我需要在课堂上显示学生的数字标记以及他们的字母成绩。 我的代码不输出字母。 我怎样才能解决这个问题？

Question

import java.io.*;
class finalGrade
{
    //declare variables
    String name;
    double quizTotal = 0;
    double midterm = 0;
    double exam = 0;
    double mark = 0;
    char grade;


    //initialize variables
    public finalGrade (String nameStudent, double quizMark, double midtermMark, double examMark)
    {
        name = nameStudent;
        quizTotal = quizMark;
        midterm = midtermMark;
        exam = examMark;
    }

    public double marks()
    {
        mark = ((exam * 0.25) + (midterm * 0.25) + (quizTotal * 0.50));

        System.out.println((name) + ", your mark is " + (mark) + " and you get a(n) " + (grade));

        if (mark >= 90)
        {
            return (grade) = 'A';
        }
        else if (mark >= 80 && mark < 90)
        {
            return (grade) = 'B';
        }
        else if (mark >= 70 && mark < 80)
        {
            return (grade) = 'C';
        }
        else if (mark >= 60 && mark < 70)
        {
            return (grade) = 'D';
        }
        else if (mark < 60)
        {
            return (grade) = 'F';
        }
        else
        {
            return (grade) = 'F';
        }


    }
}



class finalGradeTester
{
    public static void main(String[] args)
    {
    InputStreamReader inStream = new InputStreamReader(System.in);
    BufferedReader sub = new BufferedReader(inStream);

    finalGrade Student1 = new finalGrade("Student", 89, 100, 21);
    finalGrade Student2 = new finalGrade("Student", 34, 21, 9);
    finalGrade Student3 = new finalGrade("Student", 89, 100, 21);
    finalGrade Student4 = new finalGrade("Student", 89, 100, 21);
    finalGrade Student5 = new finalGrade("Student", 89, 100, 21);

    Student1.marks();
    Student2.marks();

    }

}

This is supposed to calculate the mark, two tests worth 25%, and an exam worth 50%. It works fine for the calculations but when displaying the letter grade it is blank. I do not know how to fix this. The output I get when I run the code is: Student, your mark is 74.75 and you get a(n) Student, your mark is 24.5 and you get a(n)

It does not display the letter grade.

Answer 1

You are printing before computing the grade . Also, there is no need to return anything here.

public double marks()
{
    mark = ((exam * 0.25) + (midterm * 0.25) + (quizTotal * 0.50));

    if (mark >= 90)
    {
        grade = 'A';
    }
    else if (mark >= 80 && mark < 90)
    {
        grade = 'B';
    }
    else if (mark >= 70 && mark < 80)
    {
        grade = 'C';
    }
    else if (mark >= 60 && mark < 70)
    {
        grade = 'D';
    }
    else if (mark < 60)
    {
        grade = 'F';//This must be E
    }
    else
    {
        grade = 'F';
    }
    System.out.println((name) + ", your mark is " + (mark) + " and you get a(n) " + (grade));

}

Also, there is no reason to compute mark and grade each time the method is called. You can compute the grade with a private method and call it from the constructor.

Answer 2

that's because you return the mark, instead of including ot on the System.out also, no need to re-verify if mark is <90, as otherwise it would be an A.

Also, class name have uppercase while variable have lowercase

import java.io.*;
class FinalGrade
{
    //declare variables
    String name;
    double quizTotal = 0;
    double midterm = 0;
    double exam = 0;
    double mark = 0;
    char grade;


    //initialize variables
    public FinalGrade (String nameStudent, double quizMark, double midtermMark, double examMark)
    {
        name = nameStudent;
        quizTotal = quizMark;
        midterm = midtermMark;
        exam = examMark;
    }

    public void marks()
    {
        mark = ((exam * 0.25) + (midterm * 0.25) + (quizTotal * 0.50));

        if (mark >= 90)
        {
            grade = 'A';
        }
        else if (mark >= 80)
        {
            grade = 'B';
        }
        else if (mark >= 70)
        {
            grade = 'C';
        }
        else if (mark >= 60)
        {
            grade = 'D';
        }
        else
        {
            grade = 'F';
        }

        System.out.println((name) + ", your mark is " + (mark) + " and you get a(n) " + (grade));




    }
}



class finalGradeTester
{
    public static void main(String[] args)
    {
    InputStreamReader inStream = new InputStreamReader(System.in);
    BufferedReader sub = new BufferedReader(inStream);

    FinalGrade student1 = new FinalGrade("Student", 89, 100, 21);
    FinalGrade student2 = new FinalGrade("Student", 34, 21, 9);
    FinalGrade student3 = new FinalGrade("Student", 89, 100, 21);
    FinalGrade student4 = new FinalGrade("Student", 89, 100, 21);
    FinalGrade student5 = new FinalGrade("Student", 89, 100, 21);

    student1.marks();
    student2.marks();

    }

}