String (String filePath, int rootPathLength) { boolean isClassFile = SystemInfo.isFileSystemCaseSensitive ? StringUtil.endsWith(filePath, CLASS_EXTENSION) : StringUtil.endsWithIgnoreCase(filePath, CLASS_EXTENSION); if (!isClassFile) return null; String withoutExtension = filePath.substring(rootPathLength, filePath.length() - CLASS_EXTENSION.length()); return withoutExtension.replace('/', '.'); }