parseFileExt static method

String parseFileExt(
  1. String fileName
)

Returns the file extension of fileName.

Throws FormatException if fileName does not end with a file extension.

fileExt("my_image.jpg") == ".jpg"
fileExt("/path/to/my_image.png") == ".png"
fileExt("my_doc.info.pdf") == ".pdf"
fileExt("my_undefined") => throws FormatException
fileExt("my_unfinished.") => throws FormatException

Implementation

static String parseFileExt(String fileName) {
  try {
    String fileExt = fileName.substring(fileName.lastIndexOf("."));

    if (_isValidFileExt(fileExt)) {
      return fileExt;
    } else {
      throw FormatException("$fileExt is not a valid file extension.");
    }
  } on RangeError {
    throw const FormatException("File names must contain a \".\" character.");
  }
}