JM Chapter 10 #17

// No description, too long to write out

JM Chapter 10 #17

"1STFILE.TXT", "1STFILE.TXT"
"HI:IamAllen", null
"blah.blah.blah", null
"HItherewhereareyou", null
"1STFILE", "1STFILE.TXT"
"1stFile", "1STFILE.TXT"
"1stfile.", "1STFILE"
"1STFILE.L", "1STFILE.L"
"1STFILE.l", "1STFILE.l"
"hello!?.txt", null
"h.ello!.txt", "null"
"hello!.jpeg", "null"
"\\hello", "null"

private String validFileName(String fileName) {
		if (fileName.length() > 11) {
			return null;
		}
		// There are more than two dots in the fileName or the extension is too
		// long
		if (fileName.indexOf(".") != -1 && (fileName.indexOf(".") != fileName.lastIndexOf(".")
				|| (fileName.length() - fileName.lastIndexOf(".") > 4))) {
			return null;
		}
		// Check that there are no illegal characters, "." was checked for
		// before
		if (fileName.contains(":") || fileName.contains("\\")
				|| fileName.contains("?") || fileName.contains("*")) {
			return null;
		}
		if (fileName.indexOf(".") == fileName.length() - 1) {
			return fileName.toUpperCase().substring(0, fileName.length() - 1);
		}
		if (fileName.indexOf(".") == -1) {
			return fileName.toUpperCase() + ".TXT";
		}
		return fileName.substring(0, fileName.indexOf(".")).toUpperCase()
				+ fileName.substring(fileName.indexOf("."));
	}