在for语句中的if语句中，java程序计算成绩然后分配字母编号。扫描仪类请为循环提供帮助

问：

有人可以帮我处理 for 循环中的 if 语句，Java 新手，当插入“999”时，会破坏循环。谢谢。另外，签署程序的退出或只是用中断语句退出循环会好吗？

package java_1.java;
import java.util.Scanner;

public class HelloWorld {
    public static void main(String[] args) {
        int marks[] = new int[10];
        int i;
        float total=0,avg;
        Scanner scanner = new Scanner(System.in);
        int b = 999;
        for(i=0; i<10; i++) {
            System.out.print("Enter Marks of Subject"+(i+1)+":");
            marks[i] = scanner.nextInt();
            total = total + marks[i];
            if(marks[i]==b)
            {
                break;
            }
        }
        scanner.close();
        
        int sum = 0;
        float average = 0.0f;
        
        // Calculating the average in for loop
        for (i=0; i<marks.length;i++) {
            sum += marks[i];
        }
        average = (float) sum / marks.length;
        
        // Printing the calculating averated value
        System.out.print("The average of he given array: " + average);
        //Calculating the average
        avg = total/10;
        System.out.printf("%n");
        System.out.print("Average student grade out of the scores is: ");
        
        // Define variables for for loop

        if(avg>=80)
        {
            System.out.print("A");
        }
        else if(avg>=60 && avg<80)
        {
            System.out.print("B");
        }
        else if(avg>=40 && avg<60)
        {
            System.out.print("C");
        }
        else
        {
            System.out.print("D");
        }
    }
}