Eclipse allows you to add folders to the classpath of your Tomcat run configuration by following these steps:

• Go to the Run Configurations window.
• Select the Tomcat run configuration that you want to add the folders to.
• Click on the Classpath tab and select User Entries.
• Click on the Advanced button. In the Add Library dialog, select the folders that you want to add to the classpath.

The folders will be added to the classpath of your Tomcat run configuration and you will be able to run your application.

This is useful when you need to extend your classpath but can’t add the folder as a project dependency, source or resource folder because the folder might be something that is generated after compilation. As you can see, it is pretty straightforward in the Eclipse IDE. But, how would you do the same in IntelliJ? As of today, IntelliJ doesn’t provide a way to extend classpath for Tomcat in it’s run configuration editor. Though there might be many workarounds, the one that worked for me was to use -Xbootclasspath command-line option.

-Xbootclasspath/a: appends the specified resources to the end of the bootstrap class path. To use the -Xbootclasspath/a option to add multiple folders to the boot classpath in Java, you can separate the paths using the platform-specific path separator (; on Windows or : on Unix/Linux/Mac). Here’s an example command line that adds two folders to the boot classpath:

java -Xbootclasspath/a:path/to/folder1;path/to/folder2 MyClass

Replace path/to/folder1 and path/to/folder2 with the actual paths to the folders you want to add, and MyClass with the name of your main class. This command should add both path/to/folder1 and path/to/folder2 to the boot classpath.

Now, to add multiple folders to the boot classpath in a Tomcat run configuration in IntelliJ IDEA, you can use the following steps:

• Open the “Run/Debug Configurations” dialog in IntelliJ IDEA.
• Select your Tomcat run configuration.
• In the “Configuration” tab, click on the “VM options” field.
• Add the following command line:
  • -Xbootclasspath/a:path/to/folder1:path/to/folder2
  • Replace path/to/folder1 and path/to/folder2 with the actual paths to the folders you want to add to the boot classpath.
• Click “Apply” and “OK” to save the run configuration.

Now, when you run your Tomcat instance using this run configuration, the path/to/folder1 and path/to/folder2 folders should be added to the boot classpath. If relative paths or macros aren’t working and you’re not able to see the paths being made available in the classpath, try using absolute paths to the folders. I hope this helps.