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• hudson.util.ProcessTreeTest test error

  - by senzacionale

  error: Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.011 sec Running hudson.util.ProcessTreeTest Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.181 sec <<< FAILURE! Running hudson.model.LoadStatisticsTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.089 sec Running hudson.util.ArgumentListBuilderTest Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.053 sec Running hudson.util.RobustReflectionConverterTest Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 sec Running hudson.util.VersionNumberTest Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.074 sec Running hudson.util.CyclicGraphDetectorTest Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.038 sec Results : Tests in error: testRemoting(hudson.util.ProcessTreeTest) Tests run: 102, Failures: 0, Errors: 1, Skipped: 0 [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] There are test failures. Please refer to D:\PROJEKTI\Maven\hudson\main\core\target\surefire-reports for the individual test results. [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 17 minutes 58 seconds [INFO] Finished at: Fri Jun 11 21:04:46 CEST 2010 [INFO] Final Memory: 85M/152M [INFO] ------------------------------------------------------------------------ error log: ------------------------------------------------------------------------------- Test set: hudson.util.ProcessTreeTest ------------------------------------------------------------------------------- Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.181 sec <<< FAILURE! testRemoting(hudson.util.ProcessTreeTest) Time elapsed: 0.169 sec <<< ERROR! org.jvnet.winp.WinpException: Failed to read environment variable table error=299 at .\envvar-cmdline.cpp:114 at org.jvnet.winp.Native.getCmdLineAndEnvVars(Native Method) at org.jvnet.winp.WinProcess.parseCmdLineAndEnvVars(WinProcess.java:114) at org.jvnet.winp.WinProcess.getEnvironmentVariables(WinProcess.java:109) at hudson.util.ProcessTree$Windows$1.getEnvironmentVariables(ProcessTree.java:419) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:274) at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:255) at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:215) at hudson.remoting.UserRequest.perform(UserRequest.java:114) at hudson.remoting.UserRequest.perform(UserRequest.java:48) at hudson.remoting.Request$2.run(Request.java:270) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) does anyone have any idea what can be wrong in test? Regards

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• Tab Sweep: HTML5 Attributes, MDB, JasperReports, Delphi, Security, JDBCRealm, Joomla, ...

  - by arungupta

  Recent Tips and News on Java, Java EE 6, GlassFish & more : • JMS and MDB in Glassfish for 20 minutes (nik_code) • Installing Java EE 6 SDK with Glassfish on a headless system (jvmhost) • JSF + JPA + JasperReports (iReport) Part 2 (Rama krishnnan E P) • Serving Static Content on WebLogic and GlassFish (cdivilly) • Whats the problem with JSF? A rant on wrong marketing arguments (Über Thomas Asel) • JPA 2.1 will support CDI Injection in EntityListener - in Java EE 7 (Craig Ringer) • Java Delphi integration with Glassfish JMS OpenMQ (J4SOFT) • Java EE Security using JDBCRealm Part1 (acoustic091409) • Adding HTML5 attributes to standard JSF components (Bauke Scholtz) • Configuring SAS 9.1 to Use Java 5 or above on Windows (Java EE Tips) • Inject Java Properties in Java EE Using CDI (Piotr Nowicki) • NoClassDefFoundError in Java EE Applications - Part 2 (Java Code Geeks) • NoClassDefFoundError in Java EE Applications - Part 1 (Java Code Geeks) • EJB 3 application in Glassfish 3x (Anirban Chowdhury) • How To Install Mobile Server 11G With GlassFish Server 3.1 (Oracle Support) • Joomla on GlassFish (Survivant)

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• Did Oracle make public any plans to charge for JDK in the near future? [closed]

  - by Eduard Florinescu

  I recently read an article: Twelve Disaster Scenarios Which Could Damage the Technology Industry which mentioned among other the possible "disaster scenarios" also: Oracle starts charging for the JDK, giving the following as argument: Oracle could start requiring license fees for the JDK from everyone but desktop users who haven't uninstalled the Java plug-in for some reason. This would burn down half the Java server-side market, but allow Oracle to fully monetize its acquisitions and investments. [...] Oracle tends to destroy markets to create products it can fully monetize. Even if you're not a Java developer, this would have a ripple effect throughout the market. [...] I actually haven't figured out why Larry hasn't decided Java should go this route yet. Some version of this scenario is actually in my company's statement of risks. I know guessing for the future is impossible, and speculating about that would be endless so I will try to frame my question in an objective answarable way: Did Oracle or someone from Oracle under anonymity, make public, or hinted, leaked to the public such a possibility or the above is plain journalistic speculation? I am unable to find the answer myself with Google generating a lot of noise by searching JDK.

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• Eclipse DemoCamp, June 13, Redwood Shores, CA

  - by Tori Wieldt

  Oracle is hosting an Eclipse DemoCamp next week, Wednesday, June 13, in Redwood Shores, CA (@Oracle HQ) from 6pm - 9pm. Come view presentations from folks who are developing exciting technologies for the Eclipse platform and network with your colleagues and peers over beer and pizza.  The evening have a nice mix of technology and vendors.  The following presenters are currently scheduled : The evolution of Java persistence, Doug Clarke, EclipseLink Project Lead, Oracle Integrating BIRT into Applications, Ashwini Verma, Actuate Corporation Developing Rich ADF Applications with Java EE, Greg Stachnick, Oracle Leveraging OSGi In The Enterprise, Kamal Muralidharan, Lead Engineer, eBay NVIDIA® Nsight™ Eclipse Edition, Goodwin (Tech lead - Visual tools), Eugene Ostroukhov (Senior engineer – Visual tools) Did we mention beer and pizza? Learn more.  Register now!

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• Accessing a Web Service: Learning Resource needed

  - by abel

  I have been searching for resources to learn (Java) Web Services. Although I have found a lot of resources and tutorials on JWS, I am confused with the version numbers, the abbreviations and Metro. Plus the last update to Metro was in 2008. Is it a worthwile thing to learn? I wanted to learn how to access Web Services, since an upcoming project is about accessing one. I have some experience with OAuth on Twitter(using code available). Things I know about the project: I have to access a Web Service. Java is the preferred platform to use(Although I know I can use any). Axis can be used to access the Web Service(I have never used Axis) I have a meeting scheduled to learn more, but I sure don't want to look silly since I am no Java expert, have never created or accessed Web Services using Java. My Questions: 1.Can someone point me to a tutorial which will help me learn how to access a already running Web Service (Preferably SOAP(?), not REST. It's XML based) 2. Will you recommend using PHP or Python to do the work of accessing the web service? I am expecting a lot of nay saying, but I hope I get some answers too. I will clarify things if needed.

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• Performance triage

  - by Dave

  Folks often ask me how to approach a suspected performance issue. My personal strategy is informed by the fact that I work on concurrency issues. (When you have a hammer everything looks like a nail, but I'll try to keep this general). A good starting point is to ask yourself if the observed performance matches your expectations. Expectations might be derived from known system performance limits, prototypes, and other software or environments that are comparable to your particular system-under-test. Some simple comparisons and microbenchmarks can be useful at this stage. It's also useful to write some very simple programs to validate some of the reported or expected system limits. Can that disk controller really tolerate and sustain 500 reads per second? To reduce the number of confounding factors it's better to try to answer that question with a very simple targeted program. And finally, nothing beats having familiarity with the technologies that underlying your particular layer. On the topic of confounding factors, as our technology stacks become deeper and less transparent, we often find our own technology working against us in some unexpected way to choke performance rather than simply running into some fundamental system limit. A good example is the warm-up time needed by just-in-time compilers in Java Virtual Machines. I won't delve too far into that particular hole except to say that it's rare to find good benchmarks and methodology for java code. Another example is power management on x86. Power management is great, but it can take a while for the CPUs to throttle up from low(er) frequencies to full throttle. And while I love "turbo" mode, it makes benchmarking applications with multiple threads a chore as you have to remember to turn it off and then back on otherwise short single-threaded runs may look abnormally fast compared to runs with higher thread counts. In general for performance characterization I disable turbo mode and fix the power governor at "performance" state. Another source of complexity is the scheduler, which I've discussed in prior blog entries. Lets say I have a running application and I want to better understand its behavior and performance. We'll presume it's warmed up, is under load, and is an execution mode representative of what we think the norm would be. It should be in steady-state, if a steady-state mode even exists. On Solaris the very first thing I'll do is take a set of "pstack" samples. Pstack briefly stops the process and walks each of the stacks, reporting symbolic information (if available) for each frame. For Java, pstack has been augmented to understand java frames, and even report inlining. A few pstack samples can provide powerful insight into what's actually going on inside the program. You'll be able to see calling patterns, which threads are blocked on what system calls or synchronization constructs, memory allocation, etc. If your code is CPU-bound then you'll get a good sense where the cycles are being spent. (I should caution that normal C/C++ inlining can diffuse an otherwise "hot" method into other methods. This is a rare instance where pstack sampling might not immediately point to the key problem). At this point you'll need to reconcile what you're seeing with pstack and your mental model of what you think the program should be doing. They're often rather different. And generally if there's a key performance issue, you'll spot it with a moderate number of samples. I'll also use OS-level observability tools to lock for the existence of bottlenecks where threads contend for locks; other situations where threads are blocked; and the distribution of threads over the system. On Solaris some good tools are mpstat and too a lesser degree, vmstat. Try running "mpstat -a 5" in one window while the application program runs concurrently. One key measure is the voluntary context switch rate "vctx" or "csw" which reflects threads descheduling themselves. It's also good to look at the user; system; and idle CPU percentages. This can give a broad but useful understanding if your threads are mostly parked or mostly running. For instance if your program makes heavy use of malloc/free, then it might be the case you're contending on the central malloc lock in the default allocator. In that case you'd see malloc calling lock in the stack traces, observe a high csw/vctx rate as threads block for the malloc lock, and your "usr" time would be less than expected. Solaris dtrace is a wonderful and invaluable performance tool as well, but in a sense you have to frame and articulate a meaningful and specific question to get a useful answer, so I tend not to use it for first-order screening of problems. It's also most effective for OS and software-level performance issues as opposed to HW-level issues. For that reason I recommend mpstat & pstack as my the 1st step in performance triage. If some other OS-level issue is evident then it's good to switch to dtrace to drill more deeply into the problem. Only after I've ruled out OS-level issues do I switch to using hardware performance counters to look for architectural impediments.

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• Rainbows and Unicorns at the Devoxx OTN Hack Fest

  - by Tori Wieldt

  At the OTN Hack Fest at Devoxx, several developers did their first "hello world" with the Internet of Things (IoT). They had fun and built basic applications with Java Embedded, Raspberry Pi and Leap Motion controllers. Experts Yara & Vinicius Senger and Geert Bevin provided the basics and support. Geert Bevin did a bit of hacking too. Check out this video to see what he came up with a short amount of time: &amp;amp;amp;amp;lt;span id=&amp;amp;amp;amp;quot;XinhaEditingPostion&amp;amp;amp;amp;quot;&amp;amp;amp;amp;gt;&amp;amp;amp;amp;lt;/span&amp;amp;amp;amp;gt; Learn more about Java Embedded at the Oracle Technology Network. 

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• Stepping outside Visual Studio IDE [Part 1 of 2] with Eclipse

  - by mbcrump

  “If you're walking down the right path and you're willing to keep walking, eventually you'll make progress." – Barack Obama In my quest to become a better programmer, I’ve decided to start the process of learning Java. I will be primary using the Eclipse Language IDE. I will not bore you with the history just what is needed for a .NET developer to get up and running. I will provide links, screenshots and a few brief code tutorials. Links to documentation. The Official Eclipse FAQ’s Links to binaries. Eclipse IDE for Java EE Developers the Galileo Package (based on Eclipse 3.5 SR2)  Sun Developer Network – Java Eclipse officially recommends Java version 5 (also known as 1.5), although many Eclipse users use the newer version 6 (1.6). That's it, nothing more is required except to compile and run java. Installation Unzip the Eclipse IDE for Java EE Developers and double click the file named Eclipse.exe. You will probably want to create a link for it on your desktop. Once, it’s installed and launched you will have to select a workspace. Just accept the defaults and you will see the following: Lets go ahead and write a simple program. To write a "Hello World" program follow these steps: Start Eclipse. Create a new Java Project: File->New->Project. Select "Java" in the category list. Select "Java Project" in the project list. Click "Next". Enter a project name into the Project name field, for example, "HW Project". Click "Finish" Allow it to open the Java perspective Create a new Java class: Click the "Create a Java Class" button in the toolbar. (This is the icon below "Run" and "Window" with a tooltip that says "New Java Class.") Enter "HW" into the Name field. Click the checkbox indicating that you would like Eclipse to create a "public static void main(String[] args)" method. Click "Finish". A Java editor for HW.java will open. In the main method enter the following line.      System.out.println("This is my first java program and btw Hello World"); Save using ctrl-s. This automatically compiles HW.java. Click the "Run" button in the toolbar (looks like a VCR play button). You will be prompted to create a Launch configuration. Select "Java Application" and click "New". Click "Run" to run the Hello World program. The console will open and display "This is my first java program and btw Hello World". You now have your first java program, lets go ahead and make an applet. Since you already have the HW.java open, click inside the window and remove all code. Now copy/paste the following code snippet. Java Code Snippet for an applet. 1: import java.applet.Applet; 2: import java.awt.Graphics; 3: import java.awt.Color; 4:  5: @SuppressWarnings("serial") 6: public class HelloWorld extends Applet{ 7:  8: String text = "I'm a simple applet"; 9:  10: public void init() { 11: text = "I'm a simple applet"; 12: setBackground(Color.GREEN); 13: } 14:  15: public void start() { 16: System.out.println("starting..."); 17: } 18:  19: public void stop() { 20: System.out.println("stopping..."); 21: } 22:  23: public void destroy() { 24: System.out.println("preparing to unload..."); 25: } 26:  27: public void paint(Graphics g){ 28: System.out.println("Paint"); 29: g.setColor(Color.blue); 30: g.drawRect(0, 0, 31: getSize().width -1, 32: getSize().height -1); 33: g.setColor(Color.black); 34: g.drawString(text, 15, 25); 35: } 36: } The Eclipse IDE should look like Click "Run" to run the Hello World applet. Now, lets test our new java applet. So, navigate over to your workspace for example: “C:\Users\mbcrump\workspace\HW Project\bin” and you should see 2 files. HW.class java.policy.applet Create a HTML page with the following code: 1: <HTML> 2: <BODY> 3: <APPLET CODE=HW.class WIDTH=200 HEIGHT=100> 4: </APPLET> 5: </BODY> 6: </HTML> Open, the HTML page in Firefox or IE and you will see your applet running.  I hope this brief look at the Eclipse IDE helps someone get acquainted with Java Development. Even if your full time gig is with .NET, it will not hurt to have another language in your tool belt. As always, I welcome any suggestions or comments.

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• spring annotation configuration issue

  - by shrimpy

  I don't know why spring 2.5.6 keeps complaining, but I don't have any "orderBy" annotation. 2009-10-10 13:55:37.242::WARN: Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.context.annotation.internalPersiste nceAnnotationProcessor': Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'order' of bean class [org.springfra mework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor]: Bean property 'order' is not writable or has an invalid setter method. Does the parameter type of the setter match the re turn type of the getter?: org.springframework.beans.NotWritablePropertyException: Invalid property 'order' of bean class [org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor]: Bean propert y 'order' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter? at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:801) at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:651) at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:78) at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:59) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1276) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1010) or even when I swap to use lower version spring 2.5.1, it's still complaining: 2009-10-10 13:57:56.062::WARN: failed ContextHandlerCollection@5da0b94d java.lang.NoClassDefFoundError: org/springframework/context/support/AbstractRefreshableConfigApplicationContext at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:621) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at java.net.URLClassLoader.defineClass(URLClassLoader.java:260) at java.net.URLClassLoader.access$000(URLClassLoader.java:56) at java.net.URLClassLoader$1.run(URLClassLoader.java:195) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:366) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:337) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:621) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at java.net.URLClassLoader.defineClass(URLClassLoader.java:260) at java.net.URLClassLoader.access$000(URLClassLoader.java:56) at java.net.URLClassLoader$1.run(URLClassLoader.java:195) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:366) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:337) at org.springframework.util.ClassUtils.forName(ClassUtils.java:230) at org.springframework.util.ClassUtils.forName(ClassUtils.java:183) at org.springframework.web.context.ContextLoader.determineContextClass(ContextLoader.java:283) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:243) If I do not use annotation, it works fine. No problem at all, Everything happened after this <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd" default-autowire="byName"> <context:component-scan base-package="demo.dao"> <context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/> </context:component-scan> </beans> and I am sure my spring is configured properly. <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:util="http://www.springframework.org/schema/util" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd" default-autowire="byName"> <!-- For mail settings and future properties files --> <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>classpath:jdbc.properties</value> </list> </property> </bean> <!-- Check all the beans managed by Spring for persistence-related annotations. e.g. PersistenceContext --> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}"/> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSource"/> <!-- jpaVendorAdapter Hibernate, injected into emf --> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="${hibernate.show_sql}"/> <!-- Data Definition Language script is generated and executed for each run --> <property name="generateDdl" value="${jdbc.generateDdl}"/> </bean> </property> <!--<property name="hibernateProperties"> --> <property name="jpaProperties"> <props> <prop key="hibernate.dialect">${hibernate.dialect} </prop> <prop key="hibernate.show_sql">${hibernate.show_sql}</prop> <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto} </prop> </props> </property> </bean> <tx:annotation-driven transaction-manager="transactionManager" /> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory"/> <property name="dataSource" ref="dataSource"/> </bean> </beans> Can anyone tell me what is wrong? How can I fix this?

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• NetBeans has broken interface with OpenJDK

  - by Krzysztof Stanislawek

  Sorry for English. Usually (say, at 4/5 of times), when I start NetBeans, interface is partially broken. For example, menu items are appearing and at once disappearing after click; some parts of editor are also blocked for cursor actions. Another issue is broken Options window - I can show it only once for NetBeans execution. There are more similar issues. $ java -version java version "1.7.0_55" OpenJDK Runtime Environment (IcedTea 2.4.7) (7u55-2.4.7-1ubuntu1~0.13.10.1) OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode) Version of NetBeans is 7.0.1. Linux version is Mint 16. I use Mate. I had the same issue at other computer, at the same operating system. I know that installing Sun version of Java could help, but I also know that there shouldn't be such issue with OpenJDK. Also, I had other problem with NetBeans and Sun Java 8 - NetBeans suddenly crashed before he fully started, so I want to stick with OpenJDK. What causes my problem? Should I use other version of NetBeans/OpenJDK?

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• Embedded Tomcat Cluster

  - by ThreaT

  Can someone please explain with an example how an Embedded Tomcat Cluster works. Would a load balancer be necessary? Since we're using embedded tomcat, how would two separate jar files (each a standalone web application with their own embedded tomcat instance) know where eachother are and let eachother know their status, etc? Here is the code I have so far which is just a regular embedded tomcat without any clustering: import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.File; import java.io.IOException; import java.io.Writer; public class Main { public static void main(String[] args) throws LifecycleException, InterruptedException, ServletException { Tomcat tomcat = new Tomcat(); tomcat.setPort(8080); Context ctx = tomcat.addContext("/", new File(".").getAbsolutePath()); Tomcat.addServlet(ctx, "hello", new HttpServlet() { protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { Writer w = resp.getWriter(); w.write("Hello, World!"); w.flush(); } }); ctx.addServletMapping("/*", "hello"); tomcat.start(); tomcat.getServer().await(); } } Source: java dzone

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• Graphical Interface and Object Selection/Manipulation

  - by ToriArendt

  I have a project I want to try to implement, but I'm kind of stuck on how to get started. I know there are probably a lot of resources that I can look at, but I'm really just stuck on what to even search for and where to begin. Basically, I have a program written in Java that separates 3D coordinates from a 3D reconstructed model into different objects. I then want to be able to perform a logistic regression on these objects to determine if they are type A or type B. But first, I need to classify a training set of objects as type A or B by hand. I don't know ANYTHING about graphing or user interfaces in Java, so I have been plotting the coordinates of a given object in MATLAB so that I can visualize the object and assign it a type. Now, as I am trying to make this program more "user friendly" I want to create an interface in Java where I can simply graph all the coordinates of the objects from the entire 3D model (on the same graph). I then want to be able to click on the each object and assign it to be either of type A or type B. I hope this description makes sense and someone can point me in the direction of something that will help me. I'm sorry if some of this terminology is off; I'm a bit new to software development. P.S. If anyone also has some tips on implementing logistic regression in Java, I'm sure I'll need them down the road :).

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• JCP Elections, JUG Candidates

  - by Tori Wieldt

  The JCP elections for the JCP Executive Committee (EC) have started today. The ratified candidates are:  Cinterion, Credit Suisse, Fujitsu and HP.The elected candidates are (9 candidates, 2 open seats):  Cisco Systems, CloudBees, Giuseppe Dell'Abate, Liferay, London Java Community, MoroccoJUG, North Sixty-One, Software AG, and Zero Turnaround. For community representation, the London Java Community is running for re-election. They have helped with JUGs participation on the JCP, and they need community votes to stay there doing great work! Also, the Morroco JUG is running for election for the first time.  Learn more about the JCP Elections, read the JCP Program Office blog "2012 EC Election Ballot open; Meet the Candidates Call Tomorrow." So, please, if you are a registered JCP member, don't forget to cast your vote!

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• Jython & Mysql - what is the current practice for connection?

  - by Sector7B

  Just trying jython for the first time, because something came up at work that would fit for this perfect for it. I assume jython can make mysql jdbc connection using the mysql jdbc driver. After googling and reading, however I am having problems and it seems jython specific and probably simple. so i do jython: Jython 2.5.1 (Release_2_5_1:6813, Sep 26 2009, 13:47:54) [Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_17 Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> print sys.path ['', '/JYTHONPATH/mysql-connector-java-5.1.10-bin.jar', '/WorkArea/Apps/jython/jython2.5.1/Lib', '__classpath__', '__pyclasspath__/', '/WorkArea/Apps/jython/jython2.5.1/Lib/site-packages'] >>> code i'm running from java.lang import * from java.sql import * driverName="com.mysql.jdbc.Driver" Class.forName(driverName) url = "jdbc:mysql://localhost/test?user=jgreenaw&password=" con = DriverManager.getConnection(url) stmt = con.createStatement() output riux:Desktop$ jython pymysql.py Traceback (most recent call last): File "pymysql.py", line 7, in <module> Class.forName(driverName) at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:315) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:250) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) java.lang.ClassNotFoundException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver any advice? thanks

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• Interfaces: profit of using

  - by Zapadlo

  First of all, my ubiquitous language is PHP, and I'm thinking about learning Java. So let me split my question on two closely related parts. Here goes the first part. Say I have a domain-model class. It has some getters, setters, some query methods etc. And one day I want to have a possibility to compare them. So it looks like: class MyEntity extends AbstractEntity { public function getId() { // get id property } public function setId($id) { // set id property } // plenty of other methods that set or retrieve data public function compareTo(MyEntity $anotherEntity) { // some compare logic } } If it would have been Java, I should have implemented a Comparable interface. But why? Polymorphism? Readbility? Or something else? And if it was PHP -- should I create Comparable interface for myself? So here goes the second part. My colleague told me that it is a rule of thumb in Java to create an interface for every behavioral aspect of the class. For example, if I wanted to present this object as a string, I should state this behaviour by something like implements Stringable, where in case of PHP Stringable would look like: interface Stringable { public function __toString(); } Is that really a rule of thumb? What benefits are gained with this approach? And does it worth it in PHP? And in Java?

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• 7?????JavaOne Tokyo 2012???????????!

  - by hideki ito

  2012?4?4???????????????49???JavaOne Tokyo 2012???????????7???4????????????4??5??2??????????????????? ???????????JavaOne Tokyo 2012??????????????! ??????Java Strategy Keynote???????????????????Java????????????????Java?????????????????????????Java???????????4????????????Java?????????????????????????????????????7?????????????????????????????????????? ????·?????????????????·??????????Henrik Stahl?JDK??????????????2012?4??JDK7??4????????????????2013??JDK8????????????? ????????????·?????·??????????Rob Benson?????·???????????Twitter?Java????????????????? ????·???????? Java??????????????·???????Nandini Ramani?????Java??????????????Java FX??????????????? ????·???????? ????????·???????Cameron Purdy???????????????????????Java EE 7?????????????????????????? ?????????????????????????????????????Core Java??Client Java??Enterprise Java??Embedded Jave??4??????????????????????????????????????????????????????? ??????????????????????! ???????????????????????????????? ??????????????????????????????????????????????????? ?????????JavaOne Tokyo 2012???2???????????????????????????????????????! ???????Java ???????Duke????????????????!

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• ?????????????????????WebLogic Server??????????|WebLogic Channel|??????

  - by ???02

  ????????IT?????????????????·???????????????????????????????????????????????·???????????????????????????????????――??????Publickey???????IT?????????????????????????????????WebLogic Server????????????????????(???)??????????????????????――??IT??????????????????????????????WebLogic Server????????????????????????????????:?????????????????????????????????????????????????????????1????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????????·???????????????????????????????????????????　??WebLogic Server???????JVM?????????????????????????????????????????????????????????????????????????????????????????JVM?????????????????????????????????????????·???????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????WebLogic Server????????????????Oracle Exalogic Elastic Cloud??????????Java EE 6?????????·??????????????――???Java SE 7??????????????Java EE???????????Java EE 6?????????????????????:Java EE???????Java EE???????????????????????????????POJO(Plain Old Java Object)????????????????????????????????????????Java???????????Spring Framework??????????Java EE 6????Spring???????????????????????????????:?????????Spring????Seasar??????????·??????????????????????????????????????????????????????????????????????????????????????????　?????????????????????????????????????????????????????????????????????????????????Java EE 6???????????????????????????????????????????????????　WebLogic Server???????????Java EE 6?????????????????????????????????????――???????????????·????????Oracle Fusion Applications??Java??????WebLogic Server??????????????????WebLogic Server??????????????????????????????????:?????????????·?????????????????????????????????????·??????????????????????????????????????????????????????????????·???????――????????????WebLogic Server?????????????????:??????????????IT???????????????????????·????????????????????????????????????????????????????????????????????????????　?????????????????·?????????????????????·???????????????????????????????????????????????????????????????????????????·????????????????????――WebLogic Server?????Exalogic??????????1???????????????????????????:??????????????????????????????????????????????????????????????1???????????????Exalogic??Oracle Exadata?????????????????·???????????????????????????????????????????????????????????????????????????????――????????????????????　????????????WebLogic Server???????????????????WebLogic Server????????????????????　????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Java EE????????????·???????????????????????????????????????????????????????????????????????????????????????????????????????WebLogic Server??Java EE????????·?????????????????????????????????????????????????????????????????????

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• javaws not found

  - by Hunt

  i have a server which has centos installed in it , recently i have installed jdk 1.6 into it. when i try to run java command from shell its working perfectly fine but when i tried running javaws (which comes with the jdk 1.6 only ) it is showing me following error java is stored into /usr/java/jdk1.6.0_25 and path is set to /usr/bin/ when i type which java Java Web Start splash screen process exiting ... Bad installation: JAVAWS_HOME not set: No such file or directory

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• How to run a program and get its PID in the background

  - by Ivan

  I have a Minecraft server startup script that looks like this: #!/bin/bash cd "$(dirname "$0")" exec java -Xmx4096M -Xms4096M -jar minecraft_server.jar How do I get java process's PID while being able to enter input into the Java process? if I change the exec line to exec java -Xmx4096M -Xms4096M -jar minecraft_server.jar & echo $! > pid it won't let me input any text into the Minecraft server java process.

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• Java Spotlight Episode 57: Live From #Devoxx - Ben Evans and Martijn Verburg of the London JUG with Yara Senger of SouJava

  - by Roger Brinkley

  Tweet Live from Devoxx 11,  an interview with Ben Evans and Martijn Verburg from the London JUG along with  Yara Senger from the SouJava JUG on the JCP Executive Committee Elections, JSR 248, and Adopt-a-JSR program. Both the London JUG and SouJava JUG are JCP Standard Edition Executive Committee Members. Joining us this week on the Java All Star Developer Panel are Geertjan Wielenga, Principal Product Manger in Oracle Developer Tools; Stephen Chin, Java Champion and Java FX expert; and Antonio Goncalves, Paris JUG leader. 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 Netbeans 7.1 JDK 7 upgrade tools Netbeans First Patch Program OpenJFX approved as an OpenJDK project Devoxx France April 18-20, 2012 Events Nov 22-25, OTN Developer Days in the Nordics Nov 22-23, Goto Conference, Prague Dec 6-8, Java One Brazil, Sao Paulo Feature interview Ben Evans has lived in "Interesting Times" in technology - he was the lead performance testing engineer for the Google IPO, worked on the initial UK trials of 3G networks with BT, built award-winning websites for some of Hollywood's biggest hits of the 90s, rearchitected and reimagined technology helping some of the most vulnerable people in the UK and has worked on everything from some of the UKs very first ecommerce sites, through to multi-billion dollar currency trading systems. He helps to run the London Java Community, and represents the JUG on the Java SE/EE Executive Committee. His first book "The Well-Grounded Java Developer" (with Martijn Verburg) has just been published by Manning. Martijn Verburg (aka 'the Diabolical Developer') herds Cats in the Java/open source communities and is constantly humbled by the creative power to be found there. Currently he resides in London where he co-leads the London JUG (a JCP EC member), runs a couple of open source projects & drinks too much beer at his local pub. You can find him online moderating at the Javaranch or discussing (ranting?) subjects on the Prgorammers Stack Exchange site. Most recently he's become a regular speaker at conferences on Java, open source and software development and has recently wrapped up his first Manning title - "The Well-Grounded Java Developer" with his co-author Ben Evans. Yara Senger is the partner and director of teacher education and Globalcode, graduated from the University of Sao Paulo, Sao Carlos, has significant experience in Brazil and abroad in developing solutions to critical Java. She is the co-creator of Java programs Academy and Academy of Web Developer, accumulating over 1000 hours in the classroom teaching Java. She currently serves as the President of Sou Java. In this interview Ben, Martijn, and Yara talk about the JCP Executive Committee Elections, JSR 348, and the Adopt-a-JSR program. Mail Bag What's Cool Show Transcripts Transcript for this show is available here when available.

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• How to implement a 2d collision detection for Android

  - by Michael Seun Araromi

  I am making a 2d space shooter using opengl ES. Can someone please show me how to implement a collision detection between the enemy ship and player ship. The code for the two classes are below: Player Ship Class: package com.proandroidgames; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import javax.microedition.khronos.opengles.GL10; public class SSGoodGuy { public boolean isDestroyed = false; private int damage = 0; private FloatBuffer vertexBuffer; private FloatBuffer textureBuffer; private ByteBuffer indexBuffer; private float vertices[] = { 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; private float texture[] = { 0.0f, 0.0f, 0.25f, 0.0f, 0.25f, 0.25f, 0.0f, 0.25f, }; private byte indices[] = { 0, 1, 2, 0, 2, 3, }; public void applyDamage(){ damage++; if (damage == SSEngine.PLAYER_SHIELDS){ isDestroyed = true; } } public SSGoodGuy() { ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length * 4); byteBuf.order(ByteOrder.nativeOrder()); vertexBuffer = byteBuf.asFloatBuffer(); vertexBuffer.put(vertices); vertexBuffer.position(0); byteBuf = ByteBuffer.allocateDirect(texture.length * 4); byteBuf.order(ByteOrder.nativeOrder()); textureBuffer = byteBuf.asFloatBuffer(); textureBuffer.put(texture); textureBuffer.position(0); indexBuffer = ByteBuffer.allocateDirect(indices.length); indexBuffer.put(indices); indexBuffer.position(0); } public void draw(GL10 gl, int[] spriteSheet) { gl.glBindTexture(GL10.GL_TEXTURE_2D, spriteSheet[0]); gl.glFrontFace(GL10.GL_CCW); gl.glEnable(GL10.GL_CULL_FACE); gl.glCullFace(GL10.GL_BACK); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer); gl.glDrawElements(GL10.GL_TRIANGLES, indices.length, GL10.GL_UNSIGNED_BYTE, indexBuffer); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glDisable(GL10.GL_CULL_FACE); } } Enemy Ship Class: package com.proandroidgames; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import java.util.Random; import javax.microedition.khronos.opengles.GL10; public class SSEnemy { public float posY = 0f; public float posX = 0f; public float posT = 0f; public float incrementXToTarget = 0f; public float incrementYToTarget = 0f; public int attackDirection = 0; public boolean isDestroyed = false; private int damage = 0; public int enemyType = 0; public boolean isLockedOn = false; public float lockOnPosX = 0f; public float lockOnPosY = 0f; private Random randomPos = new Random(); private FloatBuffer vertexBuffer; private FloatBuffer textureBuffer; private ByteBuffer indexBuffer; private float vertices[] = { 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; private float texture[] = { 0.0f, 0.0f, 0.25f, 0.0f, 0.25f, 0.25f, 0.0f, 0.25f, }; private byte indices[] = { 0, 1, 2, 0, 2, 3, }; public void applyDamage() { damage++; switch (enemyType) { case SSEngine.TYPE_INTERCEPTOR: if (damage == SSEngine.INTERCEPTOR_SHIELDS) { isDestroyed = true; } break; case SSEngine.TYPE_SCOUT: if (damage == SSEngine.SCOUT_SHIELDS) { isDestroyed = true; } break; case SSEngine.TYPE_WARSHIP: if (damage == SSEngine.WARSHIP_SHIELDS) { isDestroyed = true; } break; } } public SSEnemy(int type, int direction) { enemyType = type; attackDirection = direction; posY = (randomPos.nextFloat() * 4) + 4; switch (attackDirection) { case SSEngine.ATTACK_LEFT: posX = 0; break; case SSEngine.ATTACK_RANDOM: posX = randomPos.nextFloat() * 3; break; case SSEngine.ATTACK_RIGHT: posX = 3; break; } posT = SSEngine.SCOUT_SPEED; ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length * 4); byteBuf.order(ByteOrder.nativeOrder()); vertexBuffer = byteBuf.asFloatBuffer(); vertexBuffer.put(vertices); vertexBuffer.position(0); byteBuf = ByteBuffer.allocateDirect(texture.length * 4); byteBuf.order(ByteOrder.nativeOrder()); textureBuffer = byteBuf.asFloatBuffer(); textureBuffer.put(texture); textureBuffer.position(0); indexBuffer = ByteBuffer.allocateDirect(indices.length); indexBuffer.put(indices); indexBuffer.position(0); } public float getNextScoutX() { if (attackDirection == SSEngine.ATTACK_LEFT) { return (float) ((SSEngine.BEZIER_X_4 * (posT * posT * posT)) + (SSEngine.BEZIER_X_3 * 3 * (posT * posT) * (1 - posT)) + (SSEngine.BEZIER_X_2 * 3 * posT * ((1 - posT) * (1 - posT))) + (SSEngine.BEZIER_X_1 * ((1 - posT) * (1 - posT) * (1 - posT)))); } else { return (float) ((SSEngine.BEZIER_X_1 * (posT * posT * posT)) + (SSEngine.BEZIER_X_2 * 3 * (posT * posT) * (1 - posT)) + (SSEngine.BEZIER_X_3 * 3 * posT * ((1 - posT) * (1 - posT))) + (SSEngine.BEZIER_X_4 * ((1 - posT) * (1 - posT) * (1 - posT)))); } } public float getNextScoutY() { return (float) ((SSEngine.BEZIER_Y_1 * (posT * posT * posT)) + (SSEngine.BEZIER_Y_2 * 3 * (posT * posT) * (1 - posT)) + (SSEngine.BEZIER_Y_3 * 3 * posT * ((1 - posT) * (1 - posT))) + (SSEngine.BEZIER_Y_4 * ((1 - posT) * (1 - posT) * (1 - posT)))); } public void draw(GL10 gl, int[] spriteSheet) { gl.glBindTexture(GL10.GL_TEXTURE_2D, spriteSheet[0]); gl.glFrontFace(GL10.GL_CCW); gl.glEnable(GL10.GL_CULL_FACE); gl.glCullFace(GL10.GL_BACK); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer); gl.glDrawElements(GL10.GL_TRIANGLES, indices.length, GL10.GL_UNSIGNED_BYTE, indexBuffer); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glDisable(GL10.GL_CULL_FACE); } }

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• Here's your chance: MOS Feedback Sessions @OOW

  - by cwarticki

  Bring your questions, comments, concerns, opinions, recommendations, enhancement requests and any emotional outbursts!   As I travel the world and speak to thousands of customers, I receive plenty of feedback about My Oracle support.  Come hear directly from the source. Meet Dennis Reno, VP of Customer Portal Experience. The Customer Portal Experience team will host a My Oracle Support Tips and Techniques session and three roundtable feedback sessions at this year’s Oracle OpenWorld. The sessions will include a Hardware Support component, as well as best practices that are sure to benefit all My Oracle Support users. The events planned will give our users the opportunity to learn more about how the My Oracle Support customer portal adds value to the support process and to their business needs. The roundtable feedback sessions will allow customers to meet, give feedback, and share their experiences directly with the team responsible for the customer portal experience. Date Time (PT) Session Name Mon, Oct 1 01:45 PM My Oracle Support: Tips and Techniques for Getting the Best Hardware Support Possible (Session #CON9745) Tue, Oct 2 11:00 AM Roundtable - My Oracle Support General Feedback Wed, Oct 3 11:00 AM Roundtable - My Oracle Support Community Feedback Thr, Oct 4 11:00 AM Roundtable - My Oracle Support General Feedback Customers can find more information, including specific details about how to attend, by accessing My Oracle Support at OpenWorld (Article ID 1484508.1). Enjoy OpenWorld everyone! -Chris Warticki Global Customer Management

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• Adding complexity by generalising: how far should you go?

  - by marcog

  Reference question: http://stackoverflow.com/questions/4303813/help-with-interview-question The above question asked to solve a problem for an NxN matrix. While there was an easy solution, I gave a more general solution to solve the more general problem for an NxM matrix. A handful of people commented that this generalisation was bad because it made the solution more complex. One such comment is voted +8. Putting aside the hard-to-explain voting effects on SO, there are two types of complexity to be considered here: Runtime complexity, i.e. how fast does the code run Code complexity, i.e. how difficult is the code to read and understand The question of runtime complexity is something that requires a better understanding of the input data today and what it might look like in the future, taking the various growth factors into account where necessary. The question of code complexity is the one I'm interested in here. By generalising the solution, we avoid having to rewrite it in the event that the constraints change. However, at the same time it can often result in complicating the code. In the reference question, the code for NxN is easy to understand for any competent programmer, but the NxM case (unless documented well) could easily confuse someone coming across the code for the first time. So, my question is this: Where should you draw the line between generalising and keeping the code easy to understand?

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• Adding complexity by generalising: how far should you go?

  - by marcog

  Reference question: http://stackoverflow.com/questions/4303813/help-with-interview-question The above question asked to solve a problem for an NxN matrix. While there was an easy solution, I gave a more general solution to solve the more general problem for an NxM matrix. A handful of people commented that this generalisation was bad because it made the solution more complex. One such comment is voted +8. Putting aside the hard-to-explain voting effects on SO, there are two types of complexity to be considered here: Runtime complexity, i.e. how fast does the code run Code complexity, i.e. how difficult is the code to read and understand The question of runtime complexity is something that requires a better understanding of the input data today and what it might look like in the future, taking the various growth factors into account where necessary. The question of code complexity is the one I'm interested in here. By generalising the solution, we avoid having to rewrite it in the event that the constraints change. However, at the same time it can often result in complicating the code. In the reference question, the code for NxN is easy to understand for any competent programmer, but the NxM case (unless documented well) could easily confuse someone coming across the code for the first time. So, my question is this: Where should you draw the line between generalising and keeping the code easy to understand?

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• Null reading in stream images? Unable to start activity ComponentInfo

  - by lasmith

  I have reviewed a lot of similar questions regarding not being able to launch an activity but they don't seem to quite match my problem. I am working on a simple black jack game but its force quitting. I suspect there is a problem with loading up the card png images I have. Stepping through the debugger it crashes right while in the resetGame() function. I'm sure I am doing something dumb. My Logcat: 10-15 20:21:43.309: E/AndroidRuntime(2863): FATAL EXCEPTION: main 10-15 20:21:43.309: E/AndroidRuntime(2863): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smith.blackjack/com.smith.blackjack.Main}: java.lang.NullPointerException 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.access$600(ActivityThread.java:130) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Handler.dispatchMessage(Handler.java:99) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Looper.loop(Looper.java:137) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.main(ActivityThread.java:4745) 10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invokeNative(Native Method) 10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invoke(Method.java:511) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-15 20:21:43.309: E/AndroidRuntime(2863): at dalvik.system.NativeStart.main(Native Method) 10-15 20:21:43.309: E/AndroidRuntime(2863): Caused by: java.lang.NullPointerException 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.DeckOfCards.<init>(DeckOfCards.java:17) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.Main.resetGame(Main.java:98) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.Main.onCreate(Main.java:67) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Activity.performCreate(Activity.java:5008) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 10-15 20:21:43.309: E/AndroidRuntime(2863): ... 11 more My androidmanifest: <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.smith.blackjack" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="11" android:targetSdkVersion="15" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".Main" android:label="@string/title_activity_main" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> Here is my Main.java package com.smith.blackjack; import android.os.Bundle; import android.app.Activity; import android.content.res.AssetManager; import android.graphics.drawable.Drawable; import java.io.IOException; import java.io.InputStream; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ImageView; public class Main extends Activity { private ImageView dealerCard0; private ImageView dealerCard1; private ImageView dealerCard2; private ImageView dealerCard3; private ImageView playerCard0; private ImageView playerCard1; private ImageView playerCard2; private ImageView playerCard3; private ImageView imgResult; private Button btnDeal; private Button btnDraw; private Button btnHold; private DeckOfCards deckOfCards; private int[] dealerValues; private int dealerSum; private int dealerCardNumber; private int[] playerValues; private int playerSum; private int playerCardNumber; private InputStream dealerHiddenCard; private Card dealerCard; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); dealerCard0 = (ImageView) findViewById(R.id.dealerCard0); dealerCard1 = (ImageView) findViewById(R.id.dealerCard1); dealerCard2 = (ImageView) findViewById(R.id.dealerCard2); dealerCard3 = (ImageView) findViewById(R.id.dealerCard3); playerCard0 = (ImageView) findViewById(R.id.playerCard0); playerCard1 = (ImageView) findViewById(R.id.playerCard1); playerCard2 = (ImageView) findViewById(R.id.playerCard2); playerCard3 = (ImageView) findViewById(R.id.playerCard3); imgResult = (ImageView) findViewById(R.id.imgResult); btnDeal = (Button) findViewById(R.id.deal); btnDraw = (Button) findViewById(R.id.draw); btnHold = (Button) findViewById(R.id.hold); btnDeal.setOnClickListener(btnDealListener); btnDraw.setOnClickListener(btnDrawListener); btnHold.setOnClickListener(btnHoldListener); resetGame(); } private void resetGame(){ AssetManager assets = getAssets(); dealerValues = new int[4]; playerValues = new int[4]; dealerSum = 0; playerSum = 0; dealerCardNumber = 0; playerCardNumber = 0; for (int i = 0; i < 4; i++) { dealerValues[i] = 0; playerValues[i] = 0; } try { InputStream stream = assets.open("cardback.png"); // stream = assets.open("cardback.png"); Drawable cardImage = Drawable.createFromStream(stream, null); dealerCard0.setImageDrawable(cardImage); dealerCard1.setImageDrawable(cardImage); dealerCard2.setImageDrawable(cardImage); dealerCard3.setImageDrawable(cardImage); playerCard0.setImageDrawable(cardImage); playerCard1.setImageDrawable(cardImage); playerCard2.setImageDrawable(cardImage); playerCard3.setImageDrawable(cardImage); imgResult.setImageDrawable(cardImage); deckOfCards = new DeckOfCards(); deckOfCards.shuffle(); assets.close(); } catch (IOException e){ Log.e("Reset Game", "Error Loading", e); } } public OnClickListener btnDealListener = new OnClickListener() { // @Override public void onClick(View v) { try { AssetManager assets = getAssets(); InputStream stream; // first player card Card newCard; newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); Drawable cardImage = Drawable.createFromStream(stream, newCard.File); playerCard0.setImageDrawable(cardImage); assets.close(); // second player card newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); playerCard1.setImageDrawable(cardImage); assets.close(); // first dealer card hidden newCard = deckOfCards.dealCard(); dealerCard = newCard; dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; dealerHiddenCard = assets.open(newCard.File); stream = assets.open("cardback.png"); cardImage = Drawable.createFromStream(stream, "cardback"); dealerCard0.setImageDrawable(cardImage); assets.close(); // second dealer card open newCard = deckOfCards.dealCard(); dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); dealerCard1.setImageDrawable(cardImage); assets.close(); } catch (IOException e){ Log.e("Deal", "Error Loading", e); } }; }; public OnClickListener btnDrawListener = new OnClickListener() { // @Override public void onClick(View v) { try { AssetManager assets = getAssets(); InputStream stream; // get next player card Card newCard; newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); Drawable cardImage = Drawable.createFromStream(stream, newCard.File); switch (playerCardNumber){ case 3: playerCard2.setImageDrawable(cardImage); case 4: playerCard3.setImageDrawable(cardImage); } assets.close(); } catch (IOException e){ Log.e("Draw", "Error Loading", e); } }; }; public OnClickListener btnHoldListener = new OnClickListener() { // @Override public void onClick(View v) { Drawable cardImage; // evaluate player hand playerSum = evaluate(playerValues); if (playerSum > 21){ // player losses } // flip over the dealer hidden card cardImage = Drawable.createFromStream(dealerHiddenCard, dealerCard.File); Card newCard; InputStream stream; AssetManager assets = getAssets(); for (int i=2; i<4; i++){ dealerSum = evaluate(dealerValues); if (dealerSum < 16 ) { newCard = deckOfCards.dealCard(); dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; try { stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); switch (dealerCardNumber){ case 3: dealerCard2.setImageDrawable(cardImage); case 4: dealerCard3.setImageDrawable(cardImage); } assets.close(); } catch (IOException e){ Log.e("Draw", "Error Loading", e); } if (dealerSum < playerSum) { // player wins } if (dealerSum > playerSum){ // dealer wins } if (dealerSum == playerSum){ // it is a draw } } } }; }; public int evaluate (int[]values) { int sumCards = 0; for (int i = 0; i < 4; i++){ sumCards += values[i]; } if (sumCards > 21) { for (int i = 0; i < 4; i++){ if (values[i] == 11) { values[i] = 1; sumCards -= 10; continue; } } } return sumCards; } } My DeckOfCards class: package com.smith.blackjack; import java.util.Random; public class DeckOfCards { private Card [] deck; private int currentCard; private static final int NUMBER_OF_CARDS = 52; private static final Random randomNumbers = new Random(); public DeckOfCards () { deck = new Card[NUMBER_OF_CARDS]; currentCard = 0 ; for(int count = 0; count < deck.length; count++) { deck[count].faceValue = count + 1; } } public void shuffle () { currentCard = 0; for (int first = 0; first < deck.length; first ++){ int second = randomNumbers.nextInt(NUMBER_OF_CARDS); int temp = deck[first].faceValue; deck[first].faceValue=deck[second].faceValue; deck[second].faceValue = temp; } } public Card dealCard(){ Card temp = new Card(); temp.faceValue = 0; temp.File = ""; if(currentCard < deck.length) { temp.faceValue = deck[currentCard].faceValue / 4; int suit = deck[currentCard].faceValue % 4; String suitString = ""; switch (suit){ case 0: suitString = "c"; case 1: suitString = "d"; case 2: suitString = "h"; case 3: suitString = "s"; } Integer face = temp.faceValue / 4 ; String faceString = face.toString(); temp.File = faceString + suitString + ".png"; switch (temp.faceValue){ case 11: temp.faceValue = 10; case 12: temp.faceValue = 10; case 13: temp.faceValue = 10; } return temp; } else return temp; } }

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