Scanner,nextInt和InputMismatchException

Question

我正在尝试读取一个文本文件,然后使用Java中的nextInt()函数在循环中打印出整数.我的文本文件的格式如下:

a 2000 2
b 3000 1
c 4000 5
d 5000 6

这是我的代码:

public static void main(String[] args) throws FileNotFoundException {

  String fileSpecified = args[0] + ".txt";

  FileReader fr = new FileReader(fileSpecified);
  BufferedReader br = new BufferedReader (fr);
  Scanner in = new Scanner (br);

  while (in.hasNextLine()) {
    System.out.println ("next int = " + in.nextInt());
  }
}

我总是得到的错误是:

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)

每次在任何程序中使用nextInt()时都会出现此错误.

Answer 1

我认为它将找到字符,例如"a","b","c"这是一个字符串,并且未能将其作为int.您可以通过调试来解决这个问题:

System.out.println ("next value= " + in.next());
//System.out.println ("next int = " + in.nextInt());

您也可以使用API​​保护来防止这种情况

if(in.hasNextInt()) {
        System.out.println ("next int = " + in.nextInt());
}