1 Write a Java program of student grading system Your progra

1. Write a Java program of student grading system. Your program will need two classes – class Student, and class StudentGrading.

2. Write a program of student grading system. Your program will need two classes – class Student, and class StudentGrading

Solution

StudentGrading.java

   import java.io.*;
   import java.util.*;

    public class StudentGrading {
       public static void main(String[] args) throws Exception {
       
         ArrayList<Student> studentGradeList = new ArrayList<Student>(); //studentGradeList = An ArrayList/Vector array that has no set length so it can store multiple student objects
         Student[] studentGradeArray; //studentGradeArray = array used to store the sorted ArrayList of student objects by average grade*/
    
         if (args.length == 0 || args.length < 2) { // throw error if the command line args array has to many args or not enough args.
            System.out.print(\"Command Line Interface Usage: java StudentGrading sourceFileName targetFileName\");
            System.exit(0);
         }
    
      // 1. Read contents of file from command line
         File sourceFile = new File(args[0]);
    
         if (!sourceFile.exists()) { // check if file exists, if not safely exit program.
            System.out.print(\"The file \" + args[0] + \"does not exist.\");
            System.exit(0);
         }
         else {
            Scanner readFile = new Scanner(sourceFile); // create scanner to read in file data
            while(readFile.hasNext()) { // while input exists, create the objects with the input data and store them in the ArrayList
               studentGradeList.add(new Student(readFile.next(), readFile.next(), readFile.nextDouble(), readFile.nextDouble(), readFile.nextDouble(), readFile.nextDouble()));
            }
            readFile.close(); // close file when done reading
         }
        
      // 2. Sort the ArrayList of student objects in ascending order using bubble sort
         studentGradeArray = sortByAverageGrade(studentGradeList); // call bubble sort method.
    
         if (studentGradeArray == null) // if a null pointer was returned, exit the program safely.
            System.exit(0);
    
      // 3. Mark each student and print results
         markAndPrintResults(studentGradeArray, args[1]);
      } // end main

       public static Student[] sortByAverageGrade(ArrayList studentGradeList) {
    
         boolean needNextPass = true; // boolean flag variable that stops bubble sort from passing again when the array is sorted.
         int counter = 0; // counter used to tell when the array is sorted
         Student[] studentGradeArray = new Student[studentGradeList.size()]; // holds sorted array of ArrayList size
    
         if (studentGradeList == null) { // if the arrayList is referenced to null, return null
            System.out.println(\"Please pass an array that is not null.\");
            return null;
         } // end if
    
         for (int i = 0; i <= studentGradeArray.length - 1; i++) { // Transition the objects in the ArrayList to a StudentGrade object array for easier coding and readability. (Could have been done with ArrayList)
            studentGradeArray[i] = ((Student)studentGradeList.get(i));
         } // end for
    
         for (int j = 1; j < studentGradeArray.length && needNextPass; j++) {
            counter = 0; // contiually reset counter until only one sort is done
            for (int k = 0; k < studentGradeArray.length - j; k++) {
               if (studentGradeArray[k].computeAverageGrade() > studentGradeArray[k + 1].computeAverageGrade()) { // bubble sort algorithm that moves large average grades to the highest index of the array, sorts in ascending order
                  Student temp = studentGradeArray[k];
                  studentGradeArray[k] = studentGradeArray[k + 1];
                  studentGradeArray[k + 1] = temp;
                  counter++; // count each \"bubble\" or swap
               } // end if
          
               if (counter > 1) // if more than 1 sort was passed, another pass is needed, otherwise there is no pass required. Used to end sort if the array is already sorted and provides an early exit out of the algorithm loops
                  needNextPass = true;
               else
                  needNextPass = !needNextPass;
            // end if
            } // end for
         } // end for
    
         return studentGradeArray;
    
      } // end sortByAverageGrade
    
       public static void markAndPrintResults(Student[] resultArray, String args) throws Exception {
    
         char gradeMark; //gradeMark = stores the character value/letter grade based on each students average grade points.
    
         File targetFile = new File(args); // create targetFile for saving information. Name specified at command line.
    
         if (targetFile.exists()) { // check if file with same name as target file exists in same directory, if there is throw error.
            System.out.println(\"The file already exists, please enter a new target file name.\");
            System.exit(0);
         }
    
         PrintWriter output = new PrintWriter(targetFile); // create a PrintWriter object and write to targetFile object
    
         for (int i = 0; i <= resultArray.length - 1; i++) {
            gradeMark = resultArray[i].markStudentGrade(resultArray[i].computeAverageGrade()); // compute appropriate grade marking
            output.printf(resultArray[i].getName() + \" \" + resultArray[i].getLastName() + \" %.1f\" + \" %c\" + \"\ \", resultArray[i].computeAverageGrade(), gradeMark); // print results in ascending order with average grade to one place after decimal
         }
    
         output.close(); // close and save file after writing
      }

   } // end class

   Student.java

       public class Student{

      private String name; //name = String for first students name read from file
      private String lastName; //lastName = String for students last name read from file
      private double grade1; //grade 1-4 = students grades in each individual course
      private double grade2;
      private double grade3;
      private double grade4;

       Student() { // Zero arg constructor
         this(null, null, 0, 0, 0, 0);
      } // end StudentGrade

       Student(String name, String lastName, double grade1, double grade2, double grade3, double grade4) { // 4 arg constructor that creates object based on file input
         this.name = name; // assigns name to current instance
         this.lastName = lastName; // assigns last name to current student instance
         this.grade1 = grade1; // assigns grades 1-4 to current student instance for each student instance
         this.grade2 = grade2;
         this.grade3 = grade3;
         this.grade4 = grade4;
      } // end StudentGrade

       public String getName() { // Accessor to return the name of a student object
         return name;
      } // end getFirstName

       public String getLastName() { // Accessor to return the last name of a student object
         return lastName;
      } // end getLastName

       public double getGrade1() { // Accessors for each students name (**NOT NEEDED--USED FOR TEST PURPOSES**)
         return grade1;
      } // end getGrade1

       public double getGrade2() {
         return grade2;
      } // end getGrade2

       public double getGrade3() {
         return grade3;
      } // end getGrade3

       public double getGrade4() {
         return grade4;
      } // end getGrade4

       public double computeAverageGrade() { // Method to compute the average of a student objects 4 individual grades
         return (grade1 + grade2 + grade3 + grade4) / 4;
      } // end computeAverageGrade

       public char markStudentGrade(double averageGrade) { // Method used to assign a letter grade to a student object based off that students average grade.
    
         if (averageGrade >= 90) // rules that assign grading
            return \'A\';
         else if (averageGrade >= 80 && averageGrade < 90)
            return \'B\';
         else if (averageGrade >= 70 && averageGrade < 80)
            return \'C\';
         else
            return \'D\';
    
      } // end markStudentGrade
   } // end class

input.txt

John Parlmer 20 89 60 78
Mark Twain   19 89 67 80
Poor Guy     20 30 56 40
Genius Boy   19 100 100 100
Jon Carlson 20 76 34 65
Mark Johnson 20 78 86 96
Wells Jackson 18 45 80 78
Clark Peterson 19 87 84 88
Ryan Davison   20 90 93 91