Java GPA 计算器问题

Question

我无法找出我的程序的问题，非常感谢任何帮助!不幸的是，我是一名初学者程序员......当我运行该程序时，它会正确要求类(class)数量、学分和成绩，但它会忽略输入的学分，只给出字母成绩的正常值。最后它还写着“你的 GPA 是 0.0”，但这显然是不正确的。再次感谢!

public class QualityPoints 
{
public static void main(String[] args) 
{
    // Needed variables

    String grade;
    int totalCredits = 0;
    int totalCreditsEarned = 0;
    int credits;
    int classes;
    double gpa;
    double number=0;

    String greeting = "This program will calculate your GPA.";
    JOptionPane.showMessageDialog(null, greeting, "GPA Calculator", 1);


    classes = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter the number of classes you are taking"));



    //Loop that ends once the student has put information in on all his classes
    for(int count = 0; count < classes; count++)
    {   
        credits = Integer.parseInt(JOptionPane.showInputDialog(null, "How many credit was this class?:"));
        //reads the letter grade using the String Grade prompt



    // gathers input from user and assigns a string into JOptionPane
    grade = JOptionPane.showInputDialog(null, "Enter letter grade: ",
            "Quality Points Converter", JOptionPane.INFORMATION_MESSAGE);
    // calls separate method (computeQualityPoints) using parameter grade




        if (!grade.equalsIgnoreCase("a") && !grade.equalsIgnoreCase("a-")
                && !grade.equalsIgnoreCase("b+") && !grade.equalsIgnoreCase("b")
                && !grade.equalsIgnoreCase("b-") && !grade.equalsIgnoreCase("c+")
                && !grade.equalsIgnoreCase("c") && !grade.equalsIgnoreCase("c-")
                && !grade.equalsIgnoreCase("d+") && !grade.equalsIgnoreCase("d")
                && !grade.equalsIgnoreCase("d-") && !grade.equalsIgnoreCase("f")) {
            JOptionPane.showMessageDialog(null, "Invalid grade entered");
        } else {
            JOptionPane.showMessageDialog(null, "You received "
                    + computeQualityPoints(grade) + " quality points");
            computeQualityPoints(grade);

        }

        //algorithm for finding the GPA
        totalCredits += credits;
        totalCreditsEarned += (credits * number);
        }
        //for loop ends

        //GPA is calculated for all the students classes
        gpa = totalCreditsEarned / totalCredits;

    JOptionPane.showMessageDialog(null, "Your GPA is: " + gpa);

}

/**
 * Uses the letter grade given as the parameter to compute quality points
 * received, thus displaying quality points as the output
 * 
 * @param grade
 * @return JOptionPane message box with the number of quality points, given
 *         a valid letter grade.
 */

public static double computeQualityPoints(String grade) {

    /**
     * If/else statments providing the message attached to the output
     * corresponding to the grade
     */


    if (grade.equalsIgnoreCase("a")) {
        return 4.0;
    }
    if (grade.equalsIgnoreCase("a-")) {
        return 3.7;
    }
    if (grade.equalsIgnoreCase("b+")) {
        return 3.3;
    }
    if (grade.equalsIgnoreCase("b")) {
        return 3.0;
    }
    if (grade.equalsIgnoreCase("b-")) {
        return 2.7;
    }
    if (grade.equalsIgnoreCase("c+")) {
        return 2.3;
    }
    if (grade.equalsIgnoreCase("c")) {
        return 2.0;
    }
    if (grade.equalsIgnoreCase("c-")) {
        return 1.7;
    }
    if (grade.equalsIgnoreCase("d+")) {
        return 1.3;
    }
    if (grade.equalsIgnoreCase("d")) {
        return 1.0;
    }
    if (grade.equalsIgnoreCase("d-")) {
        return 0.7;
    }
    if (grade.equalsIgnoreCase("f")) {
        return 0.0;
    }
    return 0.0;
}
}

Answer 1

totalCreditsEarned += (credits * number);

number 仍为 0.0，这意味着 totalCreditsEarned 和 gpa 也将保持为 0.0 >.

我怀疑

computeQualityPoints(grade);

您忽略返回值的地方应该是

number = computeQualityPoints(grade);

(至少我假设这就是 number 应该包含的内容)