static File makeFileNameUnique_withExtension(File f, S ext) { File orig = f; int n = 0; ext = addPrefixIfNempty(".", dropPrefix(".", ext)); S name = dropSuffixIC(ext, orig.getName()); f = new File(dirOfFile(orig), name + ext); while (f.exists()) f = new File(dirOfFile(orig), name + "." + (++n) + ext); ret f; }