How to code using java

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 interfaces—what 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.

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Getting Started with Java in VS Code

This tutorial shows you how to write and run Hello World program in Java with Visual Studio Code. It also covers a few advanced features, which you can explore by reading other documents in this section.

For an overview of the features available for Java in VS Code, see Java Language Overview.

If you run into any issues when following this tutorial, you can contact us by entering an issue.

Setting up VS Code for Java development

Coding Pack for Java

To help you set up quickly, you can install the Coding Pack for Java, which includes VS Code, the Java Development Kit (JDK), and essential Java extensions. The Coding Pack can be used as a clean installation, or to update or repair an existing development environment.

Note: The Coding Pack for Java is only available for Windows and macOS. For other operating systems, you will need to manually install a JDK, VS Code, and Java extensions.

Installing extensions

If you are an existing VS Code user, you can also add Java support by installing the Extension Pack for Java, which includes these extensions:

The Extension Pack for Java provides a Quick Start guide and tips for code editing and debugging. It also has a FAQ that answers some frequently asked questions. Use the command Java: Tips for Beginners from the Command Palette ( ⇧⌘P (Windows, Linux Ctrl+Shift+P ) ) to launch the guide.

You can also install extensions separately. The Extensions Guide is provided to help you. You can launch the guide with the Java: Extensions Guide command.

For this tutorial, the only required extensions are:

Installing and setting up a Java Development Kit (JDK)

To use Java within Visual Studio Code, you need to install a Java Development Kit (JDK) on your local environment. JDK is a software development environment used for developing Java applications.

Supported Java versions

The Extension Pack for Java supports Java version 1.5 or above.

Note: To configure JDKs for your projects, see Configure Runtime for Projects. To enable Java preview features, see How can I use VS Code with new Java versions.

Installing a Java Development Kit (JDK)

If you have never installed a JDK before and need to install one, we recommend you to choose from one of these sources:

Creating a source code file

Create a folder for your Java program and open the folder with VS Code. Then in VS Code, create a new file and save it with the name Hello.java . When you open that file, the Java Language Server automatically starts loading, and you should see a language status item with a loading icon on the right side of the Status Bar showing the language status is busy. After it finishes loading, you can hover on the language status item and find the loading process has been finished successfully. You can also choose to pin the status item in the status bar.

Note: If you open a Java file in VS Code without opening its folder, the Java Language Server might not work properly.

VS Code will also try to figure out the correct package for the new type and fill the new file from a template. See Create new file.

You can also create a Java project using the Java: Create Java Project command. Bring up the Command Palette ( ⇧⌘P (Windows, Linux Ctrl+Shift+P ) ) and then type java to search for this command. After selecting the command, you will be prompted for the location and name of the project. You can also choose your build tool from this command.

Visual Studio Code also supports more complex Java projects — see Project Management.

Editing source code

You can use code snippets to scaffold your classes and methods. VS Code also provides IntelliSense for code completion, and various refactor methods.

To learn more about editing Java, see Java Editing.

Running and debugging your program

To run and debug Java code, set a breakpoint, then either press F5 on your keyboard or use the Run > Start Debugging menu item. You can also use the Run|Debug CodeLens option in the editor. After the code compiles, you can see all your variables and threads in the Run and Debug view.

The debugger also supports advanced features such as Hot Code Replace and conditional breakpoints.

More features

The editor also has many more capabilities to assist with your Java workload.

• Editing Java explains how to navigate and edit Java in more details
• Debugging illustrates all the key features of the Java Debugger
• Testing provides comprehensive support for JUnit and TestNG framework
• Java Project Management shows you how to use a project view and work with Maven
• Spring Boot and Tomcat and Jetty demonstrate great framework support
• Java Web Apps shows how to work with Java Web App in VS Code

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