Before you start to develop a new action, please have a look at the available actions and screens. If it's just a few lines of code, you can use the "Run script" action to enter them directly into install4j. If you would like to collect user input, most use cases can be solved with a "Configurable form" screen.
All classes used by your custom code have to be included in these locations (except for Java runtime classes and install4j framework classes).
The control buttons allow you to modify the contents of the list of custom code locations, theAfter you have chosen your custom code locations, you will be able to select your own screens, actions and form components.
Note: The installed JAR files will be available only after the "Install files" action has run. All your custom code that depends on these JAR files must be placed after the "Install files" action, otherwise a runtime error will occur. If you use installation components, these libraries should be part of a mandatory component.
The "use installed JAR files where possible" option changes the initialization strategy of the installer. If selected, the installer initialized screens and actions up to the "Install files" action at startup and the rest after the "Install files" action has run. If not selected, all screens and actions are initialized at startup.