Program with Arrays (Please try and trace)

import java.util.Scanner;

public class GradeCalculatorUsingArrays {
static Scanner keyboard=new Scanner(System.in);

public static void main(String[] args) {
int[] quizScore; // array to hold quiz scores of students
int[] examScore; // array to hold exam scores of students
String[] names; // array to hold names of students
int perfectQuizScore; // variable to hold perfect quiz score
int perfectExamScore; // variable to hold perfect exam score
double[] quizGrade; // array to hold quiz grades of students.
double[] examGrade; // array to hold examination grades of students
double[] subjectGrade; // array to hold subject grades of students
int size;

/**
*Accept the number of students( class size).
*The class size must be greater than 0.
**/
do {
System.out.print("Enter the number of students: ");
size = Integer.parseInt(keyboard.nextLine());
if (size <0)
System.out.println("The number of students must be greater than 0.");
} while (size < 0);

// Instantiate arrays, the number of cells for each array must be equal to size
quizScore = new int[size];
examScore = new int[size];
names = new String[size];
quizGrade = new double[size];
examGrade = new double[size];
subjectGrade = new double[size];

/* Accept the perfect quiz score. The perfect score must be greater than 0.
*The do while construct enables the computer to let the user re-enter
*a perfect score in case the value entered is invalid.
**/
do {
System.out.print("Enter the Perfect Quiz Score : ");
perfectQuizScore = Integer.parseInt(keyboard.nextLine());
if (perfectQuizScore <= 0){
System.out.println("Invalid value! The perfect score must be greater than 0.");
}
} while (perfectQuizScore <= 0);

/* Accept the perfect exam score. The perfect score must be greater than 0.
*The do while construct enables the computer to let the user re-enter
*a perfect score in case the value entered is invalid.
**/
do {
System.out.print("Enter the Perfect Examination Score : ");
perfectExamScore = Integer.parseInt(keyboard.nextLine());
if (perfectExamScore <= 0){
System.out.println("Invalid value! Value must be greater than 0.");
}
} while (perfectExamScore <= 0);


// Accept names and scores and compute the grade of each student
for (int x=0; x System.out.print("Enter the name of student "+ (x+1) + ": ");
names[x] = keyboard.nextLine();

/* Accept the quiz score of a student.
*The quiz score must not be greater than the
*perfect quiz score.
*The do while construct enables the computer to let the user re-enter
*a score in case the value entered is invalid.
**/
do {
System.out.print("Enter the quiz score of "+ names[x] +" : ");
quizScore[x] = Integer.parseInt(keyboard.nextLine());
if (quizScore[x] > perfectQuizScore){
System.out.println("Invalid value! Score must not be greater than perfect score.");
}
} while (quizScore[x] > perfectQuizScore);

/* Accept the exam score.
*The exam score must not be greater than the
*perfect exam score.
*The do while construct enables the computer to let the user re-enter
*a score in case the value entered is invalid.
**/
do {
System.out.print("Enter the examination score of " + names[x] + " : ");
examScore[x] = Integer.parseInt(keyboard.nextLine());
if (examScore[x] > perfectExamScore){
System.out.println("Invalid value! Score must not be greater than perfect score.");
}
} while (examScore[x] > perfectExamScore);

quizGrade[x] = (double) quizScore[x]/perfectQuizScore*50 + 50;
examGrade[x] = (double) examScore[x]/perfectExamScore*50 + 50;
subjectGrade[x] = (quizGrade[x] + examGrade[x])/ 2;

// Check if subject grade is 100 then reset it to 99
if (subjectGrade[x] > 99)
subjectGrade[x] = 99;
//Check if subject grade is lesst than 65 then reset it to 65
if (subjectGrade[x] < 65 )
subjectGrade[x] = 65;

} // end of for

// Display the scores and grades of students
System.out.println("\n\nPerfect Quiz Score = " + perfectQuizScore);
System.out.println("\nPerfect Exam Score = " + perfectExamScore);
System.out.printf("%10s%10s%10s%10s%10s%10s\n","", "Quiz", "Exam", "Quiz", "Exam", "");
System.out.printf("%10s%10s%10s%10s%10s%10s\n","name", "Score", "Score", "Grade", "Grade", "Grade");
System.out.printf("%10s%10s%10s%10s%10s%10s\n","--------", "--------", "--------", "-------", "--------", "--------");
for (int y= 0; y < subjectGrade.length; y++){
System.out.printf("%10s%10d%10d%10.0f%10.0f%10.0f\n",names[y], quizScore[y], examScore[y], quizGrade[y], examGrade[y], subjectGrade[y]);
}
System.out.printf("%10s%10s%10s%10s%10s%10s\n","--------", "--------", "--------", "-------", "--------", "--------");
// Compute and show the average of the subject grades
// get the total of all the subject grades
double totalGrade=0; // variable to hold the sum of grades
for (int g=0; g totalGrade += subjectGrade[g];
}
double averageGrade = totalGrade/subjectGrade.length;
System.out.printf("%n%25s%5.2f%n", "Average Grade =", averageGrade);


// determine and show the lowest subject grade
double lowestGrade= subjectGrade[0]; // first grade is the lowest grade initially
for (int gr=1; gr if (lowestGrade > subjectGrade[gr])
lowestGrade = subjectGrade[gr];
}
System.out.printf("%n%25s%5.2f%n", "Lowest Grade =", lowestGrade);

// determine and show the highest subject grade
double highestGrade= subjectGrade[0]; // first grade is the highest grade initially
for (int h=1; h if (highestGrade < subjectGrade[h])
highestGrade = subjectGrade[h];
}
System.out.printf("%n%25s%5.2f%n", "Highest Grade =", highestGrade);


System.exit(0);
} // end of the main method
} // end of class