The best replacement for pmd is findbugs.

The best alternatives to pmd are rated as following:
★★★★★  findbugs
★★★★  checkstyle
★★★★  pmd pro
★★★★  clarisonic
★★★  nubrilliance
★★★  riiviva
★★  microderm md
★★  sonar
★  dermawand
★  diamond microdermabrasion
★  orthopnea
★  macro exfoliator
★  neutrogena microdermabrasion
  crystalift
  dgd
  nubrillance microderm

Your alternative for pmd is not listed? Suggest!
Speaking about pmd, one probably shouldn't forget about sonar.

Other search terms related to pmd and their ratings are:
★★★★★ sonar
You have in mind a companion for pmd and it is not yet here? Propose!



Google Trends

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pmd
findbugs
checkstyle