引发与扫描仪相关的错误的引用数组

Question

这是有问题的代码：

 public class GradeBookRunner
 {
 public static void main( String args[] )
  {
    out.println("Welcome to the Class Stats program!");
    int num = 1;
    int count = 0;
    String stuGrades = "";
    String stuName = "";
    Scanner keyboard = new Scanner(System.in);
    out.print("What is the name of this class? ");
    String clsName = keyboard.nextLine();
    out.println("\n");
    out.print("How many students are in this class? ");
    int clsNum = keyboard.nextInt();
    Class CSAB = new Class(clsName, clsNum);
    out.println("\n");
    out.print("Enter the name of student 1 : ");
    stuName = keyboard.nextLine();
    keyboard.next();
    out.print("Enter the grades for " + stuName + "\nUse the format x - grades ( 2 - 100 100) : ");
    //count = keyboard.nextInt();
    //keyboard.next();
    //for(int i = 0; i < count; i++)
    //{
        stuGrades += keyboard.nextLine() + " ";
    //}

    Student add = new Student(stuName,stuGrades);
    CSAB.addStudent(num, add);
    stuGrades = "";
    num++;
    out.println();

使用的类的代码可以在以下链接中找到：

Grades.java：http://pastebin.com/ahYRS2WD

Student.java：http://pastebin.com/EBF4BBCb

Class.java：http://pastebin.com/A1C9fCL1

我的问题是在我运行代码并输入班级名称、班级人数、学生姓名后发生的，这些都很好，当我输入学生的成绩时，下一点会引发错误，例如3 - 70.2 65.3 45.1

编辑 这是我得到的错误：

欢迎来到班级统计计划！ 这个班级的名字是什么？应用

这个班有多少学生？ 1

输入学生 1 的姓名：几乎没有

输入几乎没有的成绩

使用格式 x - 等级 (2 - 100 100)：线程“主”中的异常

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 lab19b.Grades.setGrades(Grades.java:31)

at lab19b.Grades.<init>(Grades.java:25)

at lab19b.Student.<init>(Student.java:27)

at lab19b.GradeBookRunner.main(GradeBookRunner.java:42)

EDIT2

我现在认为问题是我需要 stuGrades 读取整行，例如 3 - 70.2 65.3 45.1 但我不知道需要哪个扫描仪语句将键盘输入放入字符串

EDIT3

这是我证明grades.java 正常工作的证据：

package lab19b;

import java.util.Arrays;
import java.util.Scanner;
import static java.lang.System.*;
import static java.util.Arrays.*;

 public class GradesTester
 {
public static void main( String args[] )
 {
    Grades test = new Grades("5 - 90 85 95.5 77.5 88");
    out.println(test);
    out.println("sum = " + test.getSum());  
    out.println("num grades = " + test.getNumGrades());                                         
    out.println("low grade = " + test.getLowGrade());       
    out.println("high grade = " + test.getHighGrade()+ "\n\n");

    test.setGrades("9 - 10 70 90 92.5 85 95.5 77.5 88 100.0");
    out.println(test);
    out.println("sum = " + test.getSum());  
    out.println("num grades = " + test.getNumGrades());                                         
    out.println("low grade = " + test.getLowGrade());       
    out.println("high grade = " + test.getHighGrade());

输出如下： 90.0 85.0 95.5 77.5 88.0

总和 = 436.0

成绩数 = 5

低等级 = 77.5

高等级 = 95.5

10.0 70.0 90.0 92.5 85.0 95.5 77.5 88.0 100.0

总和 = 708.5

年级数 = 9

低等级 = 10.0

高等级 = 100.0

Answer 1

您的问题是成绩中的 public void setGrades(String gradeList) 函数Line 27 这意味着整个gradeList 类似于“a b c”。将此转换为数组函数并读取单个字符串。 [a]，[b]，[c]。使用 String 的split 函数形成一个数组并填充您的grades[i]

Scanner 中的这个方法导致了这个问题，这意味着在scan.nextInt() 之后没有输入要解析；

 // If we are at the end of input then NoSuchElement;
  903     // If there is still input left then InputMismatch
  904     private void throwFor() {
  905         skipped = false;
  906         if ((sourceClosed) && (position == buf.limit()))
  907             throw new NoSuchElementException();
  908         else
  909             throw new InputMismatchException();
  910     }