Uri.file constructor Null safety

Creates a new file URI from an absolute or relative file path.

The file path is passed in path.

This path is interpreted using either Windows or non-Windows semantics.

With non-Windows semantics the slash (/) is used to separate path segments in the input path.

With Windows semantics, backslash (\) and forward-slash (/) are used to separate path segments in the input path, except if the path starts with \\?\ in which case only backslash (\) separates path segments in path.

If the path starts with a path separator, an absolute URI (with the file scheme and an empty authority) is created. Otherwise a relative URI reference with no scheme or authority is created. One exception from this rule is that when Windows semantics is used and the path starts with a drive letter followed by a colon (":") and a path separator, then an absolute URI is created.

The default for whether to use Windows or non-Windows semantics determined from the platform Dart is running on. When running in the standalone VM, this is detected by the VM based on the operating system. When running in a browser non-Windows semantics is always used.

To override the automatic detection of which semantics to use pass a value for windows. Passing true will use Windows semantics and passing false will use non-Windows semantics.

Examples using non-Windows semantics:

// xxx/yyy
new Uri.file("xxx/yyy", windows: false);

// xxx/yyy/
new Uri.file("xxx/yyy/", windows: false);

// file:///xxx/yyy
new Uri.file("/xxx/yyy", windows: false);

// file:///xxx/yyy/
new Uri.file("/xxx/yyy/", windows: false);

// C%3A
new Uri.file("C:", windows: false);

Examples using Windows semantics:

// xxx/yyy
new Uri.file(r"xxx\yyy", windows: true);

// xxx/yyy/
new Uri.file(r"xxx\yyy\", windows: true);

file:///xxx/yyy
new Uri.file(r"\xxx\yyy", windows: true);

file:///xxx/yyy/
new Uri.file(r"\xxx\yyy/", windows: true);

// file:///C:/xxx/yyy
new Uri.file(r"C:\xxx\yyy", windows: true);

// This throws an error. A path with a drive letter, but no following
// path, is not allowed.
new Uri.file(r"C:", windows: true);

// This throws an error. A path with a drive letter is not absolute.
new Uri.file(r"C:xxx\yyy", windows: true);

// file://server/share/file
new Uri.file(r"\\server\share\file", windows: true);

If the path passed is not a valid file path, an error is thrown.