Compile on save: You need to compile the source file first. Although IDEA does not contain this feature, you can simulate it with keymap settings and map CTRL+S to the Compile action (it gets saved anyway):
You can always run Compile file (CTRL+SHIFT+F9) or Build project (CTRL+F9) manually.
Enable automatic Hotswap after compile
If you don’t enable this feature, you will need to hotswap changes manually by Run -> Reload changed files.
Maven Run/Debug configuration If you run your project with a maven action (usually a plugin like maven-jetty-plugin or maven-tomcat-plugin), use standard setup:
And add VM Options for dcevm and javaagent. If your project JDK does not contain DCEVM patch, select alternative JRE with DCEVM.
Setup application server Or if you run your application on an application server (Tomcat, JBoss, Glassfish), just set VM options for DCEVM and javaagent. If your project JDK does not contain DCEVM patch, select alternative JRE with DCEVM.