All Code

import java.util.Scanner;

public class studentGrades
{
   public static void main(String[] args)
   {
      Scanner keyboard = new Scanner(System.in);
      String sName, sAddress, sYear;
      int age, gradeAmt, grade, sAmt;

      System.out.println("How many students are you maintaining ?");
      sAmt = keyboard.nextInt();

      studentInfo[] studentArray = new studentInfo[sAmt];
      for(int j = 0; j < sAmt; j++)
      {
      System.out.print("Enter the student's name: ");
      sName = keyboard.next();
      System.out.print("Enter age: ");
      age = keyboard.nextInt();
      System.out.print("Enter address: ");
      sAddress = keyboard.next();
      System.out.print("Enter students's year(Freshman, Sophomore, Junior or Senior): ");
      sYear = keyboard.next();

      studentInfo sInfo = new studentInfo(sName, age, sAddress, sYear);
      studentArray[j] = sInfo;


      for(int i = 0; i < 2; i++)
      {
         System.out.print("How many grades does the student have for quarter " + (i+1) + ": ");
         gradeAmt = keyboard.nextInt();

         while(gradeAmt <= 1)
          {
          System.out.println("You need to enter at least two grades.");
          System.out.print("Enter again: ");
          gradeAmt = keyboard.nextInt();
          }
         int[] gradeArray = new int[gradeAmt];

         for(int k = 0; k < gradeArray.length; k++)
            {
            System.out.print("Enter test " + (k+1) + ": ");
             gradeArray[k] = keyboard.nextInt();
            }
      }

      for(j = 0; j < sAmt; j++)
            {
            studentArray[j].studentDisplay();
            System.out.println();
            }

      public static char numConversion(int[] gradeArray)
      {
      char[] gradeLetter = {'A', 'B', 'C', 'D', 'F'};
      char grade
        for(k = 0; k < gradeArray.length; k++)
         if(gradeArray[k] >= 90 && gradeArray[k] <= 100)
         {  grade = gradeLetter[0]
         }
         else if(gradeArray[k] >= 80 && gradeArray[k] < 90)
         {  grade = gradeLetter[1]
         }
         else if(gradeArray[k] >= 70 && gradeArray[k] < 80)
         {  grade = gradeLetter[2]
         }
         else if(gradeArray[k] >= 60 && gradeArray[k] < 70)
         {  grade = gradeLetter[3]
         }
         else
         {  grade = gradeLetter[4]
         }

         return grade
       }

}
}