我一直得到"线程中的异常"主"java.util.NoSuchElementException"

Question

所以我试图在Java中创建一个简单的程序来读取文本文件(来自命令行参数),用户可以检查他们输入的数字是否在文本文件中.

File inputFile = new File(args[0]);
Scanner scanman = new Scanner(inputFile); //Scans the input file
Scanner scanman_2 = new Scanner(System.in); //Scans for keyboard input
int storage[] = new int[30]; //Will be used to store the numbers from the .txt file

for(int i=0; i<storage.length; i++) {
  storage[i]=scanman.nextInt();
  }
System.out.println("WELCOME TO THE NUMERICAL DATABASE"+
                  "\nTO CHECK TO SEE IF YOUR NUMBER IN THE DATABASE"+
                  "\nPLEASE ENTER IT BELOW! TO QUIT: HIT CTRL+Z!");
while(scanman_2.hasNext()){
  int num_store = scanman_2.nextInt();
  boolean alert = false;
  for (int i=0; i<storage.length; i++) {
     if(storage[i]==num_store){
        alert=true;
        }
     }
  if (alert) {
     System.out.println("Yep "+num_store+" is in the database\n");
     }
  else {
     System.out.println("Nope, "+num_store+" is not in the database\n");
     }
  }
System.out.println("See ya!");                
  }
}

每当我试图运行它时,我会一直得到:

Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:907)
at java.util.Scanner.next(Scanner.java:1530)
at java.util.Scanner.nextInt(Scanner.java:2160)
at java.util.Scanner.nextInt(Scanner.java:2119)
at Database.main(Database.java:17)

我做了类似的程序,没有任何问题.有谁知道我做错了什么？

Answer 1

您反复调用nextInt(),而不是测试,看看是否有是下一个int类型.改变这个

for(int i=0; i<storage.length; i++) {
  storage[i]=scanman.nextInt();
}

对此

for(int i=0; i<storage.length  &&  scanman.hasNext(); i++) {
  storage[i]=scanman.nextInt();
}

根据您的要求,您需要确定这是否可接受,如果没有,请确定为什么storage.length和int-inputs的数量与您预期的不同.