为什么我收到错误“线程中的异常”主“java.util.NoSuchElementException”

Question

对不起，如果有noob错误。我是noob。

package lab7fall2015;

import java.io.File;
import java.io.FileReader;
import java.util.Scanner;
import java.io.FileNotFoundException;

import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileNameExtensionFilter;

public class Lab7{ 
public static String computeMessage(double inputGpa){
    String feedback = "";
    if(inputGpa >= 3.8){
        feedback = "Excellent!";
        return feedback;
    }
    else if(inputGpa >= 3.4 && inputGpa < 3.8){
        feedback = "Very Good!";
        return feedback;
    }
    else if(inputGpa >= 2.8 && inputGpa < 3.4){
        feedback = "Okay";
        return feedback;
    }
    else if(inputGpa < 2.8){
        feedback = "see your advisor";
        return feedback;
    }
    else{
        feedback = "error";
        return feedback;
    }
}

public static void main(String[] args) throws FileNotFoundException{
    String myReaderRef = null;



    JFileChooser chooser = new JFileChooser();
    chooser.setDialogTitle("Lab 7 Josh Peel");
    FileNameExtensionFilter filter = new FileNameExtensionFilter(
                                    "TXT - text files", "txt");
    chooser.setFileFilter(filter);
    chooser.setCurrentDirectory(new File("C:\\Java"));

    int picked = chooser.showOpenDialog(null);
    if (picked == JFileChooser.APPROVE_OPTION){ //user picked something
        myReaderRef = chooser.getSelectedFile().getAbsolutePath();
    }
    else{
        System.exit(0);
    }

    FileReader myReader = new FileReader(myReaderRef);
    Scanner input = new Scanner(myReader);

    String output = "";
    double gpaSum = 0.00;

    while(input.hasNextLine()){
        String readLastName = input.next();
        String readFirstName = input.next();
        String readMiddleName = input.next();
        Double readGpa = input.nextDouble();

        Student aStudent = new Student(readLastName, readFirstName, readMiddleName, readGpa);

        String message = computeMessage(aStudent.getGPA());

        gpaSum += aStudent.getGPA();
        output += aStudent + "   " + message + "\n";    
    }
    input.close();

    String blank = " ";
    Student actor = new Student(blank, blank, blank, 0.0);
    double gpaAvg = gpaSum / actor.getStudentCount();

    output += "\n\nInput file read: " + myReaderRef + "\n";
    output += "That file contains data on " + actor.getStudentCount() + " students\n";
    output += "Average of all GPA's in that file is: " + gpaAvg;

    JOptionPane.showMessageDialog(null, output, "Lab 7 by Josh Peel",
            JOptionPane.INFORMATION_MESSAGE);
}

}
class Name{
private String lastName, firstName, middleName;
public Name(String studentLastName, String studentFirstName, String studentMiddleName){
    lastName = studentLastName;
    firstName = studentFirstName;
    middleName = studentMiddleName;
}
public String toString(){
    String studentName = firstName + " " + middleName + " " + lastName + " ";
    return studentName;
}
}
class Student{
private static Name name;
private double gpa = 0.00;
private int numberOfStudents = 0;

public Student(String newLastName, String newFirstName, 
                String newMiddleName, double newGpa){
    name = new Name(newLastName, newFirstName, newMiddleName);
    gpa = newGpa;
    numberOfStudents++;
}
public double getGPA(){
    return gpa;
}
public String toString(){
    return name + "(" + gpa + ")";
}
public int getStudentCount(){
    return numberOfStudents - 1;
}
}

返回运行时错误，内容如下：

Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at lab7fall2015.Lab7.main(Lab7.java:64)

输入文件读取：

Smith Bob D. 3.14
Jones Mary K. 3.92
Wilson Donald J. 2.91
Martin Mark P. 3.44
Miller Marsha H. 3.66
Dummy Iam A. 1.11
Brilliant Johnny B. 4.0

我在代码中没有错误消息，但我是新手使用扫描仪并从文本文档中分配变量。我使用JFilechooser选择我的文件后失败了。

出于调试目的，我添加了“System.out.print（readLastName）”并输出所有姓氏。所以它可以逐行完成整个文档......