Functions and Arrays for computation of result - JAVA & BLUE J PROGRAM

/*
 * Computer Science Project on result
Class : Result
Member Variables:
rollno, Name, ,avg  ,grade, array of marks in 5 subjects
Functions used :
Default constructor
Parameterized constructor
void new_student( int , String, int, int , int, int, int) // Function to accept rollno, name, eng, maths, science, art, geo marks from user.
void display_details(  )// Function to display the details
void calcavg() // to calculate the average marks and store in avg
void calcgrade()// to calculate the grade using the following formula
    avg         grade
    >90         A
    >70 &<= 90      B
    >60 &  <=70     C
    >40 & <=60      D
    <40         F  
double  return_average( ) // To return the average marks
String return_name()//To return the name
char return_grade( ) // To return the grade
Class Useresult
Write a main method which creates an object of the above class and call all the methods

 */



import java.io.*;
class useresult
{
    public static void main(String args[])throws IOException
    {
        result ob=new result();  //automatically calls default constructor
        int mks[]={89,99,90,88,78};
        result ob1=new result(007,"John",mks); //automatically calls parameterized constructor
       
        ob.new_student(1001, "Robin", 90, 98,95,90,96);
        ob.display_details();
        ob.calcavg();
        ob.calcgrade();
        System.out.println("\n**********FINAL RESULT**********");
        System.out.println("NAME   \t AVERAGE \t GRADE ");
        System.out.println(ob.return_name()+"\t "+ob.return_average()+"\t           "+ob.return_grade());

    }
}



class result
{
      int rollno;
      String name;
      double avg;
      char grade;
      int marks[]=new int[5];
      int i;
     
     
      result()
      {
          rollno=0;
          name="";
          marks[0]=0;
          marks[1]=0;
          marks[2]=0;
          marks[3]=0;
          marks[4]=0;
                }
     
      result(int rn, String n, int m[])
      {
          rollno=rn;
          name=n;
         
        for(i=0;i<5;i++)
        {
            marks[i]=m[i];
        }
      }
     
      void new_student(int r, String stu_name, int eng, int maths, int sci, int arts, int geo)
      {
          rollno=r;
          name=stu_name;
          marks[0]=eng;
          marks[1]=maths;
          marks[2]=sci;
          marks[3]=arts;
          marks[4]=geo;
         
      }
      void display_details()
      {
          System.out.println("ROLL NO\tNAME  \tENG\tMATHS\tSCI\tARTS\tGEO");
          System.out.println(+rollno+"\t"+name+"\t"+marks[0]+"\t "+marks[1]+"\t "+marks[2]+"\t "+marks[3]+"\t "+marks[4]);
        }
      void calcavg()
      {
          int sum=0;
          for(i=0;i<5;i++)
          {
              sum=sum+marks[i];
          }
          avg=sum/5;
      }
      void calcgrade()
      {
          if(avg>90)
          {
              grade='A';
          }
          else if(avg>70 && avg<=90)
          {
              grade='B';
          }
          else if(avg>60 && avg<=70)
          {
              grade='C';
          }
          else if(avg>40 && avg<=60)
          {
              grade='D';
          }
          else
          {
              grade='F';
          }
      }
      double return_average()
      {
          return avg;
      }
      String return_name()
      {
          return name;
      }
      char return_grade()
      {
          return grade;
      }
}

       
         
/*
 *
 *
OUTPUT:
ROLL NO    NAME      ENG    MATHS    SCI    ARTS    GEO
1001    Robin    90     98     95     90     96

**********FINAL RESULT**********
NAME        AVERAGE      GRADE
Robin     93.0               A

 */