Automate Java Class and Method Javadoc Generation with IntelliJ Live Templates

1. Class Comment Template

Open Settings → Editor → File and Code Templates, select the File tab, then the Class sub‑tab and paste the template shown in the red box.

/**
 * @author jitwxs
 * @date ${YEAR}年${MONTH}月${DAY}日 ${TIME}
 */

Note

The Description field lists all template variables supported by IDEA, such as ${DATE} and ${TIME}. After saving, new classes automatically receive the comment. To apply the same template to interfaces, configure the Interface tab similarly.

2. Method Comment Template

The goal is to generate @param and @return annotations automatically based on method signatures.

In Settings → Editor → Live Templates, click the + button, choose 2. Template Group... and create a group named userDefine:

Then select the newly created group, click + again and choose 1. Live Template:

In the template editor set:

Abbreviation must be * Description can describe the template purpose

Template text contains the Javadoc skeleton (the first line must start with * and there must be no leading /)

Expand with set to

Enter

Define the variables used in the template. IDEA does not recognize $date$, $time$, $param$ and $return$ by default, so we map them with Groovy scripts.

For $param$ use:

groovyScript("def result = '';def params = \"${_1}\".replaceAll('[\\[|\\]|\\s]', '').split(',').toList(); for(i = 0; i < params.size(); i++) {if(params[i] != '')result+='* @param ' + params[i] + ((i < params.size() - 1) ? '
 ' : '')}; return result == '' ? null : '
 ' + result", methodParameters())

For $return$ use:

groovyScript("return \"${_1}\" == 'void' ? null : '
 * @return ' + \"${_1}\"", methodReturnType())

After clicking Edit variables, assign the appropriate expressions (IDEA built‑in functions for date and time, custom Groovy for param and return).

Set the Expression for each variable as shown:

Make sure the Skip if defined option is unchecked, then save the template.

3. Verify the Result

3.1 Class Comment

Creating a new class now automatically inserts the class comment:

3.2 Method Comment

The template works for various method signatures (no parameters, single/multiple parameters, with/without return value). Example output:

4. Q & A

(1) Why must the Abbreviation be * and Expand with be Enter? Because IDEA triggers a template when the abbreviation followed by the expand key is typed; * + Enter produces the opening /** of a Javadoc comment.

(2) Why is there an empty line with * in the template? It reserves a line for a method description; you can delete it if not needed.

(3) Why are $time$$param$ placed together? The custom param script was adjusted to avoid generating an empty @param line when there are no parameters, so $param$ must stay on the same line as $time$ to handle backspace correctly.

(4) Why implement return manually instead of using methodReturnType() ? The built‑in function returns void for methods without a return value, which is not useful; the custom script only emits @return when a real return type exists.

(5) Why is $return$ not on a separate line? When methodReturnType() returns null, a separate line would cause backspace handling issues, so it is merged with the preceding line.