorite gnome tricks just to make life easier, but none that could have caused this. Added script to add shortcuts to desktop, open terminal in any menu from inside it, access root terminal, etc. System was firewalled and using avast antivirus (o.k., I'm paranoid. Used to do Windows sys-op and security.) But relative newbie to Linux.

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• How to void checked exceptions in Java?

  - by deamon

  I consider checked exception for a design mistake in the Java language. They lead to leaky abstractions and a lot of clutter in the code. It seems that they force the programmer to handle exceptions early although they are in most cases better handled lately. So my question is how to avoid checked exception? My idea is to execute the actual code inside an exception translator using lambda expressions. Example: ExceptionConverter.convertToRuntimeException(() => { // do things that could throw checked exceptions here }); If for example a IOException occurs it gets rethrown as an exception with the same name but from a different class hierarchy (based on RuntimeException). This approach would effectivly remove the need to handle or declare checked exceptions. Exceptions could then be handled where and if it makes sense. Another solution would be to declare IOException throws Exception on each method. What do you think which solution is better? Do you know any better approach to avoid (suppress) checked exceptions in Java?

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• How to start a high school Java/Android development club for 13-17 year olds

  - by PaulHurleyuk

  My wife is a high school maths teacher, and is considering starting a programming club for 13-17 years olds who show an interest. Their interest seems to be around Apps and Android which I have little experience of. The kids would be (presumably) interested in programming, and have a fairly high level of computing knowledge. We would provide them with resources and some knowledge, but hopefully a lot would be self guided. I'm hoping stack overflow'ers can provide some tips or starting points. Specific things I think I'll need are; A development Environment; Currently I'm looking towards Java and Android, developed in Eclipse, probably installed on donated older hardware Some initial direction; There seem to be a plethora or 'start android' tutorials, so some recommendations for good ones are valuable, as are recommended paper books A Target; Some final project they should be shooting for A Route; This is where I'm most stuck, how to lead them through the required Java concepts and learning they would need Some related questions already out there Language+IDE for teaching high school students? Teaching "web design/development" to high-school home-school group. Good sources? How can I bootstrap a software development community at my school?

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• "sha256sum mismatch jdk-7u3-linux-x64.tar.gz " error when trying to install Oracle Java

  - by Fawkes5

  i recently tried installed java 7 on ubuntu 12.04 and i think i screwed something up I followed the instructions given here. First you need to remove openjdk for this run the following command from your terminal sudo apt-get purge openjdk* Now you can install Java7 by adding the following repository: sudo add-apt-repository ppa:eugenesan/java sudo apt-get update sudo apt-get install oracle-java7-installer Now everytime i install a new program i get the following error: Download done. sha256sum mismatch jdk-7u3-linux-x64.tar.gz Oracle JDK 7 is NOT installed. dpkg: error processing oracle-java7-installer (--configure): subprocess installed post-installation script returned error exit status 1 Setting up python-central (0.6.17ubuntu1) ... Setting up python-eggtrayicon (2.25.3-11) ... Setting up gmail-notify (1.6.1.1-1ubuntu1) ... Processing triggers for python-central ... Errors were encountered while processing: oracle-java7-installer Error in function: However.The program seems to install and work just fine so it doesn't seem to be a problem preventing me from doing anything So then i reinstalled openjdk by going: sudo apt-get install openjdk* But i still get the same error. going: sudo apt-get install oracle-java7-installer gives me the same error. What is going on? Please let me know if this is clear or not and ill try to explain my issue better

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• Freescale One Box Unboxing (then installing Java SE Embedded technology)

  - by hinkmond

  So, I get a FedEx delivery the other day... "What cool device could be inside this FedEx Overnight Express Large Box?" I was wondering... Could it be a new Linux/ARM target device board, faster than a Raspberry Pi and better than a BeagleBone Black??? Why, yes! Yes, it was a Linux/ARM target device board, faster than anything around! It was a Freescale i.MX6 Sabre Smart Device Board (SDB)! Cool... Quad Core ARM Cortex A9 1GHz with 1GB of RAM. So, cool... I installed the Freescale One Box OpenWRT Linux image onto its SD card and booted it up into Linux. But, wait! One thing was missing... What was it? What could be missing? Why, it had no Java SE Embedded installed on it yet, of course! So, I went to the JDK 7u45 download link. Clicked on "Accept License Agreement", and clicked on "jdk-7u45-linux-arm-vfp-sflt.tar.gz", installed the bad boy, and all was good. Java SE Embedded 7u45 on a Freescale One Box. Nice... Hinkmond

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• Java - Using Linear Coordinates to Check Against AI [closed]

  - by Oliver Jones

  I'm working on some artificial intelligence, and I want my AI not to run into given coordinates as these are references of a wall/boundary. To begin with, every time my AI hits a wall, it makes a reference to that position (x,y). When it hits the same wall three times, it uses linear check points to 'imagine' there is a wall going through these coordinates. I want to now prevent my AI from going into that wall again. To detect if my coordinates make a straight line, i use: private boolean collinear(double x1, double y1, double x2, double y2, double x3, double y3) { return (y1 - y2) * (x1 - x3) == (y1 - y3) * (x1 - x2); } This returns true is the given points are linear to one another. So my problems are: How do I determine whether my robot is approaching the wall from its current trajectory? Instead of Java 'imagining' theres a line from 1, to 3. But to 'imagine' a line all the way through these linear coordinantes, until infinity (or close). I have a feeling this is going to require some confusing trigonometry? (REPOST: http://stackoverflow.com/questions/13542592/java-using-linear-coordinates-to-check-against-ai)

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• Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 3)

  - by hinkmond

  So, let's now connect the parts together to make a Java Embedded ghost sensor using a Raspberry Pi. Grab your JFET transistor, LED light, wires, and breadboard and follow the connections on this diagram. The JFET transistor plugs into the breadboard with the flat part facing left. Then, plug in a wire to the same breadboard hole row as the top JFET lead (green in the diagram) and keep it unconnected to act as an antenna. Then, connect a wire (red) from the middle lead of the JFET transistor to Pin 1 on your RPi GPIO header. And, connect another wire (blue) from the lower lead of the JFET transistor to Pin 25 on your RPi GPIO header, then connect another (blue) wire from the lower lead of the JFET transistor to the long end of a common cathode LED, and finally connect the short end of the LED with a wire (black) to Pin 6 (ground) of the RPi GPIO header. That's it. Easy. Now test it. See: Ghost Sensor Testing Here's a video of me testing the Ghost Sensor circuit on my Raspberry Pi. We'll cover the Java SE app needed to record the ghost analytics in the next post. Hinkmond

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• Maintaining C/C++/Java skills as a web developer

  - by wwwuser

  When I was in college I learned how to program in C, C++, and Java. Currently, I'm a web developer using front end and back end technologies (HTML/CSS/JS, PHP, MYSQL). While the sorting algorithms and OOP concepts that I learned in college can be applied to web development, I'm looking for ways to keep up my knowledge of all languages. I enjoy programming in C-Style (C/C++/Java) languages and front-end/back-end technologies. Unfortunately, there aren't many options to use C-style languages to build websites. However, I would like to keep up my knowledge and skills in the languages I learned in college as I know they will continue to help me with my growth. What resources are available to keep challenging myself in C-style languages that are relevant to web development? Would contract work for C-style languages be beneficial? Are there sites that offer algorithm challenges? Any help is appreciated. I'm also interested in how others that have asked themselves this have solved this problem.

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• Should I go with Java or Python for my next project, after using PHP for 5 years? [closed]

  - by vim

  I have a full-time PHP job and I've been working with PHP for 5 years. I'm not willing to stay within this technology stack any more. I also worked with Java for 2 year before, so for me it looks more obvious to switch back to Java. However during last 5 years I was thinking about starting my own project, and now I think I have a very good SAAS idea. I'm completely confused what technology should I use for my project. I don't want to do it in PHP, and after reading many articles about rapid prototype development it seems to me that Django is the best option. I will continue to work full time for my current employer because I need to pay my bills and will work on my project in my free time. The concern I have is should I do my project in Java or Python? To be realistic there is always a risk when you are doing your own project/start-up. If I do it in Java in the worst case scenario I believe I will be able to find a full time Java position because I already have some experience in Java + recent experience in my project. With regards to Python it looks like it is not very popular in my area and salaries are much more lower then for Java. On the other hand I have a feeling that if I chose Java it will take me a way longer to finish my project. Guys I'm completely confused and I need your advice. P.S. I have moved to London 2 years ago from another country, local guys are very welcome to share their thoughts about London's job market.

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• Java or Python? Career/Start-up advice needed [closed]

  - by vim

  I have a full-time PHP job and I've been working with PHP for 5 years. As you can guess after spending 5 years I'm not willing to stay within this technology stack any more. I also worked with Java for 2 year before, so for me it looks more obvious to switch back to Java. However during last 5 years I was thinking about starting my own project, and now I think I have a very good SAAS idea. I'm completely confused what technology should I use for my project. I don't want to do it in PHP, and after reading many articles about rapid prototype development it seems to me that Django/Ruby is the best option. I will continue to work full time for my current employer because I need to pay my bills and will work on my project in my free time. The concern I have is should I do my project in Java or Python? To be realistic there is always a risk when you are doing your own project/start-up. If I do it in Java in the worst case scenario I believe I will be able to find a full time Java position because I already have some experience in Java + recent experience in my project. With regards to Python it looks like it is not very popular in my area and salaries are much more lower then for Java. On the other hand I have a feeling that if I chose Java it will take me a way longer to finish my project. Guys I'm completely confused and I need your advice. P.S. I have moved to London 2 years ago from another country, local guys are very welcome to share their thoughts about London's job market.

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• Which field of programming is known as the best practice for Java? [closed]

  - by user1276509

  I'm a CS student and I have some programming background such as PHP, JavaScript and Pascal. Since Java is so popular among local companies and Java is known as market skill, I'm going to learn it. But I don't know in which field I can use it. So I wonder, what can I do with Java? I heard that Java is not good for web development, although there is Play! Framework. I know a lot of people who prefer to use Python, Ruby and PHP for web development instead of Java and its Play. I also heard that Java is not good to write destkop applications, although it's cross-platform. Many programmers prefer C# for destkop. So I see there's only one field which I can use Java for it - is Android development. But I'm not interested in mobile application development. So my question is which field of programming is known as the best practice for Java? Thanks in advance.

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• Problems with HMAC when switching to Java 6

  - by Pablo Fernandez

  We have recently switched to java6 and it's mandatory in the project. One of our apps that used to work is failing, with this stacktrace (relevant part) java.lang.NoClassDefFoundError: Could not initialize class com.apple.crypto.provider.HmacSHA1 sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) java.lang.reflect.Constructor.newInstance(Constructor.java:513) java.lang.Class.newInstance0(Class.java:355) java.lang.Class.newInstance(Class.java:308) java.security.Provider$Service.newInstance(Provider.java:1221) javax.crypto.Mac.a(DashoA13*..) javax.crypto.Mac.init(DashoA13*..) Has anyone had this problem before? Thanks a lot

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• on Google App Engine 500 Error, it should be 200 instead of 500

  - by Faisal Amjad

  requestToken = function() { var getTokenURI = '/gettoken?userid=' + userid; var httpRequest = makeRequest(getTokenURI, true); httpRequest.onreadystatechange = function() { if (httpRequest.readyState == 4) { if (httpRequest.status == 200) { openChannel(httpRequest.responseText); } else { alert('ERROR: AJAX request status = ' + httpRequest.status); } } } }; function makeRequest(url, async) { var httpRequest; if (window.XMLHttpRequest) { httpRequest = new XMLHttpRequest(); } else if (window.ActiveXObject) { // IE try { httpRequest = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { httpRequest = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { } } } if (!httpRequest) { return false; } httpRequest.open('POST', url, async); httpRequest.send(); return httpRequest; } it is running excellent on localhost...but on google app engine it httpRequest.status equals 500 and goes in else statement. WHY? LOG on google app engine: /getFriendList?userid=d 500 253ms 0kb Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11 175.110.179.86 - - [17/Dec/2012:08:35:33 -0800] "POST /getFriendList?userid=d HTTP/1.1" 500 0 "http://faisalimmsngr.appspot.com/" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11" "faisalimmsngr.appspot.com" ms=254 cpu_ms=110 instance=00c61b117caf2d11ca57d2a2296ccd0b902b038a W 2012-12-17 08:35:33.272 Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@10ff62a{/,/base/data/home/apps/s~faisalimmsngr/1.363934467542140431} org.mortbay.util.MultiException[java.lang.UnsupportedClassVersionError: adv/web/mid/exam/FriendServlet : Unsupported major.minor version 51.0, java.lang.UnsupportedClassVersionError: adv/web/mid/exam/MessageServlet : Unsupported major.minor version 51.0, java.lang.UnsupportedClassVersionError: adv/web/mid/exam/TokenServlet : Unsupported major.minor version 51.0] at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:656) at org.mortbay.jetty.servlet.Context.startContext(Context.java:140) at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250) at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219) at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:447) at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454) at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461) at com.google.tracing.TraceContext.runInContext(TraceContext.java:703) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330) at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458) at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251) at java.lang.Thread.run(Thread.java:679) java.lang.UnsupportedClassVersionError: adv/web/mid/exam/FriendServlet : Unsupported major.minor version 51.0 at com.google.appengine.runtime.Request.process-c04431eac3a1f275(Request.java) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at org.mortbay.util.Loader.loadClass(Loader.java:91) at org.mortbay.util.Loader.loadClass(Loader.java:71) at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73) at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685) at org.mortbay.jetty.servlet.Context.startContext(Context.java:140) at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250) at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454) at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461) at com.google.tracing.TraceContext.runInContext(TraceContext.java:703) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330) at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458) at java.lang.Thread.run(Thread.java:679)

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• Copying a java text file into a String.

  - by Deepak Konidena

  Hi, I run into the following errors when i try to store a large file into a string. Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:2882) at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:100) at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:515) at java.lang.StringBuffer.append(StringBuffer.java:306) at rdr2str.ReaderToString.main(ReaderToString.java:52) As is evident, i am running out of heap space. Basically my pgm looks like something like this. FileReader fr = new FileReader(<filepath>); sb = new StringBuffer(); char[] b = new char[BLKSIZ]; while ((n = fr.read(b)) > 0) sb.append(b, 0, n); fileString = sb.toString(); Can someone suggest me why i am running into heap space error? Thanks.

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