Maven PMD plug-in not generating a report with 'mvn site' command or 'pmd:pmd'

Question

I am reading an interesting tutorial here: http://www.avajava.com/tutorials/lessons/how-do-i-generate-pmd-and-cpd-reports-for-a-site.html?page=1

This tutorial shows

Answer 1

The maven-pmd-plugin by default skips nowadays empty reports (property skipEmptyReport). You'll need to set this to false, to get in your site always a PMD/CPD report:

<reporting>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-pmd-plugin</artifactId>
      <version>3.4</version>
      <configuration>
        <skipEmptyReport>false</skipEmptyReport>
      </configuration>
    </plugin>
  </plugins>
</reporting>

This applies for both PMD and CPD. I assume, this is your problem, as in Figure 2, you show, there are no PMD violations detected (pmd.xml file is empty).

The property minimumTokens configures CPD and defines how long a code snipped at a minimum must be to be declared as a duplicate. The lower the number, the more duplicates are detected, but the duplicates can also be much shorter and therefore maybe more often false positives.

Without further configuring maven-pmd-plugin it uses by default these three PMD rulesets: java-basic, java-imports, java-unusedcode. See also property rulesets. If you want to detect specific problems, then you'll need to enable these rules. See also How to make a ruleset.