Question

FOR JAVA:

Summary: Create a program that adds students to the class list (list below).

The solution should be named Roster402_v2.java. Allow the user to control the number of students added to the roster. Ask if the user would like to see their new roster to confirm additions. If yes, then display contents of the file, if no, end the program.

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List of student names and IDs for class (this will be your separate text file):

• Jones, Jim,45
• Hicks, Josh,56
• Perry, Andy,82
• Rush, Ashely,19
• Salenga, Aaron,55
• Matos, Pamela,22
• Jeffries, Rick,87
• Bush, Fred,40
• Ashford, Kate,52
• Naamah, Ester,68
• Lachlan, Bae,35
• Eachann, Steven,41
• Ubon, Peter,16
• Bacon, Gabe,59
• Rockson, Kurt,77

Answer 1

Code

Student,java class

public class Student {
private String lastName, firstName;
private int ID;
  
public Student()
{
this.lastName = this.firstName = "";
this.ID = 0;
}

public Student(String lastName, String firstName, int ID) {
this.lastName = lastName;
this.firstName = firstName;
this.ID = ID;
}

public String getLastName() {
return lastName;
}

public String getFirstName() {
return firstName;
}

public int getID() {
return ID;
}
  
@Override
public String toString()
{
return(this.ID + " - " + this.firstName + " " + this.lastName);
}
}

Roster.java class

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.Scanner;

public class Roster {
private LinkedList<Student> students;
  
public Roster()
{
this.students = new LinkedList<>();
}
  
public void readStudents(String fileName)
{
Scanner fileReader;
int i=0;
try
{
fileReader = new Scanner(new File(fileName));
while(fileReader.hasNextLine())
{
String[] data = fileReader.nextLine().trim().split(",");
String lastName = data[0];
String firstName = data[1];
int ID = Integer.parseInt(data[2]);
i++;
this.students.add(new Student(lastName, firstName, ID));
}
fileReader.close();
}catch(FileNotFoundException fnfe){
System.out.println("Couldn't find " + fileName);
System.exit(1);
}
}
  
public void sortByLastName()
{
Collections.sort(this.students, new CompareByLastName());
}
  
public void sortByID()
{
Collections.sort(this.students, new CompareByID());
}
  
public void displayList()
{
for(Student student : this.students)
{
System.out.println(student);
}
}
private class CompareByLastName implements Comparator<Student>
{
@Override
public int compare(Student o1, Student o2) {
if(o1.getLastName().compareTo(o2.getLastName()) < 0)
return -1;
else if(o1.getLastName().compareTo(o2.getLastName()) == 0)
return 0;
else
return 1;
}
}
  
class CompareByID implements Comparator<Student>
{
@Override
public int compare(Student o1, Student o2) {
if(o1.getID() < o2.getID())
return -1;
else if(o1.getID() == o2.getID())
return 0;
else
return 1;
}
}
}

Roster402_v2.java

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class Roster402_v2 {
  
private static final String FILENAME = "students.txt";

public static void main(String[] args) throws IOException
{
Scanner sc = new Scanner(System.in);
Roster roster = new Roster();
String fname,lname,choice,str;
int id;
File file = new File(FILENAME);
   FileWriter fr = null;
   fr = new FileWriter(file, true);
do
{
//ask user for student information
System.out.println("Enter Last name of the student; ");
lname=sc.next();
System.out.println("Enter First name of the student; ");
fname=sc.next();
System.out.println("Enter Student ID: ");
id=sc.nextInt();
str="\n"+lname+", "+fname+","+id;
fr.write(str);//append data to the file
System.out.println("Student added to the roster.");
System.out.print("Do you want to add another student?(y/n): ");
choice=sc.next();
}while(choice.equalsIgnoreCase("y"));
fr.close();
roster.readStudents(FILENAME);
System.out.print("Do you want to see student roster?(y/n): ");
choice=sc.next();
System.out.println("\n");
if(choice.equalsIgnoreCase("y"))
roster.displayList();
}
  
}

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