This problem can be solve installing the google-java-format Plugin.

1. Open plugins window (CTRL+Shift+A): plugins

2. Click on browse repositories.

3. Search for google-java-format

4. Install the plugin.

5. Restart the IDE.

6. Enable the plugin executing the action (Ctrl+Shift+A): Reformat with google-java-format Update: in the newer version of the plugin select Reformat since the plugin overrides / enhances the functionality of the standard "Reformat" command.

Additional notes from the google-java-format README

The plugin will be disabled by default. To enable it in the current project, go to File→Settings...→google-java-format Settings (or IntelliJ IDEA→Preferences...→Other Settings→google-java-format Settings on macOS) and check the Enable google-java-format checkbox. (A notification will be presented when you first open a project offering to do this for you.)

To enable it by default in new projects, use File→Other Settings→Default Settings....

Feb 2023 with the latest google-java-format Intellij plugin we need to add following custom VM options. ( Go to Help -> Edit Custom VM Options )

-Xmx2018m
--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
--add-exports=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED

Just follow the updated README file. Updated README file

Question 1: In the keymap settings there is an entry for that called Main Menu -> Code -> Reformat Code. It has a default hotkey mapped to it (in my IntelliJ 2019.1 EAP for Mac).

Question 2: I don't use the git hook, but I do use the google code format and it's checked in our CI pipelines and sonar etc. I sometimes use this hotkey but I've also installed the save actions plugin and configured it to trigger format code (cvs changed lines only) on save. This way it is automatically formatted according to googles code style upon commit and I never have any conflicts.

Question 3: Depends on the plugins I suppose. I think it's best to have no more than 1 code style plugin per language / file type to avoid conflicts.

Quoting the github page:

Note: There is no configurability as to the formatter's algorithm for formatting. This is a deliberate design decision to unify our code formatting on a single format.

Either use google-java-formatter, or don't. (I simply stopped caring about GJF's choices years ago, because I'm used to it; and even in cases where it doesn't format it exactly how I'd like, the formatting is not totally disagreeable).