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  • why there is no power operator in java / c ++?

    - by RanZilber
    While there is such operator - ** in Python , i was wondering why java and c++ havent got one too. It is easy to make one for classes you define in C++ with operator overloading ( and i believe such thing is possible also in java) , but when talking about primitive types such as int, double and so on , you'll have to use library function like Math.power (and usaully have to cast both to double). So - why not define such operator for primitive types ?

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  • Why has the accessor methods from the JavaBean specification become the standard for Java development?

    - by Dakotah North
    The JavaBeans Specification describes a JavaBean as A Java Bean is a reusable software component that can be manipulated visually in a builder tool Since the majority of the lines of code that are written seem to have nothing to do with being manipulated visually in a builder tool, why has the JavaBean specification been the "way" to write object oriented code? I would like to forgo the traditional getter/setter in favor of Fluent Interfaces all throughout the code, not just in builders but fear doing so since this is traditionally not the way way object oriented code is written in Java.

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  • Is beginner knowledge of Java enough to develop for Android? [closed]

    - by teenCoder
    I just finished the book "Tech Yourself Java in 24 Hours, 6th Edition" I have an understanding of the language (by understanding I mean, the basics and everything covered in the book) and I have been experimenting and building little things with my knowledge. I want to learn about Android and was wondering if I need to increase my knowledge in Java before moving on to Android or can I just go straight to Android?

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  • Where do all these Java technologies lead to? [on hold]

    - by user1502178
    For a new job, the HR gave me list of Java technologies to study: JSP/Servlet Ant, Maven Hibernate Spring Core, Spring MVC REST JMS Mongo, Cassandra Solr, Elastic Search I have never been a java guy, but I am ready to learn these, but I need to know where all these technologies lead to, are they worth doing? and how long will they approximately take if I have university level experience in programming and CS?

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  • Strange Jmeter connection refuse on Tomcat

    - by Tommy
    I tried difference setting in Jmeter and Tomcat. If the Threads number in JMeter is 1~200, Then tomcat is okay. If It is 300, Then after serving few requests, tomcat starts to output errors. Here is the error show in JMeter java.net.ConnectException: Connection refused: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at sun.net.NetworkClient.doConnect(Unknown Source) at sun.net.www.http.HttpClient.openServer(Unknown Source) at sun.net.www.http.HttpClient.openServer(Unknown Source) at sun.net.www.http.HttpClient.<init>(Unknown Source) at sun.net.www.http.HttpClient.New(Unknown Source) at sun.net.www.http.HttpClient.New(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source) at org.apache.jmeter.protocol.http.sampler.HTTPJavaImpl.sample(HTTPJavaImpl.java:483) at org.apache.jmeter.protocol.http.sampler.HTTPSamplerProxy.sample(HTTPSamplerProxy.java:62) at org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1018) at org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1004) at org.apache.jmeter.threads.JMeterThread.process_sampler(JMeterThread.java:411) at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:297) at java.lang.Thread.run(Unknown Source) My tomcat server.xml in eclipse <!--The connectors can use a shared executor, you can define one or more named thread pools--> <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="2000" minSpareThreads="250" acceptCount="2000"/> <Connector executor="tomcatThreadPool" URIEncoding="UTF-8" connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443" /> Any idea why this is happening ? How do i check the server.xml is correctly used? It is a JSF2 application if it helps. Thanks in advance.

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  • Why can't I install Java?

    - by Patrick
    I've been searching high and low for someone who can help me. I've been trying for a month. A month. to install Java on my new PC to no avail. No tech support forum can seem to help me. It all started while playing tekkit one day. I kept running out of memory (using the 32-bit JRE 7 u45) so I decided to install the 64-bit version. I uninstalled the 32-bit version first, for some reason, and downloaded the 64 bit runtime. In the installer, I go through all the normal screens until the installation progress bar appears. Then, it just sits there. No progress is made. No CPU is used by the installer, or any of its dependencies. The installer will stay like this for hours, days, and in one case a whole week without doing anything at all. I've tried installing older versions, the 32-bit version, even Java 6 and none of them will install. UAC is disabled, I've run regedit, CCleaner, and any other "fix-it" program there is. It's getting to the point where I may just have to wipe my hard drives and start over. I have several applications that require java, so this is an absolute necessity. Please, please, someone have the answer. Here are my system specs: -Intel i7-3770k -AsRock z77 Extreme3 -Samsung 840 pro SSD -WD Caviar Black 1tb

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  • Can't update scala on Gentoo

    - by xhochy
    As I wanted to test Scala 2.9.2 on my gentoo system I tried updated the package but ended up with this error. I can't figure out where the problem may be: Calculating dependencies ...... done! >>> Verifying ebuild manifests >>> Jobs: 0 of 1 complete, 1 running Load avg: 0.23, 0.16, 0.20 >>> Emerging (1 of 1) dev-lang/scala-2.9.2 >>> Jobs: 0 of 1 complete, 1 running Load avg: 0.23, 0.16, 0.20 >>> Failed to emerge dev-lang/scala-2.9.2, Log file: >>> Jobs: 0 of 1 complete, 1 running Load avg: 0.23, 0.16, 0.20 >>> '/var/tmp/portage/dev-lang/scala-2.9.2/temp/build.log' >>> Jobs: 0 of 1 complete, 1 running Load avg: 0.23, 0.16, 0.20 >>> Jobs: 0 of 1 complete, 1 running, 1 failed Load avg: 0.23, 0.16, 0.20 >>> Jobs: 0 of 1 complete, 1 failed Load avg: 0.23, 0.16, 0.20 * Package: dev-lang/scala-2.9.2 * Repository: gentoo * Maintainer: [email protected] * USE: amd64 elibc_glibc kernel_linux multilib userland_GNU * FEATURES: sandbox [01m[31;06m!!! ERROR: Couldn't find suitable VM. Possible invalid dependency string. Due to jdk-with-com-sun requiring a target of 1.7 but the virtual machines constrained by virtual/jdk-1.6 and/or this package requiring virtual(s) jdk-with-com-sun[0m * Unable to determine VM for building from dependencies: NV_DEPEND: virtual/jdk:1.6 java-virtuals/jdk-with-com-sun !binary? ( dev-java/ant-contrib:0 ) app-arch/xz-utils >=dev-java/java-config-2.1.9-r1 source? ( app-arch/zip ) >=dev-java/ant-core-1.7.0 dev-java/ant-nodeps >=dev-java/javatoolkit-0.3.0-r2 >=dev-lang/python-2.4 * ERROR: dev-lang/scala-2.9.2 failed (setup phase): * Failed to determine VM for building. * * Call stack: * ebuild.sh, line 93: Called pkg_setup * scala-2.9.2.ebuild, line 43: Called java-pkg-2_pkg_setup * java-pkg-2.eclass, line 53: Called java-pkg_init * java-utils-2.eclass, line 2187: Called java-pkg_switch-vm * java-utils-2.eclass, line 2674: Called die * The specific snippet of code: * die "Failed to determine VM for building." * * If you need support, post the output of `emerge --info '=dev-lang/scala-2.9.2'`, * the complete build log and the output of `emerge -pqv '=dev-lang/scala-2.9.2'`. !!! When you file a bug report, please include the following information: GENTOO_VM= CLASSPATH="" JAVA_HOME="" JAVACFLAGS="" COMPILER="" and of course, the output of emerge --info * The complete build log is located at '/var/tmp/portage/dev-lang/scala-2.9.2/temp/build.log'. * The ebuild environment file is located at '/var/tmp/portage/dev-lang/scala-2.9.2/temp/die.env'. * Working directory: '/var/tmp/portage/dev-lang/scala-2.9.2' * S: '/var/tmp/portage/dev-lang/scala-2.9.2/work/scala-2.9.2-sources' * Messages for package dev-lang/scala-2.9.2: * Unable to determine VM for building from dependencies: * ERROR: dev-lang/scala-2.9.2 failed (setup phase): * Failed to determine VM for building. * * Call stack: * ebuild.sh, line 93: Called pkg_setup * scala-2.9.2.ebuild, line 43: Called java-pkg-2_pkg_setup * java-pkg-2.eclass, line 53: Called java-pkg_init * java-utils-2.eclass, line 2187: Called java-pkg_switch-vm * java-utils-2.eclass, line 2674: Called die * The specific snippet of code: * die "Failed to determine VM for building." * * If you need support, post the output of `emerge --info '=dev-lang/scala-2.9.2'`, * the complete build log and the output of `emerge -pqv '=dev-lang/scala-2.9.2'`. * The complete build log is located at '/var/tmp/portage/dev-lang/scala-2.9.2/temp/build.log'. * The ebuild environment file is located at '/var/tmp/portage/dev-lang/scala-2.9.2/temp/die.env'. * Working directory: '/var/tmp/portage/dev-lang/scala-2.9.2' * S: '/var/tmp/portage/dev-lang/scala-2.9.2/work/scala-2.9.2-sources' The following eix output may help: % eix java-virtuals/jdk-with-com-sun [I] java-virtuals/jdk-with-com-sun Available versions: 20111111 {{ELIBC="FreeBSD"}} Installed versions: 20111111(16:08:51 18/04/12)(ELIBC="-FreeBSD") Homepage: http://www.gentoo.org Description: Virtual ebuilds that require internal com.sun classes from a JDK Both virtual jdks 1.6 and 1.7 are installed: % eix virtual/jdk [I] virtual/jdk Available versions: (1.4) ~1.4.2-r1[1] (1.5) 1.5.0 ~1.5.0-r3[1] (1.6) 1.6.0 1.6.0-r1 (1.7) (~)1.7.0 Installed versions: 1.6.0-r1(1.6)(23:22:48 10/11/12) 1.7.0(1.7)(23:21:09 10/11/12) Description: Virtual for JDK [1] "java-overlay" /var/lib/layman/java-overlay

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  • Live screen annotation?

    - by TreyK
    Hey all, I'm in need of some software that will allow me to make annotations on the screen to ease the frustration of using a piece of low-quality software to verify some data. I've tried a few programs out, but so far none of them have one essential feature: I must be able to switch between the annotation software and the program without losing the annotations that I've previously made. Every program so far has cleared my annotations when I switch out and then back in to it. Running Windows XP. Thanks for any help,

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  • Hung Java JVM failing to respond to kill -3

    - by Hans
    I have a Java VM that is hanging "randomly". I quote the randomly bit, because there is obviously a reason that the VM is hanging, but the hang does not occur periodically. We have the same software running in different customer environments and in those environments the JVM is not hanging. In the process of attempting to troubleshoot the hang the process exists with zero CPU utilization. I then attempt to execute kill -3 and the kill command hangs. No JVM Thread Dump is produced. I have spent time instrumenting the code to periodically log the thread stack traces hoping to catch the JVM in a state that would indicate where the issue lies, but so far this attempt has not born much fruit. Unfortunately I have not been able to reproduce this issue in my lab environment so I am limited by what can be done at the Customer site. The OS's in question are Red Hat Enterprise 5.4 and SUSE 10 running java version 1.6.0_05-b13 Has anyone had this problem? Any ideas on why kill -3 is failing to produce a Java Thread Dump? Thanks!

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  • Java in a browser on Ubuntu

    - by Peter
    So I am running an old version of Ubuntu and all of a sudden, my capabilities to run Java in a browser have stopped and it no longer executes properly. Someone else set this up for me, but I believe it's running icedtea plugin 6 and jre 6. What would be the best ways to troubleshoot this? I suppose I could try downloading icedtea 7 and jre 7 (sun or openjdK) and see if that works? Also, in general, is installing icedtea, installing a java runtime environment, and then symlinking something to the plugins directory of your browser the best way to get Java working on most Linux systems? Unfortunately, there are many guides all over the internet offering totally different solutions, but this is probably the most common I've seen (not sure how well it works). My main use is downloading an executing .jnlp files (browsers should open it automatically). Although, I've seen people using "javasw" to run the file outside of a browser. Is this something I could consider doing? I can't seem to find javasw packaged for my version of Ubuntu.

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  • Java games applet not connecting to Yahoo

    - by Steve
    Hi. I am trying to play a Y! game which use a java applet. The applet displays the message: Alert. Unable to connect to server. One of four things could have caused this: 1) You are behind a firewall. 2) You are not connected to the internet. 3) The games server is down. 4) You have a stale page in your cache. I have added an exception to the Windows firewall for java.exe. I am obviously connected to the Internet okay. The games server is not down when I am at home. I doubt it is down when I am at work. I have never successfully loaded this page before, so I doubt I have a stale page in cache. Could it be the corporate firewall? Nothing else in my web browser has been blocked before. Maybe the java applet connects on a different port to the browser. What should I test?

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  • Deployment and monitoring tools for java/tomcat/linux environment

    - by Ran
    I'm a developer for many years, but don't have tons of experience in ops, so apology if this is a newbe question. In my company we run a web service written in Java mainly based on a Tomcat web server. We have two datacenters with about 10 hosts each. Hosts are of several types: Dababase, Tomcats, some offline java processes, memcached servers. All hosts are Linux CentOS Up until now, when releasing a new version to production we've been using a set of inhouse shell script that copy jars/wars and restart the tomcats. The company has gotten bigger so it has become more and more difficult operating all this and taking code from development, through QA, staging and to production. A typical release many times involves human errors that cost us precious uptime. Sometimes we need to revert to last known good and this isn't easy to say the least... We're looking for a tool, a framework, a solution that would provide the following: Supports the given list of technology (java, tomcat, linux etc) Provides easy deployment through different stages, including QA and production Provides configuration management. E.g. setting server properties (what's the connection URL of each host etc), server.xml or context configuration etc Monitoring. If we can get monitoring in the same package, that'll be nice. If not, then yet another tool we can use to monitor our servers. Preferably, open source with tons of documentation ;) Can anyone share their experience? Suggest a few tools? Thanks!

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  • Unauthorized Sharepoint WSDL from Coldfusion 8

    - by antony.trupe
    How do I solve the error: Unable to read WSDL from URL: https://workflowtest.site.edu/_vti_bin/Lists.asmx?WSDL. Error: 401 Unauthorized. I can successfully view the WSDL from the browser using the same user account. I'm not sure which authentication is being used (Basic or Integrated). How would I find that out? The code making the call is: <cfinvoke username="username" password="password" webservice="https://workflowtest.liberty.edu/_vti_bin/Lists.asmx?WSDL" method="GetList" listName="{CB02EB71-392E-4906-B512-8EC002F72436}" > The impression I get is that coldfusion doesn't like being made to authenticate to get the WSDL. Full stack trace: coldfusion.xml.rpc.XmlRpcServiceImpl$CantFindWSDLException: Unable to read WSDL from URL: https://workflowtest.liberty.edu/_vti_bin/Lists.asmx?WSDL. at coldfusion.xml.rpc.XmlRpcServiceImpl.retrieveWSDL(XmlRpcServiceImpl.java:709) at coldfusion.xml.rpc.XmlRpcServiceImpl.access$000(XmlRpcServiceImpl.java:53) at coldfusion.xml.rpc.XmlRpcServiceImpl$1.run(XmlRpcServiceImpl.java:239) at java.security.AccessController.doPrivileged(Native Method) at coldfusion.xml.rpc.XmlRpcServiceImpl.registerWebService(XmlRpcServiceImpl.java:232) at coldfusion.xml.rpc.XmlRpcServiceImpl.getWebService(XmlRpcServiceImpl.java:496) at coldfusion.xml.rpc.XmlRpcServiceImpl.getWebServiceProxy(XmlRpcServiceImpl.java:450) at coldfusion.tagext.lang.InvokeTag.doEndTag(InvokeTag.java:413) at coldfusion.runtime.CfJspPage._emptyTcfTag(CfJspPage.java:2662) at cftonytest2ecfm1787185330.runPage(/var/www/webroot/tonytest.cfm:16) at coldfusion.runtime.CfJspPage.invoke(CfJspPage.java:196) at coldfusion.tagext.lang.IncludeTag.doStartTag(IncludeTag.java:370) at coldfusion.filter.CfincludeFilter.invoke(CfincludeFilter.java:65) at coldfusion.filter.ApplicationFilter.invoke(ApplicationFilter.java:279) at coldfusion.filter.RequestMonitorFilter.invoke(RequestMonitorFilter.java:48) at coldfusion.filter.MonitoringFilter.invoke(MonitoringFilter.java:40) at coldfusion.filter.PathFilter.invoke(PathFilter.java:86) at coldfusion.filter.ExceptionFilter.invoke(ExceptionFilter.java:70) at coldfusion.filter.BrowserDebugFilter.invoke(BrowserDebugFilter.java:74) at coldfusion.filter.ClientScopePersistenceFilter.invoke(ClientScopePersistenceFilter.java:28) at coldfusion.filter.BrowserFilter.invoke(BrowserFilter.java:38) at coldfusion.filter.NoCacheFilter.invoke(NoCacheFilter.java:46) at coldfusion.filter.GlobalsFilter.invoke(GlobalsFilter.java:38) at coldfusion.filter.DatasourceFilter.invoke(DatasourceFilter.java:22) at coldfusion.CfmServlet.service(CfmServlet.java:175) at coldfusion.bootstrap.BootstrapServlet.service(BootstrapServlet.java:89) at jrun.servlet.FilterChain.doFilter(FilterChain.java:86) at coldfusion.monitor.event.MonitoringServletFilter.doFilter(MonitoringServletFilter.java:42) at coldfusion.bootstrap.BootstrapFilter.doFilter(BootstrapFilter.java:46) at jrun.servlet.FilterChain.doFilter(FilterChain.java:94) at jrun.servlet.FilterChain.service(FilterChain.java:101) at jrun.servlet.ServletInvoker.invoke(ServletInvoker.java:106) at jrun.servlet.JRunInvokerChain.invokeNext(JRunInvokerChain.java:42) at jrun.servlet.JRunRequestDispatcher.invoke(JRunRequestDispatcher.java:286) at jrun.servlet.ServletEngineService.dispatch(ServletEngineService.java:543) at jrun.servlet.jrpp.JRunProxyService.invokeRunnable(JRunProxyService.java:203) at jrunx.scheduler.ThreadPool$DownstreamMetrics.invokeRunnable(ThreadPool.java:320) at jrunx.scheduler.ThreadPool$ThreadThrottle.invokeRunnable(ThreadPool.java:428) at jrunx.scheduler.ThreadPool$UpstreamMetrics.invokeRunnable(ThreadPool.java:266) at jrunx.scheduler.WorkerThread.run(WorkerThread.java:66)

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  • Jetty and Access Denied

    - by Laurent
    Hello, I am using several libraries in a maven project and one of these libraries is Jetty (6.1.18). It is a mandatory dependency for an another library. If I run my application from eclipse, with the eclipse classpath which is set by the maven eclipse plugin, all works. However, if I generate a one jar with dependencies and then I run my application from this jar, I get the following exception : Exception in thread "main" java.lang.ExceptionInInitializerError at org.mortbay.jetty.nio.SelectChannelConnector.<init>(SelectChannelConnector.java:70) ... Caused by: java.security.AccessControlException: access denied (java.util.PropertyPermission org.mortbay.io.nio.JVMBUG_THRESHHOLD read) at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) at java.security.AccessController.checkPermission(AccessController.java:546) at java.lang.SecurityManager.checkPermission(SecurityManager.java:532) at java.lang.SecurityManager.checkPropertyAccess(SecurityManager.java:1285) at java.lang.System.getProperty(System.java:650) at java.lang.Integer.getInteger(Integer.java:865) at java.lang.Integer.getInteger(Integer.java:823) at org.mortbay.io.nio.SelectorManager.<clinit>(SelectorManager.java:47) ... 27 more I think it is due to a file which is overridden by an another with the same name when the one jar is built but I have no idea where to look for. Does someone has an idea ?

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  • What's a good way to teach my son to program Java

    - by Software Monkey
    OK, so I've read through various posts about teaching beginner's to program, and there were some helpful things I will look at more closely. But what I want to know is whether there are any effective tools out there to teach a kid Java specifically? I want to teach him Java specifically because (a) with my strong background in C I feel that's too complex, (b) Java is the other language I know extremely well and therefore I can assist meaningfully without needing to teach myself a new but (to me) useless language, and (c) I feel that managed languages are the future, and lastly (d) Java is one of the simplest of all the languages I know well (aside from basic). I learned in basic, and I am open to teaching that first, but I am unaware of a decent free basic shell for Windows (though I haven't really searched, yet since it's not my first choice), and would anyway want to progress quickly to Java. My son is 8, so that's a couple of years earlier than I started - but he has expressed an interest in learning to program (possibly because I work from home a lot and he sees me programming all the time). If no-one can suggest a tool designed for this purpose, I will probably start him off with text/console based apps to teach the basics, and then progress to GUI building. Oh, one last thing, I am not a fan of IDE's (old school text editor type), so I would not be put off at all by a system that has him typing real code, and would likely prefer that to a toy drag/drop system. EDIT: Just to clarify; I really am specifically after ways to teach him Java; there are already a good many posts with good answers for other language alternatives - but that's not what I am looking for here. EDIT: What about Java frameworks for 2D video games - can anyone recommend any of them from personal experience? I like the idea of him starting with the mechanics in place (main game loop, scoring, etc) and adding the specifics for a game of his own imagining - that's what I did, though for me it was basic on a Commodore VIC-20 and a Sinclair ZX-81.

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  • Client-Server Networking Between PHP Client and Java Server

    - by Muhammad Yasir
    Hi there, I have a university project which is already 99% completed. It consists of two parts-website (PHP) and desktop (Java). People have their accounts on the website and they wish to query different information regarding their accounts. They send an SMS which is received by desktop application which queries database of website (MySQL) and sends the reply accordingly. This part is working superbly. The problem is that some times website wishes to instruct the desktop application to send a specific SMS to a particular number. Apparently there seems no way other than putting all the load to the DB server... This is how I made it work. Website puts SMS jobs in a specific table. Java application polls this table again and again and if it finds a job, it executes it. Even this part is working correctly but unfortunately it is not acceptable by my university to poll the DB like this. :( The other approach I could think of is to use client-server one. I tried making Java server and its PHP client. So that whenever an SMS is to be sent, the website opens a socket connection to desktop application and sends two strings (cell # and SMS message). Unfortunately I am unable to do this. I was successfully to make a Java server which works fine when connected by a Java client, similarly my PHP client connects correctly to a PHP server, but when I try to cross them, they start hating each other... PHP shows no error but Java gives StreamCorruptedException when it tries to read header of input stream. Could someone please tell what I can try to make PHP client and Java server work together? Or if the said purpose can be achieved by another means, how? Regards, Yasir

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  • Observations in Migrating from JavaFX Script to JavaFX 2.0

    - by user12608080
    Observations in Migrating from JavaFX Script to JavaFX 2.0 Introduction Having been available for a few years now, there is a decent body of work written for JavaFX using the JavaFX Script language. With the general availability announcement of JavaFX 2.0 Beta, the natural question arises about converting the legacy code over to the new JavaFX 2.0 platform. This article reflects on some of the observations encountered while porting source code over from JavaFX Script to the new JavaFX API paradigm. The Application The program chosen for migration is an implementation of the Sudoku game and serves as a reference application for the book JavaFX – Developing Rich Internet Applications. The design of the program can be divided into two major components: (1) A user interface (ideally suited for JavaFX design) and (2) the puzzle generator. For the context of this article, our primary interest lies in the user interface. The puzzle generator code was lifted from a sourceforge.net project and is written entirely in Java. Regardless which version of the UI we choose (JavaFX Script vs. JavaFX 2.0), no code changes were required for the puzzle generator code. The original user interface for the JavaFX Sudoku application was written exclusively in JavaFX Script, and as such is a suitable candidate to convert over to the new JavaFX 2.0 model. However, a few notable points are worth mentioning about this program. First off, it was written in the JavaFX 1.1 timeframe, where certain capabilities of the JavaFX framework were as of yet unavailable. Citing two examples, this program creates many of its own UI controls from scratch because the built-in controls were yet to be introduced. In addition, layout of graphical nodes is done in a very manual manner, again because much of the automatic layout capabilities were in flux at the time. It is worth considering that this program was written at a time when most of us were just coming up to speed on this technology. One would think that having the opportunity to recreate this application anew, it would look a lot different from the current version. Comparing the Size of the Source Code An attempt was made to convert each of the original UI JavaFX Script source files (suffixed with .fx) over to a Java counterpart. Due to language feature differences, there are a small number of source files which only exist in one version or the other. The table below summarizes the size of each of the source files. JavaFX Script source file Number of Lines Number of Character JavaFX 2.0 Java source file Number of Lines Number of Characters ArrowKey.java 6 72 Board.fx 221 6831 Board.java 205 6508 BoardNode.fx 446 16054 BoardNode.java 723 29356 ChooseNumberNode.fx 168 5267 ChooseNumberNode.java 302 10235 CloseButtonNode.fx 115 3408 CloseButton.java 99 2883 ParentWithKeyTraversal.java 111 3276 FunctionPtr.java 6 80 Globals.java 20 554 Grouping.fx 8 140 HowToPlayNode.fx 121 3632 HowToPlayNode.java 136 4849 IconButtonNode.fx 196 5748 IconButtonNode.java 183 5865 Main.fx 98 3466 Main.java 64 2118 SliderNode.fx 288 10349 SliderNode.java 350 13048 Space.fx 78 1696 Space.java 106 2095 SpaceNode.fx 227 6703 SpaceNode.java 220 6861 TraversalHelper.fx 111 3095 Total 2,077 79,127 2531 87,800 A few notes about this table are in order: The number of lines in each file was determined by running the Unix ‘wc –l’ command over each file. The number of characters in each file was determined by running the Unix ‘ls –l’ command over each file. The examination of the code could certainly be much more rigorous. No standard formatting was performed on these files.  All comments however were deleted. There was a certain expectation that the new Java version would require more lines of code than the original JavaFX script version. As evidenced by a count of the total number of lines, the Java version has about 22% more lines than its FX Script counterpart. Furthermore, there was an additional expectation that the Java version would be more verbose in terms of the total number of characters.  In fact the preceding data shows that on average the Java source files contain fewer characters per line than the FX files.  But that's not the whole story.  Upon further examination, the FX Script source files had a disproportionate number of blank characters.  Why?  Because of the nature of how one develops JavaFX Script code.  The object literal dominates FX Script code.  Its not uncommon to see object literals indented halfway across the page, consuming lots of meaningless space characters. RAM consumption Not the most scientific analysis, memory usage for the application was examined on a Windows Vista system by running the Windows Task Manager and viewing how much memory was being consumed by the Sudoku version in question. Roughly speaking, the FX script version, after startup, had a RAM footprint of about 90MB and remained pretty much the same size. The Java version started out at about 55MB and maintained that size throughout its execution. What About Binding? Arguably, the most striking observation about the conversion from JavaFX Script to JavaFX 2.0 concerned the need for data synchronization, or lack thereof. In JavaFX Script, the primary means to synchronize data is via the bind expression (using the “bind” keyword), and perhaps to a lesser extent it’s “on replace” cousin. The bind keyword does not exist in Java, so for JavaFX 2.0 a Data Binding API has been introduced as a replacement. To give a feel for the difference between the two versions of the Sudoku program, the table that follows indicates how many binds were required for each source file. For JavaFX Script files, this was ascertained by simply counting the number of occurrences of the bind keyword. As can be seen, binding had been used frequently in the JavaFX Script version (and does not take into consideration an additional half dozen or so “on replace” triggers). The JavaFX 2.0 program achieves the same functionality as the original JavaFX Script version, yet the equivalent of binding was only needed twice throughout the Java version of the source code. JavaFX Script source file Number of Binds JavaFX Next Java source file Number of “Binds” ArrowKey.java 0 Board.fx 1 Board.java 0 BoardNode.fx 7 BoardNode.java 0 ChooseNumberNode.fx 11 ChooseNumberNode.java 0 CloseButtonNode.fx 6 CloseButton.java 0 CustomNodeWithKeyTraversal.java 0 FunctionPtr.java 0 Globals.java 0 Grouping.fx 0 HowToPlayNode.fx 7 HowToPlayNode.java 0 IconButtonNode.fx 9 IconButtonNode.java 0 Main.fx 1 Main.java 0 Main_Mobile.fx 1 SliderNode.fx 6 SliderNode.java 1 Space.fx 0 Space.java 0 SpaceNode.fx 9 SpaceNode.java 1 TraversalHelper.fx 0 Total 58 2 Conclusions As the JavaFX 2.0 technology is so new, and experience with the platform is the same, it is possible and indeed probable that some of the observations noted in the preceding article may not apply across other attempts at migrating applications. That being said, this first experience indicates that the migrated Java code will likely be larger, though not extensively so, than the original Java FX Script source. Furthermore, although very important, it appears that the requirements for data synchronization via binding, may be significantly less with the new platform.

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  • Matlab crashes on library initialize when called from Java

    - by David Sauter
    Hello everyone. The setup I have is I'm using a Java application to call native C-code with JNI, which in turn starts up the MATLAB runtime and calls functions on it (I know there are other solutions to call MATLAB methods from Java). The problem is that the MATLAB engine crashes at some point during the initialization and I don't know what's causing it exactly. The crash causes my jvm to terminate, I assume it's some kind of memory corruption. The C++ code calling MATLAB functions that is actually crashing is JNIEXPORT void JNICALL some_jni_vodoo_initializeLibrary(JNIEnv* env, jclass thisClass) { try { if (!mclInitializeApplication(NULL, 0)) { THROW_EXCEPTION(env, "Could not initialize the application properly."); return; } if (!<library>Initialize()) { THROW_EXCEPTION(env, "Could not initialize the library."); return; } } ... The function <library>Initialize() crashes here, the Java error log reads Stack Trace: [0] jmi.dll:0x793f4175(0x7934cdca, 1, 0x7937e67c "à;.y`[email protected] in C:\BUILD_ARE..", 0x792d6a32) [1] jvm.dll:0x792df9a5(0xc0000005, 0x79356791, 0x4961b400 "Ð\8y", 0x6d8b29de) [2] jvm.dll:0x792e0431(0x8b515008, 0x70f0e8ce, 0x8b5ffffa, 0xc25d5ec6) ------------------------------------------------------------------------ Fatal Java Exception detected at Fri Apr 30 11:08:08 2010 ------------------------------------------------------------------------ Configuration: MATLAB Version: 7.8.0.347 (R2009a) MATLAB License: unknown Operating System: Microsoft Windows Vista Window System: Version 6.0 (Build 6002: Service Pack 2) Processor ID: x86 Family 6 Model 10 Stepping 5, GenuineIntel Virtual Machine: Java is not enabled Default Encoding: windows-1252 Java is not enabled I really have no idea what could be wrong. Is there not enough memory from the jvm? I guess the problem is somehow related to Java, since calling the JNI functions from a simple test C++ program works fine... Thanks

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  • Weblogic 10.3.0 : Loosing a stateless session bean in the bean pool

    - by KlasE
    Hi, We have a strange situation where we loose a Stateless SessionBean in a Bean Pool in Weblogic 10.3.0 Since we only have one bean in the pool, this effectively hangs all incoming calls. We do not want more than one instance in the pool because of application restrictions. In the Weblogic admin console, we can see that there are 1 instance in the bean pool, 0 beans in use and 1 waiting incoming request. The question is, what can have caused the system to not send the request to the one obviously free bean instance? This happens after several hours and over 100000 incoming requests, and the same scenario worked fine in the old weblogic 8 environment. We get the following stacktrace: "[ACTIVE] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'" waiting for lock java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject@b0d484 TIMED_WAITING sun.misc.Unsafe.park(Native Method) java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198) java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2054) weblogic.ejb.container.pool.StatelessSessionPool.waitForBean(StatelessSessionPool.java:269) weblogic.ejb.container.pool.StatelessSessionPool.getBean(StatelessSessionPool.java:111) weblogic.ejb.container.manager.StatelessManager.preInvoke(StatelessManager.java:148) weblogic.ejb.container.internal.BaseRemoteObject.preInvoke(BaseRemoteObject.java:227) weblogic.ejb.container.internal.StatelessRemoteObject.preInvoke(StatelessRemoteObject.java:52) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl.isMyStuffValid(MessageLogFacace_n73y0z_EOImpl.java:261) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl_WLSkel.invoke(Unknown Source) weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:589) weblogic.rmi.cluster.ClusterableServerRef.invoke(ClusterableServerRef.java:230) weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:477) weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:363) weblogic.security.service.SecurityManager.runAs(Unknown Source) weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:473) weblogic.rmi.internal.wls.WLSExecuteRequest.run(WLSExecuteRequest.java:118) weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) weblogic.work.ExecuteThread.run(ExecuteThread.java:173) Any help would be very welcome. Regards Klas

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  • How do I connect to a Java command-line tool with the YourKit Java Profiler?

    - by Daryl Spitzer
    I've build a command-line tool in Java, which I would now like to profile with YourKit. I launch the command-line tool with something like: $ java -classpath .:foo.bar.jar com.foobar.tools.TheTool arg1 arg2 arg3 It runs to completion in less than 2 seconds. After reading http://www.yourkit.com/docs/80/help/agent.jsp, I tried the following: $ java -agentpath:/home/dspitzer/yjp-8.0.24/bin/linux-x86-32/libyjpagent.so -classpath .:foo.bar.jar com.foobar.tools.TheTool arg1 arg2 arg3 ...and I get: [YourKit Java Profiler 8.0.24] JVMTI version 3001016d; 14.3-b01; Sun Microsystems Inc.; mixed mode, sharing; Linux; 32-bit JVM [YourKit Java Profiler 8.0.24] Profiler agent is listening on port 10001... [YourKit Java Profiler 8.0.24] *** HINT ***: To get profiling results, connect to the application from the profiler UI ... But I guess YourKit is designed to only connect to running application. How should I modify my command-line tool to allow connection from YourKit? I could add a command-line option that will have it pause for input, and I won't press return for it to continue until I've connected to it from YourKit. Is there a YourKit API that I could add to my tool that would cause it to block until I've connected with YourKit? Is there a YourKit API or a java command-line option that would create a profiling "snapshot" that I could load and analyze later (after the command-line tool has completed) with YourKit?

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  • Thread safe double buffering

    - by kdavis8
    I am trying to implement a draw map method that will draw the tiled image across the surface of the component. I'm having issue with this code. The double buffering does not seem to be working, because the sprite flickers like crazy; my source code: package myPackage; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; public class GameView extends JFrame implements Runnable { public BufferedImage backbuffer; public Graphics2D g2d; public Image img; Thread gameloop; Scene scene; public GameView() { super("Game View"); setSize(600, 600); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); backbuffer = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); Toolkit tk = Toolkit.getDefaultToolkit(); img = tk.getImage(this.getClass().getResource("cage.png")); scene = new Scene(g2d, this); gameloop = new Thread(this); gameloop.start(); } public static void main(String args[]) { new GameView(); } public void paint(Graphics g) { g.drawImage(backbuffer, 0, 0, this); repaint(); } @Override public void run() { // TODO Auto-generated method stub Thread t = Thread.currentThread(); while (t == gameloop) { scene.getScene("dirtmap"); g2d.drawImage(img, 80, 80,this![enter image description here][1]); } } private void drawScene(String string) { // TODO Auto-generated method stub // g2d.setColor(Color.white); // g2d.fillRect(0, 0, getWidth(), getHeight()); scene.getScene(string); } } package myPackage; import java.awt.Color; import java.awt.Component; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; public class Scene { Graphics g2d; Component c; boolean loaded = false; public Scene(Graphics2D gr, Component co) { g2d = gr; c = co; } public void getScene(String mapName) { Toolkit tk = Toolkit.getDefaultToolkit(); Image tile = tk.getImage(this.getClass().getResource("dirt.png")); // g2d.setColor(Color.red); for (int y = 0; y <= 18; y++) { for (int x = 0; x <= 18; x += 1) { g2d.drawImage(tile, x * 32, y * 32, c); } } loaded = true; } }

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  • Java to JavaScript (Encryption related)

    - by balexandre
    Hi guys, I'm having difficulties to get the same string in Javascript and I'm thinking that I'm doing something wrong... Java code: import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Date; import java.util.GregorianCalendar; import sun.misc.BASE64Encoder; private static String getBase64Code(String input) throws UnsupportedEncodingException, NoSuchAlgorithmException { String base64 = ""; byte[] txt = input.getBytes("UTF8"); byte[] text = new byte[txt.length+3]; text[0] = (byte)239; text[1] = (byte)187; text[2] = (byte)191; for(int i=0; i<txt.length; i++) text[i+3] = txt[i]; MessageDigest md = MessageDigest.getInstance("MD5"); md.update(text); byte digest[] = md.digest(); BASE64Encoder encoder = new BASE64Encoder(); base64 = encoder.encode(digest); return base64; } I'm trying this using Paj's MD5 script as well Farhadi Base 64 Encode script but my tests fail completely :( my code: function CalculateCredentialsSecret(type, user, pwd) { var days = days_between(new Date(), new Date(2000, 1, 1)); var str = type.toUpperCase() + user.toUpperCase() + pwd.toUpperCase() + days; var md5 = hex_md5(str); var b64 = base64Encode(md5); return encodeURIComponent(b64); } Does anyone know how can I convert this Java method into a Javascript one? Thank you Tests (for today, 3740 days after January 1st, 2000 var secret = CalculateCredentialsSecret('AAA', 'BBB', 'CCC'); // secret SHOULD be: S3GYAfGWlmrhuoNsIJF94w==

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  • Jmap can't connect to to make a dump

    - by Jasper Floor
    We have an open beta of an app which occasionally causes the heapspace to overflow. The JVM reacts by going on a permanent vacation. To analyze this I would like to peek into the memory at the point where it failed. Java does not want me to do this. The process is still in memory but it doesn't seem to be recognized as a java process. The server in question is a debian Lenny server, Java 6u14 /opt/jdk/bin# ./jmap -F -dump:format=b,file=/tmp/apidump.hprof 11175 Attaching to process ID 11175, please wait... sun.jvm.hotspot.debugger.NoSuchSymbolException: Could not find symbol "gHotSpotVMTypeEntryTypeNameOffset" in any of the known library names (libjvm.so, libjvm_g.so, gamma_g) at sun.jvm.hotspot.HotSpotTypeDataBase.lookupInProcess(HotSpotTypeDataBase.java:390) at sun.jvm.hotspot.HotSpotTypeDataBase.getLongValueFromProcess(HotSpotTypeDataBase.java:371) at sun.jvm.hotspot.HotSpotTypeDataBase.readVMTypes(HotSpotTypeDataBase.java:102) at sun.jvm.hotspot.HotSpotTypeDataBase.<init>(HotSpotTypeDataBase.java:85) at sun.jvm.hotspot.bugspot.BugSpotAgent.setupVM(BugSpotAgent.java:568) at sun.jvm.hotspot.bugspot.BugSpotAgent.go(BugSpotAgent.java:494) at sun.jvm.hotspot.bugspot.BugSpotAgent.attach(BugSpotAgent.java:332) at sun.jvm.hotspot.tools.Tool.start(Tool.java:163) at sun.jvm.hotspot.tools.HeapDumper.main(HeapDumper.java:77) 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 sun.tools.jmap.JMap.runTool(JMap.java:179) at sun.tools.jmap.JMap.main(JMap.java:110) Debugger attached successfully. sun.jvm.hotspot.tools.HeapDumper requires a java VM process/core!

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  • Not able to compile ActionScript from Java SDK

    - by Heang S.
    I was reading the Flex Compiler API User Guide at http://livedocs.adobe.com/flex/3/compilerAPI_flex3.pdf and tried to follow the example to create a Java application to compile a Flex application. Here is my program: import flex2.tools.oem.Application; import java.io.*; public class MyAppCompiler { public static void main(String[] args) { try { Application application = new Application( new File("../apps/TestApp.mxml")); application.setOutput(new File("../apps/TestApp.swf")); long result = application.build(true); if (result 0) System.out.println("Compile Success"); else System.out.println("Compile Failed"); } catch (Exception ex){ ex.printStackTrace(); } } } Unfortunately, I get "java.lang.ExceptionInInitializerError" on the very first line. Internally, the error appears to be on the following line: Exception in thread "main" java.lang.ExceptionInInitializerError at myApps.MyAppCompiler.main(MyAppCompiler.java:9) Caused by: java.lang.NullPointerException at flex2.tools.oem.Application. (Application.java:184) I am using Eclipse 3.3. However, I see the problem when I run my program either from Eclipse or from a command line. Any suggestions would be greatly appreciated.

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  • Connection reset when calling disconnect() using enterprisedt's ftp java framework

    - by Frederik Wordenskjold
    I'm having trouble disconnecting from a ftp-server, using the enterprisedt java ftp framework. I can simply not call disconnect() on a FileTransferClient object without getting an error. I do not do anything, besides connecting to the server, and then disconnecting: // create client log.info("Creating FTP client"); ftp = new FileTransferClient(); // set remote host log.info("Setting remote host"); ftp.setRemoteHost(host); ftp.setUserName(username); ftp.setPassword(password); // connect to the server log.info("Connecting to server " + host); ftp.connect(); log.info("Connected and logged in to server " + host); // Shut down client log.info("Quitting client"); ftp.disconnect(); log.info("Example complete"); When running this, the log reads: INFO [test] 28 maj 2010 16:57:20.216 : Creating FTP client INFO [test] 28 maj 2010 16:57:20.263 : Setting remote host INFO [test] 28 maj 2010 16:57:20.263 : Connecting to server x INFO [test] 28 maj 2010 16:57:20.979 : Connected and logged in to server x INFO [test] 28 maj 2010 16:57:20.979 : Quitting client ERROR [FTPControlSocket] 28 maj 2010 16:57:21.026 : Read failed ('' read so far) And the stacktrace: com.enterprisedt.net.ftp.ControlChannelIOException: Connection reset at com.enterprisedt.net.ftp.FTPControlSocket.readLine(FTPControlSocket.java:1029) at com.enterprisedt.net.ftp.FTPControlSocket.readReply(FTPControlSocket.java:1089) at com.enterprisedt.net.ftp.FTPControlSocket.sendCommand(FTPControlSocket.java:988) at com.enterprisedt.net.ftp.FTPClient.quit(FTPClient.java:4044) at com.enterprisedt.net.ftp.FileTransferClient.disconnect(FileTransferClient.java:1034) at test.main(test.java:46) It should be noted, that I without problems can connect, and do stuff with the server, like getting a list of files in the current working directory. But I cant, for some reason, disconnect! I've tried using both active and passive mode. The above example is by the way copy/pasted from their own example. I cannot fint ANYTHING related to this by doing a Google-search, so I was hoping you have any suggestions, or experience with this issue.

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