Java Language Retrieving information using the filesystem


Example

To interact with the filesystem you use the methods of the class Files.

Checking existence

To check the existence of the file or directory a path points to, you use the following methods:

Files.exists(Path path)

and

Files.notExists(Path path)

!Files.exists(path) does not neccesarily have to be equal to Files.notExists(path), because there are three possible scenarios:

  • A file's or directory's existence is verified (exists returns true and notExists returns false in this case)
  • A file's or directory's nonexistence is verfied (exists returns false and notExists returns true)
  • Neither the existence nor the nonexistence of a file or a directory can be verified (for example due to access restrictions): Both exists and nonExists return false.

Checking whether a path points to a file or a directory

This is done using Files.isDirectory(Path path) and Files.isRegularFile(Path path)

Path p1 = Paths.get("/var/www");
Path p2 = Paths.get("/home/testuser/File.txt");
Files.isDirectory(p1) == true
Files.isRegularFile(p1) == false

Files.isDirectory(p2) == false
Files.isRegularFile(p2) == true

Getting properties

This can be done using the following methods:

Files.isReadable(Path path)
Files.isWritable(Path path)
Files.isExecutable(Path path)

Files.isHidden(Path path)
Files.isSymbolicLink(Path path)

Getting MIME type

Files.probeContentType(Path path)

This tries to get the MIME type of a file. It returns a MIME type String, like this:

  • text/plain for text files
  • text/html for HTML pages
  • application/pdf for PDF files
  • image/png for PNG files