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How to use Iterator Java - Example Tutorial The Iterator is used to iterate over all elements of a Collections in Java. By Iteration, I mean, going over each element stored in the collection and optionally performing some operation like printing value of an element, updating object or removing an object from Collection. Iterator was not part of the first Java release, and a similar class Enumeration was there to provide Iteration functionality. Iterator in Java was introduced from JDK 1.4 and it provides an alternative to Enumeration, which is obsolete nowadays. An iterator is different from Enumeration in two main ways, first, Iterator allows a programmer to remove elements from Collection during iteration. Java Interview questions and tutorials Read: http://www.java67.com/2013/02/java-iterator-example.html

Java 8 Optional isPresent(), OrElse() and get() Examples The Optional class in Java is one of many goodies we have got from the Java 8 release. If you use it correctly, Optional can result in clean codeand can also help you to avoid NullPointerException which has bothered Java developers from its inception. Even though many of us have used null to indicate the absence of something, the big problem is that if you call a method or access a field on the null object (except static fields), you will get a NullPointerException and your whole program may crash. Java Interview questions and tutorials Read: http://www.java67.com/2018/06/java-8-optional-example-ispresent-orElse-get.html

Polymorphism, Overloading, and Overriding in Java and Object Oriented Programming? Polymorphism vs Overloading vs Overriding Someone asked me the other day,  what are the difference between Polymorphism and Overriding in Java and the similar difference between Polymorphism and Overloading. After explaining to him personally, I thought to write a blog post about it and here we are. Well, they are not two different things, Polymorphismis an object-oriented or OOP concept much like Abstraction, Encapsulation, or Inheritance which facilitates the use of the interface and allows Java program to take advantage of dynamic binding in Java. Polymorphism adds flexibility to your code which makes it more extensible and maintainable. Java Interview questions and tutorials Read: http://www.java67.com/2012/10/difference-between-polymorphism-overloading-overriding-java.html

Default Methods and Multiple Inheritance in Java 8 Ever since Java 8 introduced default and static methods in JDK 8, it's become possible to define non-abstract methods in interfaces. SinceJava, one class can implement multiple interfaces and because there can be concrete methods in interfaces, the diamond problem has surfaced again. What will happen if two interfaces have methods o the same name and a Java class inherit from it? Many Java programmer also asks me the question that, is Java 8 is also supporting multiple inheritancesof classes? Well, it's not but the doubt is genuine because the interface with methods is similar to an abstract class or in that any Class in Java. Java Interview questions and tutorials Read: http://www.java67.com/2017/08/default-methods-in-interface-multiple.html

Top 10 OCAJP and OCPJP Exam Simulators and Practice Test for Java Certifications There is no doubt that exam simulators play an essential role in preparing for any Java certification like OCAJP, OCPJP, OCEJWCD, OCMJEA exams. In fact, they are one of the most crucial pillars because choosing a good exam simulator with a good book is generally the success mantra of many Java certification aspirants. The exam simulators prepare you well for exams by presenting the level of questions you can expect in real exams. They provide the much-needed practice in the exam like environment to increase your speed and accuracy required to pass a time-bound exam like OCAJP and OCPJP. It also helps you to find out your strong and weak areas well before the exam, so that you can focus more on weak areas. Java Interview questions and tutorials Read: http://www.java67.com/2017/03/top-10-ocajp-and-ocpjp-exam-simulators.html

Top 21 String Programming and Coding Interview Questions With Solutions In this article, I am going to share 21 of the most common String-based Programming and Coding interview questions from Java developer interviews. These questions require you to write code to solve the problem and they are different from traditional Java String questions like how the substring method works in Java or when to use the intern() method of String in Java? Since coding and problem solving are an important part of any programming job interview, it's imperative that you know how to solve them in time and in a pressure situation, which comes only after doing practice with the right set of questions. Since these questions are already tried and tested and appeared in many interviews, they will provide you the experience you need to crack your coding interview. Java Interview questions and tutorials Read: http://www.java67.com/2018/04/21-string-programming-and-coding-interview-questions-answers.html

Top 10 Free Python Programming Books - Download PDF or Read Online Every Programmer loves free eBook and free courses, even more, if it comes from renowned technical book publishers like Oreilly and Manning. In the last article, I have shared some of the best free Java programming books, and today I am going to share some of the equally best free Python Programming books. These books are not illegal copies that are uploaded into the internet, but they are legal books, made free by their authors and publishers, much like free Udemy courses, which their instructor made free for educational and promotional reasons. Though these are not full-fledged books but concise eBooks, they are very informative and comprehensive enough to learn things like Data Science and Functional programming in Python. Java Interview questions and tutorials Read: http://www.java67.com/2017/05/top-7-free-python-programming-books-pdf-online-download.html

Book Review Effective Java 3rd Edition by Joshua Bloch – A Must Read Book for Java Developers Hello guys, you might have heard about Effective Java, one of the most recommended books for Java programmers. This is one of those books which every Java developer wants to read because it will not teach you syntax but how and when to use a particular feature. After the huge success of Effective Java 1st Edition and 2nd Edition, the 3rd edition of Effective Java released a couple of years ago.  After 10 years of long wait by Java programmers from all over the world, finally, an updated version of, probably, the most popular Java book on the planet is released and I am going to talk about this new version of Effective Java, I mean Effective Java 3rd Editionin this article and share my thought that why its a must-read book for every Java developer around the world. Java Interview questions and tutorials Read: http://www.java67.com/2018/01/effective-java-3rd-edition-by-joshua-bloch-must-read-book-for-java-develoeprs.html

Top 5 Books to learn Scrum, Sprint, and Agile in 2023 - Best of Lot Hello guys, Are you a senior Java developer who wants to become a Scrum Master to advance in your career? Well, at this time, a person needs to wear many hats for job security. You not only have to perform your duty as a Software developer, I mean coding and debugging, but also need to support your application as Level 2 or Level 3 Support. You also need to wear a project management or product development hat, which involves talking to stakeholders and clients. If this is not enough, you may need to play the role of Scrum master in your daily Scrum meeting and drive your Sprint review and Sprint planning meeting. To do all these, you must understand Agile methodologies and how the process works. Java Interview questions and tutorials Read: http://www.java67.com/2020/06/top-5-books-to-become-scrum-master-in.html

Top 10 REST API, Microservices, and RESTful Web Services Book for Java Web Developers In recent years, REST has become the standard style for developing web services, also known as RESTful Web Services. These web services take advantage of REST principles, which leverages all goodness of HTTP to provide scalable and robust web services. As a Java Web developer, it's high time that you get familiar with the REST concepts and the REST style of developing web services in Java, also known as RESTful web services, and nothing is better than to start with a good book. I often receive a request about which book should I read to learn REST? Or what are some best books to learn to develop RESTful Web services in Java, etc.? In this article, I will suggest some books which will teach you both designing a REST API and developing RESTful web services in Java. Java Interview questions and tutorials Read: http://www.java67.com/2017/06/top-10-rest-api-and-restful-web-services-book.html

10 Examples of Collectors + Stream in Java 8 - groupingBy(), toList(), toMap() As the name suggests, the Collectors class is used to collect elements of a Stream into Collection. It acts as abridge between Stream and Collection, and you can use it to convert a Stream into different types of collections like List, Set, Map in Java using Collectors' toList(), toSet(), and toMap() method. Btw, Collector is not just limited to collection stream pipeline results into various collection class, it even provides functionalities to join String, group by, partition by, and several other reduction operators to return a meaningful result. It's often used along with the collect() method of Stream class which accepts Collectors. In this article, you will learn how to effectively use java.util.stream.Collectors in Java by following some hands-on examples. Java Interview questions and tutorials Read: http://www.java67.com/2018/11/10-examples-of-collectors-in-java-8.html

Difference between @Component, @Controller, @Service, and @Repository in Spring Hello guys if you are wondering what is the difference between @Component, @Controller, @Service, and @Reposistory annotation in Spring Framework then you have come to the right place. In the past, I have shared 15 Spring Boot Interview Questions and 30 Spring MVC questions and in this article, I am going to answer the fundamental and popular Spring questions about @Component, @Controller, @Service, and @Repository annotation, but before we go into differences, let's understand the similarity first. Java Interview questions and tutorials Read: http://www.java67.com/2022/06/difference-between-component-service-repository-in-spring.html

How to use Spliterator in Java 8 - Example Tutorial Hello friends, we are here today again on the journey of Java. And today, we are gonna learn about SplitIterator class from Stream package that may not be used in your day-to-day life but can be very useful to know as Java internally does use this with both normal streams and parallel streams. As always, let’s take an example of a situation. I will present you with a situation and you guys can think about it. So, let’s say we have an array with 50k records in it. Now, these all records need to be modified, let’s say they are strings and we need to append the string with a name. Now, traversing the array sequentially would be time-consuming. Any innovative ideas my friends? Java Interview questions and tutorials Read: http://www.java67.com/2021/11/how-to-use-spliterator-in-java-8.html

What is Circuit Breaker Design Pattern in Microservices? How to implement it? Hello guys, Microservices design patterns are very important concepts for Java developers to learn, not just to create a robust, scalable, and high-performance Microservice architecture but also to do well on Java developer interviews. In the past, I have shared several Microservices design patterns like e Event Sourcing, SAGA, Database Per Microservices, CQRS, API Gateway, and also shared best practices to design Microservices and in this article, I am going to talk about Circuit-Breaker Design Pattern, and how you can implement in Java using Spring Cloud Framework.  This is not just an important Microservice Pattern but also a popular Microservice question which I have also mentioned earlier in my article about 15 Microservices questions for Interviews. If you haven't read that article yet, I suggest read it, especially if you are preparing for Java and Microservice interviews. Java Interview questions and tutorials Read: http://www.java67.com/2023/04/what-is-circuit-breaker-design-pattern.html

JEP 444: Virtual Threads Arrive in JDK 21, Ushering a New Era of Concurrency JEP 444, Virtual Threads, was promoted from Candidate to Proposed to Target status for JDK 21. This feature offers a lightweight threading model to simplify the creation, management, and monitoring of high-throughput concurrent Java applications, allowing developers to efficiently handle millions of tasks and make better use of system resources. By A N M Bazlur Rahman Read: https://www.infoq.com/news/2023/04/virtual-threads-arrives-jdk21/

Строка на 1,5 гигабайта На своей предыдущей работе я занимался поддержкой Java-сервиса, обеспечивавшего удалённую функциональность UI подобно RDP или Citrix. Этот сервис был устроен на основе сессий, состоявших из взаимосвязанных объектов Java, которые должны были очищаться или после выхода пользователя, или после истечения заданного таймаута. На этапе планирования нагрузок мы обнаружили существенные траты памяти, о причинах которых я бы хотел рассказать в этой статье. Читать: https://habr.com/ru/articles/727854/?utm_campaign=727854

18 Spring Cloud Features for Microservices Architecture in Java? Hello guys, If you are doing Java development using Spring Boot then you may already know that Spring Cloud is a popular open-source framework for implementing microservices in Java. It provides a wide range of features that simplify the development, deployment, and management of microservices in Java. In this article, we will discuss some of the key features of the Spring Cloud framework that makes it an excellent framework for developing Microservices in Java. Microservices architecture is a modern approach to building complex applications as a collection of loosely coupled, independently deployable services. In this article, you will learn about the features that Spring Cloud framework offers to implement microservices in Java. This includes capabilities such as service discovery and registration, load balancing, circuit breaking, distributed configuration management, centralized logging, API gateway, security, and monitoring. Java Interview questions and tutorials Read: http://www.java67.com/2023/04/spring-cloud-features-for-microservices.html