description

# Uri.file constructor Null safety

Uri.file(

1. String path,
2. {bool? windows}

)

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.

## Implementation

    factory Uri.file(String path, {bool? windows}) = _Uri.file;