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  • Problem during JBoss Launch

    - by Rob
    Hi folks, I've a problem with JBoss 3.2.6. When I try to launch it, I get this error. 09:19:22,449 ERROR [StatefulSessionContainer] Starting failed jboss.j2ee:jndiName=TypicalBean,service=EJB java.rmi.ServerException: Could not bind home; nested exception is: javax.naming.CommunicationException: Network is unreachable [Root exception is java.io.IOException: Network is unreachable] at org.jboss.proxy.ejb.ProxyFactory.bindProxy(ProxyFactory.java:385) at org.jboss.proxy.ejb.ProxyFactory.start(ProxyFactory.java:187) and so on ... I use Java 1.6, and I can access to the Web, so I can't really figure out why this problem appears ... Thanks (and sorry for my poor english) Rob

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  • How do you fix "Too many open files" problem in Hudson?

    - by Randyaa
    We use Hudson as a continuous integration system to execute automated builds (nightly and based on CVS polling) of a lot of our projects. Some projects poll CVS every 15 minutes, some others poll every 5 minutes and some poll every hour. Every few weeks we'll get a build that fails with the following output: FATAL: java.io.IOException: Too many open files java.io.IOException: java.io.IOException: Too many open files at java.lang.UNIXProcess.<init>(UNIXProcess.java:148) The next build always worked (with 0 changes) so we always chalked it up to 2 build jobs being run at the same time and happening to have too many files open during the process. This weekend we had a build fail Friday night (automatic nightly build) with the message and every other nightly build also failed. Somehow this triggered Hudson to continuously build every project which failed until the issue was resolved. This resulted in a build every 30 minutes or so of every project until sometime Saturday night when the issue magically disappeared.

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  • Which langauge should i use for Artificail intelligence on web projects

    - by Mirage
    I have to do one project for my thesis involving Artificail intelligence , collaborative filtering and machine learning methods. I only know PHP/mysq/JS and there is not much AI stuff examples in PHP. There are some books on AI on internet but they use Java , Python. Now i have to apply AI techniques on web application. WHich language should i choose java or python. I searhed on internet that i can call java classes inside my php so that can help as as i am very good at php i have also seen that python can also be used with php as well So which way should i go and roughly how much it will take me to learn java i have done java basics but that was 6 years ago

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  • What should I do to practice?

    - by simion
    I start a year long industrial placement in September where i will be coding in Java predominantly. I am going to use the summer to brush up on my Java as in year one of the degree Java was the main language taught for OOP modules. However this year i have had no Java exposure except for an algorithms module, which was one of eight, so as you can see i am probably getting really rusty!. What i wanted to know is, how does the "real world" java programming differ from university coding and what do you suggest i brush up on that would be different to my normal workings. As a start I definitely need to get familiar with a professional IDE like NetBeans, opposed to having used BlueJ throughout but more specifically what coding practices should I get more familiar with. I appreciate they wont expect me to be a qualified full developer and will give me time, but I would like to hit the ground running as it were, with me having full hopes to secure a permanent position after I finish my degree.

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  • What should i do to practise?

    - by simion
    Hi guys I start a year long industrial placement in september where i will be coding in java predominantly. I am going to use the summer to brush up on my java as in year one of the degree java was the main language taught for OOP modules. However this year i have had no java exposure except for an algorithms module, which was one of eight, so as you can see i am probably getting really rusty!. What i wanted to know is, how does the "real world" java programming differ from university coding and what do you suggest i brush up on that would be different to my normal workings. As a start i definatley need to get familiar with a professional IDE like netbeans, opoosed to havign used BlueJ throughout but more specifically what coding practises should i get more familiar with I appreciate they wont expect me to be a qualified full developer and will give me time, but i would like to hit the ground running as it were, with me having full hopes to secure a perminant position after i finish my degree. Thanks for reading

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  • Authentication Failed exception - In the middle of bulk mail sending code.

    - by Ezhil
    We have a thread program that sends bulk mail. The information like 1. To 2. Subject Etc., are fetched from database, mail is composed and pushed to SMTP server. One of our customer sent a bulk mail with 2390 email. After sending 40 emails, suddenly the following exception occurred EXCEPTION javax.mail.AuthenticationFailedException STACKTRACE javax.mail.Service.connect(Service.java:306) javax.mail.Service.connect(Service.java:156) javax.mail.Service.connect(Service.java:105) ............... java.lang.Thread.run(Thread.java:619) and the rest 2350 emails failed. Why does this occur? Thanks for the Suggestions and Help Ezhil

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  • gwt - Using List<Serializable> in a RPC call?

    - by Garagos
    I have a RPC service with the following method: public List<Serializable> myMethod(TransactionCall call) {...} But I get a warning when this method is analyzed, and then the rpc call fails Analyzing 'my.project.package.myService' for serializable types Analyzing methods: public abstract java.util.List<java.io.Serializable> myMethod(my.project.package.TransactionCall call) Return type: java.util.List<java.io.Serializable> [...] java.io.Serializable Verifying instantiability (!) Checking all subtypes of Object wich qualify for serialization It seems I can't use Serializable for my List... I could use my own interface instead (something like AsyncDataInterface, wich implements the Serializable interface) but the fact is that my method will return a list custom objects AND basic objects (such as Strings, int....). So my questions are: Is it a standart behaviour? (I can't figure out why I can't use this interface in that case) Does anyone have a workaround for that kind of situation?

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  • InetAddress.getLocalHost() throws UnknownHostException

    - by jhwist
    Hi, I am testing our server-application (written Java) on different operating systems and thought that OpenSolaris (2008.11) would be the least troublesome due to the nice Java integration. Turns out I was wrong, as I end up with a UnknownHostException try { computerName = InetAddress.getLocalHost().getHostName(); if (computerName.indexOf(".") > -1) computerName = computerName.substring(0, computerName.indexOf(".")).toUpperCase(); } catch (UnknownHostException e) { e.printStackTrace(); } The output is: java.net.UnknownHostException: desvearth01: desvearth01 at java.net.InetAddress.getLocalHost(InetAddress.java:1353) However, nslookup desvearth01 returns the correct IP address, and nslookup localhost returns 127.0.0.1 as expected. Also, the same code works perfectly on FreeBSD. Is there anything special to OpenSolaris that I am not aware of? Any hints appreciated, thanks.

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  • Package not found; javac

    - by Muneeb
    This is annoying. I have a directory structure like this -lib --some jar files -packageName --Main.java --SomeOtherPackage --SomeOtherJavaClass.java Main.java imports SomeOtherPackage. And both java files uses jars in the lib. What I do is add the jar files independently in the CLASSPATH. And then run as: javac packageName/Main.java but it gives the error that Package not found SomeOtherPackage . Shouldn't it automatically realize the dependency and build SomeOtherPackage as well? What would be the javac command and the classpath for the above case? Thanks

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  • Are upper bounds of indexed ranges always assumed to be exclusive?

    - by polygenelubricants
    So in Java, whenever an indexed range is given, the upper bound is almost always exclusive. From java.lang.String: substring(int beginIndex, int endIndex) Returns a new string that is a substring of this string. The substring begins at the specified beginIndex and extends to the character at index endIndex - 1 From java.util.Arrays: copyOfRange(T[] original, int from, int to) from - the initial index of the range to be copied, inclusive to - the final index of the range to be copied, exclusive. From java.util.BitSet: set(int fromIndex, int toIndex) fromIndex - index of the first bit to be set. toIndex - index after the last bit to be set. As you can see, it does look like Java tries to make it a consistent convention that upper bounds are exclusive. My questions are: Is this the official authoritative recommendation? Are there notable violations that we should be wary of? Is there a name for this system? (ala "0-based" vs "1-based")

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  • Scanner's Read Line returning NoSuchElementException

    - by Brian
    This is my first time using StackOverflow. I am trying to read a text file which consists of a single number one the first line. try { Scanner s = new Scanner(new File("HighScores.txt")); int temp =Integer.parseInt(s.nextLine()); s.close(); return temp; } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } However, I get an error: java.util.NoSuchElementException: No line found at java.util.Scanner.nextLine(Unknown Source) at GameStart.getHighScore(GameStart.java:334) at GameStart.init(GameStart.java:82) at sun.applet.AppletPanel.run(Unknown Source) at java.lang.Thread.run(Unknown Source) I know that HighScores.txt is not empty, so why is this problem occuring? I tried using BufferedReader, and BufferReader.readLine() return null.

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  • How to use JNI, but only when available for current platform?

    - by Mecki
    What is the common way (or best practice) to optionally use JNI? E.g. I have a Java class and this class is 100% pure Java, so it can run on all platforms. However, on some platforms I'd like to speed up some heavy calculations using JNI - which works fine. Unfortunately I cannot support any existing Java platform in the world. So I guess it is fine to initially only support the big three: Linux, Windows, Mac OS X. So what I'd like to do is to use JNI on those three platforms and use the 100% pure Java version on all other platforms. Now I can think of various ways how to do that (loading class dynamically for example and either loading the JNI class or the pure Java one), but thinking that this is a common issue that thousands of projects had to solve in the past for sure, I'm really surprised to not find any documentation or references to the question how to solve this most elegantly or effectively.

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  • JTable.removeColumn() method throws exception

    - by sanjeev
    To hide a column from only the view of JTable, i am using the removeColumn() method. But it throws the exception Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 7 >= 7 at java.util.Vector.elementAt(Vector.java:470) at javax.swing.table.DefaultTableColumnModel.getColumn(DefaultTableColumnModel.java:294) at javax.swing.plaf.basic.BasicTableHeaderUI.paint(BasicTableHeaderUI.java:648) i think, after removing column from the view, if i modified the model, then this exception pops out. is it because of there is no column in view, while the model is updating the table ? What is the best way to hide the column in view in JTable ? insteading of setting the sizes to 0.

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  • How to setup tomcat 7 as a server on windows 2008 server

    - by birdy
    I setup the tomcat7 as a service as below: c:\Program Files (x86)\Tomcat7\apache-tomcat-7.0.32\bin>service.bat install Installing the service 'Tomcat7' ... Using CATALINA_HOME: "C:\Program Files (x86)\Tomcat7\apache-tomcat-7.0.32" Using CATALINA_BASE: "C:\Program Files (x86)\Tomcat7\apache-tomcat-7.0.32" Using JAVA_HOME: "C:\Program Files (x86)\Java\jdk1.7.0_09" Using JRE_HOME: "C:\Program Files (x86)\Java\jdk1.7.0_09\jre" Using JVM: "C:\Program Files (x86)\Java\jdk1.7.0_09\jre\bin\server\ jvm.dll" However, when I try to start the service, I Get the error below: c:\Program Files (x86)\Tomcat7\apache-tomcat-7.0.32\bin>tomcat7.exe %1 is not a valid Win32 application. Failed to run service as console application This is the file I downloaded from apache: apache-tomcat-7.0.32-windows-x64.zip. I am able to successfully start tomcat on port 8080 as a standalong thing. Meaning I go to command prompt and type startup.bat and it starts up successfully. Question How can I resolve this and what are the things I should be troubleshooting for?

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  • How to pin NetBeans to Windows 7 taskbar?

    - by Vilx-
    I've googled around and it seems that I'm not the only one with the problem, however I couldn't find the solution. Maybe someone around here has figured it out. The problem is that netbeans.exe is actually a stub which is calling javaw.exe. When I try to pin the NetBeans process to the taskbar I actually pin "Java(TM) Platform SE Binary". That changes the icon and the pin doesn't work. The funny thing is that it works on another machine. I don't know whether it's because it's a different version of NetBeans, or a different version of Java. Has anyone figured this out? Added: I know this is sort of not programming related; on the other hand there are plenty of topics around here about how to better your programming environment, and this one is no worse than those. Oh, and btw - Windows 7 Enterprise x64; Java JDK 1.6.17; Netbeans 6.8

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  • wait after call command minecraft

    - by smeagogol
    I'm trying to create a batch file for a friend because he has some problems on minecraft. He needs to launch minecraft 80 times without closing java error... I have 2 batches, one with a while, and an other one executing java command for launching minecraft. ::Launcher.bat title Script Minecraft set tour=10 set tour2=tour :boucle set /a tour=tour-1 call "D:\thepath\Minecraft2.bat" if %tour%==0 goto suite goto boucle :suite wait javaw.exe :boucle2 set /a tour2=tour2-1 taskkill /F /IM "javaw.exe" if %tour2%==0 goto fin goto boucle2 :fin echo Appuyez sur une touche pour quitter... pause >nul and the other one ::Minecraft2.bat @echo off java -Xmx2048m -Xms1024m -cp "D:\thepath\Minecraft.exe" net.minecraft.LauncherFrame My problem is that when it calls the second batch, it's waiting for closure of the window but we must leave them opened ! If someone has already encountered this problem, I'd be grateful. Thanks PS: If my english is bad, it's because I'm french ;)

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  • Error when I am trying to run Activiti BPM explorer

    - by test test
    I am facing the following problem : I have downloaded Activiti BPM which runs under Apache. I have installed both; Java jre7 & Java jdk1.7.0_06. I set the JAVA_HOME to be C:\Program Files\Java\jdk1.7.0_06. But when I try to run the Activiti BPM by typing the following in windows 7 command line : C:\activiti-5.10\activiti-5.10\setup>ant demo.start, the Tomcat server will start and the demo will build successfully, but if I try to navigate to the following link http://localhost:8080/activiti-explorer I get the following error : HTTP Status 404 - /activiti-explorer type Status report message /activiti-explorer description The requested resource (/activiti-explorer) is not available. Apache Tomcat/6.0.32

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  • JDBC CLASSPATH Not Working

    - by AeroDroid
    I'm setting up a simple JDBC connection to my working MySQL database on my server. I'm using the Connector-J provided by MySQL. According to their documentation, I'm suppose to create the CLASSPATH variable to point to the directory where the mysql-connector-java-5.0.8-bin.jar is located. I used export set CLASSPATH=/path/mysql-connector-java-5.0.8-bin.jar:$CLASSPATH. When I type echo $CLASSPATH to see if it exists, everything seems fine. But then when I open a new terminal and type echo $CLASSPATH it's no longer there. I think this is the main reason why my Java server won't connect to the JDBC, because it isn't saving the CLASSPATH variable I set. Anyone got suggestions or fixes on how to set up JDBC in the first place?

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  • The JRockit Performance Counters

    - by Marcus Hirt
    Every now and then I get a question regarding what the attributes in the PerfCounters dynamic MBean represent. Now, all the MBeans under the oracle.jrockit.management (bea.jrockit.management pre R28) domain are part of what we call JMXMAPI (the JRockit JMX based Management API), which is unsupported. Therefore there is no official documentation for the API. I did however write a bit about JMXMAPI in my recent JRockit book, Oracle JRockit: The Definitive Guide. The information in the table below is from that book: Counter Description java.cls.loadedClasses The number of classes loaded since the start of the JVM. java.cls.unloadedClasses The number of classes unloaded since the start of the JVM. java.property.java.class.path The class path of the JVM. java.property.java.endorsed.dirs The endorsed dirs. See the Endorsed Standards Override Mechanism. java.property.java.ext.dirs The ext dirs, which are searched for jars that should be automatically put on the classpath. See the Java documentation for java.ext.dirs. java.property.java.home The root of the JDK or JRE installation. java.property.java.library.path The library path used to find user libraries. java.property.java.vm.version The JRockit version. java.rt.vmArgs The list of VM arguments. java.threads.daemon The number of running daemon threads. java.threads.live The total number of running threads. java.threads.livePeak The peak number of threads that has been running since JRockit was started. java.threads.nonDaemon The number of non-daemon threads running. java.threads.started The total number of threads started since the start of JRockit. jrockit.gc.latest.heapSize The current heap size in bytes. jrockit.gc.latest.nurserySize The current nursery size in bytes. jrockit.gc.latest.oc.compaction.time How long, in ticks, the last compaction lasted. Reset to 0 if compaction is skipped. jrockit.gc.latest.oc.heapUsedAfter Used heap at the end of the last OC, in bytes. jrockit.gc.latest.oc.heapUsedBefore Used heap at the start of the last OC, in bytes. jrockit.gc.latest.oc.number The number of OCs that have occurred so far. jrockit.gc.latest.oc.sumOfPauses The paused time for the last OC, in ticks. jrockit.gc.latest.oc.time The time the last OC took, in ticks. jrockit.gc.latest.yc.sumOfPauses The paused time for the last YC, in ticks. jrockit.gc.latest.yc.time The time the last YC took, in ticks. jrockit.gc.max.oc.individualPause The longest OC pause so far, in ticks. jrockit.gc.max.yc.individualPause The longest YC pause so far, in ticks. jrockit.gc.total.oc.compaction.externalAborted Number of aborted external compactions so far. jrockit.gc.total.oc.compaction.internalAborted Number of aborted internal compactions so far. jrockit.gc.total.oc.compaction.internalSkipped Number of skipped internal compactions so far. jrockit.gc.total.oc.compaction.time The total time spent doing compaction so far, in ticks. jrockit.gc.total.oc.ompaction.externalSkipped Number of skipped external compactions so far. jrockit.gc.total.oc.pauseTime The sum of all OC pause times so far, in ticks. jrockit.gc.total.oc.time The total time spent doing OC so far, in ticks. jrockit.gc.total.pageFaults The number of page faults that have occurred during GC so far. jrockit.gc.total.yc.pauseTime The sum of all YC pause times, in ticks. jrockit.gc.total.yc.promotedObjects The number of objects that all YCs have promoted. jrockit.gc.total.yc.promotedSize The total number of bytes that all YCs have promoted, in bytes. jrockit.gc.total.yc.time The total time spent doing YC, in ticks. oracle.ci.jit.count The number of methods JIT compiled. oracle.ci.jit.timeTotal The total time spent JIT compiling, in ticks. oracle.ci.opt.count The number of methods optimized. oracle.ci.opt.timeTotal The total time spent optimizing, in ticks. oracle.rt.counterFrequency Used to convert ticks values to seconds. Note that many of these counters are excellent choices for attributes to plot in the Management Console. Also note that many values are in ticks – to convert them to seconds, divide by the value in the oracle.rt.counterFrequency counter.

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  • Talking JavaOne with Rock Star Martijn Verburg

    - by Janice J. Heiss
    JavaOne Rock Stars, conceived in 2005, are the top-rated speakers at each JavaOne Conference. They are awarded by their peers, who, through conference surveys, recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized. Martijn Verburg has, in recent years, established himself as an important mover and shaker in the Java community. His “Diabolical Developer” session at the JavaOne 2011 Conference got people’s attention by identifying some of the worst practices Java developers are prone to engage in. Among other things, he is co-leader and organizer of the thriving London Java User Group (JUG) which has more than 2,500 members, co-represents the London JUG on the Executive Committee of the Java Community Process, and leads the global effort for the Java User Group “Adopt a JSR” and “Adopt OpenJDK” programs. Career highlights include overhauling technology stacks and SDLC practices at Mizuho International, mentoring Oracle on technical community management, and running off shore development teams for AIG. He is currently CTO at jClarity, a start-up focusing on automating optimization for Java/JVM related technologies, and Product Advisor at ZeroTurnaround. He co-authored, with Ben Evans, "The Well-Grounded Java Developer" published by Manning and, as a leading authority on technical team optimization, he is in high demand at major software conferences.Verburg is participating in five sessions, a busy man indeed. Here they are: CON6152 - Modern Software Development Antipatterns (with Ben Evans) UGF10434 - JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group (with Csaba Toth) BOF4047 - OpenJDK Building and Testing: Case Study—Java User Group OpenJDK Bugathon (with Ben Evans and Cecilia Borg) BOF6283 - 101 Ways to Improve Java: Why Developer Participation Matters (with Bruno Souza and Heather Vancura-Chilson) HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Kirk Pepperdine, Ellen Kraffmiller and Henri Tremblay) When I asked Verburg about the biggest mistakes Java developers tend to make, he listed three: A lack of communication -- Software development is far more a social activity than a technical one; most projects fail because of communication issues and social dynamics, not because of a bad technical decision. Sadly, many developers never learn this lesson. No source control -- Developers simply storing code in local filesystems and emailing code in order to integrate Design-driven Design -- The need for some developers to cram every design pattern from the Gang of Four (GoF) book into their source code All of which raises the question: If these practices are so bad, why do developers engage in them? “I've seen a wide gamut of reasons,” said Verburg, who lists them as: * They were never taught at high school/university that their bad habits were harmful.* They weren't mentored in their first professional roles.* They've lost passion for their craft.* They're being deliberately malicious!* They think software development is a technical activity and not a social one.* They think that they'll be able to tidy it up later.A couple of key confusions and misconceptions beset Java developers, according to Verburg. “With Java and the JVM in particular I've seen a couple of trends,” he remarked. “One is that developers think that the JVM is a magic box that will clean up their memory, make their code run fast, as well as make them cups of coffee. The JVM does help in a lot of cases, but bad code can and will still lead to terrible results! The other trend is to try and force Java (the language) to do something it's not very good at, such as rapid web development. So you get a proliferation of overly complex frameworks, libraries and techniques trying to get around the fact that Java is a monolithic, statically typed, compiled, OO environment. It's not a Golden Hammer!”I asked him about the keys to running a good Java User Group. “You need to have a ‘Why,’” he observed. “Many user groups know what they do (typically, events) and how they do it (the logistics), but what really drives users to join your group and to stay is to give them a purpose. For example, within the LJC we constantly talk about the ‘Why,’ which in our case is several whys:* Re-ignite the passion that developers have for their craft* Raise the bar of Java developers in London* We want developers to have a voice in deciding the future of Java* We want to inspire the next generation of tech leaders* To bring the disparate tech groups in London together* So we could learn from each other* We believe that the Java ecosystem forms a cornerstone of our society today -- we want to protect that for the futureLooking ahead to Java 8 Verburg expressed excitement about Lambdas. “I cannot wait for Lambdas,” he enthused. “Brian Goetz and his group are doing a great job, especially given some of the backwards compatibility that they have to maintain. It's going to remove a lot of boiler plate and yet maintain readability, plus enable massive scaling.”Check out Martijn Verburg at JavaOne if you get a chance, and, stay tuned for a longer interview yours truly did with Martijn to be publish on otn/java some time after JavaOne. Originally published on blogs.oracle.com/javaone.

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  • Talking JavaOne with Rock Star Martijn Verburg

    - by Janice J. Heiss
    JavaOne Rock Stars, conceived in 2005, are the top-rated speakers at each JavaOne Conference. They are awarded by their peers, who, through conference surveys, recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized. Martijn Verburg has, in recent years, established himself as an important mover and shaker in the Java community. His “Diabolical Developer” session at the JavaOne 2011 Conference got people’s attention by identifying some of the worst practices Java developers are prone to engage in. Among other things, he is co-leader and organizer of the thriving London Java User Group (JUG) which has more than 2,500 members, co-represents the London JUG on the Executive Committee of the Java Community Process, and leads the global effort for the Java User Group “Adopt a JSR” and “Adopt OpenJDK” programs. Career highlights include overhauling technology stacks and SDLC practices at Mizuho International, mentoring Oracle on technical community management, and running off shore development teams for AIG. He is currently CTO at jClarity, a start-up focusing on automating optimization for Java/JVM related technologies, and Product Advisor at ZeroTurnaround. He co-authored, with Ben Evans, "The Well-Grounded Java Developer" published by Manning and, as a leading authority on technical team optimization, he is in high demand at major software conferences.Verburg is participating in five sessions, a busy man indeed. Here they are: CON6152 - Modern Software Development Antipatterns (with Ben Evans) UGF10434 - JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group (with Csaba Toth) BOF4047 - OpenJDK Building and Testing: Case Study—Java User Group OpenJDK Bugathon (with Ben Evans and Cecilia Borg) BOF6283 - 101 Ways to Improve Java: Why Developer Participation Matters (with Bruno Souza and Heather Vancura-Chilson) HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Kirk Pepperdine, Ellen Kraffmiller and Henri Tremblay) When I asked Verburg about the biggest mistakes Java developers tend to make, he listed three: A lack of communication -- Software development is far more a social activity than a technical one; most projects fail because of communication issues and social dynamics, not because of a bad technical decision. Sadly, many developers never learn this lesson. No source control -- Developers simply storing code in local filesystems and emailing code in order to integrate Design-driven Design -- The need for some developers to cram every design pattern from the Gang of Four (GoF) book into their source code All of which raises the question: If these practices are so bad, why do developers engage in them? “I've seen a wide gamut of reasons,” said Verburg, who lists them as: * They were never taught at high school/university that their bad habits were harmful.* They weren't mentored in their first professional roles.* They've lost passion for their craft.* They're being deliberately malicious!* They think software development is a technical activity and not a social one.* They think that they'll be able to tidy it up later.A couple of key confusions and misconceptions beset Java developers, according to Verburg. “With Java and the JVM in particular I've seen a couple of trends,” he remarked. “One is that developers think that the JVM is a magic box that will clean up their memory, make their code run fast, as well as make them cups of coffee. The JVM does help in a lot of cases, but bad code can and will still lead to terrible results! The other trend is to try and force Java (the language) to do something it's not very good at, such as rapid web development. So you get a proliferation of overly complex frameworks, libraries and techniques trying to get around the fact that Java is a monolithic, statically typed, compiled, OO environment. It's not a Golden Hammer!”I asked him about the keys to running a good Java User Group. “You need to have a ‘Why,’” he observed. “Many user groups know what they do (typically, events) and how they do it (the logistics), but what really drives users to join your group and to stay is to give them a purpose. For example, within the LJC we constantly talk about the ‘Why,’ which in our case is several whys:* Re-ignite the passion that developers have for their craft* Raise the bar of Java developers in London* We want developers to have a voice in deciding the future of Java* We want to inspire the next generation of tech leaders* To bring the disparate tech groups in London together* So we could learn from each other* We believe that the Java ecosystem forms a cornerstone of our society today -- we want to protect that for the futureLooking ahead to Java 8 Verburg expressed excitement about Lambdas. “I cannot wait for Lambdas,” he enthused. “Brian Goetz and his group are doing a great job, especially given some of the backwards compatibility that they have to maintain. It's going to remove a lot of boiler plate and yet maintain readability, plus enable massive scaling.”Check out Martijn Verburg at JavaOne if you get a chance, and, stay tuned for a longer interview yours truly did with Martijn to be publish on otn/java some time after JavaOne.

    Read the article

  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    Originally published on blogs.oracle.com/javaone It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • io Exception error in wordcount example

    - by Anitha
    I have installed Hadoop 1.0.3 in Ubuntu 12.04 version (64bit) based on michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/ . I am trying to run a mapreduce job using the wordcount example. Running the command hduser@ubuntu: $/usr/local/hadoop/bin/hadoop jar hadoop-examples-1.0.3.jar wordcount /user/hduser/gutenberg /user/hduser/gutenberg-output gives the following error: Warning: $HADOOP_HOME is deprecated. Exception in thread "main" java.io.IOException: Error opening job jar: hadoop-examples-1.0.3.jar at org.apache.hadoop.util.RunJar.main(RunJar.java:90) Caused by: java.util.zip.ZipException: error in opening zip file at java.util.zip.ZipFile.open(Native Method) at java.util.zip.ZipFile.<init>(ZipFile.java:131) at java.util.jar.JarFile.<init>(JarFile.java:150) at java.util.jar.JarFile.<init>(JarFile.java:87) at org.apache.hadoop.util.RunJar.main(RunJar.java:88) Thanks in advance.

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  • StringIndexOutOfBoundsException error in main method

    - by Ro Siv
    I am obtaining a StringIndexOutOfBoundsError when running my main method. Here is the output of my program in the command line. "Please enter the shift, 1 for day, 2 for night" 1 "you entered a number for the shift" "Please enter the hourly pay Rate" 2 "you entered a number for the pay Rate" "Please enter the employees name" brenda "cat6b" "your value you entered is correct 0-9 or a - z" "Please enter the employee number" 100e "cat41" "your value you entered is correct 0-9 or a - z" "Please enter current date in XXYYZZZZ format, X is day, Y is month, Z is year" 10203933 "cat81 " "your value you entered is correct 0-9 or a - z" 90 1 valye of array is 1 81 0 value of array is 0 82 2 value of array is 2 83 0 value of array is 0 84 3 value of array is 3 85 9 value of array is 9 86 3 value of array is 3 87 3 value of array is 3 "Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 8 at java.lang.String.charAt(String.java:658) at ProductionWorker<init>(ProductionWorker.java:66) at labBookFiftyFour.main(labBookFiftyFour.java:58)" "Press any key to continue . . ." Ignore the cat parts in the code, i was using a println statement to test the code. Ignore the value of array output as well, as i wanted to use an array in the program later on. Here is my main method. import java.math.*; import java.text.DecimalFormat; import java.io.*; import java.util.*; public class labBookFiftyFour { public static void main(String[] args) { Scanner myInput = new Scanner(System.in); int shift = -1; double pRate = -2; String name = " "; String number = " "; String date = " "; while(shift < 0 || pRate < 0 ) { System.out.println("Please enter the shift, 1 for day, 2 for night"); if(myInput.hasNextInt()){ System.out.println("you entered a number for the shift"); shift = myInput.nextInt(); } System.out.println("Please enter the hourly pay Rate"); if(myInput.hasNextDouble()){ System.out.println("you entered a number for the pay Rate"); pRate = myInput.nextDouble(); } else if (myInput.hasNext()) { System.out.println("Please enter a proper value"); myInput.next(); } else { System.err.println("No more input"); System.exit(1); } } myInput.nextLine(); //consume newLine System.out.println("Please enter the employees name"); name = myInput.nextLine(); //use your isValid method if(isValid(name)) { System.out.println("your value you entered is correct 0-9 or a - z "); } System.out.println("Please enter the employee number"); number = myInput.nextLine(); //use your isValid method if(isValid(number)) { System.out.println("your value you entered is correct 0-9 or a - z "); } System.out.println("Please enter current date in XXYYZZZZ format, X is day, Y is month, Z is year"); date = myInput.nextLine(); //use your isValid method if(isValid(date)) { System.out.println("your value you entered is correct 0-9 or a - z "); } ProductionWorker myWorker = new ProductionWorker(shift, pRate, name, number, date); //int day and night , double payRate System.out.println("THis is the shift " + myWorker.getShift() + " This is the pay Rate " + myWorker.getPRate() + " " + myWorker.getName() + " " + myWorker.getNumber() + " " + myWorker.getDate()); } //Made this method for testing String input for 0-9 or a - z values , put AFTER main method, but before end of class public static boolean isValid(String stringName) //This method has to be static, for some reason? { System.out.println("cat" + stringName.length() + stringName.charAt(0)); boolean flag = true; int index = 0; while(index < stringName.length()) { if(Character.isLetterOrDigit(stringName.charAt(index))) { flag = true; } else { flag = false; } ++index; } return flag; } } Here is my employeeOne. java Superclass public class employeeOne { private String name; private String number; private String date; public employeeOne(String name, String number, String date) { this.name = name; this.number = number; this.date = date; } public String getName() { return name; } public String getNumber() { return number; } public String getDate() { return date; } } Here is my ProductionWorker.java subclass, which extends employeeOne public class ProductionWorker extends employeeOne { private int shift; //shift represents day or night, day = 1, night = 2 private double pRate; //hourly pay rate public ProductionWorker(int shift, double pRate, String name, String number, String date) { super(name, number, date); this.shift = shift; if(this.shift >= 3 || this.shift <= 0) { System.out.println("You entered an out of bounds shift date, enter 1 for day or 2 for night, else shift will be day"); this.shift = 1; } this.pRate = pRate; boolean goodSoFar = true; int indexNum = 0; int indexDate = 0; if(name.length() <= 10 && number.length() <= 4 && date.length() < 9 ) { goodSoFar = true; } else { goodSoFar = false; } while(goodSoFar && indexNum < 3) //XXXL XXX digits 1-9, L is a letter A -M { if(Character.isDigit(number.charAt(indexNum))) { goodSoFar = true; } else { goodSoFar = false; } ++indexNum; } while(goodSoFar && indexNum < 4) { if(Character.isLetter(number.charAt(indexNum))) { goodSoFar = true; } else if(Character.isDigit(number.charAt(indexNum))) { goodSoFar = false; } else if(Character.isDigit(number.charAt(indexNum)) == false && Character.isLetter(number.charAt(indexNum)) == false) { goodSoFar = false; } ++indexNum; } int[] dateValues = new int[date.length()]; while(goodSoFar && indexDate <= date.length()) //XXYYZZZZ { System.out.println("" + date.length() + indexDate + " " + date.charAt(indexDate)); if(Character.isDigit(date.charAt(indexDate))) { dateValues[indexDate] = Character.getNumericValue(date.charAt(indexDate)); System.out.println("value of array is " + dateValues[indexDate]); ++indexDate; } else { goodSoFar = false; } } if(goodSoFar) { System.out.println("your input is good so far"); } else { System.out.println("your input is wrong for name or number or date"); } } public int getShift() { return shift; } public double getPRate() { return pRate; } }

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