我有一個帶有靜態方法的測試類來獲取輸入。 class Test { public static Student readStudent() throws IOException { Scanner s = new Scanner(System.in); System.out.println("Enter first name of student"); String fname = s.nextLine(); System.out.println("Enter middle name of student"); String mname = s.nextLine(); System.out.println("Enter last name of student"); String lname = s.nextLine(); System.out.println("Enter name format(1 for ',' and 2 for ';') "); int num = s.nextInt(); System.out.println("Enter age of student"); int age = s.nextInt(); s.close(); return new Student(new Name(String.join((num == 1) ? "," : ";", fname, mname, lname)), age); } }我能夠接受一名學生的輸入，但是一旦我將其放入 for 循環中，我就會收到錯誤java.util.NoSuchElementException: No line found。這是我的循環for (int i = 0; i < 10; i++) { Student s = Test.readStudent(); }為什么我會收到此錯誤？謝謝。
1 回答
慕俠2389804
TA貢獻1719條經驗 獲得超6個贊
s.close();關閉當前Scanner對象，以及所有底層流（System.in在本例中就是如此）。一旦標準輸入流關閉，您就無法再打開它。
因此，總而言之，在確定不再需要掃描儀并重新構建代碼后，最好關閉它，如下所示：
Scanner sc = new Scanner(System.in);
for (int i = 0; i < 10; i++) {
Student s = Test.readStudent(sc);
// do something with your student object here
}
sc.close();
并將你的方法更改為
public static Student readStudent(Scanner s) throws IOException {
Scanner s = new Scanner(System.in);
System.out.println("Enter first name of student");
String fname = s.nextLine();
System.out.println("Enter middle name of student");
String mname = s.nextLine();
System.out.println("Enter last name of student");
String lname = s.nextLine();
System.out.println("Enter name format(1 for ',' and 2 for ';') ");
int num = s.nextInt();
s.nextLine(); // Need to consume new line
System.out.println("Enter age of student");
int age = s.nextInt();
s.nextLine(); // Need to consume new line
// no closing here
return new Student(new Name(String.join((num == 1) ? "," : ";", fname,
mname, lname)), age);
}
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