[java] Path#getParent() can return null

Calling getParent() on a Path object can result in a potential NullPointerException. I am not sure if SonarQube could do something about this, but I share it here. Maybe it give you some idea how you can implement or extend a rule.

Example Java Code:

Path file = /* some value */;

… is creating following NPE:

	at java.nio.file.Files.provider(Files.java:97)
	at java.nio.file.Files.createDirectory(Files.java:674)
	at java.nio.file.Files.createAndCheckIsDirectory(Files.java:781)
	at java.nio.file.Files.createDirectories(Files.java:727)

Because file.getParent() returns null when the path is not absolute (and is a single path-segment). To be more concrete:

  • file = Paths.get("out/file.txt") will work
  • file = Paths.get("/tmp/file.txt") will work
  • file = Paths.get("file.txt") does not work and creates the NullPointerException

My fix is: