Question

我已经完成了代码并反复尝试新事物，似乎无法摆脱这个错误。我正在写一个程序，我扫描一个文件作为输入，它通过并找到平均值，最大值和最小值。但是我已经在代码的末尾遇到了问题，我必须给每个分数评分，然后计算每个分数的数量。它编译得很好，但是当我去运行它时，java.langNoClassDefFoundError：不断出现请尽可能帮助。

import java.io.*;
import java.util.*;


class Exam
{
public static void main(String [] args) throws IOException
{
int A;
int B;
int C;
int D;
int F;
// Greets user and prompts to enter name of the file containing there grades.
  System.out.println("***Welcome to the Exam Statistics Program!!***");   
  Scanner cin = new Scanner(System.in);
  System.out.println("Please enter a filename:");
  String filename = cin.next();


// Scanner built for new file and puts grades into an array.  
Scanner file = new Scanner(new FileReader(filename));
  int g;
    g=file.nextInt();
    int [] grades = new int[g];
    for(int i=0; i<grades.length; i++)
    {
      grades[i] = file.nextInt();
    }
    System.out.println("Minimum Score:  " + getMinValue(grades));
    System.out.println("Maximum Score:  " + getMaxValue(grades));
    System.out.println("Average Score:  " + Average(grades));
    System.out.println(" ");
    System.out.println(" ");
    System.out.println(" ");

    System.out.println("A:  " +A);
    System.out.println("B:  " +B);
    System.out.println("C:  " +C);
    System.out.println("D:  " +D);
    System.out.println("F:  " +F);
    System.out.println("The grade count is: "+ g);
}


// Calculates the average of the array and returns the variable containing that values.
static double Average( int [] grades)
{
    double sum=0;
    double x;
    for(int i=0; i<grades.length; i++)
        sum += (double)grades[i];
    if(grades.length==0) return 0;
      x = sum/grades.length;
    return x;

}
// Calculates the lowest grade in the file.
public static int getMinValue(int[] grades)
{  
  int minValue = grades[0];  
  for(int i=1;i<grades.length;i++)
  {

      if(grades[i] < minValue)
      {
        minValue = grades[i];  
      }  
      }return minValue;
}
// Calculates the highest grade in the file.
public static int getMaxValue(int[] grades)
{  
    int maxValue = grades[0];  
    for(int i=1;i < grades.length;i++)
    {  
        if(grades[i] > maxValue)
        {  
          maxValue = grades[i];  
        }  
    }  return maxValue;  
}  

// Adds up the total number of letter grades you have in the file.
public static int countA(int[] grades) //throws IOException
{
  int A=0;
  for(int i=1; i<grades.length;i++)
        {
            if(grades[i]>89||grades[i]<=100)
            {
              A = A++;
            }
        }
  return A;
}
public static int countB(int[] grades)
{
  int B=0;
  for(int i=1; i<grades.length;i++)
        {
            if(grades[i]>79||grades[i]<=89)
            {
              B = B++;
            }
        }
  return B;

}
public static int countC(int[] grades)
{
  int C = 0;
  for(int i=1; i<grades.length;i++)
        {
            if(grades[i]>69||grades[i]<=79)
            {
              C = C++;
            }
        }
  return C;
}
public static int countD(int[] grades)
{
  int D = 0;
  for(int i=1; i<grades.length;i++)
        {
            if(grades[i]>59||grades[i]<=69)
            {
              D = D++;
            }
        }
  return D;
}
public static int countF(int[] grades)
{
  int F = 0;
  for(int i=1; i<grades.length;i++)
        {
            if(grades[i]<=59)
            {
              F = F++;
            }
  }
  return F;
 }
 }

Answer 1

您的堆栈跟踪显示错误Exception in thread "main" java.lang.NoClassDefFoundError: Exam2。

但是你的班级名为Exam。因此，请将您的文件名从Exam.java

更改为Exam2.java

Answer 2

在这里，您创建了一个名为Exam2.java的Java文件。根据Java的文件命名约定，您必须提供与包含Main Method的类名相同的文件名。但根据你的主要方法的课程，它是考试，所以我建议你把它改为Exam2而不是考试。

线程“main”java.lang.NoClassDefFoundError中的异常：

2 个答案: