IntelliJ IDEA Community Edition

These instructions will help you build IntelliJ IDEA Community Edition from source code, which is the basis for IntelliJ Platform development. The following conventions will be used to refer to directories on your machine:

<USER_HOME> is your home directory.
<IDEA_HOME> is the root directory for the IntelliJ source code.

Getting IntelliJ IDEA Community Edition Source Code

IntelliJ IDEA Community Edition source code is available from github.com/JetBrains/intellij-community by either cloning or downloading a zip file (based on a branch) into <IDEA_HOME>. The default is the master branch.

The master branch contains the source code which will be used to create the next major version of IntelliJ IDEA. The branch names and build numbers for older releases of IntelliJ IDEA can be found on the page of Build Number Ranges.

Speed Tip: If the complete repository history isn't needed then using a shallow clone (git clone --depth 1) will save significant time.

These Git operations can also be done through the IntelliJ IDEA user interface.

IntelliJ IDEA Community Edition requires additional Android modules from separate Git repositories. To clone these repositories, run one of the getPlugins scripts located in the <IDEA_HOME> directory. These scripts clone their respective master branches.

getPlugins.sh for Linux or macOS.
getPlugins.bat for Windows.

Note: Always git checkout the intellij-community and android Git repositories to the same branches/tags.

Building IntelliJ Community Edition

Version 2020.1 or newer of IntelliJ IDEA Community Edition or IntelliJ IDEA Ultimate Edition is required to build and develop for the IntelliJ Platform.

Opening the IntelliJ Source Code for Build

Using IntelliJ IDEA File | Open, select the <IDEA_HOME> directory.

If IntelliJ IDEA displays an error about a missing or out of date required plugin (e.g. Kotlin), enable, upgrade, or install that plugin and restart IntelliJ IDEA.
If IntelliJ IDEA displays an error about a Gradle configuration not found, refresh the Gradle projects.

IntelliJ Build Configuration

Configure a JDK named "corretto-11", pointing to installation of JDK 11. It's recommended to use Amazon Corretto JDK, but other distributions based on OpenJDK should work as well. You may download it directly from Project Structure dialog.
If the Maven Integration plugin is disabled, add the path variable "MAVEN_REPOSITORY" pointing to <USER_HOME>/.m2/repository directory.
Speed Tip: If you have enough RAM on your computer, configure the compiler settings to enable the "Compile independent modules in parallel" option. Also, increase build process heap size:
- if you use IntelliJ IDEA 2020.3 or newer, set "User-local build process heap size" to 2048.
- if you use IntelliJ IDEA 2020.2 or older, copy value from "Shared build process VM options" to "User-local build process VM options" and add -Xmx2G to it.
These changes will greatly reduce compilation time.

Building the IntelliJ Application Source Code

To build IntelliJ IDEA Community Edition from source, choose Build | Build Project from the main menu.

To build installation packages, run the ant command in <IDEA_HOME> directory. See the build.xml file for details.

Running IntelliJ IDEA

To run the IntelliJ IDEA built from source, choose Run | Run from the main menu. This will use the preconfigured run configuration "IDEA".

To run tests on the build, apply these setting to the Run | Edit Configurations... | Templates | JUnit configuration tab:

Working dir: <IDEA_HOME>/bin
VM options:
- -ea
- -Didea.config.path=../test-config
- -Didea.system.path=../test-system

You can find other helpful information at https://www.jetbrains.com/opensource/idea. The "Contribute Code" section of that site describes how you can contribute to IntelliJ IDEA.