Question

我试图打印“学费会增加”，当至少有三名学生平均达到70％以上时，如果少于3名学生平均达到70％以上，则“学费不会增加”。我的问题是，即使平均值不高于70％，该计划也将打印出“学费会增加”。我不确定我做错了什么。我试过改变if语句，我觉得我错过了很简单的东西。

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

        // Create array to store 5 students and 3 classes per student
        int[][] grades = new int[5][3]; 

        // Create array to store students first and last name
        String[] names = new String[5]; 

        // Create array to store average scores
        double[] avgScores = new double[5]; 

        // Prompt user to input name
        for (int i = 0; i < names.length; i++)
        {
            System.out.print("Enter the student's first and last name: ");
            names[i] = input.nextLine(); 
        }


        double average = 0; 
        int score; // student's grade
        int finalGrade = 0; // collective grades
        int goodStudents = 0; // students that received average of 70+

        // Prompt user to input grades using nested for loop
        for (int i = 0; i <= 4; i++) // from student 1 to student 5
        {
            for (int k = 0; k <= 2; k++) // from class 1 to class 3 
            {
                System.out.print("Enter the grade for class " + (k + 1) + " " + "for student "
                        + (i + 1) + " : "); 
                grades[i][k] = input.nextInt();

                score = grades[i][k]; 
                finalGrade = finalGrade + score; 
            }

            // Calculate the average score for the 3 classes
            avgScores[i] = finalGrade / 3; 

            finalGrade = 0; // reset 
        }   
            for (int j = 0; j <= 4; j++)
            {
                if (avgScores[j] < 70)
                {
                    goodStudents++; 
                }

        }

        // count the number of students that have 70+ average

            if (goodStudents >= 3)
            {
                System.out.println("Tuition will be increased by 10% next semester.");
            } else if (goodStudents < 3)
            {
                System.out.println("Tuition will not be increased.");
            }   

    }

Answer 1

我很确定你的逻辑不正确

< 70

您的标准至少有三名学生平均为70％+ ，但您正在测试if (avgScores[j] >= 70) { goodStudents++; }。改变它，

/Users/useraccount/Google Drive Family/code/Rails/12-Week-Challenge/Week_0 [Dry Run]/testapp/

Answer 2

您需要获得分数的最大值并获得百分比（70％），稍后您必须使用该分数。这是其中一种方式：

import java.util.Scanner;

class Dot {

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

        int max_score = 5;  // Max score 
        double persn = 5 *0.7; // 0.7 is 70%
        // Create array to store 5 students and 3 classes per student
        int[][] grades = new int[5][3];

        // Create array to store students first and last name
        String[] names = new String[5];

        // Create array to store average scores
        double[] avgScores = new double[5];

        // Prompt user to input name
        for (int i = 0; i < names.length; i++) {
            System.out.print("Enter the student's first and last name: ");
            names[i] = input.nextLine();
        }

        double average = 0;
        int finalGrade = 0; // collective grades
        int goodStudents = 0; // students that received average of 70+

        // Prompt user to input grades using nested for loop
        for (int i = 0; i <= 4; i++) // from student 1 to student 5
        {
            for (int k = 0; k <= 2; k++) // from class 1 to class 3 
            {
                System.out.print("Enter the grade for class (max = )"+max_score+ + (k + 1) + " " + "for student "
                        + (i + 1) + " : ");
                grades[i][k] = input.nextInt();

                finalGrade += grades[i][k];
            }

            // Calculate the average score for the 3 classes
            avgScores[i] = finalGrade / 3.0;

            finalGrade = 0; // reset 
        }
        for (int j = 0; j < 5; j++) {
            if (avgScores[j] <= persn) {   //here is 70% as persn
                goodStudents++;
            }

        }

        // count the number of students that have 70+ average
        if (goodStudents >= 3) {
            System.out.println("Tuition will be increased by 10% next semester.");
        } else if (goodStudents < 3) {
            System.out.println("Tuition will not be increased.");
        }
    }
}

JAVA if语句的问题？无法正确显示最终结果。

2 个答案: