Question

Create a Student grading system. You should use a person base class (stores the name of the student). Derive a student class from the person class. The student class stores the student ID. The student class should also store the students 3 exams (Test 1, Test 2, and Test 3) and calculate a final grade (assume the 3 tests count equally). Create an array of students for a class size of 15 students. You can use the keyboard to read in all of the data for the 15 students (name, ID, and 3 grades), or read this data from a text file (PrintWriter). If using a text file, you can use Comma Seperated values (see Case study in Chapter 10 page 748 for examples how to do this), below also shows how you can read CSV (see below).

String line = "4039,50,0.99,SODA" String[] ary = line.split(","); System.out.println(ary[0]); // Outputs 4039 System.out.println(ary[1]); // Outputs 50 System.out.println(ary[2]); // Outputs 0.99 System.out.println(ary[3]); // Outputs SODA Once all the data is Imported, you can average all the exams and create a final letter grade for all students.

A - 90-100

B - 80-89

C - 70-79

D - 64-69

F < 64

The program should create an output showing all the data for each student as well as writing all the results to a file (using PrintWrite class).

Answer 1

//file name: Student.java

import java.io.*;
import java.util.*;
class Person{
   String name;
   Person(String name)
   {
       this.name = name; // assining name to studet name.
   }
}
class Student extends Person{ //sub class(Student) extends to super class Person
   //instance variables.
   String studentId;
   int test1,test2,test3;
   //parameterized constructor.
   Student(String name,String studentId,int test1,int test2,int test3)
   {
       super(name); // assinging student name to super class.
       this.studentId = studentId;
       this.test1=test1;
       this.test2=test2;
       this.test3=test3;
   }
   String computeGrade() //function to compute grades.
   {
       int sum = test1+test2+test3;
       double avg = sum/3;
       if(avg>=90)
       {
           return "A";
       }
       if(avg>=80)
       {
           return "B";
       }
       if(avg>=70)
       {
           return "C";
       }
       if(avg>=64)
       {
           return "D";
       }
       else{
           return "F";
       }
   }
}
class driverClass{
   public static void main(String[] args)throws IOException {
       FileReader fr=null; // for opening and reading a input file.
       BufferedReader br =null;//reading file line by line.
       PrintWriter fw =null; // for writing a file
       String line="";
       try
       {
           fr = new FileReader(new File("input.txt")); // opening a file
           br = new BufferedReader(fr); // instance assining to buffered reader.
           fw = new PrintWriter(new File("output.txt")); // creating a output file for writing.
       }
       catch(Exception e) // exception handling incase of file not found.
       {
           System.out.println("File not found");
       }
       fw.append("name,id,test1,test2,test3,grade "); //appending header to output file.
       while((line=br.readLine())!=null) // reading line by line from input file.
       {
           String arr[] = line.split(","); //splitting input file based on coma(',')
           // passing parameters to student class and creating object for student class.
           Student student = new Student(arr[0],arr[1],Integer.parseInt(arr[2]),Integer.parseInt(arr[3]),Integer.parseInt(arr[4]));
           String grade = student.computeGrade(); //calling compute function to compute the grade.
           fw.append(line+","+grade+" "); //writing student data to outputfile.
       }
       fr.close(); //closing the file reader
       fw.close(); //closing the printwriter.
      
   }
}

//input file name: input.txt

/*

bhargavi,156887,43,66,78
bhanu,121825,67,79,65
anitha,151845,44,99,89
sravs,171856,67,77,79
ravi,111887,84,80,89
yedu,121856,55,85,79
sravanthi,171687,89,84,99
naseem,131484,67,89,29
bhuvana,181857,90,70,39
pavani,151837,45,30,79
paddu,181981,90,40,79
ramu,101896,98,60,79
pravallika,101881,87,70,69
ramana,121887,78,80,69
rahul,121887,66,80,89

*/

//compiling.

//output file