我对 Java 很陌生,但正在阅读《Java:如何编程》(第 9 版)一书,并找到了一个例子,我一生都无法弄清楚问题是什么。
这是教科书中源代码示例的(稍微)增强版本:
import java.util.Scanner;
public class Addition {
public static void main(String[] args) {
// creates a scanner to obtain input from a command window
Scanner input = new Scanner(System.in);
int number1; // first number to add
int number2; // second number to add
int sum; // sum of 1 & 2
System.out.print("Enter First Integer: "); // prompt
number1 = input.nextInt(); // reads first number inputted by user
System.out.print("Enter Second Integer: "); // prompt 2
number2 = input.nextInt(); // reads second number from user
sum = number1 + number2; // addition takes place, then stores the total of the two numbers in sum
System.out.printf( "Sum is %d\n", sum ); // displays the sum on screen
} // end method main
} // end class Addition
我收到“NoSuchElementException”错误:
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:838)
at java.util.Scanner.next(Scanner.java:1461)
at java.util.Scanner.nextInt(Scanner.java:2091)
at java.util.Scanner.nextInt(Scanner.java:2050)
at Addition.main(Addition.java:16)
Enter First Integer:
我知道这可能是由于源代码中的某些内容与Scanner
班级来自java.util
,但在推断问题所在方面我真的无法比这更进一步。
NoSuchElementException
抛出的nextElement
枚举的方法,指示枚举中不再有元素。
http://docs.oracle.com/javase/7/docs/api/java/util/NoSuchElementException.html http://docs.oracle.com/javase/7/docs/api/java/util/NoSuchElementException.html
这个怎么样 :
if(input.hasNextInt() )
number1 = input.nextInt(); // if there is another number
else
number1 = 0; // nothing added in the input
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