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• Hibernate+PostgreSQL throws JDBCConnectionException: Cannot open connection

  - by Omer Salmanoglu

  false true auto thread org.postgresql.Driver 1234 jdbc:postgresql://localhost/postgres postgres public org.hibernate.dialect.PostgreSQLDialect false true org.hibernate.transaction.JDBCTransactionFactory false false false false 100 When I press "Save" button I get the following exception: javax.servlet.ServletException: org.hibernate.exception.JDBCConnectionException: Cannot open connection javax.faces.webapp.FacesServlet.service(FacesServlet.java:325) root cause javax.faces.el.EvaluationException: org.hibernate.exception.JDBCConnectionException: Cannot open connection javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312) root cause org.hibernate.exception.JDBCConnectionException: Cannot open connection org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:98) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52) org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449) org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167) org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142) org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85) org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) $Proxy108.beginTransaction(Unknown Source) com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.apache.el.parser.AstValue.invoke(AstValue.java:196) org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276) com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98) javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312) root cause java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost/postgres java.sql.DriverManager.getConnection(Unknown Source) java.sql.DriverManager.getConnection(Unknown Source) org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133) org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446) org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167) org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142) org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85) org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) $Proxy108.beginTransaction(Unknown Source) com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.apache.el.parser.AstValue.invoke(AstValue.java:196) org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276) com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98) javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)

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• JSF HIBERNATE POSTGRESQL

  - by user312619

  When I press "Save" button I get an exception like that ; javax.servlet.ServletException: org.hibernate.exception.JDBCConnectionException: Cannot open connection javax.faces.webapp.FacesServlet.service(FacesServlet.java:325) root cause javax.faces.el.EvaluationException: org.hibernate.exception.JDBCConnectionException: Cannot open connection javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312) root cause org.hibernate.exception.JDBCConnectionException: Cannot open connection org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:98) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52) org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449) org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167) org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142) org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85) org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) $Proxy108.beginTransaction(Unknown Source) com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.apache.el.parser.AstValue.invoke(AstValue.java:196) org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276) com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98) javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312) root cause java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost/postgres java.sql.DriverManager.getConnection(Unknown Source) java.sql.DriverManager.getConnection(Unknown Source) org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133) org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446) org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167) org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142) org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85) org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) $Proxy108.beginTransaction(Unknown Source) com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) org.apache.el.parser.AstValue.invoke(AstValue.java:196) org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276) com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98) javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) javax.faces.component.UICommand.broadcast(UICommand.java:315) javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775) javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267) com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)

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• java.rmi.UnmarshalException: unable to pull client classes by server

  - by andrews

  Hi, I have an RMI client/server set-up on two machines that works fine in a simple situation when the server doesn't require a client-side defned class. However, when I need to use a class defined on the client side I am unable to have the server unmarshall those classes. I suspect this is an issue with my java.rmi.server.codebase property that I pass in as argument to the client app. I followed Sun's RMI Tutorial trail and I think I have followed the steps exactly except that I don't specify a classpath argument when executing client and server because they execute in the directory right above the root package directory (however I tried that too with no effect). The exceptions I get when attempting to execute the different client-side combinations described in detail below are all the same: RmiServer exception: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is: java.lang.ClassNotFoundException: test.MyTask at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:353) at sun.rmi.transport.Transport$1.run(Transport.java:177) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:173) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:553) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:808) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:667) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:636) at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255) at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233) at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:142) at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:178) at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:132) at $Proxy0.execute(Unknown Source) at test.myClient.main(myClient.java:32) The details are: My client/server rmi is set up over a home network behind a router. The router is assigned to a static ip address I will call myhostname. Appropriate port-mapping is set-up in the router that points to the right machines. role, machine, os, ip-address: server, venice, linux ubuntu 9.10, 10.0.1.2 client, naples, mac os x leopard, 10.0.1.4 I startup the server side as follows inside /home/andrews/workspace/epsilon/bin: 1 starting registry on the default port 1099: venice% rmiregistry & 2 starting web-server on port 2001 pointing to code base for common interfaces: venice% java webserver/ClassFileServer 2001 /home/andrew/workspace/epsilon/bin 3 starting server app (main class in test/myServer) which registers the server object: venice% java -Djava.rmi.server.codebase="http://myhostname:2001/" -Djava.security.policy=server.policy -Djava.rmi.server.hostname=myhostname test/myServer & Now the client side inside /Users/andrews/Development/Java/workspace/epsilon/bin: 1 start a local web server that can server client-side classes to the server (not sure if this is needed, but I added I tried it, and still no success; I have added port-mapping to the router for 2001 to venice, for 2002 to naples) naples$ java webserver/ClassFileServer 2002 /Users/andrews/Development/Java/workspace/epsilon/bin/ Trying to run the client (note: I don't specify the -cp argument because client executes right above the root package directory): 1 try #1 using an http hostname naples$ java -Djava.rmi.server.codebase=http://10.0.1.4:2002/ -Djava.security.policy=client.policy test.myClient myhostname Note 1: the myhostname argument at the end is passed-in to the client so that it resolves to server's rmi hostname. Note 2: I tried using localhost:2002 instead of 10.0.1.4:2002 too. Note 3: I tried using myhostname:2002 since myhostname is assigned to the router and I have proper port-mapping set-up, this address should resolve to naples and not venice 2 try #2: naples$ java -Djava.rmi.server.codebase=file:/Users/andrews/Development/Java/workspace/epsilon/bin/ -Djava.security.policy=client.policy test.myClient myhostname Note 1: the code base url format is correct, I created a small program to convert current file directory path into a url and used that. using file:///Users... has same effect. Other notes: 1 my server and client policy files correctly specify the path, as I've tested this setup with good and bad paths, and getting a security exception for bad path 2 this setup works if I don't use client-side defined objects, the client connects correctly to the server and the server executes. 3 when I place the client-side class on the server in the server's classpath, all executes fine. All help is appreciated.

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• Error in java code.

  - by user243680

  I am getting the following error when i try to use a blue tooth dongle to transfer a video file from pc to mobile phone. does anyone know run: BlueCove log redirected to log4j log4j:WARN No appenders could be found for logger (com.intel.bluetooth). log4j:WARN Please initialize the log4j system properly. BlueCove version 2.1.0 on bluesoleil java.io.IOException: Device not discovered BlueCove stack shutdown completed at com.intel.bluetooth.BluetoothStackBlueSoleil.connectionRfOpenClientConnection(BluetoothStackBlueSoleil.java:361) at com.intel.bluetooth.BluetoothRFCommClientConnection.<init>(BluetoothRFCommClientConnection.java:37) at com.intel.bluetooth.MicroeditionConnector.openImpl(MicroeditionConnector.java:379) at com.intel.bluetooth.MicroeditionConnector.open(MicroeditionConnector.java:162) at javax.microedition.io.Connector.open(Connector.java:83) at de.avetana.obexsolo.OBEXConnector.open(OBEXConnector.java:103) at OBEXTest.main(OBEXTest.java:23)

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• Java EE and JDK

  - by user269799

  I want to move from Java SE to Java EE. I will be using some of the sample projects that come with the Java EE. I have uninstalled the JDK but I think this may have been a mistake? When I download the latest Java EE (6), upon installation it asks me for the location of the JDK (which is uninstalled). I was under the impression that the JDK was specific to each version of Java i.e. SE or EE. Am I wrong here? I would have thought that when I download Java EE 6 that it was actually the EE JDK? Can anybody please clarify this for me? GF

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• Spring 3, Java EE 6

  - by arg20

  I'm learning Java EE 6. I've seen how much progress it has achieved in this release of the umbrella specification. EJBs 3.1 are far easier and more lightweight than previous versions, and CDI is amazing. I'm not familiar with Spring, but I often read that it offered some neat features that the Java EE stack didn't. Yet I also read now that JEE has caught up, and can now fully compete with Spring. I know that choosing from both depends on many factors, but if we only focus on features, say the latest trends etc. Which one has the leading edge?. Can Spring 3 offer some assets The JAVA EE 6 stack can't? Also, what about Seam framework? From what I read it's like java ee 6 but with some additions?

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• Boston: Free Java Developer Event March 3rd!

  - by Jacob Lehrbaum

  Attention Boston area developers!  Oracle has been running a series of free one-day Java Developer events in the US, Europe, and Asia since last November, and on March 3rd, this highly popular series is coming to the Westin Copley Place in Boston.  The Java Developer Day will include four tracks of sessions and hands-on-labs designed for developers interested in Server, Desktop, Embedded, and core Java SE platform topics.  Technologies covered include Java EE, Java ME and Java SE (including the JDK).  From the event page: Come to this free event if you are interested in:Evaluating the Java platformUsing other languages on the JVMBuilding server side JavaConstructing Rich Web or Desktop ApplicationsUnderstanding the JVM and its built in diagnosticsMaking Smart Devices even smarterCheck out the event page to read more and/or register.  The event is free, but space is limited so register today!

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• scalablity of Scala over Java

  - by Marcus

  I read an article that says Scala handles concurrency better than Java. http://www.theserverside.com/feature/Solving-the-Scalability-Paradox-with-Scala-Clojure-and-Groovy ...the scalability limitation is confined specifically to the Java programming language itself, but it is not a limitation of the Java platform as a whole... The scalability issues with Java aren't a new revelation. In fact, plenty of work has been done to address these very issues, with two of the most successful projects being the programming languages named Scala and Clojure... ...Scala is finding ways around the problematic thread and locking paradigm of the Java language... How is this possible? Doesn't Scala use Java's core libraries which brings all the threading and locking issues from Java to Scala?

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• Java - learning / migrating fast

  - by Yippie-Kai-Yay

  This is not one of those questions like "How do I learn Java extremely fast, I know nothing about programming, but I heard Java is cool, yo". I have an interview for a Java Software Developer in a couple of weeks and the thing is that I think that I know C++ really good and I am somewhat good at C# (like, here I can probably answer on a lot of questions related to these languages), but I have almost zero experience with Java. I have a lot of projects written in both languages, I participiated in several open-source projects (mostly C++, though). Now, what should I do (in your opinion) to prepare myself for this Java interview. I guess migrating from C# to Java should be kind of fast, especially when you know a lot about programming in global, patterns, modern techniques and have a lot of practical experience behind you. But still two weeks is obviously not enough to get Java in-depth - so what should I focus on to have the best chances to pass the interview? Thank you.

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• Java - learning / migrating fast

  - by Yippie-Kai-Yay

  Hello! This is not one of those questions like "How do I learn Java extremely fast, I know nothing about programming, but I heard Java is cool, yo". I have an interview for a Java Software Developer in a couple of weeks and the thing is that I think that I know C++ really good and I am somewhat good at C# (like, here I can probably answer on a lot of questions related to these languages), but I have almost zero experience with Java. I have a lot of projects written in both languages, I participiated in several open-source projects (mostly C++, though). Now, what should I do (in your opinion) to prepare myself for this Java interview. I guess migrating from C# to Java should be kind of fast, especially when you know a lot about programming in global, patterns, modern techniques and have a lot of practical experience behind you. But still two weeks is obviously not enough to get Java in-depth - so what should I focus on to have the best chances to pass the interview? Thank you.

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• Maker Faire 2012 Attendees build with Java Technology

  - by hinkmond

  Looks like Daniel Green, systems engineer from Oracle, and the panel of Java experts had a successful Java Technology booth at this year's Maker Faire 2012. See: Maker Faire 2012 adds Java Here's a quote: "We made a huge impact for Java and Oracle, creating positive perception, building brand awareness, and introducing fun and engaging ways for future technologists to learn Java programming," says Michelle Kovac, Oracle director, Java Marketing and Operations. Good stuff, considering all the future developers of exploding robots and fire-breathing dragon metal sculptures attend the Maker Faire. They can blow up stuff with Java technology just as effectively as other programming languages. Hinkmond

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• Java Plugin - Firefox

  - by Tomassino

  Having trouble getting Java to work with Firefox (22), I have followed the advice in this question and on the official Java site, but nothing seems to work. I have the latest Java (1.7.0_25) in /opt/java and have set a symlink in /usr/libs/mozilla/plugins for the libnpjp2.so file. I can see the file in the terminal and Java runs fine. However Firefox shows nothing in about:plugins. I have also run export JAVA_HOME="/opt/java/jre1.7.0_05/bin/java" to be on the safe side. I know there are multiple plugin directories such as /usr/lib/firefox/plugins and /usr/lib/firefox-addons/plugins, but all my current plugins show they are located in /usr/lib/mozilla/plugins when viewing the about:plugins page. A bit stuck on where to go next?

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• Understanding the Java Ecosystem

  - by syrion

  I have traditionally had the "luxury" of being a one-man development team. I've used Python extensively, have a reasonable command of Perl, PHP, and JavaScript. My problem is Java. I can write Java code. I'm not great at it--unlike Python, I rarely make use of anything unique to Java when I'm writing it. Furthermore, my experience is mostly in simple GUI/console programming. Unfortunately, I'm currently pursuing an IT degree where Java is the lingua franca. My database class is requiring that our projects be written in Java using servlets, and I just can't wrap my head around the ecosystem. Is there a good online overview of or tutorial on how the Java web ecosystem works? I have Thinking in Java, but it's mostly just the language itself (which I understand well enough to get by). I have looked at the Sun servlet tutorial, but it seems outdated.

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• Active - like-minded Java mailing lists

  - by Lewis Robbins

  I need to find an active Java mailing list, I have looked onto the GNU Java mailing list, to my surprise there had been not too much activity this month, it also focused on any GNU related Java - I'd really help me progress my Java ability, if I had an active, likeminded Java mailing list. Questions' that are not suited to Stackoverflow, or provide little benefit to any user that see's the question: discussing a new API change; best practices; open source discussion; trivia type questions on Java ArrayList boxining-unboxing; Community atmosphere. I also read Jon Skeets blog post about his previous Java/C# mailing lists examples - I did not catch any names, though I did they would be of benefit to me, if I had access to any of them.

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• how to learn Java

  - by Sarang

  This question I am asking because I couldn't find any source which gives complete overview of java development. I just want to know where java technology currently in market & what is preferable for development ! Java always remain top programming language for development point of view. However, java is combo of, j2ee, j2me, jsp, jsf, spring, other frameworks, ui components, jndi, networking tools and various other "J" are there ! However, learning java is definitely dependent on the development requirement, but still, to be a well-experienced java developer, what is the organised way of learning java? What is preferable in current technology ? and what is deprecated, currently ?

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• New Java Tutorials Updated

  - by hinkmond

  The new Java Tutorials are here! The new Java Tutorials are here! So what? So, you can read them on your iPad thingie--if that's how you roll, that is... See: Read New Java Tutorials Here's a quote: What's New The Java Tutorials are continuously updated to keep up with changes to the Java Platform and to incorporate feedback from our readers. Recent updates include the following features: The Generics lesson has been completely reworked... The Java Tutorials are now available in two ebook formats: mobi ebook files for Kindle. ePub ebook files for iPad, Nook, and other eReaders that support the ePub format. Just kick back, open up your favorite tablet or eReader and learn all about the new things in the Java platform. Nice. All you need now is a cool drink and you're all set! Hinkmond

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• New to Java Programming - Error help

  - by JJJ

  I am going through a Java book and drafting the examples and have run into the following error when compiling this code. Any help would be appreciated thank you. Error: Main.java:3: class Addition is public, should be declared in a file named Addition.java public class Addition        ^ 1 error Code: import java.io.*; import java.util.Scanner; public class Addition {   public static void main(String[] args) { java.util.Scanner input = new java.util.Scanner(System.in);  int number1; int number2; int sum; System.out.print( "Enter first digit: " ); number1 = input.nextInt(); System.out.print( "Enter second digit:" ); number2 = input.nextInt(); sum = number1 + number2; System.out.printf( "Sum is %d\n, sum" );      } }

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• Java RMI (Server: TCP Connection Idle/Client: Unmarshalexception (EOFException))

  - by Perry Dahl Christensen

  I'm trying to implement Sun Tutorials RMI application that calculates Pi. I'm having some serious problems and I cant find the solution eventhough I've been searching the entire web and several javaskilled people. I'm hoping you can put an end to my frustrations. The crazy thing is that I can run the application from the cmd on my desktop computer. Trying the exact same thing with the exact same code in the exact same directories on my laptop produces the following errors. The problem occures when I try to connect the client to the server. I don't believe that the error is due to my policyfile as I can run it on the desktop. It must be elsewhere. Have anyone tried the same and can you give me a hint as to where my problem is, please? POLICYFILE SERVER: grant { permission java.security.AllPermissions; permission java.net.SocketPermission"*", "connect, resolve"; }; POLICYFILE CLIENT: grant { permission java.security.AllPermissions; permission java.net.SocketPermission"*", "connect, resolve"; }; SERVERSIDE ERRORS: Microsoft Windows XP [Version 5.1.2600] (C) Copyright 1985-2001 Microsoft Corp. C:\Documents and Settings\STUDENTcd\ C:start rmiregistry C:java -cp c:\java;c:\java\compute.jar -Djava.rmi.server.codebase=file:/c:/jav a/compute.jar -Djava.rmi.server.hostname=localhost -Djava.security.policy=c:/jav a/servertest.policy engine.ComputeEngine ComputeEngine bound Exception in thread "RMI TCP Connection(idle)" java.security.AccessControlExcept ion: access denied (java.net.SocketPermission 127.0.0.1:1440 accept,resolve) at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at java.lang.SecurityManager.checkAccept(Unknown Source) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.checkAcceptPermi ssion(Unknown Source) at sun.rmi.transport.tcp.TCPTransport.checkAcceptPermission(Unknown Sour ce) at sun.rmi.transport.Transport$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Unknown Source) at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Sou rce) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Sour ce) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source ) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) CLIENTSIDE ERRORS: Microsoft Windows XP [Version 5.1.2600] (C) Copyright 1985-2001 Microsoft Corp. C:\Documents and Settings\STUDENTcd\ C:java -cp c:\java;c:\java\compute.jar -Djava.rmi.server.codebase=file:\C:\jav a\files\ -Djava.security.policy=c:/java/clienttest.policy client.ComputePi local host 45 ComputePi exception: java.rmi.UnmarshalException: Error unmarshaling return header; nested exception is: java.io.EOFException at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source) at sun.rmi.server.UnicastRef.invoke(Unknown Source) at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unkn own Source) at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source) at $Proxy0.executeTask(Unknown Source) at client.ComputePi.main(ComputePi.java:18) Caused by: java.io.EOFException at java.io.DataInputStream.readByte(Unknown Source) ... 6 more C: Thanks in advance Perry

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• java.sql.SQLWarning: [Microsoft][SQLServer 2000 Driver for JDBC]Database changed to X

  - by adisembiring

  Hi all, I'm using Hibernate 3.2.1 and database SQLServer2000 while I'm try to insert some data using my dao, some warning occurred like this: java.sql.SQLWarning: [Microsoft][SQLServer 2000 Driver for JDBC]Database changed to BTN_SPP_DB at com.microsoft.jdbc.base.BaseWarnings.createSQLWarning(Unknown Source) at com.microsoft.jdbc.base.BaseWarnings.get(Unknown Source) at com.microsoft.jdbc.base.BaseConnection.getWarnings(Unknown Source) at org.hibernate.util.JDBCExceptionReporter.logAndClearWarnings(JDBCExceptionReporter.java:22) at org.hibernate.jdbc.ConnectionManager.closeConnection(ConnectionManager.java:443) at org.hibernate.jdbc.ConnectionManager.aggressiveRelease(ConnectionManager.java:400) at org.hibernate.jdbc.ConnectionManager.afterTransaction(ConnectionManager.java:287) at org.hibernate.jdbc.JDBCContext.afterTransactionCompletion(JDBCContext.java:221) at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:119) at co.id.hanoman.btnmw.spp.dao.TagihanDao.save(TagihanDao.java:43) at co.id.hanoman.btnmw.spp.dao.TagihanDao.save(TagihanDao.java:1) at co.id.hanoman.btnmw.spp.dao.test.TagihanDaoTest.testSave(TagihanDaoTest.java:81) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.junit.internal.runners.TestMethodRunner.executeMethodBody(TestMethodRunner.java:99) at org.junit.internal.runners.TestMethodRunner.runUnprotected(TestMethodRunner.java:81) at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34) at org.junit.internal.runners.TestMethodRunner.runMethod(TestMethodRunner.java:75) at org.junit.internal.runners.TestMethodRunner.run(TestMethodRunner.java:45) at org.junit.internal.runners.TestClassMethodsRunner.invokeTestMethod(TestClassMethodsRunner.java:66) at org.junit.internal.runners.TestClassMethodsRunner.run(TestClassMethodsRunner.java:35) at org.junit.internal.runners.TestClassRunner$1.runUnprotected(TestClassRunner.java:42) at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34) at org.junit.internal.runners.TestClassRunner.run(TestClassRunner.java:52) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:45) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196) my hibernate initialization log is: 2010-04-26 22:54:05,203 INFO [Version] Hibernate Annotations 3.3.0.GA 2010-04-26 22:54:05,234 INFO [Environment] Hibernate 3.2.1 2010-04-26 22:54:05,234 INFO [Environment] hibernate.properties not found 2010-04-26 22:54:05,234 INFO [Environment] Bytecode provider name : cglib 2010-04-26 22:54:05,234 INFO [Environment] using JDK 1.4 java.sql.Timestamp handling 2010-04-26 22:54:05,343 INFO [Configuration] configuring from resource: /hibernate.cfg.xml 2010-04-26 22:54:05,343 INFO [Configuration] Configuration resource: /hibernate.cfg.xml 2010-04-26 22:54:05,406 DEBUG [DTDEntityResolver] trying to resolve system-id [http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd] 2010-04-26 22:54:05,406 DEBUG [DTDEntityResolver] recognized hibernate namespace; attempting to resolve on classpath under org/hibernate/ 2010-04-26 22:54:05,406 DEBUG [DTDEntityResolver] located [http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd] in classpath 2010-04-26 22:54:05,453 DEBUG [Configuration] hibernate.dialect=org.hibernate.dialect.SQLServerDialect 2010-04-26 22:54:05,453 DEBUG [Configuration] hibernate.connection.driver_class=com.microsoft.jdbc.sqlserver.SQLServerDriver 2010-04-26 22:54:05,453 DEBUG [Configuration] hibernate.connection.url=jdbc:microsoft:sqlserver://12.56.11.65:1433;databaseName=BTN_SPP_DB 2010-04-26 22:54:05,453 DEBUG [Configuration] hibernate.connection.username=spp 2010-04-26 22:54:05,453 DEBUG [Configuration] hibernate.connection.password=spp

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• JCP.Next - Early Adopters of JCP 2.8

  - by Heather VanCura

  JCP.Next is a series of three JSRs (JSR 348, JSR 355 and JSR 358), to be defined through the JCP process itself, with the JCP Executive Committee serving as the Expert Group. The proposed JSRs will modify the JCP's processes  - the Process Document and Java Specification Participation Agreement (JSPA) and will apply to all new JSRs for all Java platforms.   The first - JCP.next.1, or more formally JSR 348, Towards a new version of the Java Community Process - was completed and put into effect in October 2011 as JCP 2.8. This focused on a small number of simple but important changes to make our process more transparent and to enable broader participation. We're already seeing the benefits of these changes as new and existing JSRs adopt the new requirements. The second - JSR 355, Executive Committee Merge, is also Final. You can read the JCP 2.9 Process Document .  As part of the JSR 355 Final Release, the JCP Executive Committee published revisions to the JCP Process Document (version 2.9) and the EC Standing Rules (version 2.2).  The changes went into effect following the 2012 EC Elections in November. The third JSR 358, A major revision of the Java Community Process was submitted in June 2012.  This JSR will modify the Java Specification Participation Agreement (JSPA) as well as the Process Document, and will tackle a large number of complex issues, many of them postponed from JSR 348. For these reasons, the JCP EC (acting as the Expert Group for this JSR), expects to spend a considerable amount of time working on. The JSPA is defined by the JCP as "a one-year, renewable agreement between the Member and Oracle. The success of the Java community depends upon an open and transparent JCP program.  JSR 358, A major revision of the Java Community Process, is now in process and can be followed on java.net. The following JSRs and Spec Leads were the early adopters of JCP 2.8, who voluntarily migrated their JSRs from JCP 2.x to JCP 2.8 or above.  More candidates for 2012 JCP Star Spec Leads! JSR 236, Concurrency Utilities for Java EE (Anthony Lai/Oracle), migrated April 2012 JSR 308, Annotations on Java Types (Michael Ernst, Alex Buckley/Oracle), migrated September 2012 JSR 335, Lambda Expressions for the Java Programming Language (Brian Goetz/Oracle), migrated October 2012 JSR 337, Java SE 8 Release Contents (Mark Reinhold/Oracle) – EG Formation, migrated September 2012 JSR 338, Java Persistence 2.1 (Linda DeMichiel/Oracle), migrated January 2012 JSR 339, JAX-RS 2.0: The Java API for RESTful Web Services (Santiago Pericas-Geertsen, Marek Potociar/Oracle), migrated July 2012 JSR 340, Java Servlet 3.1 Specification (Shing Wai Chan, Rajiv Mordani/Oracle), migrated August 2012 JSR 341, Expression Language 3.0 (Kin-man Chung/Oracle), migrated August 2012 JSR 343, Java Message Service 2.0 (Nigel Deakin/Oracle), migrated March 2012 JSR 344, JavaServer Faces 2.2 (Ed Burns/Oracle), migrated September 2012 JSR 345, Enterprise JavaBeans 3.2 (Marina Vatkina/Oracle), migrated February 2012 JSR 346, Contexts and Dependency Injection for Java EE 1.1 (Pete Muir/RedHat) – migrated December 2011

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• Read next word in java

  - by ArtWorkAD

  Hi, I have a text file that has following content: ac und accipio annehmen ad zu adeo hinzugehen ... I read the text file and iterate through the lines: Scanner sc = new Scanner(new File("translate.txt")); while(sc.hasNext()){ String line = sc.nextLine(); } Each line has two words. Is there any method in java to get the next word or do I have to split the line string to get the words?

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

  - by Janice J. Heiss

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

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

  - by Janice J. Heiss

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

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• Java Spotlight Episode 109: Pete Muir on CDI 1.1 @plmuir

  - by Roger Brinkley

  Interview with Pete Muir of Red Hat on CDI 1.1. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News Getting started with Java Embedded Videos CDI 1.1 Public Review and Feedback Events Nov 20, JCP Public Meeting (see details below) Nov 20-22, DOAG 2012, Nuremberg, Germany Dec 3-5, jDays, Göteborg, Sweden Dec 4-6, JavaOne Latin America, Sao Paolo, Brazil Dec 14-15, IndicThreads, Pune, India Feature InterviewPete Muir is leading the CDI 1.1 specification, and work on JBoss Developer Framework, a set of tutorials and examples for all JBoss users. Previously, Pete has worked on Infinispan and I led the Seam and Weld projects, and is a founder of the Arquillian project. Pete has worked on a number of specifications including JSF 2.0, AtInject and Java EE 7. Pete is a regular speaker at JUGs and conferences such as JavaOne, Devoxx, JAX, JavaBlend, JSFDays, JBoss World, Red Hat Developer Day and JUDCon.Pete is currently employed by Red Hat Inc. working on JBoss open source projects. Before working for Red Hat, Pete used and contributed to Seam whilst working at a UK based staffing agency as IT Development Manager.

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• Java EE 6: How to get module name and app name

  - by user12798506

  Java EE 6??????????????????????????????????????????????? ???????????????[1] ?????????????JNDI???????????????????"java:module/ModuleName"?????? ?????"java:app/AppName"???????? InitialContext ctx = new InitialContext(); String moduleName = ctx.lookup("java:module/ModuleName"); // ?????? String appName = ctx.lookup("java:app/AppName"); // ????????? ???@Resource?????????????????????????????????????????? @Resource(lookup="java:module/ModuleName") String moduleName; // ?????????????????? @Resource(lookup="java:app/AppName") String appName; // ????????????????????? ???EAR???????Web????????EJB??????????????????AppName???????????????? ?????????GlassFish V3 (3.1.2.2)?WebLogic 12c (12.1.1)?JBoss AS 7 (7.1.1)?????????? ????????????????AppName???ModuleName??????????????? ?????????Web Profile??????????????????(GlassFish?JBoss?????Web Profile ?????)?????Apache TomEE (1.5.0)????????ModuleName???"localhost/<Web?????? >"?????????????????????????????????????? Java EE 6??????????????????????????????????????????????? ??????????????????????????????????????????????????? ???????????????????????????????????????????????????? ???????? ???Apache Tomcat 7.0?Servlet 3.0??????????????????????????????·??? ???????JNDI???????????????????????? ??:?Tomcat????????Java EE?????????????????????? [1] Java EE 6????(JSR 316)????????????? (pp.122-123): EE.5.15 Application Name and Module Name References A component may access the name of the current application using the pre-defined JNDI name java:app/AppName. A component may access the name of the current module using the pre-defined JNDI name java:module/ModuleName. Both of these names are represented by String objects.

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