What is IntelliJ IDEA?

Even if this is your first time using an IDE, it shouldn’t take you long to get your first project up and running. In the New Project wizard, you can specify the desired language, build tools (like Maven and Gradle), and JDK version. If the JDK you need is not available, the IDE will download it for you. All the remaining settings will be configured automatically. This means you’ll be able to start working just moments after launching IntelliJ IDEA. You can also open projects, import existing Maven or Gradle projects, and pull projects from version control systems.

IntelliJ IDEA has keyboard shortcuts for pretty much everything, from viewing recent files to running and debugging your project. One universally applicable shortcut is double Shift (Search Everywhere). It allows you to find just about any item inside or outside of the project. The range of your search can vary from files, actions, classes, and symbols to settings, UI elements, and even Git history.

You can spend long days coding in front of a screen as a developer, so making the UI easy on your eyes is important. We have several options available that allow you to create a comfortable environment to work in. You can use one of the standard color themes, like IntelliJ Light or Darcula, or configure IntelliJ IDEA to synchronize its theme with your OS preferences.

Alternatively, you can give your IDE a completely new look, with over 100 interface custom themes to choose from. So whether you are in the mood for Solarized’s Californian sun vibe or feeling a little purple with Dark Purple Theme, IntelliJ IDEA has a theme for you.

IntelliJ IDEA is very good at checking over the quality and validity of your code with on-the-fly inspections. These inspections help you code faster, comply with the highest quality standards, and stay confident through the whole development process. We provide a host of standard inspections, as well as dozens of framework-specific ones covering a wide range of problems, such as Spring bean class autowiring errors, etc.

If IntelliJ IDEA finds any issues, it offers to help solve them via context actions, which include quick-fixes for highlighted errors and intention actions for changing your code if the issues are minor. To invoke a context action, click the light bulb icon or press Alt+Enter.

IntelliJ IDEA provides context-sensitive code completion, offering you suggestions that are only valid for the current caret position. You don’t need to use any shortcuts or configure additional settings; code completion will start as soon as you begin typing your code in the editor.

IntelliJ IDEA uses machine learning to ensure the most relevant suggestion is at the top of the list.

To learn more about code completion, check out this blog post.

IntelliJ IDEA lets you work with elements of code in other languages embedded in your code. You won’t notice a difference between your experience working with the core Java code and your experience with the code that you’ve injected. We provide code highlighting, completion, error detection, and other coding assistance features for embedded code fragments. To add a snippet of alternative code into Java, just press Alt+Enter, select Inject language or reference, and select the desired language from the list.

IntelliJ IDEA has lots of useful diagrams that can help you visualize and analyze your code and navigate through it. Depending on their types, these diagrams can reflect the structure of classes and methods in your application, of the database objects, of entity beans defined in your module, and so on. You can call a list of available diagrams via Diagrams / Show Diagram from the context menu.

Live templates is a powerful feature that helps speed up your coding. Just type in an abbreviation predefined in the template to insert standard code constructs into your work quickly. You can also create your own custom templates, which you can use to insert snippets of code that you use repeatedly.

IntelliJ IDEA’s automatic refactoring feature lets you update your code safely and efficiently, both simplifying it and making it more readable and easier to maintain. The IDE offers a wide selection of refactorings that will help you safely rename code elements, change the signature of a class or a method, extract a code fragment to a method, and introduce variables. Watch our video on the refactorings that are essential to everyday coding.

Another powerful search tool is Find in Files, which makes it possible to search for a text string in your project and apply a variety of options to narrow down your search. For example, you can use various scopes, find occurrences, and exclude certain items from the search.

To call this tool, highlight the string you want to find and press Ctrl+Shift+F. The IDE will automatically put it in the search field.

You can run your application in IntelliJ IDEA by simply clicking the green play button in the toolbar at the top of the window or near a class declaration in the editor gutter. If you need to customize how your program starts up, you can use run/debug configurations that contain various run and build properties, including the desired JDK/JRE, the environment in which you want to run your project, and more.

The Run Targets feature lets you run, test, profile, and debug your application in Docker containers and on remote machines. IntelliJ IDEA Ultimate provides the ability to run Java applications and JUnit tests, as well as Maven, Gradle, Micronaut, Maven-based Quarkus, and Spring Boot projects on Docker, SSH, and WSL targets.

Check out this blog post for more information.

IntelliJ IDEA supports the most popular testing frameworks, like JUnit, TestNG, Cucumber, Arquillian JUnit, and Selenium (available in the plugin Marketplace). The IDE is equipped with an environment and a set of tools for developing and running effective and readable automated tests. You can switch between test classes and source code with a shortcut, run multiple tests, view statistics for each test, and more. For analytics, use the Code Coverage feature which shows the percentage of code covered by unit tests.

A debugger is an indispensable tool for detecting bugs and reviewing what's happening under the hood of your program. To prepare for debugging, set breakpoints in the places where you want to suspend the program’s execution and examine the program’s state and behavior. Once the breakpoints are set, you can start debugging. You’ll find the results in the Debug tool window.

IntelliJ IDEA’s debugger has several unique features. When you debug your code, the IDE shows you variable values in the source code next to their usages and lets you change the values. You can also use the Smart Step-Into action to choose the specific method call you want to debug.

To learn about all the other debugger features, check out this video playlist.

IntelliJ IDEA includes fully functional integration with the Maven, Gradle, Ant, and Gant build tools, which help automate the build process. The IDE provides built-in options for compiling and packaging Java code, running tests, deployment, and other activities.

IntelliJ IDEA’s built-in terminal lets you work with the command-line shell from your IDE without having to switch to a dedicated terminal application. It supports all the same commands as your operating system. From the terminal you can easily get back to the IntelliJ IDEA UI by clicking on URLs and stack traces or by pressing Ctrl+Enter when you see a highlighted command.

You can manage databases right from the IDE with the Database tools that are shipped with IntelliJ IDEA Ultimate. Take advantage of intelligent coding assistance when editing SQL queries, connect to live databases, run queries, browse and export data, and even manage your schemes in a visual interface.

The built-in profiler helps you get a big picture of what happens at runtime. It provides accurate snapshots that help you identify CPU- and memory-intensive sections, threading issues, and suboptimal code. The results are easy to analyze and compare through convenient graphical and hierarchical representations. You can either attach the profiler to your own processes or analyze snapshots made by someone else. The IntelliJ IDEA profiler provides an easy entry-point to profiling, as it is user friendly and requires absolutely no setup. At the same time, should fine-tuning become necessary, it gives you the same level of flexibility as standalone tools.

If you develop a web service, you will likely test it by sending and receiving HTTP requests. Such requests are stored in .http or .rest files, which you can create, edit, and execute in the HTTP client. This tool is built into the IntelliJ IDEA editor, providing extensive coding assistance for your HTTP requests, including code completion, highlighting, refactorings, and so on. You can easily access the HTTP Client from the source code: click the globe icon next to the URL and select Open in HTTP client.

IntelliJ IDEA comes with a built-in decompiler that lets you convert bytecode into human-readable Java code and then debug it. For example, when you open a library in a .jar file without having the source code for it, the IDE will display its readable contents. The yellow panel above the editor will inform you that you are working with a decompiled file. If you want to, you can set breakpoints in the decompiled code and debug it. Read this blog post to learn more about the decompiler.

IntelliJ IDEA offers Git integration that lets you clone projects from Git, commit and push changes, work with several branches, manage changelists, and stage updates before committing them. In IntelliJ IDEA, you can access the history of the entire project and of individual folders and files using the Log tab in the Git tool window, or by using the respective History views. In the editor, it is possible to annotate files with historical data as git blame does.

You can manage Git projects hosted on the GitHub platform right from IntelliJ IDEA.

It is possible to clone repositories, share projects, and share code through gists. What’s more, IntelliJ IDEA supports creating, merging, and viewing pull requests. Watch our video to learn more about working with GitHub pull requests.

For the Spring and Spring Boot frameworks, IntelliJ IDEA Ultimate features smart code insight, inspections, instant code navigation, and highly customizable run configurations. It also offers built-in tools that let you run and test Spring apps and work with HTTP requests and database tools. You can also get an aggregated view of the client and server APIs used in your project for HTTP and WebSocket protocols in the Endpoints tool window.

For a more detailed description of what IntelliJ IDEA has for Spring and Spring Boot, check out this webpage.

In IntelliJ IDEA Ultimate, you can develop Java enterprise applications based on Jakarta EE and MicroProfile specifications. IntelliJ IDEA Ultimate supports all Jakarta EE features, including CDI, JPA, Batch, Bean Validation, JSF, JAX-RS, WebSocket, Servlets, JSP, JSON Binding and Processing, Security, and the EJB and JTA specifications.

For a more detailed description of what IntelliJ IDEA has for Jakarta EE, check out this webpage.

IntelliJ IDEA Ultimate has support for the most commonly used microservice frameworks – Micronaut, Quarkus, and Helidon. IntelliJ IDEA provides intelligent coding assistance, integration with Endpoints, and project creation wizards for all of them.

When you work with a vast number of Java objects, you may want to store them in a database. Persistence frameworks provide a collection of methods and classes to make this possible. IntelliJ IDEA Ultimate integrates with the most frequently used frameworks of this kind – Jakarta Persistence (JPA), Hibernate, and R2DBC. Right out of the box, you get framework-specific coding assistance, the opportunity to customize framework configurations, and the Persistence tool window for viewing and managing various JPA, Hibernate, and R2DBC items.

IntelliJ IDEA Ultimate comes with first-class support for Ktor – an end-to-end multiplatform framework that allows you to build various connected applications, from microservices to multiplatform HTTP client apps. In conjunction with Kotlin coroutines, it makes creating asynchronous applications a breeze. Ktor allows developers to provide the best user experience in an easy and straightforward way.

For a more detailed description of what IntelliJ IDEA has for Ktor, check out this webpage.

You can use IntelliJ IDEA Ultimate to build applications with JavaScript, TypeScript, React, Vue, Angular, Node.js, and other related technologies. You can expect the same advanced coding assistance that you are used to when working with Java in all of them.

You can also work with HTML and style sheets in IntelliJ IDEA. Just like with other languages and technologies, you will get advanced coding assistance, including code completion, navigation, and refactorings. Additionally, you can preview static HTML files right in the IDE. The changes you make to an HTML file or the linked CSS and JavaScript files will be saved, with the preview reloaded automatically.

In IntelliJ IDEA, you can run and debug your Node.js code and client-side apps with the help of Chrome. Put breakpoints, step through the code, set watches, and more – all from the editor with a unified experience across different kinds of applications, from vanilla JavaScript to TypeScript and Vue projects.

IntelliJ IDEA Ultimate supports Thymeleaf, Velocity, Liquid, Go Template, Mustache, and other template languages. It provides code highlighting, autocompletion, inspections, context actions, and more smart features to help you develop templates with ease.

IntelliJ IDEA provides integration with major application servers: Tomcat, JBoss, WebSphere, WebLogic, Glassfish, and more. Right from your IDE, you can start and stop local servers, connect to running remote servers, deploy your artifacts on those servers, and even debug your applications on them.

IntelliJ IDEA fully supports Docker integration. You can run and debug your applications in Docker containers, download and build images, run multi-container applications using Docker Compose, and more, all from the IDE.

IntelliJ IDEA Ultimate provides integration with Docker out of the box. For IntelliJ IDEA Community Edition, you can download the Docker plugin from JetBrains Marketplace by going to Preferences/Settings | Plugins from inside your IDE.

Code With Me is an online collaborative experience in IntelliJ IDEA. It lets you work remotely on a shared project with your teammates, with everyone using their own screen and keyboard. You can explore code, edit it together, and see changes appear in real time. It also features built-in voice and audio calls to enhance your one-on-ones or group collaboration sessions.

IntelliJ IDEA offers integration with JetBrains Space, a complete software development platform. When you connect your IDE to a Space organization, you can view and clone project repositories, create and perform code reviews with merge requests, add reactions in code review chats, and assign and mention team members. It is also possible to write and edit Space Automation scripts in IntelliJ IDEA and then track an automation job’s progress in the Git log.

Remote development functionality splits your IDE into two components: a local lightweight client that provides you with a responsive JetBrains IDE UX and a remote server that handles all the heavy processing. This functionality can be initiated from IntelliJ IDEA’s Welcome screen or from an application called JetBrains Gateway, which is available in the JetBrains Toolbox App.

JetBrains Space provides orchestration support for the remote development workflow, allowing you to create a dev environment, connect it to IntelliJ IDEA, and start coding in seconds. You no longer have to wait for projects to be built, dependencies to be downloaded, or IDEs to be indexed. Standardize your environments by installing all of the tools and libraries required by your project and reproduce them at any time to simplify onboarding.

Learn more about Space dev environments.