Question

Modify StudentLinkedList class by adding the following methods:

printStudentList: print by calling and printing “toString” of every object in the linkedList. Every student object to be printed in a separate line.

 deleteStudentByID(long id): delete student object from the list whose ID is matching with the passed parameter.

 sortListByID(): sort the linkedlist according to students IDs.

 findMarksAverage(): find the average of all marks for all students in the list.

 findMinMark(int markIndex): find the student with the minimum mark in a specific index:

o 0: Quizzes

o 1: Midterm Exam

o 2: Final Exam

import java.util.LinkedList;

public class StudentLinkedList {

public static void main(String[] args) {

LinkedList linkedlist = new LinkedList();

linkedlist.add(new Student("Ahmed Ali", 20111021, 18, 38, 38));

linkedlist.add(new Student("Sami Kamal", 20121021, 17, 39, 35));

linkedlist.add(new Student("Salem Salim", 20131021, 20, 40, 40));

linkedlist.add(new Student("Rami Mohammed", 20111031, 15, 35, 30));

linkedlist.add(new Student("Kim Joe", 20121024, 12, 32, 32));

linkedlist.addFirst(new Student("Hadi Ali", 20111025, 19, 38, 39));

linkedlist.addLast(new Student("Waleed Salim", 20131025, 10, 30, 30));

linkedlist.set(0, new Student("Khalid Ali", 20111027, 15, 30, 30));

linkedlist.removeFirst(); linkedlist.removeLast();

linkedlist.add(0, new Student("John Don", 20131025, 11, 31, 31));

linkedlist.remove(2);

}

class Student{

private String name;

private Long ID;

private int [] marks = new int [3];

public Student(String name, long ID, int quizzes, int mid, int fin) {

this.name = name; this.ID = ID;

marks[0] = quizes;

marks[1] = mid;

marks[2] = fin;

}

public String getName() {

return name;

}

public Long getID() {

return ID;

}

public int[] getMarks() {

return marks;

}

@Override public String toString() { String temp = "student: " + "name = " + name + ", ID = " + ID + ", marks = {" + marks[0] + ", " + marks[1] + ", " + marks[2] + "}"; return temp; }

}

Answer 1

Student.java

class Student{
   // instance variables
   private String name;
   private Long ID;
   private int [] marks = new int [3];
   // parameterized constructor
   public Student(String name, long ID, int quizzes, int mid, int fin) {
       this.name = name;
       this.ID = ID;
       marks[0] = quizzes;
       marks[1] = mid;
       marks[2] = fin;
   }
   // getter methods
   public String getName() {
       return name;
   }
   public Long getID() {
       return ID;
   }
   public int[] getMarks() {
       return marks;
   }
   @Override
   public String toString() {
       String temp = "student: " + "name = " + name
               + ", ID = " + ID
               + ", marks = {" + marks[0] + ", " + marks[1] + ", " + marks[2] + "}";
       return temp;
   }

}

StudentLinkedList.java

import java.util.LinkedList;

public class StudentLinkedList {
   // method to print students list
   public static void printStudentList(LinkedList<Student> list) {
       for (Student student : list)
           System.out.println(student);
   }
   // method to delete the student from list by using id
   public static void deleteStudentByID(LinkedList<Student> list,long id) {
       for (Student student : list)
           if(student.getID()==id)
               list.remove(student);
       System.out.println("Student with "+id+" ID deleted successfully");
   }
   // method to find average marks of every student
   public static void findMarksAverage(LinkedList<Student> list) {
       for (Student student : list) {
           int total=0;
           for (int marks : student.getMarks())
               total+=marks;
           System.out.println("Average marks of student "+student.getName()+": "+(total/3));
       }
   }
   // method to find the minimum marks in specified exam
   public static void findMinMark(LinkedList<Student> list,int markIndex) {
       int minimim=0;
       for (Student student : list) {
           int[] temp=student.getMarks();
           if(temp[markIndex]<minimim)
               minimim=temp[markIndex];
       }
       if(markIndex==0)
           System.out.println("Minimum marks in quizzes: "+minimim);
       else
       if(markIndex==1)
           System.out.println("Minimum marks in midterm exam: "+minimim);
       else
           System.out.println("Minimum marks in final exam: "+minimim);
   }
   public static void main(String[] args) {
       // create LinkedList with Student types
       LinkedList<Student> linkedlist = new LinkedList<Student>();
       // add student objects into list
       linkedlist.add(new Student("Ahmed Ali", 20111021, 18, 38, 38));
       linkedlist.add(new Student("Sami Kamal", 20121021, 17, 39, 35));
       linkedlist.add(new Student("Salem Salim", 20131021, 20, 40, 40));
       linkedlist.add(new Student("Rami Mohammed", 20111031, 15, 35, 30));
       linkedlist.add(new Student("Kim Joe", 20121024, 12, 32, 32));
       linkedlist.addFirst(new Student("Hadi Ali", 20111025, 19, 38, 39));
       linkedlist.addLast(new Student("Waleed Salim", 20131025, 10, 30, 30));
       linkedlist.set(0, new Student("Khalid Ali", 20111027, 15, 30, 30));
       linkedlist.add(0, new Student("John Don", 20131025, 11, 31, 31));
       printStudentList(linkedlist); // print student list
       System.out.println(); // new line
       deleteStudentByID(linkedlist, 20121024); // delete student whose id is 20121024
       System.out.println();
       findMarksAverage(linkedlist); // find average marks
       System.out.println();
       findMinMark(linkedlist, 0); // find minimum marks in quizzes
       System.out.println();
       findMinMark(linkedlist, 1); // find minimum marks in mid term exam
       System.out.println();
       findMinMark(linkedlist, 2); // find minimum marks in final exam
       System.out.println();
       printStudentList(linkedlist); // print student list
   }
}

Output