Question

Student class:

• Instance variables
  • name
  • id
• Constructors:
  • Default constructor
  • Constructor that has id and name passed to the constructor
• Methods:
  • Accessors
    • int getID( )
    • String getName( )

Class Roster: This class will implement the functionality of all roster for school.

• Instance Variables
  • a final int MAX_NUM representing the maximum number of students allowed on the roster
  • an ArrayList storing students
• Constructors
  • a default constructor should initialize the list to empty strings
  • a single parameter constructor that takes an ArrayList<Student>
  • Both constructors should initialize the instance variables
• Methods
  • Accessors
    • boolean containsStudent(String studentName) //@returns true if studentName is in roster
    • String retrieveById(int id) //@ returns Student name associated with id
    • int retrieveByName(String Student) //@returns id associated with String Student
  • Mutators:
    • boolean addStudent(String studentName, int studentId) ;//adds student name and id to end of roster
      • This method should not allow a student to be added if the name or the studentId is already in the roster. Also, make sure that the total number of students does not exceed MAX_NUM. Hint: Make user of the containsStudent() method
    • boolean removeStudent(int id) // removes student from roster based on id. Make sure that you maintain the integrity of the parallel ArrayLists.
    • boolean removeStudent(String name) //removes student based on name. Make sure that you maintain the integrity of the parallel ArrayLists.

Grading rubric

constructors

1       single parameter

1       default

        -> initializes both Array Lists

        -> initalize MAX_NUM

       

2       boolean containsStudent(String studentName)

               //@returns true if studentName is in roster

2       String retrieveById(int id)

               //@ returns Student name associated with id

     

2       int retrieveByName(String Student)

               //@returns id associated with String Student

1 boolean addStudent(String studentName, int studentId) ;

               //adds student name and id to end of roster

               This method should not allow a student to be added if the name or the studentId is already in the roster or allow the total number of students to exceed MAX_NUM. Hint: Make user of the containsStudent() method

//The next 2 methods must maintain the integrity of the parallel ArrayLists. If you remove from 1 then remove the element in the other ArrayList associated with the first list's elements. In other words, if you remove a student based on his or her name, make sure that you also remove his or her id from the other ArrayList.

3       boolean removeStudent(int id)

               // removes student from roster based on id

3       boolean removeStudent(String name)

               //removes student based on name

Total points 15

Testing data:

Student names: Jack, Jane, Janet, Jasmin

Student IDs: 1005, 1007, 1009, 1011

output

Add: Jessie, 1017

Remove: Jane

output

Remove: 1011

Retrieve ID: 1011

Retrieve student: Jessie

Output

Add Jessie, 1017, output if adding is successful

Answer 1

/******************************************************************************

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

class Student{
int id;
String name;
public Student()
{
id=0;
name="";
}
public Student(int id,String name)
{
this.name=name;
this.id=id;
}
public int getID()
{
return id;
}
public String getName()
{
return name;
}
}

class Roster{
int Max_num=10;
ArrayList<Student> arr = new ArrayList<Student>(10);
public Roster(int num ,ArrayList<Student> s)
{
Max_num=num;
arr=s;
}
//Accessors
  
public boolean containStudent(String Studentname)
{
for(int i=0;i<Max_num;i++)
{
if(Studentname.equals(arr.get(i).name))
{
return true;
}
}
return false;
}
public String retriveById(int id)
{
for(int i=0;i<Max_num;i++)
{
if((arr.get(i).id==id))
{
return arr.get(i).getName();
}
}
return "0";
}
public int reterivebyname(String name)
{
for(int i=0;i<Max_num;i++)
{
if(name.equals(arr.get(i).name))
{
return arr.get(i).getID();
}
}
return 0;
}
  
public boolean addStudent(int id, String name)
{
if(containStudent(name))
{
return false;
}
else{
Student ob=new Student(id,name);
arr.add(ob);
Max_num++;
}
return true;
}
public boolean removeStudent(int id)
{
int flag=-1;
for(int i=0;i<Max_num;i++)
{
if((arr.get(i).id==id))
{
flag =i;
break;
}
}
if(flag!=-1)
{
arr.remove(flag);
return true;
}
else{
return false;
}
}
public boolean removeStudent(String name)
{
int flag=-1;
for(int i=0;i<Max_num;i++)
{
if(name.equals(arr.get(i).name))
{
flag =i;
break;
}
}
if(flag!=-1)
{
arr.remove(flag);
return true;
}
else{
return false;
}
  
}
}

public class Main
{
   public static void main(String[] args) {
       System.out.println("program Compiled");
   Student ob= new Student(1,"abc");
   Student ob2= new Student(2,"ab");
   ArrayList<Student> stu=new ArrayList<Student>(2);
   stu.add(ob);
   stu.add(ob2);
   Roster r= new Roster(3,stu);
   int ab=r.reterivebyname("ab");
   System.out.println(ab);
   }
}

// i used my test data and it is working fine please go through the code.

i add test data of 2 students and check the id of student by name and it is giving correct output