Чашечка Java

К микросервисам через reverse engineering и кодогенерацию Разрабатывая информационную систему с нуля, мы можем выбрать практически любой вариант технологии и архитектуры в целом, в том числе — принцип взаимодействия частей системы. Но что делать, если система уже есть и у неё довольно богатая история? Как большую энтерпрайз систему, которая развивалась в режиме монолита, разделить на микросервисы и организовать взаимодействие между ними? Часто основная сложность заключается в том, что нужно одновременно поддерживать уже существующий код монолита и параллельно внедрять новые принципы и подходы.  В статье я расскажу, как мы в Wrike, используя reverse engineering и немного кодогенерации, реализовали первые шаги по выделению отдельных микросервисов и запустили первый «почти настоящий» BFF-сервис в рамках нашего монолита. Читать: https://habr.com/ru/post/678208/?utm_campaign=678208

В «Магните» работает 4000 разработчиков и ИТ инженеров, они решают интересные и амбициозные задачи, делая жизнь покупателя одного из крупнейших ритейлеров России технологичнее и удобнее. 27 июля в 13:00 (МСК) стартует Magnit IT Demo Day, где разработчики «Магнита» расскажут: - про мультиоблачную архитектуру - про корпоративную платформу сбора и анализа данных на 1 Петабайт - как они строят свой облачный Data Lake - про предикативные модели пути покупателя - BI-алгоритм отслеживания тысяч критических параметров - про гипергранулированную сегментацию аудиторий Не пропустите! Зарегистрируйтесь на эфир, и вам придёт напоминалка 27 июля в 13:00 (МСК), а еще там будет куча интересных дополнительных материалов: https://magn-it.online Это #партнёрский пост

Считаем уникальные IPv4 адреса Как создавать быстрые и эффективные алгоритмы? В статье, на примере задачи по подсчёту уникальных IPv4 адресов, рассматриваются приёмы и методы обработки больших объёмов данных. Вы узнаете, как написать код, работающий в десятки раз быстрее и использующий в несколько десятков раз меньше памяти, чем "наивные" алгоритмы. Читать: https://habr.com/ru/post/679008/?utm_campaign=679008

How to send Email with Body and Attachment from Linux Machine? mutt and mailx command Example One of the common tasks for programmers working in a Linux machine is to send emails and transfer files from Linux machine to Windows machine. While there are utilities like WinSCP which you can use to transfer files between Windows and Linux machine, I generally found using mailx command much easier, especially when you don't have WinSCP or any other utility. But, apart from transferring files between Linux and Windows, there are many more scenarios where you need to send emails from Linux machine, for example, your Java applications are running on Linux like RHEL 5 or RHEL 6 version and you need to send a report of all the clients connecting to your application. Java Interview questions and tutorials Read: http://www.java67.com/2018/01/4-examples-to-send-email-with.html

Top 15 UNIX and Linux Interview Questions Answers for 1to 3 Years Experienced UNIX and Linux Interview Questions and Answers Hello guys, if you are preparing for technical interviews like Software developer or IT support and looking for some frequently asked Linux and UNIX interview questions then you have come to the right place. In the past, I have shared free Linux courses and today, I am going to share popular Linux and UNIX questions from technical interviews. You might already know that questions from various UNIX operating systems like Solaris, Linux, IBM AIX, or any other UNIX operating system are asked on different support and programming interviews and a good knowledge of essential UNIX concepts and commands goes a long way in cracking these interview as well as working efficiently in your day job. Java Interview questions and tutorials Read: http://www.java67.com/2012/09/10-linux-and-unix-interview-questions-answers-wipro-tcs-capegemini.html

How to set JAVA_HOME and PATH in Linux? Example Hello guys, welcome to the world of Java application programming. One of the hardest things to mater is not any feature but environment-specific details which nobody teaches. To bridge that gap, I am going to cover a couple of very important environment variables like PATH and JAVA_HOME.  The JAVA_HOMEenvironment variable points to the JDK installation directory and is used by many Java tools and applications like Tomcat, Maven, Eclipse, NetBeans or IntelliJIDEA, etc. to figure out Java executables as they need Java for running. Java Interview questions and tutorials Read: http://www.java67.com/2016/06/how-to-set-javahome-and-path-in-linux.html

How to backup and load Cron Jobs from a File in Linux and UNIX? Crontab Command Example Hello guys, If you have been using Linux for some time then you might know about cron jobs. They are the scheduler that can be used to automatically start processes in a Linux box. I have worked on many projects which used cron jobs to start the Java process and environment daily or weekly basis. They are similar to Autosys when it comes to scheduling jobs but cron is a Linux command as opposed to Autosys which is a separate application altogether. In Linux, the crontab command is used for scheduling and automating jobs or processes. You can also use it for loading cron jobs from a file, listing existing cron entries, and editing them. It manages the cron tablethat is used by the cron daemon in Linux to execute the cron jobs. Java Interview questions and tutorials Read: http://www.java67.com/2017/08/how-to-backup-and-load-crontab-from-file-Linux-example.html

How to find swap space and usage in Solaris? Swap Command Example Swap space in Solarisor any UNIX host is a vital disk space that is used for the swapping process from physical memory (RAM) to disk. Virtual memory allows a process to run even if physical memory gets full by using swap space(which is located on your hard disk) to swap out memory pages that are not currently in use. This is a very important concept which every programmer and Linux user should know. It is even more important if you are working in IT support or as a system admin because if swap space is full then swapping will fail and no new process will be able to start. Java Interview questions and tutorials Read: http://www.java67.com/2012/10/how-to-find-swap-space-and-usage-Solaris-UNIX-Linux.html

How to send Logging Messages to SysLog using Log4j2 SysLogAppender in Linux ? Java Example Sometimes you may want to route your log messages to Syslog in UNIX-based environment like Linux. Since logger allows multiple appenders, you can print the same log messages to a log file, console, and route it to Syslog at the same time. In order to send log messages to Syslog using log4j2, you need to make some changes in your log4j2.xml file. This change is to include the Syslog appender and configure that, once you do that you also need to enable TCP or UDP reception by editing rsyslog.conf file. For faster transmission you can choose UDP protocol and configure a port number on which your Syslog is listening, In our example, Syslog is listening on port 618. Let's see the complete step-by-step guide to configure Syslog logging in log4j logger. Java Interview questions and tutorials Read: http://www.java67.com/2020/04/how-to-send-logger-messages-to-syslog-using-log4j-java-linux.html

5 Ways to implement Singleton Design Pattern in Java? Examples Hello guys, While Singleton is anti pattern nowadays and dependency injection is better choice as it helps unit testing, its good to know about Singleton pattern, especially if you are in the business of maintaining large and old code base. This article introduces the singleton design pattern and its 5 implementation variations in Java. You will learn different ways to implement a singleton pattern and understand the challenges of creating a singleton class, like thread-safety issues and serialization issues. Java Interview questions and tutorials Read: http://www.java67.com/2020/05/5-ways-to-implement-singleton-design.html

How to use Strategy Design Pattern in Java? Example Tutorial Hello guys, you might have heard about it, Can you tell me any design pattern which you have used recently in your project, except Singleton? This is one of the popular questions from various Java interviews in recent years. I think this actually motivated many Java programmers to explore more design patterns and actually look at the original 23 patterns introduced by GOF. The Strategy design pattern is one of the useful patterns you can mention while answering such a question. It's very popular, and there are lots of real-world scenarios where the Strategy pattern is very handy. Java Interview questions and tutorials Read: http://www.java67.com/2014/12/strategy-pattern-in-java-with-example.html

Top 18 Java Design Pattern Interview Questions Answers for Experienced Design pattern interview question in Java Hello guys, if you are preparing for Java interviews and looking for frequently asked design pattern interview questions then you have come to the right place. In the past, I have shared the best courses for Java interviews, and today, I am going to share popular design pattern questions from Java interviews. You can use these questions to both practices and check your knowledge about OOP design patterns. Both OOP and GOF design pattern interview questions are an integral part of any good list of core Java interview questions. Java is a popular Object-oriented programming language and has lots of design patterns and design principles, contributed by many developers and open-source frameworks. Java Interview questions and tutorials Read: http://www.java67.com/2012/09/top-10-java-design-pattern-interview-question-answer.html

Нормализуем логи OpenFeign Стандартный логгер OpenFeign предоставляет весьма неудобный подход в логировании коммуникаций — он записывает запрос отдельно от ответа, причём каждый заголовок и тело - это отдельная строка логов. Очень неудобно разбирать такие логи в приложении с высоким уровнем коммуникаций, особенно в многопоточной среде. Решение ‘Normalized Logger’ нацелено исправить этот изъян - этот логгер собирает в одну запись будущего лога запрос и ответ - теперь они не будут разбросаны. Читать: https://habr.com/ru/post/678916/?utm_campaign=678916

How to Calculate Compound Interest in Java? Example Tutorial Calculating simple interest or compound interest are common coding problem which are taught in schools and colleges to teach you coding. The best thing about these coding exercise in Java are that everybody are familiar with them so you know the concept already and all you need to do is convert that solution into code which is the skill needed to become a coder or programmer. If you remember your primary Maths classes then you would know that formula to calculate compound interest depends upon three things principle, rate, number of times interest is compounded per year, and time. This means you need to write a function which will accept these three data as parameters or method arguments. Java Interview questions and tutorials Read: http://www.java67.com/2022/07/compound-interest-in-java-example.html

Освой востребованную профессию Java-разработчика с нуля за 3 месяца! OTUS запускает буткемп «Java Developer» Буткемп «Java Developer» от OTUS — это онлайн-курс с ментором, методика ускоренного обучения, построенная на ежедневных вебинарах с ведущими специалистами престижных IT-компаний. А еще много-много практики. После обучения у вас будет достаточно навыков, чтобы претендовать на среднюю по рынку зарплату в 105 тысяч рублей. Оставьте заявку, чтобы присоединиться к группе по спец.цене: https://otus.pw/Cumq/ Хотите протестировать процесс обучения заранее? Тогда приходите на бесплатные открытые уроки 08 августа в 20:00 - "Структура программы на Java. Примитивные типы." 22 августа в 20:00 - "Элементы формальной логики. Базовые структуры данных в языке Java." Это #партнёрский пост

Top 5 Object Oriented Analysis and Design Interview Questions for Programmers, Software Engineers Testing the design skill of a candidate is quite common in programming job interviews. Questions like, how do you design a vending machine or a traffic control system are very popular in object-oriented programming language interviews, like Java and C++. Designing a software System requires good experience and knowledge of tools of object-oriented design and analysis. You should not only be good at OOP fundamentals like Abstraction, Inheritance, Polymorphism, Encapsulation, Coupling, Cohesion, Association, Aggregation, or Composition but also on several crucial object-oriented design principles like SOLID Principles of Object-Oriented Design, which is the building block for writing flexible and maintainable code. Java Interview questions and tutorials Read: http://www.java67.com/2016/07/top-5-object-oriented-design-interview-questions.html

Java News Roundup: JDK 19 in RDP2, Oracle Critical Patch Update, TornadoVM on M1, Grails CVE This week's Java roundup for July 18th, 2022, features news from Oracle, JDK 18, JDK 19, JDK 20, Spring Boot and Spring Security milestone and point releases, Spring for GraphQL 1.0.1, Liberica JDK updates, Quarkus 2.10.3, CVE in Grails, JobRunr 5.1.6, JReleaser maintenance, Apache Tomcat 9.0.65 and 10.1.0-M17, Tornado VM on Apple M1 and the JBNC conference. By Michael Redlich Read: https://www.infoq.com/news/2022/07/java-news-roundup-jul18-2022/

How to create a thread-safe Singleton in Java using Enum [Example] Hello guys, the Singleton pattern in Java is used to create a Singleton class that is accessed by a single instance though out the Java program life cycle. Singleton is one of the old but very useful design patterns and used in several core Java libraries including Java Development Kit (JDK); java.lang.Runtime is an example of a Singleton pattern in Java. This class represents a single instance of Java environment running as JVM and provides several utility methods to query important details about runtime like a number of available processors, Java heap memory, etc. Java Interview questions and tutorials Read: http://www.java67.com/2021/05/singleton-in-java-using-enum-example.html

Top 50 Microsoft Software Development Engineer Interview Questions Hello guys, if you are preparing for Microsoft Software Development Engineer interview or in general preparing for FAANG coding interviews and looking for common interview questions for practice then you have come to the right place. Earlier, I have shared best Coding interview courses and books and in this article, I am going to share you some of the frequently asked questions from Microsoft. Most of the things depending upon for which position you are going like technical analyst, software engineer, Java developer, web developer or internship. If you have a computer science degree and if your job involves coding then you can expect following questions, which are mainly collected from engineers who has appeared on on and off campus interviews. Java Interview questions and tutorials Read: http://www.java67.com/2022/07/top-50-microsoft-software-development.html

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