1
我有一点麻烦这个项目时出现错误。我们必须使用我们的主要方法来读取文件，然后在gradebook类中执行计算。然而，从课堂上其他人的观点来看，我们使用的方法最好是古老的，涉及并行数组。我们似乎没有其他选择，所以我尽我所能做到了。但接近我所希望的是这段代码的结束，我遇到了一个问题，它说包含学生成绩的索引超出了范围。的ArrayIndexOutOfBounds Java的并行阵列
我已经用很多不同的方式重写了我的main中的readFile方法，但不管我还是得到了这些错误。任何人都可以帮助我理解发生了什么？我会尽我所能。 我也很抱歉，如果我有点慢/无能为力，这是我第一次不幸编码java。此外，在我发布的错误中，主类的第64行是：grades [test] = inputFile.nextDouble（）;
run:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
at Package1.GradeBookDemo.readFile(GradeBookDemo.java:64)
at Package1.GradeBookDemo.main(GradeBookDemo.java:29)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)
以下是我的主要方法：
import java.util.Scanner;
import java.io.*;
public class GradeBookDemo {
public static void main(String[] args) throws IOException {
// Create a new gradebook object
Gradebook gradeBook = new Gradebook();
//Read StudentInfo file for names and test scores using readFile method
readFile(gradeBook);
//Output Student data
for (int index = 1; index <= 5; index++)
{
System.out.println("Name: " + gradeBook.getName(index) +
"\tAverage Score: " + gradeBook.getAverage(index) +
"\tGrade: " + gradeBook.getLetterGrade(index));
}
}
// This method reads from the StudentInfo file
public static void readFile(Gradebook gradeBook) throws IOException
{
int nI = 0; // Name index
int gI = 4; // Grade index
// Create a string array to hold student names and another for grades
double[] grades = new double[gI];
// Access the StudentInfo text file
File sFile = new File("StudentInfo.txt");
// Create a scanner object to read the file
Scanner inputFile = new Scanner(sFile);
// Read StudentInfo
for(int student = 1; student <= 5; student++)
{
String name = inputFile.nextLine();
gradeBook.setName(student, name);
for (int test = 0; test < 4; test++)
{
grades[test] = inputFile.nextDouble();
}
}
// Close the file
inputFile.close();
}
}
然后成绩簿类
public class Gradebook {
// Declare fields
private final int NUM_STUDENTS = 5;
private final int NUM_TESTS = 4;
// ArrayList for names of students - 5 in total
private String[] names = new String[NUM_STUDENTS];
// Array to store letter grades
private char[] grades;
// array to store each student's scores
private double[] scores1 = new double[NUM_TESTS];
private double[] scores2 = new double[NUM_TESTS];
private double[] scores3 = new double[NUM_TESTS];
private double[] scores4 = new double[NUM_TESTS];
private double[] scores5 = new double[NUM_TESTS];
// Method to set student's name
public void setName(int studentNumber, String name)
{
names[studentNumber-1] = name;
}
// Method sets student scores
public void setScores(int studentNumber, double[] scores)
{
switch(studentNumber)
{
case 1:copyArray(scores1,scores); break;
case 2:copyArray(scores2,scores); break;
case 3:copyArray(scores3,scores); break;
case 4:copyArray(scores4,scores); break;
case 5:copyArray(scores5,scores); break;
default:break;
}
}
// Returns the student's name
public String getName(int studentNumber)
{
return names[studentNumber-1];
}
// Returns student's average score
public double getAverage(int studentNumber)
{
double avg=0.0;
switch(studentNumber)
{
case 1:avg = calcAverage(scores1); break;
case 2:avg = calcAverage(scores2); break;
case 3:avg = calcAverage(scores3); break;
case 4:avg = calcAverage(scores4); break;
case 5:avg = calcAverage(scores5); break;
default:break;
}
return avg;
}
// Returns the student's letter grade
public char getLetterGrade(int studentNumber)
{
char lettergrade;
if(getAverage(studentNumber)>=90 && getAverage(studentNumber)<=100)
lettergrade = 'A';
else if(getAverage(studentNumber)>=80 && getAverage(studentNumber)<=89)
lettergrade = 'B';
else if(getAverage(studentNumber)>=70 && getAverage(studentNumber)<=79)
lettergrade = 'C';
else if(getAverage(studentNumber)>=60 && getAverage(studentNumber)<=69)
lettergrade = 'D';
else
lettergrade = 'F';
return lettergrade;
}
// Calculates the student's average
private double calcAverage(double[] scores)
{
double sum=0;
for(int i=0; i<scores.length; i++)
sum+=scores[i];
return sum/scores.length;
}
// Determines student's letter grade based on average score
public char LetterGrade(double average)
{
char lettergrade;
if(average>=90 && average<=100)
lettergrade = 'A';
else if(average>=80 && average<=89)
lettergrade = 'B';
else if(average>=70 && average<=79)
lettergrade = 'C';
else if(average>=60 && average<=69)
lettergrade = 'D';
else
lettergrade = 'F';
return lettergrade;
}
// Array copy method
private void copyArray(double[] to, double[] from)
{
System.arraycopy(from, 0, to, 0, from.length);
}
}
这里是程序读取文件 - StudentInfo.txt：
Joanne Smith
98
89
100
76
Will Jones
67
89
91
88
Kerry McDonald
78
79
88
91
Sam Young
88
98
76
56
Jill Barnes
94
93
91
98
我已经试过了，它对我没有任何问题。尝试清理并重建您的项目。 – Jens 2014-10-09 06:14:02
这很奇怪，它仍然给我同样的错误。也许我会尝试使用不同的编译器。 – Alzecha 2014-10-09 06:23:44
也许你的文件数据不正确，因为'readFile（）'发生异常' – Yazan 2014-10-09 06:25:31