Spring boot dev tools enable hot swapping and fast application restarts when a class file in the classpath changes. This speeds up development by reducing the time spent in a change, re-build and manually restarting the container.

This is done by adding the following dependency to a gradle project:

dependencies {
	compile("org.springframework.boot:spring-boot-devtools")
}

However, there is a minor catch! The devtools only swing into action when a file in the classpath is changed. This does not happen by default in IntelliJ when you make a change to a java class file and save it. To make it happen, either:

  1. Build project (Cmd + F9) which recompiles files and updates the classpath folder, thereby triggering the devtools to do a fast app restart or
  2. Make the following change to the IDE registry (Cmd + Shift + A) entry for the following attribute to true 
    compiler.automake.allow.when.app.running

I personally prefer option 1 as I have control over when I want the fast restart to happen. It however comes with a few extra keystrokes to also do a build (Cmd + F9) after a save action. I just find this a matter of getting used to and prefer the extra controlled and not having restarts happening all over the place.