Student Roster Manipulation - Java LinkList Class

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ListIterator;
import java.util.Scanner;
import java.util.*;


/**
 * This program performs the following functions:
 * - Will load student records from input.txt into their respective variables
 * - Will turn those variables into a Student Object
 * - Calculate their average % based on test scores
 * - Calculate their letter grade based on their average %
 * - Calculate their new GPA using their old GPA and their current class hours.
 * - Calculate their year rank based on the number of hours the have.
 * - Places the Student objects into a LinkedList representing the academic class.
 * - Lists the class with their % score and letter grade in the class, as well as their new GPA and year Rank.
 * - Remove the records matching ID 42P4 and 45A3
 * - Re-list the records with the removed students.
 * - Add the Student Records from Additions.txt
 * - Sort the LinkedList from Highest to lowest based on % score
 * - To prove the Generic nature of the program, a list of doubles is read in and sorted from smallest to largest
 * - Print the LinkedLists.
 *
 * @author Carlos
 * @since 02/11/2019
 **/
public class RosterManipulations {

    public static void main(String[] args) throws Exception {
        RosterManipulations me = new RosterManipulations();

        //Create a LinkedList to contain Student's from input.txt and Additions.txt
        JavaLinkedListManager<Student> JavaStudentList = new JavaLinkedListManager<Student>();

        //Create a LinkedList to contain Student's from Input.txt and Additions.Txt in Order
        JavaLinkedListManager<Student> JavaStudentListOrder = new JavaLinkedListManager<Student>();

        //Create a LinkedList of Doubles to add in order
        JavaLinkedListManager<Double> JavaDoubleOrder = new JavaLinkedListManager<Double>();

        try {
            Scanner input = new Scanner(new File("src/main/input.txt"));

            //Gather the information from the records in input.txt and set them equal to their respective variables
            while (input.hasNextLine()) {
                String StudentID = input.next();
                String Studentname = input.next();
                int test1 = input.nextInt();
                int test2 = input.nextInt();
                int test3 = input.nextInt();
                int totalHours = input.nextInt();
                float oldGPA = input.nextFloat();

                //Place those variables into a student object
                Student student1 = me.new Student(StudentID, Studentname, test1, test2, test3, totalHours, oldGPA);

                //Place that object into the LinkedList StudentLinkList
                JavaStudentList.AddNode(student1);
                JavaStudentListOrder.AddInOrder(student1);
            }

            System.out.println("\nOriginal Class Roster Before Modifications: \n");
            //Print the contents of the LinkedList including their % score and grade before any manipulation
            int number = JavaStudentList.GetNumber();
            for (int i = 0; i < number; i++) {
                System.out.println(JavaStudentList.GetNode(i));
            }

            DeleteNode(JavaStudentList, "45A3");
            DeleteNode(JavaStudentList, "42P4");
            DeleteNode(JavaStudentListOrder,"45A3");
            DeleteNode(JavaStudentListOrder,"42P4");
            System.out.println("\nStudents 45A3 & 42P4 Have Dropped The Class. Generating New Roster: \n");
            //Print the contents of the LinkedList including their % score and grade AFTER the students have dropped
            int number7 = JavaStudentList.GetNumber();
            for (int i = 0; i < number7; i++) {
                System.out.println(JavaStudentList.GetNode(i));
            }

            System.out.println("\n New Students Have Joined The Class. Generating Roster: \n");

            Scanner secondInput = new Scanner(new File("src/main/Additions.txt"));
            while (secondInput.hasNextLine()) {
                String AddedID = secondInput.next();
                String AddedName = secondInput.next();
                int AddedTest1 = secondInput.nextInt();
                int AddedTest2 = secondInput.nextInt();
                int AddedTest3 = secondInput.nextInt();
                int AddedTotalHours = secondInput.nextInt();
                float AddedoldGPA = secondInput.nextFloat();

                Student student2 = me.new Student(AddedID, AddedName, AddedTest1, AddedTest2, AddedTest3, AddedTotalHours, AddedoldGPA);

                //Adding the additional students to the LinkedList
                JavaStudentList.AddNode(student2);
                JavaStudentListOrder.AddInOrder(student2);
            }

            //Reprint the LinkedList with the additional students now added
            int number2 = JavaStudentList.GetNumber();
            for (int i = 0; i < number2; i++) {
                System.out.println(JavaStudentList.GetNode(i));
            }


            System.out.println("\nRegenerating Roster Sorted By Average Grade\n");
            //Print the Contents of the LinkedLists in order from Larger to Smaller based on Average %
            int number3 = JavaStudentListOrder.GetNumber();
            for (int i = 0; i < number3; i++) {
                System.out.println(JavaStudentListOrder.GetNode(i));
            }


            //Read the contents of doubles.txt
            Scanner inputDoubles = new Scanner(new File("src/main/doubles.txt"));
            //Add the contents of doubles.txt to the LinkedList for doubles
            while (inputDoubles.hasNextLine()) {
                JavaDoubleOrder.AddInOrder(inputDoubles.nextDouble());
            }

            //Print the sorted contents of doubles.txt from Smaller to Larger
            System.out.println("Proving Generic Sort By Printing Sorted Doubles From Smallest to Largest\n");

            //Print the sorted contents of doubles.txt from Smaller to Larger
            int number6 = JavaDoubleOrder.GetNumber();
            for (int i = number6 - 1; i >= 0; i--) {
                System.out.println(JavaDoubleOrder.GetNode(i));
            }


        } catch (FileNotFoundException e) {
            System.err.println("File Input.txt was not found");
        }

    }

    //Deletes a Student who has dropped the class from the LinkedList.
    public static void DeleteNode(JavaLinkedListManager<Student> JavaStudentList, String ID) {
        int number5 = JavaStudentList.GetNumber();
        for (int i = 0; i < number5; i++) {
            if (JavaStudentList.GetNode(i).getStudentID().equals(ID)) {
                JavaStudentList.RemoveNodeJava(i);
                return;
            }
        }
    }

    //Java's LinkedList Manager, Takes student objects and manipulates them in place of an ArrayList or manually writing a LinkedList Class
    public static class JavaLinkedListManager<T extends Comparable<T>> {
        protected LinkedList<T> JavaList = null;
        protected int number = 0;
        protected ListIterator<T> lptr = null;
        protected T y = null;

        //Constructor
        public JavaLinkedListManager() {
            JavaList = new LinkedList<T>();
            lptr = JavaList.listIterator();
            number = 0;
        }

        //Getter for Number
        public int GetNumber() {
            return number;
        }

        //Adds a Node to the LinkedList
        public int AddNode(T myGenericData) {
            JavaList.addLast(myGenericData);
            number++;
            return number;
        }

        //Finds a node in the Xth location of the LinkedList
        public T GetNode(int x) {
            if ((x < 0) || (x > number)) System.out.println("error in getnode" + x + "while list holds" + number);
            return JavaList.get(x);
        }

        //Adds to the LinkedList from Larger to Smaller using CompareTo
        public void AddInOrder(T myGenericData) {
            if (number == 0) {
                JavaList.addFirst(myGenericData);
                number = 1;
                return;
            }
            if (myGenericData.compareTo(JavaList.getFirst()) == 1) {
                JavaList.addFirst(myGenericData);
                number++;
                return;
            }
            if (myGenericData.compareTo(JavaList.getLast()) == -1) {
                JavaList.addLast(myGenericData);
                number++;
                return;
            }
            ListIterator lptr2 = JavaList.listIterator();
            for (int i = 0; i <= number - 1; i++) {
                y = (T) lptr2.next();

                if (myGenericData.compareTo(y) == 1) {
                    lptr2.previous();
                    lptr2.add(myGenericData);
                    number++;
                    return;
                }
            }
        }
        //Removes a node from the LinkedList
        public void RemoveNodeJava (int index){
            JavaList.remove(index);
            number--;
            return;
        }


    }

    //The Student class turns student records into objects ao that they an be sorted into an ArrayLIst
    public class Student implements Comparable<Student> {
        String StudentID;
        String Studentname;
        int test1;
        int test2;
        int test3;
        int average;
        int totalHours;
        float oldGPA;

        //Constructor for Student Class
        public Student(String StudentID, String Studentname, int test1, int test2, int test3, int totalHours, float oldGPA) {
            setStudentID(StudentID);
            setStudentname(Studentname);
            setTest1(test1);
            setTest2(test2);
            setTest3(test3);
            int average = (test1 + test2 + test3) / 3;
            setAverage(average);
            setTotalHours(totalHours);
            setoldGPA(oldGPA);
        }

        @Override
        //toString so that objects can be printed.
        public String toString() {
            return " ID: " + StudentID + " Name: " + Studentname + "\n Test 1 Score: " + test1 + "\n Test 2 Score: " + test2 + "\n Test 3 Score: " + test3 + "\n Test Average: " + average + "%" + "\n Class Grade: " + averageGrade(average) + "\n Total Hours: " + totalHours + "\n GPA: " + calculatenewGPA(oldGPA, gradePoint(average), totalHours) + "\n Year Rank: " + yearRank(totalHours) + "\n";
        }

        //Calculates the NEW GPA of a student
        public float calculatenewGPA(float oldGPA, int gradePoint, int totalHours) {
            return ((oldGPA * totalHours) + (2) * gradePoint) / (totalHours + 2);
        }

        //Calculate the GradePoint Value of A GPA
        public int gradePoint(int average) {
            {
                int gradePoint = 0;
                if (average >= 90) {
                    gradePoint = 4;
                } else if (average >= 80) {
                    gradePoint = 3;
                } else if (average >= 70) {
                    gradePoint = 2;
                } else if (average >= 60) {
                    gradePoint = 1;
                } else if (average >= 0) {
                    gradePoint = 0;
                }
                return gradePoint;
            }
        }

        //Calculate the Year Rank of each student
        public String yearRank(int totalHours) {
            String rank = null;
            if (totalHours <= 30) {
                rank = "Freshman";
            } else if (totalHours <= 60) {
                rank = "Sophomore";
            } else if (totalHours <= 90) {
                rank = "Junior";
            } else if (totalHours >= 91) {
                rank = "Senior";
            }
            return rank;
        }

        //Calculate the average grade of a student

        //Turn the average into a letter grade
        public String averageGrade(int average) {
            String averageLetter = null;
            if (average >= 90) {
                averageLetter = "A";
            } else if (average >= 80) {
                averageLetter = "B";
            } else if (average >= 70) {
                averageLetter = "C";
            } else if (average >= 60) {
                averageLetter = "D";
            } else if (average >= 0) {
                averageLetter = "F";
            }
            return averageLetter;
        }

        public void setoldGPA(float oldGPA) {
            this.oldGPA = oldGPA;
        }

        //Getters for the Student Class
        public String getStudentID() {
            return StudentID;
        }

        //Setters for the Student Class
        public void setStudentID(String StudentID) {
            this.StudentID = StudentID;
        }

        public String getStudentname() {
            return Studentname;
        }

        public void setStudentname(String Studentname) {
            this.Studentname = Studentname;
        }

        public int getTest1() {
            return test1;
        }

        public void setTest1(int test1) {
            this.test1 = test1;
        }

        public int getTest2() {
            return test2;
        }

        public void setTest2(int test2) {
            this.test2 = test2;
        }

        public int getTest3() {
            return test3;
        }

        public void setTest3(int test3) {
            this.test3 = test3;
        }

        public int getAverage() {
            return average;
        }

        public void setAverage(int average) {
            this.average = average;
        }

        public int getTotalHours() {
            return totalHours;
        }

        public void setTotalHours(int totalHours) {
            this.totalHours = totalHours;
        }

        public float getoldGPA() {
            return oldGPA;
        }


        public int compareTo(Student o) {
            return (this.getAverage() < o.getAverage() ? -1 :
                    (this.getAverage() == o.getAverage() ? 0 : 1));
        }
    }
}