Question

What’s the difference between getPath(), getAbsolutePath(), and getCanonicalPath() in Java?

And when do I use each one?

Answer 1

Consider these filenames:

C:\temp\file.txt – This is a path, an absolute path, and a canonical path.

.\file.txt – This is a path. It’s neither an absolute path nor a canonical path.

C:\temp\myapp\bin\..\\..\file.txt – This is a path and an absolute path. It’s not a canonical path.

A canonical path is always an absolute path.

Converting from a path to a canonical path makes it absolute (usually tack on the current working directory so e.g. ./file.txt becomes c:/temp/file.txt). The canonical path of a file just “purifies” the path, removing and resolving stuff like ..\ and resolving symlinks (on unixes).

Also note the following example with nio.Paths:

String canonical_path_string = "C:\\Windows\\System32\\";
String absolute_path_string = "C:\\Windows\\System32\\drivers\\..\\";

System.out.println(Paths.get(canonical_path_string).getParent());
System.out.println(Paths.get(absolute_path_string).getParent());

While both paths refer to the same location, the output will be quite different:

C:\Windows
C:\Windows\System32\drivers