Java теория для начинающих
The Java Tutorials have been written for JDK 8. Examples and practices described in this page don’t take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
The Java Tutorials are practical guides for programmers who want to use the Java programming language to create applications. They include hundreds of complete, working examples, and dozens of lessons. Groups of related lessons are organized into «trails».
Trails Covering the Basics
- Getting Started — An introduction to Java technology and lessons on installing Java development software and using it to create a simple program.
- Learning the Java Language — Lessons describing the essential concepts and features of the Java Programming Language.
- Essential Java Classes — Lessons on exceptions, basic input/output, concurrency, regular expressions, and the platform environment.
- Collections — Lessons on using and extending the Java Collections Framework.
- Date-Time APIs — How to use the java.time pages to write date and time code.
- Deployment — How to package applications and applets using JAR files, and deploy them using Java Web Start and Java Plug-in.
- Preparation for Java Programming Language Certification — List of available training and tutorial resources.
Creating Graphical User Interfaces
- Creating a GUI with Swing — A comprehensive introduction to GUI creation on the Java platform.
- Creating a JavaFX GUI — A collection of JavaFX tutorials.
Specialized Trails and Lessons
These trails and lessons are only available as web pages.
- Custom Networking — An introduction to the Java platform’s powerful networking features.
- The Extension Mechanism — How to make custom APIs available to all applications running on the Java platform.
- Full-Screen Exclusive Mode API — How to write applications that more fully utilize the user’s graphics hardware.
- Generics — An enhancement to the type system that supports operations on objects of various types while providing compile-time type safety. Note that this lesson is for advanced users. The Java Language trail contains a Generics lesson that is suitable for beginners.
- Internationalization — An introduction to designing software so that it can be easily adapted (localized) to various languages and regions.
- JavaBeans — The Java platform’s component technology.
- JAXB — Introduces the Java architecture for XML Binding (JAXB) technology.
- JAXP — Introduces the Java API for XML Processing (JAXP) technology.
- JDBC Database Access — Introduces an API for connectivity between the Java applications and a wide range of databases and data sources.
- JMX— Java Management Extensions provides a standard way of managing resources such as applications, devices, and services.
- JNDI— Java Naming and Directory Interface enables accessing the Naming and Directory Service such as DNS and LDAP.
- Reflection — An API that represents («reflects») the classes, interfaces, and objects in the current Java Virtual Machine.
- RMI — The Remote Method Invocation API allows an object to invoke methods of an object running on another Java Virtual Machine.
- Security — Java platform features that help protect applications from malicious software.
- Sockets Direct Protocol — How to enable the Sockets Direct Protocol to take advantage of InfiniBand.
- Sound — An API for playing sound data from applications.
- 2D Graphics — How to display and print 2D graphics in applications.
Trail: Learning the Java Language
This trail covers the fundamentals of programming in the Java programming language.
Object-Oriented Programming Concepts teaches you the core concepts behind object-oriented programming: objects, messages, classes, and inheritance. This lesson ends by showing you how these concepts translate into code. Feel free to skip this lesson if you are already familiar with object-oriented programming.
Language Basics describes the traditional features of the language, including variables, arrays, data types, operators, and control flow.
Classes and Objects describes how to write the classes from which objects are created, and how to create and use the objects.
Annotations are a form of metadata and provide information for the compiler. This lesson describes where and how to use annotations in a program effectively.
Interfaces and Inheritance describes interfaceswhat they are, why you would want to write one, and how to write one. This section also describes the way in which you can derive one class from another. That is, how a subclass can inherit fields and methods from a superclass. You will learn that all classes are derived from the Object class, and how to modify the methods that a subclass inherits from superclasses.
Numbers and Strings This lesson describes how to use Number and String objects The lesson also shows you how to format data for output.
Generics are a powerful feature of the Java programming language. They improve the type safety of your code, making more of your bugs detectable at compile time.
Packages are a feature of the Java programming language that help you to organize and structure your classes and their relationships to one another.
Java теория для начинающих
Здесь мы описали шаблон будущего объекта – класс. У него есть две переменные состояния – speed и maxSpeed, а также две функции, которые описывают поведение объекта.
Теперь приложение нужно запустить, для этого Java надо подсказать, где находится точка входа в него. Для этого существует особое соглашение – нужно добавить в описание любого объекта метод:
Наше приложение запустилось, но ничего не произошло, потому что мы не добавили никакой логики в метод. Добавим простой вывод на консоль текста:
Создатели предложили называть эти папки как доменные имена в интернете, чтобы точно разграничить их, но это не обязательно, вы можете называть их как захотите.
Это так же позволяет легко импортировать чужие классы в свой код:
Мне всё еще непонятно, с чего начинать путь в IT. Что посоветуете?
Стоит подумать, как построить свой путь в индустрию, чтобы получить качественные знания и устроиться на работу.
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