IntelliJ：Build> Rebuild Project菜单项与Maven clean install

Question

For a Maven -driven project in IntelliJ 2018, when should I choose to use…

• The IntelliJ 2018.1 menu item Build > Rebuild Project
• The Maven panel's clean and install Lifecycle items

Under what circumstances is either appropriate?

My situation is a Vaadin 8 application using the vaadin-archetype-application-multimodule Vaadin archetype .

The Question, Does IntelliJ Build > Rebuild Project invoke maven? has a single Answer that says the Rebuild Project does not invoke Maven at all. But no guidance is given on when to use route versus the other.

Answer 1

Well, if you make substancial changes within a pom.xml file (new plugins, new modules within a multi-module project), you'd better run "mvn clean install". I personally never use the "Rebuild Project" within a Maven project. usually I just "make" the project so the class files are updated, or I start a real Maven build to get new / updated dependencies.

The third important option (for me) is the "Reimport all Maven projects" option, which is quite useful if a pure Maven build runs fine, but IntelliJ still thinks that there is something wrong within your project.

Answer 2

When you have a multi-module Maven project and:

• Start your tests and application programmatically by IntelliJ (Main.java):

  You do not need to use Maven at all, no clean, no install, only Make . And Rebuild when the project gets screwed up.

  Click Reimport when you change dependencies or someone deploys a new dependency snapshot to your repo. If IntelliJ refuses to download the snapshot, then try mvn clean install .

  And why would you even do all that? It is faster and more user friendly.

• Start your tests and application by Maven in IntelliJ (mvn jetty:run):

  You have to install your modules which are as dependencies for the module on which you start your application ( mvn jetty:run ), because Maven does not use your compiled output for dependencies, but takes an artifact from your remote/local repository. For this case Make/Rebuild is useless, you have to use mvn (clean) install .

  If you have made changes only in a module on which you run mvn jetty:run then you do not need to use package/install , but sometimes you have to use clean or Rebuild as Maven does not remove deleted resources.

  Make is good for hot-swap - for that reason, it is a good idea to import all Maven projects you develop and on which you depend into a single IntelliJ project. Initial Rebuild comes handy, because without it, Make would compile the whole project instead of only changed classes, then possibly failing hot-swap or it would just take too long. Or you could just click Make before you run your application, but it could leave some old resources created by Maven in compiled output, Rebuild would take care of that.

  You can also configure your app-server to restart/reload when it detects updated files from Make or Rebuild - certainly faster than restarting the JVM or compiling by Maven, but you might like to disable that and use only hot-swap, which is still way faster if you do small changes.

Either way you might want to take a look at Maven Helper plugin for IntelliJ , it will make things way easier in big projects.