java读文件出现 java.util.InputMismatchException异常

Console框:
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at budong.Bu.main(Bu.java:9)

你这么写，它读的是“D:\a.txt”这个字符串，而不是文件里面的内容。你想读取文件，应该用File，比如：

File file = new File("D:\\a.txt");
Scanner  scanner = new Scanner(file);
int n = scanner.nextInt();