調用函數給出「NoSuchElementException」

我在一起簡單的Java程序來解釋循環。我希望每個演示都在一個單獨的功能中。現在，每個函數都可以正常工作，但只有當另一個函數沒有被調用時。如果我打電話我都得到了以下錯誤在運行時：調用函數給出「NoSuchElementException」

Please input a positive integer as the end value: 5 
The summation is: 9 
How many rows do you want your triangle to be?: Exception in thread "main" java.util.NoSuchElementException 
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 loops.exercise2(loops.java:48) 
at loops.main(loops.java:11)

代碼：

import java.util.Scanner; 

public class loops 
{ 

public static void main(String args[]) 
{ 
    exercise1(); 
    System.out.println(); 
    exercise2(); 
} 

public static void exercise1() 
{ 

    int limit; 
    int i; 
    int sum; 

    Scanner keyboard = new Scanner(System.in); 


    System.out.print ("Please input a positive integer as the end value: "); 

    limit = keyboard.nextInt(); 

    i=1; 
    sum = 0; 

    while (i <= limit) 
    { 
     sum = sum + i; 
     i = i + 2;   
    } 

    System.out.print("The summation is: " + sum); 

    keyboard.close(); 
} 

public static void exercise2() 
{ 
    int numRows, i, j; 
    Scanner keyboard = new Scanner(System.in); 

    System.out.print("How many rows do you want your triangle to be?: "); 
    numRows = keyboard.nextInt(); 

    for(i=0; i<numRows; i++) 
    { 
     for(j=0; j<=i; j++) 
     { 
      System.out.print("*");    
     } 
     System.out.println(); 
    } 

    keyboard.close(); 
}

}

來源

2013-07-29 user2112156

提示：下一次，使用更短的標題！ =） –

這是因爲兩種方法都在等待掃描器輸入（這是您的控制檯輸入），並且出現了干涉對方 – bas