java - 当我想从键盘读取内容时，出现 java.util.NoSuchElementException

Question

这个问题已经有答案了:

NoSuchElementException with Java.Util.Scanner (10 个回答)

已关闭 4 年前。

我想制作一个简单的应用程序，它从键盘读取字符串，然后打印一条消息。这是我的代码:

import java.util.Scanner; 

public class HelloWorld {   
    public static void main(String argv[]) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("enter an integer");
        int myint = keyboard.nextInt();
        System.out.println(myint+ " <- that's the string");     
    }    
}

出了点问题，因为我收到一条错误消息:

Exception in thread "main" java.util.NoSuchElementException at java.util.Scanner.throwFor(Scanner.java:862) at java.util.Scanner.next(Scanner.java:1485) at java.util.Scanner.nextInt(Scanner.java:2117) at java.util.Scanner.nextInt(Scanner.java:2076) at HelloWorld.main(HelloWorld.java:25)

我该如何解决这个问题？

Answer 1

您必须使用scanner.hasNext()和scanner.hasNextInt()。

  // find the next int token and print it
  // loop for the whole scanner
  while (scanner.hasNext()) {

     // if the next is a int, print "Found" and the int
     if (scanner.hasNextInt()) {
        System.out.println("Found " + scanner.nextInt());
     }
     // if no int is found, print "Not found" and the token
     System.out.println("Not found " + scanner.next());
  }