Recursive folder inside size statistics

/**
 * 递归判断文件夹大小
 * */
public static long fh(File dir) {
	int len = 0;
	File[] f = dir.listFiles();
	for (File f1 : f) {
		if (f1.isFile()) {
			len += len + f1.length();
		} else {
			len += fh(f1);
		}

	}
	return len;

}
public static void main(String[] args){
 System.out.println(fh(file));
}