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Kurssi: Tietojenkäsittelytieteiden perusopinnot 2012-2013
Tracing and Logging includes the following topics: Tracing Tracing is a facility to redirect any output in the Java Console to a trace file. Java Plug-in Tracing can be turned on by enabling the property javaplugin.trace. 0 — off 1 — basic 2 — network, cache, and basic 3 — security, network and basic 4 — extension, security, network and basic 5 — LiveConnect, extension, security, network, temp, and basic This enables tracing on the fly. Another way to set fine-grained tracing is through the Java Control Panel. -Djavaplugin.trace=true -Djavaplugin.trace.option=basic|net|cache|security|ext|liveconnect|temp Tracing set through the Control Panel will take effect when the Plug-in is launched, but changes made through the Control Panel while a Plug-in is running will have no effect until restart. Java Web Start To set the initial trace level for a Java Web Start application, you can create a .javawsrc file in either your home directory or the jre/bin directory. Logging -Djavaplugin.logging=true Java Linux => Tracing and Logging Java Linux => Tracing and Logging
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7 New Tools Java Developers Should Know 7 New Tools Java Developers Should Know JClarity – Performance Monitoring Launched last September, JClarity is now offering two products around Java performance: Illuminate and Censum. Illuminate is a performance monitoring tool, while Censum is an application focused on garbage collection logs analysis. More than just collecting data or visualizing it, both tools provide actionable insights to solve the issues they detect. “What we want to do is to move the problem from data collection to data analysis and insight” – JClarity Co-Founder Ben Evans. Key features: Bottleneck detection (Disk I/O, Garbage Collection, Deadlocks, and more).Action plan – Recommendations to solve the problem, such as “The application needs to increase the number of active threads”.Explanation – Defining the problem in general and the common causes for it, for example “A high percentage of time spent paused in GC may mean that the heap has been under-sized”. Bintray – Social Platform for Binaries Librato – Monitoring & Visualization Cloud Services
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XMPP IM with Smack for Java applications – Infrastructure for Instant Messaging XMPP IM with Smack for Java applications – Infrastructure for Instant Messaging This tutorial is the third part of the “Setting up an infrastructure for Instant Messaging” article series. In my previous tutorials, I showed you how to setup the Openfire IM Server and how to configure the Spark client in order to connect to that server. In this tutorial, I will show you how to add XMPP messaging capabilities to your own application. I will use the Smack library, an Open Source XMPP (Jabber) client library for instant messaging and presence. Smack is a pure Java library and can be embedded into your applications to create anything from a full XMPP client to simple XMPP integrations. XMPP is a simple XML protocol. First download the library from the Ignite Realtime site. Create a new Eclipse project, let’s say under the name “XMPPProject”, and add the “smack.jar” and “smackx.jar” files into your classpath. The main class that your client will use is XMPPConnection. From a valid XMPPConnection, you can retrieve a ChatManager object. That’s all! Happy coding!!!
Размещение объектов в оперативной памяти. Понятие указателя Автор: Костарев Александр НиколаевичИсточник: RSDN Magazine #2-2010 Опубликовано: 03.01.2011Версия текста: 1.1 Я думаю, что некоторые крупнейшие ошибки— даже на самых верхних уровнях архитектуры —происходят из-за слабого или неверного пониманиянекоторых простых вещей на самых нижних уровнях.Джоэл Спольски Язык C++ по меркам сегодняшнего дня является языком программирования относительно низкого уровня. В частности, он не берёт на себя в полной мере управление таким важным ресурсом компьютера, как оперативная память. Знание основ управления памятью будет полезным и при использовании других языков программирования. Оперативная память С точки зрения разработчика программного обеспечения оперативная память представляет собой упорядоченную последовательность ячеек — байт, предназначенных для размещения данных, которыми оперирует программа во время своего выполнения. Упорядоченность означает, что каждый элемент последовательности (каждая ячейка памяти) имеет свой порядковый номер. Рис. 1. Рис. 2. Размещение объектов в оперативной памяти. Понятие указателя
Виртуальная машина Java Типы данных, с которыми работает JVM, подразделяются на примитивные и ссылочные. Большинство примитивных типов данных JVM являются также примитивными типами в языке Java. К ним относятся: byte - 1-байтное целое со знаком; short - 2-байтное целое со знаком; int - 4-байтное целое со знаком; ong - 8-байтное целое со знаком; float - 4-байтное число с плавающей точкой; double - 8-байтное число с плавающей точкой; char - 2-байтный символ Unicode. В отличие от других языков программирования, размеры типов в языке Java и в JVM являются постоянными, не зависящими от платформы. JVM не оперирует типом boolean, являющимся примитивным типом языка Java. Примитивный тип returnAddress в JVM не имеет соответствия в языке Java. Ссылочные типы в JVM и в языке Java являются ссылками (указателями) на объекты - экземпляры классов, массивы и интерфейсы (экземпляры классов, реализующих интерфейсы). JVM поддерживает параллельное выполнение нескольких нитей (потоков). Внутреннее представление Java-программы Внутреннее представление Java-программы
Модель памяти в виртуальной Java-машине: Permanent Generation - Доступный профессиональный хостинг. PHP/Perl/CGI/MySQL хостинг, Java-хостинг, JSP-хостинг, выделенная JVM, выделенный Tomcat, аренда выделенных серверов. Модель памяти в виртуальной Java-машине: Permanent Generation - Доступный профессиональный хостинг. PHP/Perl/CGI/MySQL хостинг, Java-хостинг, JSP-хостинг, выделенная JVM, выделенный Tomcat, аренда выделенных серверов. Модель памяти в виртуальной Java-машине: Permanent Generation Данная статья содержит сведения о модели памяти для Java версии ниже 1.8.x. Начиная с версии Java 1.8.0, область PermanentGeneration отсутствует. Вместо нее введена новая область памяти Metaspace. В службу технической поддержки нашей компании от новых клиентов часто поступают вопросы, связанные с использованием памяти, которая выделяется для JVM по тому или иному тарифному плану. Как правило, покупается минимальный тарифный план "Beginner" с 50 Мб для JVM, и идет попытка разместить в них, например, каркас для разработки приложений Spring или Cocoon. Все знают, что в Java имеется, так называемая "куча" ("heap"), в которой создаются и живут объекты Ваших приложений. Куча делится на три области: Eden Space (heap): область, в которой размещается большинство вновь созданных объектов. Eden и Survivor составляют, так называемую, Young Generation область. Есть также область памяти, которая не относится к "куче" (non-heap) Ресурсы
Java Solutions

Java outsourcing is Pandora box, Open carefully | Web Development Solutions Java outsourcing is Pandora box, Open carefully | Web Development Solutions Today, Java is taken as most popular platform for software and web development. If you have also selected Java for your organization then you have taken the right decision. This is an ultra-modern programming available with best security standards. It is possible to create user friendly and flexible website with Java programming language. It is usually observed that small scale organizations are using Java language for website designing. Java websites are safe and technically sounds very good. • Define the problem clearly For developing a professional Java website, prepare all the requirements clearly. The best idea is to make proper research and prepare paper document to note down the details. • Be innovative Think out of the box and share these innovative ideas with the Java professionals. • Communication through Apps There are plenty of web apps that can be used for healthy web communication with colleagues and business associates. • Be Fast
Every year, few of the Java web development and Java J2EE development teams fall into traps due to lack of familiarity with language. In this blog, we will discuss on some of the popular Java pitfalls that will help you in practicing best Java habits and how to avoid problems as soon as they are detected Expecting too much from JLayeredPane While working on user interface layer, you should not completely rely on JLayeredPane. Visiting a vector is always tough If you would look around Enumerator classes and its implementation then its behavior is completely different from iterator classes. When boolen value is returned then it does not give much information on cause of failure. The other issue is attempting use of File object when rename() has already been defined successfully. The third issue is that File.rename() function works differently on different operating systems. Experience is always best defense against Java Web Development pitfalls - Technology News & Updates Experience is always best defense against Java Web Development pitfalls - Technology News & Updates
Passion to excel makes our Java Development India team a force to reckon with in today’s fast-changing technology world. At Technoligent, Java Outsourcing is our forte and with a highly efficient Java Development team like ours, you are guaranteed long-term excellence in business. With over 100+ Java development projects successfully delivered, we are positioned as a trusted Java Development Company with all our clients – all over the world. Our Java outsourcing model is simple and easy to implement for clients. Java Development Team With decades of experience in Java application development in 100+ projects with clients on diverse requirements, at Technoligent, we are adept at handling all kinds of mission-critical projects requiring Java competency. We have expertise in all the latest Java frameworks and technologies – J2EE, Swing, JSON, GWT, and Struts – among others. Want to learn more about our popular Java Development solutions? Technoligent’s Service highlights: Java application development – Specifying Class contracts to avoid guesswork Java application development – Specifying Class contracts to avoid guesswork
Why India is a hot spot to Hire Senior Java developers? - Techniblogic Why India is a hot spot to Hire Senior Java developers? - Techniblogic There was a time when India was regarded as a country of snake charmers and Indian women were only supposed to look after household duties. Times have changed, India has become urbanised and there is a greater emphasis on education and career. I feel very proud in saying that when it comes to Technology and especially information technology India is not only catering to its own country but also to the rest of the world. According to a recent study, it was found that India currently has more than 7000 IT service providers and the industry is in full swing and is projected to grow at continuous 40% for the next decade. Many big IT companies hire Senior Java developers from various parts of the country, train them and outsource them for onsite projects. Java is one of the most widely used languages for software development. When it comes to Hiring Senior Java developers following are few of the things which need to be kept in mind
Java Developers

Today with the advent of internet ,world has become a global village, distance and time do not seem to be barriers unlike in older times when people were willing to wait for years to get anything revolutionized. Now days’ time is money. If you can value time you would be able to make more and more money. This holds true for both services as well as product. Before liberalization of the Indian economy ,the local resources where only given an opportunity to work for the Indian companies and Indian companies where withheld to provide services to only local or domestic vendors, however after 1991 the borders are open for both the software professionals as well as the vendors. The above greatly holds true to Senior Java Developer. How liberalization of Indian economy proved to be a boon for Senior Java Developers - James Blog | Learn Perfect to Develop Advanced
Java developers using forEach and lambda expression in Java 8 | Techno FAQ Coding Published on October 26th, 2016 | by Guest In this post, experts will explain the features of Java 8 update in detail. Java 8 has got lambda expressions support, which is considered to be the best feature of Java 8. In java 8 the forEach loop of iteration is little bit change with the addition of lambda expression as compare to java 7. As we know that lambda expression is new stuff in Java 8 and in this post, we will describe how to use in forEach loop of List and Map. Following example is describing iterating loop using normal way and using lambda expression of collection Map. Normal way: Using Lambda expression: Now we will see how lambda is use in collection List: Normal Way: Normal Way: public static void main(String args[]){ List<Integer> list = new ArrayList<Integer>(0); for(int i=0; i< 15; i++){ list.add(i); } list.forEach(value->System.out.println(value)); } Filtering particular value is also one of the important parts in Collection. In Map Collection: Author bio: About the Author
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Hinweis: Der Einstellungs-Manager, den Sie oben sehen, ist kein Bild, sondern der Einstellungs-Manager selbst. Klicken Sie auf die Registerkarten, um die einzelnen Bedienfelder anzuzeigen, und auf die Optionen in den Bedienfeldern, um die Einstellungen für Adobe Flash Player zu ändern. Manchmal versuchen Websites, Informationen auf Ihrem Rechner zu speichern, wie etwa Ihren höchsten Punktestand bei einem Spiel in Flash Player oder welche Produkte Sie erworben haben. Im Bedienfeld „Globale Speichereinstellungen“ können Sie festlegen, wie viel Speicherplatz Websites zum Speichern solcher Daten verwenden dürfen. Außerdem können Sie verhindern, dass Informationen überhaupt gespeichert werden. In diesem Bedienfeld legen Sie die Standard-Speichereinstellungen für Websites fest, die Sie noch nicht besucht haben. Eine Übersicht über verschiedene Aspekte des Speichers finden Sie unter Was sind Speichereinstellungen? Adobe - Flash Player: Einstellungs-Manager 03 - Globale Speichereinstellungen
Adobe - Flash Player: Einstellungsmanager 02 - Globale Zugriffsschutzeinstellungen Hinweis: Der Einstellungsmanager, den Sie oben sehen, ist kein Bild, sondern der Einstellungsmanager selbst. Klicken Sie auf die Registerkarten, um die einzelnen Bedienfelder anzuzeigen, und auf die Optionen in den Bedienfeldern, um die Einstellungen für Adobe Flash Player zu ändern. Öffnen Sie dieses Bedienfeld, um die Zugriffsschutzeinstellungen in Flash Player neu festzulegen: Wenn Sie „Immer verweigern“ auswählen und diese Auswahl bestätigen, wird jeder Website, die Ihre Kamera oder Ihr Mikrofon verwenden möchte, der Zugriff verweigert. Wenn Sie zuvor im Bedienfeld Zugriffsschutzeinstellungen die Option „Speichern“ ausgewählt haben, um für eine oder mehrere Websites den Zugriff permanent zuzulassen bzw. zu verweigern, und jetzt die Option „Immer fragen“ bzw. Nachdem Sie die Option „Immer fragen“ bzw. Eine Übersicht über verschiedene Aspekte des Zugriffsschutzes finden Sie unter Was sind Zugriffsschutzeinstellungen?
Java interview

Java Classloader - Wikipedia When the JVM is started, three class loaders are used:[3][4] Bootstrap class loaderExtensions class loaderSystem class loader The bootstrap class loader loads the core Java libraries[5] located in the <JAVA_HOME>/jre/lib directory. The extensions class loader loads the code in the extensions directories (<JAVA_HOME>/jre/lib/ext,[6] or any other directory specified by the java.ext.dirs system property). User-defined class loaders[edit] The Java class loader is written in Java. This makes it possible (for example): to load or unload classes at runtime (for example to load libraries dynamically at runtime, even from an HTTP resource). Class Loaders in Java EE[edit] JAR hell[edit] JAR hell is a term similar to DLL hell used to describe all the various ways in which the classloading process can end up not working.[9] Three ways JAR hell can occur are: Accidental presence of two different versions of a library installed on a system. See also[edit] References[edit] External links[edit]
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