等级计算器程序

Question

public class proj2 {

 public static void main(String[] args) {
 Scanner s = new Scanner(System.in);

  System.out.println("Welcome to Gradecalculator!");

  System.out.println("Please enter the number of students:");
  int students = s.nextInt();

  System.out.println("Please enter the number of exams:");
  int exams = s.nextInt();

  int i = 0;
  int studentnumber = 1;

  int sum = 0;  
  while (i < students) {

    double average = sum/exams;

    System.out.println("Enter student " + studentnumber++ + "'s name :");
    String studentname = s.next();

    System.out.println("Enter exam scores :");

    for (; i < exams; i++) {    
     int n = s.nextInt();
     sum+=n;

     if (n < 0) {
     System.out.println("Invalid exam scores, reenter: ");      
     }
  }
  if (average <= 100 && average >= 90) {
       System.out.println("Letter grade: A");
       System.out.println(studentname + " gets 4 stars! ****");
      } if (average <= 89 && average >= 80) {
       System.out.println("Letter grade: B");
       System.out.println(studentname + " gets 3 stars! ***");
      } if (average <= 79 && average >= 70) {
       System.out.println("Letter grade: C");
       System.out.println(studentname + " gets 2 stars! **");
      } if (average <= 69 && average >= 60) {
       System.out.println("Letter grade: D");
       System.out.println(studentname + " gets 1 star! *");
      } if (average <= 59) {
       System.out.println("Letter grade: F");
       System.out.println(studentname + " gets 0 stars!");
      }
}
 }
 }

Welcome to Gradecalculator!

请输入学生人数：3请输入考试次数：3输入学生1的姓名：sam输入考试分数：80 80 80字母等级：F sam得0星！

显然三个80首先应该是一个B，所以我显然没有计算好平均数，但我想不出为什么。

Answer 1

您的条件应如下所示：

if (average <= 100 && average >=90)

不是这样的：

if (average <= 100 & average >=90)

您希望使用逻辑AND而不是按位AND。