java:40: error: bad operand types for binary operator '/'

[JeffreyAaron Smith]

Please forgive me ignorance, but I'm pulling my hair out...and I don't have much left.

The errors I'm getting are:

40: error: bad operand types for binary operator '/'
gradePoints = (earnedPoints / possiblePoints);
^
first type: int[]
second type: int[]
47: error: bad operand types for binary operator '<'
if (gradePoints < .60)
^
first type: double[]
second type: double
49: error: bad operand types for binary operator '>='
else if (gradePoints >= .60 && gradePoints < .70)
^
first type: double[]
second type: double
49: error: bad operand types for binary operator '<'
else if (gradePoints >= .60 && gradePoints < .70)
^
first type: double[]
second type: double
51: error: bad operand types for binary operator '>='
else if (gradePoints >= .70 && gradePoints < .80)
^
first type: double[]
second type: double
51: error: bad operand types for binary operator '<'
else if (gradePoints >= .70 && gradePoints < .80)
^
first type: double[]
second type: double
53: error: bad operand types for binary operator '>='
else if (gradePoints >= .80 && gradePoints < .90)
^
first type: double[]
second type: double
53: error: bad operand types for binary operator '<'
else if (gradePoints >= .80 && gradePoints < .90)
^
first type: double[]
second type: double
55: error: bad operand types for binary operator '>='
else if (gradePoints >= .90 && gradePoints <= 1.00)
^
first type: double[]
second type: double
55: error: bad operand types for binary operator '<='
else if (gradePoints >= .90 && gradePoints <= 1.00)
^
first type: double[]
second type: double
57: error: cannot return a value from method whose result type is void
return getLetterGrade;
^
67: error: method getLetterGrade in class JSHwScore cannot be applied to given types;
+ possiblePoints + " possible points: " + getLetterGrade(earnedPoints), possiblePoints);
^
required: double,double
found: int[]
reason: actual and formal argument lists differ in length
12 errors

Tool completed with exit code 1


------------------------


The java code is:

/*******************************************
* JSHwScore.java
* Jeffrey Smith
*
* Program associated with JeffreySmithProg2
* Driver program for Homework Scores Program
*******************************************/

class JSHwScore

  {
	private char getLetterGrade(double earnedPoints, double possiblePoints){}
    private double[] gradeCutoff ={0.9, 0.8, 0.7, 0.6};
    double totalEarnedPoints[];
    double totalPossiblePoints[];
    double gradePoints[];
    int gradesArray;
    int earnedPoints[];
    int possiblePoints[];


// Constructor for Total Earned Points and Total Possible Points
    public JSHwScore(int size)
    {
      this.totalEarnedPoints = new double[size];
      this.totalPossiblePoints = new double[size];
    } // End Constructor

// Assigns total earned and possible points values to earned and possible points arrays
    public void finalGrades(double earnedPoints, double possiblePoints)
    {
      totalEarnedPoints[gradesArray] = earnedPoints;
      totalPossiblePoints[gradesArray] = possiblePoints;
      gradesArray++;
    } // end finalGrades

// Constructor for gradePoints
    public void gradePoints()
    {
		gradePoints = (earnedPoints / possiblePoints);
    }

// Constructor for getLetterGrades
    public void getLetterGrades()
    {
		String getLetterGrade ="";
			if (gradePoints < .60)
				getLetterGrade = "F";
			else if (gradePoints >= .60 && gradePoints < .70)
				getLetterGrade = "D";
			else if (gradePoints >= .70 && gradePoints < .80)
				getLetterGrade = "C";
			else if (gradePoints >= .80 && gradePoints < .90)
				getLetterGrade = "B";
			else if (gradePoints >= .90 && gradePoints <= 1.00)
				getLetterGrade = "A";
			return getLetterGrade;
    } // End getLetterGrade


// Constructor for showGrade
    private void showGrade(double earnedPoints, double possiblePoints){}
    {
	for (int i=0; i<gradesArray; i++)
	  {
    	System.out.println("you earned " + earnedPoints + " out of "
    	+ possiblePoints + " possible points: " + getLetterGrade(earnedPoints), possiblePoints);
      } // End print
    } // End showGrade


// Constructor for printGrade
    public void printGrade()
    {
    for (int i=0; i<gradesArray; i++)
      {
        System.out.print("On this homework, ");
        showGrade(totalEarnedPoints[i], totalPossiblePoints[i]);
      } // End print
    } // End printGrade

} // End class JSHwScore

-------------------------------


Any help you can give would be greatly appreciated.

[Aj Prieto]

The first thing you should read are the error messages. After, you'd see that you're using a math operator on an array which you can't do.

To fix this, you'd have to take an element out of the array.

i.e.

if gradePoints[x] < .60)
...

Also, it looks like you never declare a size for you gradePoints array.

Though from your gradePoints() method, I don't think gradePoints should have been declared as an array in the first place.

Another thing, a comment about your comments. I think its rather useless to put an "//End constructor" or any other type of "//End ..." comment.

[Jeanne Boyarsky]

Jeffrey is having a problem posting. While we work with him on the error, here's what he wanted to post:

~~~~~~~~~~~~~~~~~~~~~~~~~~
Thanks for your reply, but I'm still not resolving my problems. I've spent hours trying to fix it with your suggestion and every thing I try, seems to cause two more errors. I've attached my original driver and driven classes that I couldn't seem to fix. Perhaps this is the direction I should be still working on. I would appreciate it if you could look at these to see if you might be able to determine my short comings. The problem with this version is the output only produces the last grade of the array "On this homework, you earned 16.0 out of 20.0 possible points: B" three times and then the overall grade line (correctly).

Driver:

/*******************************************
* JeffreySmithProg2.java
* Jeffrey Smith
*
* Driver program for Homework Scores Program
*******************************************/
 
public class JeffreySmithProg2
 
  {
 
  public static void main (String[] args)
 
     {
 
     JSHwScore homework = new JSHwScore(4);
     homework.finalGrades(26.5,30);
     homework.finalGrades(29.0,27.5);
     homework.finalGrades(0.0,20.0);
     homework.finalGrades(16.0,20.0);
     homework.printGrade();
     homework.printOverallGrade();
 
     } // End main
 
} // End class

Driven:

/*******************************************
* JSHwScore.java
* Jeffrey Smith
*
* Program associated with JeffreySmithProg2
* Driver program for Homework Scores Program
*******************************************/
 
class JSHwScore
 
{
    private double[] gradeCutoff ={0.9, 0.8, 0.7, 0.6}; // Grade cutoff scores
    double totalEarnedPoints[];                         // Array, total earned points
    double totalPossiblePoints[];                       // Array, total possible points
    int gradesArray;                                    // Array, numeric value for grades
 
// Constructor for Total Earned Points and Total Possible Points
    public JSHwScore(int size)
    {
      this.totalEarnedPoints = new double[size];
      this.totalPossiblePoints = new double[size];
    } // End Constructor
 
// Assigns total earned and possible points values to earned and possible points arrays
    public void finalGrades(double earnedPoints, double possiblePoints)
    {
      totalEarnedPoints[gradesArray] = earnedPoints;
      totalPossiblePoints[gradesArray] = possiblePoints;
      gradesArray++;
    } // end finalGrades
 
// Prints earned points, possible points, and letter grade
 
   public void printGrade()
   {
     for (double points:totalEarnedPoints)
     {
       double grade;              // Numeric value for grade
       double earnedPoints = 0;   // Initialize earned points and set to 0
       double possiblePoints = 0; // Initialize possible points and set to 0
 
       for (int i=0; i<totalEarnedPoints.length; i++)
       {
         earnedPoints = totalEarnedPoints[i]; // Assign earned points to total earned points
       }
 
       for (int j=0; j<totalPossiblePoints.length; j++)
       {
         possiblePoints = totalPossiblePoints[j]; // Assign possible points to total possible points
       }
 
     grade = (earnedPoints / possiblePoints); // Division operation to determine decimal grade value
 
     if (grade >= gradeCutoff[0])
 
       {
       System.out.println("On this homework, you earned " + earnedPoints + " out of " + possiblePoints +
       " possible points: A");
       }
 
     else if (grade >= gradeCutoff[1])
 
       {
       System.out.println("On this homework, you earned " + earnedPoints + " out of " + possiblePoints +
       " possible points: B");
       }
 
     else if (grade >= gradeCutoff[2])
 
       {
       System.out.println("On this homework, you earned " + earnedPoints + " out of " +
       possiblePoints + " possible points: C");
       }
 
     else if (grade >= gradeCutoff[3])
 
       {
       System.out.println("On this homework, you earned " + earnedPoints + " out of " +
       possiblePoints + " possible points: D");
       }
 
     else
 
       {
       System.out.println("On this homework, you earned " + earnedPoints +
       " out of " + possiblePoints + " possible points: F");
       } // End if, else if, else
    } // End for loop
} // End printGrade
 
// Prints total points earned, possible points, and letter grade
    public void printOverallGrade()
    {
      double overallPossiblePoints = 0.0; // Possible points of all assigments
      double overallEarnedPoints = 0.0;   // Total points earned on all assignments
      double overallGrade = 0.0;          // Grade earned from all assignments
 
      for (int i = 0; i < gradesArray; i++)
 
      {
         overallEarnedPoints += totalEarnedPoints[i];    // OverallEarnedPoints is sum of totalEarnedPoints[]
         overallPossiblePoints += totalPossiblePoints[i];  // OverallPossiblePoints is sum of totalPossiblePoints[]
      }
 
    // Division operation to produce decimal for overall grade
    overallGrade = overallEarnedPoints / overallPossiblePoints;
 
    if (overallGrade >= gradeCutoff[0])
      {
        System.out.println("On all homework, you earned " + overallEarnedPoints + " out of "
        + overallPossiblePoints + " possible points: A");
      }
 
    else if (overallGrade >= gradeCutoff[1])
      {
        System.out.println("On all homework, you earned " + overallEarnedPoints + " out of "
        + overallPossiblePoints + " possible points: B");
      }
 
    else if (overallGrade >= gradeCutoff[2])
      {
        System.out.println("On all homework, you earned " + overallEarnedPoints +
        " out of " + overallPossiblePoints + " possible points: C");
      }
 
    else if (overallGrade >= gradeCutoff[3])
      {
        System.out.println("On all homework, you earned " + overallEarnedPoints +
        " out of " + overallPossiblePoints + " possible points: D");
      }
 
    else
      {
        System.out.println("On all homework, you earned " + overallEarnedPoints +
        " out of " + overallPossiblePoints + " possible points: F");
      } // End if, else if, else
    } // End printOverallGrade
} // End class

Once again, I really appreciate your time and effort in helping me figure this out. I'm taking a Java class and when I read the book, I think I get what it's saying, but when I write the code, I obviously am not really getting it.

[Campbell Ritchie]

Teh answer has already been given: You can apply the / operator to one of the primitive number types, which are byte char short int long float and double, and nothing else. You would have to get one of the elements of your arrays, then you can divide them.
int i = numbers[123] / numbers[234]; …which requires a certain size for your numbers array and which will not work if the right‑hand operand turns out to be 0.