Java - JetBrains Guide

Tutorial

Migrating from the `javax` to `jakarta` namespace

How to transition your application from Java EE to Jakarta EE.

Tutorial

Presenting with IntelliJ IDEA.

Tips & tricks to level up your presentation skills with IntelliJ IDEA.

Tutorial

Hello World in IntelliJ IDEA

Create a new Java application and JAR file that prints `Hello World` to the console.

Tutorial

Working with Gradle

Understand how IntelliJ IDEA integrates with Gradle.

Tutorial

Working with Maven

Understand how IntelliJ IDEA integrates with Maven.

Tip

Command in chat

Use predefined command in chat.

Tip

Inline code completion

Let AI Assistant write code for you, using inline code completion.

Tip

Create an Editor Fold

Create an editor fold to hide parts of your class which can make it more readable.

Tip

Generate Overrides for equals(), hashCode() and toString()

We can generate the code to override the equals and hashCode methods.

Tip

Surround With

Surround your code with common programming constructs.

Tip

View supertype and subtype hierarchy

You can view supertypes and subtypes in the hierarchy quickly with your keyboard shortcuts.

Tip

Convert Class to Record

Use inspections to convert classes to Java 16 records.

Tip

Enable Git Staging

Git Staging is an alternative approach to IntelliJ IDEA Changelists.

Tip

Create New Class

Quickly add new classes to your project.

Tip

Explain Regexp with AI Assistant

Using AI Assistant to help you understand regexp.

Tip

Generate code with AI Assistant

Let AI Assistant write code for you, based on your prompts.

Tip

Extend Selection

Extend and shrink your current code selection.

Tip

Mnemonic bookmark

Use mnemonic bookmarks for easy navigation.

Tip

Run inspection

Run inspection by name. For example, run Vulnerable API usage to see where the vulnerable API of external dependencies is used in your code.

Tip

Custom prompts

Use a custom prompt to let AI Assistant help you.

Tip

Extract Method

Extract code to a new method.

Tip

Presentation Assistant

Use Presentation Assistant to display shortcuts being used.

Tip

Vulnerable API Usage

See whether you are using the vulnerable API of a dependency.

Tip

Download a JDK

Download or Associate a JDK With Your Project.

Tip

Generate constructors and accessor methods

Quickly generate common code constructs such as Constructors, Getters and Setters.

Tip

Generate a UML diagram

IntelliJ IDEA Ultimate allows you to generate UML diagrams.

Tip

Commit Changes

Commit your changes to VCS as you go.

Tip

Disable Usages

Disable the inlay hint for Usages if it's distracting you.

Tip

AI Assistant Chat

You can chat with JetBrains AI Assistant right inside the IDE.

Tip

Find in File

Find a specific name or string in your file.

Tip

Generate Unit Tests

Generate unit tests with AI Assistant.

Tip

Toggle Rendered View

Toggle rendered view for one or all Javadoc comments.

Tip

AI Actions

View and use AI Actions in the editor.

Tip

Close Tabs

Close inactive tabs so you an focus on your current working context.

Tip

Expand and Collapse Code

Quickly view specific parts of a class by expanding or collapsing code blocks.

Tip

Move Statement

Move a statement up or down within the same scope.

Tip

Explain Runtime Error with AI Assistant

Let AI Assistant explain runtime errors to you.

Tip

Interactive Rebase

Clean up your commit history by using interactive rebase in IntelliJ IDEA.

Tip

Write Documentation with AI Assistant

Generate documentation for your code with AI Assistant.

Tip

Dependency Matrix

Explore project structure with the Dependency Matrix.

Tip

Import Multiple Repositories

Import multiple related repositories into one IntelliJ IDEA project.

Tip

Optimize imports

Remove unused imports from your code with one keyboard shortcut.

Tip

Rename Bookmark

Rename an existing bookmark to something more suitable.

Tip

CamelCase in Code Completion

Use CamelCase in code completion to speed up your workflow.

Tip

Generate a Test Class

Generate a new test class from your Java class.

Tip

Inline Variable

Sometimes inlining a variable can make your code more readable.

Tip

Introduce Variable

Refactor your code and introduce a new variable right when you need it.

Tip

Postfix Completion

Postfix completion allows you to keep typing forwards, it minimises the amount of time you spend moving the cursor around while you're coding.

Tip

Live Templates

Use Live Templates to auto-complete common code structures for you.

Tip

Debugging Streams

Visualize the flow of data through a Java stream.

Tip

Understanding the Debugger

Use the debugger to help you understand what your code is doing.

Tip

Recent Files & Locations

Quickly navigate around your recent files & locations to stay in your current working context.

Tip

Clipboard History

Paste a subset or multiple entries such as a list from your recent copy history.

Tip

Data Flow Analysis

Data flow analysis can show us potential errors in our code logic.

Tip

Go to Next Error

Quickly move to the next (or previous) error or warning in the file.

Tip

Find in Files

Find a specific string in (a subset of files in) your code.

Tip

Inlay Hints

Inlay hints provide additional information about your code.

Tip

Structural Search

Structural Search and Replace is very helpful for finding exactly what you need in your project.

Tip

Context Actions

There are numerous ways to use Context Actions, let's explore some of them.

Tip

Generate Code

Helps you to generate commonly used code constructs.

Tip

Navigate to Test

Go to your matching test class with one keyboard shortcut.

Tip

Navigating Forward & Backward

Move forward and backward between your locations in the code so you don't need to have tabs open.

Tutorial

Explore project structure with the Dependency Matrix

Exploring project structure with the Dependency Matrix in IntelliJ IDEA.

Part of tutorial

Introduction

Explore project structure with the Dependency Matrix.

Part of tutorial

Interpret the Dependency Matrix

How to interpret the Dependency Matrix.

Part of tutorial

Opening the Dependency Matrix

Opening the Dependency Matrix for your project.

Part of tutorial

Summary and Shortcuts

Explore project structure with the Dependency Matrix Summary.

Tip

Extract Variable

Extract code to a variable

Tutorial

Getting started with IntelliJ IDEA

My favourite tips for all new starters in IntelliJ IDEA.

Tutorial

Marco Codes - Building a Text Editor

How to build a terminal-based text editor with Java.

Tip

Highlighted Commands in the Terminal

Have you ever wondered which IntelliJ IDEA terminal commands you can run in IntelliJ IDEA?

Tip

Inspections Widget

The top-right corner of your editor shows you information about the state of your class at a glance.

Tip

Restore a Deleted Breakpoint

You can restore previously configured breakpoints if you accidentally delete them.

Tip

Built in Spell Checking

IntelliJ IDEA can spell check and fix errors for you allowing you to focus on problem solving.

Tip

Merge/Unmerge If Statements

Experiment with your code without changing the semantics.

Tip

Code Completion for the Stream API

IntelliJ IDEA can add the stream() call meaning less typing for you.

Tip

Navigating a Long Class

There are various tips and tricks you can use to navigate a long class in IntelliJ IDEA.

Tip

Navigate to the Last Edited Location

Move around the files you're working on quickly with keyboard shortcuts.

Tip

Add Your Favourite Photo as a Background

If you want to look at your favourite photo while coding you can set it as your background image.

Tip

Determining the Return Type of Expression

Type Info is very helpful on a per-expression basis to understand your code.

Tip

Edit a Document in IntelliJ IDEA LightEdit Mode

Use IntelliJ IDEA’s text editing features without creating or opening a dedicated project.

Tip

Inject a Language

Language injections let you work with pieces of code in other languages embedded in your code.

Tip

Pattern Matching for Switch

This feature is available in preview from Java 17.

Tip

New Line

Start a new line below or above your current line with the correct indentation.

Tip

In Editor Doc Rendering

You can render Javadocs directly in the editor including HTML tags, images and links.

Tutorial

Writing Less Code With Live Templates

How you can use live templates to get IntelliJ IDEA to write more code for you.

Tutorial

Rearranging Code in IntelliJ IDEA.

How you can rearrange code in your classes and projects

Tutorial

Reformatting Code in IntelliJ IDEA.

Why and how you can reformat code in your projects

Tutorial

Using the Terminal in IntelliJ IDEA

IntelliJ IDEA has a built-in terminal that you can use to perform a number of functions inside your IDE.

Tutorial

Migrating JUnit 4 to JUnit 5

Migrating your JUnit 4 test suite to JUnit 5.

Playlist

Getting Started with IntelliJ IDEA

Helpful tips for working with IntelliJ IDEA for the first time.

Tip

Join Lines

Join lines of code together in your IDE.

Tip

CamelCase in Searching

Use CamelCase to find what you need faster and save your fingers.

Tip

Smart Completion

Get type aware completion in your code so you can focus on solving problems.

Tutorial

Getting Started with Spring Data JPA

Learn how to use Spring Data JPA to store and retrieve data from your database.

Tip

Generate Test Methods

Generate a test method in your test class.

Tip

Type Into Any Dialog to Search

You can start typing into a dialog box to search, even if there's not a textual search box available.

Tutorial

Writing Tests with Spock

Learn about the Spock testing framework by creating a project that uses Spock to unit test Java code.

Tutorial

Your First Spring Boot Application

In this tutorial, we will use IntelliJ IDEA to create your first "Hello World" Spring Boot application.

Tip

Profile your Application

See how your application is performing with the built-in profiler.

Tip

Run your code with Docker, SSH or WSL

Set a Run Target to change where your code runs.

Tip

Lightweight Inspection Profile on Commit

Fully customise the checks you must perform before you commit your changes to version control.

Tip

Create a Correct Child Sealed Class

Sealed types are a new idea for Java developers, let IntelliJ IDEA guide you in how to create child classes.

Tip

Create a Correct Parent Sealed Class

Sealed types are a new idea for Java developers, let IntelliJ IDEA guide you in how to use them.

Tip

Turn on Preview Features to try new Java Features

The latest versions of Java contain "Preview Features", features that are fully functional but require developer feedback. Try them out in IntelliJ IDEA.

Tip

Convert from Record

Use quick intentions to convert a record to a class.

Tip

Create Record

Let IntelliJ IDEA support you in creating a new Java record class.

Tip

Identify and Fix Deprecated Calls

IntelliJ IDEA will warn you if you're using deprecated methods, and they will be shown with a strikethrough if they're marked for removal.

Tip

Use Pattern Matching for instanceof

Inspections can guide us to use newer Java features.

Tutorial

Using the IDE Feature Trainer.

Learning new things in the IDE

Tip

Add a Breakpoint

Easily add breakpoints when you get an exception in your code

Tip

Adjust Code Style

Use quick intentions to adjust the style of your code right where your cursor is.

Tip

Add Overload Bool

Refactor a method to change its signature and update your code to reflect the new signature.

Tip

Assert That Import

Use quick intentions to manage imports and keep your code compiling.

Tip

Change Method Signature

Refactor the signature of a method at any time.

Tip

Remove Unnecessary Condition

Use quick intentions to remove redundant code so it's not cluttering up your codebase.

Tip

Drag and Dock Editor Tabs

You can move editor tabs around as required to suit your needs.

Tip

Enable Machine Learning for Code Completion

Code completion may be enhanced with Machine Learning.

Tip

Exclude a Completion Option

Helps to reduce options that are not relevant for your code.

Tip

Extract Field

Extract code to a field.

Tip

Extract Constant

Extract a value to a constant.

Tip

Extract Parameter

Extract code to a parameter.

Tip

Find Next Word

Find next word and highlight all instances.

Tip

Find Usages

Use Find Usages to search for references in your code base.

Tip

Inline a Method

Sometimes inlining a method can improve the readability of your code.

Tip

Meaningless Arguments

Use quick intentions to remove redundant code so it's not cluttering your codebase.

Tip

Move Line

Move a line throughout your class, but watch out for errors!

Tip

Replace With var

Use quick intentions to replace a local variable type with `var`.

Tip

Rename an Interface

Renaming in IntelliJ IDEA including comments and texts.

Tip

Run in Current Context

Run just a file or a single script.

Tip

Show Virtual Whitespace

Add virtual whitespace to the bottom of a file so you can scroll to the end half way up your screen.

Tip

Refactor an Unreachable Statement

Use quick intentions to remove redundant code.

Tip

IntelliJ IDEA Welcome Screen

Get a project from source control, open an existing project, or create a new project.

Tutorial

Writing JUnit 5 Tests

Writing JUnit 5 Tests from start to finish.