不返回正確的值

Question

主類：

public class Student 
{ 
    private int numberOfQuizzes; 
    private double newQuizScore; 
    private double averageScore; 
    private double totalScore; 
    private double average; 
    private double gpa; 
    private double finalGpa; 
    private double gpa1; 
    private double gpa2; 
    private String className; 
    private double gpa3; 
    private boolean addQuiz; 
    private String studentName; 
    public Student(String studentName) 
    { 
     this.studentName = studentName; 
    } 
    public void addQuiz(double newQuizScore) 
    { 
     this.newQuizScore = newQuizScore; 
     if(newQuizScore >= 0) 
     { 
      totalScore = totalScore + newQuizScore; 
      numberOfQuizzes++; 
     } 
    } 
    public void setAverageScore() 
    { 
     averageScore = totalScore/numberOfQuizzes; 
    } 
    public void resetScore() 
    { 
     averageScore = 0; 
     totalScore = 0; 
     numberOfQuizzes = 0; 
     newQuizScore = 0; 
    } 
    public void setGpaValue(double average, String className) 
    { 
    if(className.equalsIgnoreCase("Biology")) 
    { 
     if(average >= 93.0) 
     { 
      gpa1 = 4.0; 
     } else if(average < 93.0 && average >= 90.0) 
     { 
      gpa1 = 3.66; 
     } else if(average < 90.0 && average >= 87.0) 
     { 
      gpa1 = 3.33; 
     } else if(average < 87.0 && average >= 83) 
     { 
      gpa1 = 3.00; 
     } else if(average < 84.0 && average >= 80.0) 
     { 
      gpa1 = 2.66; 
     } else if(average < 80 && average >= 77) 
     { 
      gpa1 = 2.33; 
     } else if(average < 77 && average >= 73) 
     { 
      gpa1 = 2.00; 
     } else if(average < 73 && average >= 70) 
     { 
      gpa1 = 1.66; 
     } else if(average < 70 && average >= 67) 
     { 
      gpa1 = 1.33; 
     } else if(average < 67 && average >= 63) 
     { 
      gpa1 = 1.00; 
     } else if(average < 63 && average >= 60.0) 
     { 
      gpa1 = .66; 
     } else if(average < 60 && average >= 0) 
     { 
      gpa1 = .00; 
     } 
    } 
    if(className.equalsIgnoreCase("Calculus")) 
    { 
     if(average >= 93.0) 
     { 
      gpa2 = 4.0; 
     } else if(average < 93.0 && average >= 90.0) 
     { 
      gpa2 = 3.66; 
     } else if(average < 90.0 && average >= 87.0) 
     { 
      gpa2 = 3.33; 
     } else if(average < 87.0 && average >= 83) 
     { 
      gpa2 = 3.00; 
     } else if(average < 84.0 && average >= 80.0) 
     { 
      gpa2 = 2.66; 
     } else if(average < 80 && average >= 77) 
     { 
      gpa2 = 2.33; 
     } else if(average < 77 && average >= 73) 
     { 
      gpa2 = 2.00; 
     } else if(average < 73 && average >= 70) 
     { 
      gpa2 = 1.66; 
     } else if(average < 70 && average >= 67) 
     { 
      gpa2 = 1.33; 
     } else if(average < 67 && average >= 63) 
     { 
      gpa2 = 1.00; 
     } else if(average < 63 && average >= 60.0) 
     { 
      gpa2 = .66; 
     } else if(average < 60 && average >= 0) 
     { 
      gpa2 = .00; 
     } 
    } 
    if(className.equalsIgnoreCase("CompSci")) 
    { 
     if(average >= 93.0) 
     { 
      gpa3 = 4.0; 
     } else if(average < 93.0 && average >= 90.0) 
     { 
      gpa3 = 3.66; 
     } else if(average < 90.0 && average >= 87.0) 
     { 
      gpa3 = 3.33; 
     } else if(average < 87.0 && average >= 83) 
     { 
      gpa3 = 3.00; 
     } else if(average < 84.0 && average >= 80.0) 
     { 
      gpa3 = 2.66; 
     } else if(average < 80 && average >= 77) 
     { 
      gpa3 = 2.33; 
     } else if(average < 77 && average >= 73) 
     { 
      gpa3 = 2.00; 
     } else if(average < 73 && average >= 70) 
     { 
      gpa3 = 1.66; 
     } else if(average < 70 && average >= 67) 
     { 
      gpa3 = 1.33; 
     } else if(average < 67 && average >= 63) 
     { 
      gpa3 = 1.00; 
     } else if(average < 63 && average >= 60.0) 
     { 
      gpa3 = .66; 
     } else if(average < 60 && average >= 0) 
     { 
      gpa3 = .00; 
     } 
    } 
    } 
    public void setTotalGpa() 
    { 
     finalGpa = (gpa1 * gpa2 * gpa3)/3; 
    } 
    public double getAverageScore() 
    { 
     return averageScore; 
    } 
    public double getTotalGpa() 
    { 
     return finalGpa; 
    } 
    public double totalScore() 
    { 
     return totalScore; 
    } 
    public double getGpaValue() 
    { 
     return average; 
    } 
    public String toString() 
    { 
     String toString = "\nStudent Name: " + studentName + 
          "\nStudent Gpa: " + finalGpa; 
     return toString; 
    } 
} 

Tester類： http://pastebin.com/meh3Vqvq

我有一個問題GPA總是返回0.0。其他的一切似乎都運行良好，除了GPA無法工作。

Answer 1

private double average; 
... 
public double getGpaValue() 
{ 
    return average; 
} 

該方法返回一個永不分配的成員，所以默認情況下其值保持爲0.0。

您正在將average傳遞給public void setGpaValue(double average, String className)方法，但不會將其存儲在實例變量中。