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Справочник по Java Collections Framework 

Данная публикация не является полным разбором или анализом (не покрывает пакет java.util.concurrent). Это, скорее, справочник, который поможет начинающим разработчикам понять ключевые отличия одних коллекций от других, а более опытным разработчикам просто освежить материал в памяти.

Что такое Java Collections Framework?

Java Collection Framework — иерархия интерфейсов и их реализаций, которая является частью JDK и позволяет разработчику пользоваться большим количесвом структур данных из «коробки».

Базовые понятия

На вершине иерархии в Java Collection Framework располагаются 2 интерфейса: Collection и Map. Эти интерфейсы разделяют все коллекции, входящие во фреймворк на две части по типу хранения данных: простые последовательные наборы элементов и наборы пар «ключ — значение» (словари).

image

Collection — этот интерфейс находится в составе JDK c версии 1.2 и определяет основные методы работы с простыми наборами элементов, которые будут общими для всех его реализаций (например size(), isEmpty(), add(E e) и др.). Интерфейс был слегка доработан с приходом дженериков в Java 1.5. Так же в версии Java 8 было добавлено несколько новых метода для работы с лямбдами (такие как stream(), parallelStream(), removeIf(Predicate<? super E> filter) и др.).

Writing feedback to colleague. Useful phrases, links.

Now working in this big 1000+ employee company, so we are required to write feedbacks to each other every half of year. Here is my collection of links to useful phrases where you can pick up on some nice smart words, so this “Bill is cool” can become something like “Bill establishes effective working relationships”.

Here it goes:
1) SAMPLE PERFORMANCE COMMENTS
2) 100 USEFUL PHRASES FOR PERFORMANCE REVIEWS
3) 240+ Performance Evaluation Phrases – Sample Performance Review Statements
4) 94 Example Performance Review Phrases and Comments for Skills and Competencies

Gonna put some of them beneath, just in case these sites will go down in future.

READ MORE if you are not scared of A LOT OF TEXT   Read more of this post

Java Interview. Autoboxing.

1 Что такое autoboxing?
Автоупаковка это механизм неявной инициализации объектов классов-оберток (Byte, Short, Character, Integer, Long, Float, Double) значениями соответствующих им исходных примитивных типов (соотв. byte, short, char, int, long, float, double), без явного использования конструктора класса.
Автоупаковка происходит при прямом присвоении примитива — классу-обертке (с помощью оператора”=”), либо при передаче примитива в параметры метода (типа «класса-обертки»). Автоупаковке в «классы-обертки» могут быть подвергнуты как переменные примитивных типов, так и константы времени компиляции(литералы и final-примитивы). При этом литералы должны быть синтаксически корректными для инициализации переменной исходного примитивного типа.
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Spring MVC Framework Interview Questions & Answers

Following Spring interview questions are for freshers and experienced users

1)  What is a spring?

Spring is set to be a framework which helps Java programmer for development of code and it provides IOC container, Dependency Injector, MVC flow and many other APIs for the java programmer.
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GIT Interview Questions & Answers

1)      What is GIT?

GIT is a distributed version control system and source code management (SCM) system with an emphasis to handle small and large projects with speed and efficiency.

2)      What is a repository in GIT?

A repository contains a directory named .git, where git keeps all of its metadata for the repository. The content of the .git directory are private to git.

3)      What is the command you can use to write a commit message?

Git

The command that is used to write a commit message is “git commit –a”.  The –a on the command line instructs git to commit the new content of all tracked files that have been modified. You can use “git add” before git commit –a if new files need to be committed for the first time.
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Tomcat Interview Questions & Answers

1) Explain what is Jasper?

  • Jasper is a Tomcat’s JSP engine
  • It parses JSP files to compile them into JAVA code as servlets
  • At runtime, Jasper allows to automatically detect JSP file changes and recompile them

2) Mention what is the output of select * from tab?

It displays the default tables in the database

3) Explain how you can configure Tomcat to work with IIS and NTLM?

You have to follow the standard instructions for when the isapi_redirector.dll

Configure IIS to use “integrated windows security”

Ensure that in the server.xml you have disable tomcat authentication

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OOPs Interview Questions & Answers

1. What is OOPS?

OOPS is abbreviated as Object Oriented Programming system in which programs are considered as a collection of objects. Each object is nothing but an instance of a class.

2. Write basic concepts of OOPS?

Following are the concepts of OOPS and are as follows:.

  1. Abstraction.
  2. Encapsulation.
  3. Inheritance.
  4. Polymorphism.

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JavaScript Interview Questions & Answers

1. What is JavaScript?

JavaScript is a client-side as well as server side scripting language that can be inserted into HTML pages and is understood by web browsers. JavaScript is also an Object Oriented Programming language

2. Enumerate the differences between Java and JavaScript?

Java is a complete programming language. In contrast, JavaScript is a coded program that can be introduced to HTML pages. These two languages are not at all inter-dependent and are designed for the different intent.  Java is an object – oriented programming (OOPS) or structured programming language like C++ or C whereas JavaScript is a client-side scripting language and it is said to be unstructured programming.

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Design Patterns – MVC Pattern

MVC Pattern stands for Model-View-Controller Pattern. This pattern is used to separate application’s concerns.

  • Model – Model represents an object or JAVA POJO carrying data. It can also have logic to update controller if its data changes.
  • View – View represents the visualization of the data that model contains.
  • Controller – Controller acts on both model and view. It controls the data flow into model object and updates the view whenever data changes. It keeps view and model separate.

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Design Patterns. Behavioral.

Behavioral Design Patterns

1. Template Method Pattern
2. Mediator Pattern
3. Chain of Responsibility Pattern
4. Observer Pattern
5. Strategy Pattern
6. Command Pattern
7. State Pattern
8. Visitor Pattern
9. Interpreter Pattern
10. Iterator Pattern
11. Memento Pattern

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Design Patterns. Structural.

Structural Design Patterns

1. Adapter Pattern
2. Composite Pattern
3 .Proxy Pattern
4. Flyweight Pattern
5. Facade Pattern
6. Bridge Pattern
7. Decorator Pattern

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Design Patterns – Creational.

Creational:

1. Factory Pattern
2. Abstract Factory Pattern
3. Singleton Pattern
4. Builder Pattern
5. Prototype Pattern

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Design Patterns

Creational Design Patterns

1. Factory Pattern
2. Abstract Factory Pattern
3. Singleton Pattern
4. Builder Pattern
5. Prototype Pattern

Structural Design Patterns

1. Adapter Pattern
2. Composite Pattern
3 .Proxy Pattern
4. Flyweight Pattern
5. Facade Pattern
6. Bridge Pattern
7. Decorator Pattern

Behavioral Design Patterns

1. Template Method Pattern
2. Mediator Pattern
3. Chain of Responsibility Pattern
4. Observer Pattern
5. Strategy Pattern
6. Command Pattern
7. State Pattern
8. Visitor Pattern
9. Interpreter Pattern
10.Iterator Pattern
11. Memento Pattern

Java Interview Q&A. Exception Handling.[52-81/240]

52) What is an exception in java?
In java exception is an object. Exceptions are created when an abnormal situations are arised in our program. Exceptions can be created by JVM or by our application code. All Exception classes are defined in java.lang. In otherwords we can say Exception as run time error. Read more of this post

Java Interview Q&A.Coding Standards.[26-51/240]

Core java Interview questions on Coding Standards

26) Explain Java Coding Standards for classes or Java coding conventions for classes?
Sun has created Java Coding standards or Java Coding Conventions . It is recommended highly to follow java coding standards.
Classnames should start with uppercase letter. Classnames names should be nouns. If Class name is of multiple words then the first letter of inner word must be capital letter.
Ex : Employee, EmployeeDetails, ArrayList, TreeSet, HashSet
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Java Interview Q&A. Java Core.[1-25/240]

This post opens series of posts about Java Core Interview Questions and Answers.

1) what are static blocks and static initializers in Java ?
Static blocks or static initializes are used to initialize static fields in java. we declare static blocks when we want to initialize static fields in our class. Static blocks gets executed exactly once when the class is loaded . Static blocks are executed even before the constructors are executed.

2) How to call one constructor from the other constructor ?
With in the same class if we want to call one constructor from other we use this() method. Based on the number of parameters we pass appropriate this() method is called.
Restrictions for using this method :
1) this must be the first statement in the constructor
2)we cannot use two this() methods in the constructor

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Вопросы на интервью по технологиям Java Spring и Hibernate

1. Объясните суть паттерна DI или IoC

Dependency injection (DI) – паттерн проектирования и архитектурная модель, так же известная как Inversion of Control (IoC). DI описывает ситуацию, когда один объект реализует свой функционал через другой объект. Например, соединение с базой данных передается конструктору объекта через аргумент, вместо того чтобы конструктор сам устанавливал соединение. Термин “dependency injection” немного неправильный, т.к. внедряются не зависимости, а функциональность или ресурсы. Существуют три формы внедрения (но не типа) зависимостей: сэттер, конструктор и внедрение путем интерфейса.
DI – это способ достижения слабой связанности. IoC предоставляет возможность объекту получать ссылки на свои зависимости. Обычно это реализуется через lookup-метод. Преимущество IoC в том, что эта модель позволяет отделить объекты от реализации механизмов, которые он использует. В результате мы получаем большую гибкость как при разработке приложений, так и при их тестировании.  Read more of this post

69 Spring Interview Questions and Answers

Spring overview

1. What is Spring?

Spring is an open source development framework for Enterprise Java. The core features of the Spring Framework can be used in developing any Java application, but there are extensions for building web applications on top of the Java EE platform. Spring framework targets to make Java EE development easier to use and promote good programming practice by enabling a POJO-based programming model.

2. What are benefits of Spring Framework?

  • Lightweight: Spring is lightweight when it comes to size and transparency. The basic version of spring framework is around 2MB.
  • Inversion of control (IOC): Loose coupling is achieved in Spring, with the Inversion of Control technique. The objects give their dependencies instead of creating or looking for dependent objects.
  • Aspect oriented (AOP): Spring supports Aspect oriented programming and separates application business logic from system services.
  • Container: Spring contains and manages the life cycle and configuration of application objects.
  • MVC Framework: Spring’s web framework is a well-designed web MVC framework, which provides a great alternative to web frameworks.
  • Transaction Management: Spring provides a consistent transaction management interface that can scale down to a local transaction and scale up to global transactions (JTA).
  • Exception Handling: Spring provides a convenient API to translate technology-specific exceptions (thrown by JDBC, Hibernate, or JDO) into consistent, unchecked exceptions.

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Reveal.js – new presentations look

Онлайн презентації в декількох вимірах. Дуже зручний фреймоворк з простим юаєм від Hakim El Hattab .
Демо можна подивитися тут: http://lab.hakim.se/reveal-js/
create-an-html5-presentation-with-revealjs
Знайти всю інфу на гутхабі тут: https://github.com/hakimel/reveal.js
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Adding an existing project to GitHub using the command line

Create New Repository drop-down

  1. Create a new repository on GitHub. To avoid errors, do not initialize the new repository with README, license, or gitignore files. You can add these files after you
    r project has been pushed to GitHub.
  2. Open Git Bash.
  3. Change the current working directory to your local project.

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