Question

Create a program in Java for storing the personal information of students and teachers of a school in a .csv (comma-separated values) file.

The program gets the personal information of individuals from the console and must store it in different rows of the output .csv file.

Input Format

User enters personal information of n students and teachers using the console in the following

format:

n

Position1 Name1 StudentID1 TeacherID1 Phone1

Position2 Name2 StudentID2 TeacherID2 Phone2

Position3 Name3 StudentID3 TeacherID3 Phone3

. . .

Positionn Namen StudentIDn TeacherIDn Phonen

Please note that the first line contains only an integer counting the number of lines

following the first line.

In each of the n given input lines,

• Position must be one of the following three strings “student”, “teacher”, or “TA”.

• Name must be a string of two words separated by a single comma only.

• StudentID and TeacherID must be either “0” or a string of 5 digits. If Position is “teacher”, StudentID is zero, but TeacherID is not zero. If Position is “student”, TeacherID is zero, but StudentID is not zero. If Position is “TA”, neither StudentID nor TeacherID are zero.

• Phone is a string of 10 digits.

If the user enters information in a way that is not consistent with the mentioned format,

your program must use exception handling techniques to gracefully handle the situation

by printing a message on the screen asking the user to partially/completely re-enter the

information that was previously entered in a wrong format.

Data Structure, Interface and Classes

Your program must have an interface called “CSVPrintable” containing the following three methods:

• String getName ();

• int getID ();

• void csvPrintln ( PrintWriter out);

You need to have two classes called “Student” and “Teacher” implementing CSVPrintable

interface and another class called “TA” extending Student class. Both Student and Teacher classes must have appropriate variables to store Name and ID.

In order to store Phone, Student class must have a phone variable of type long that can store a 10-digit integer; while the Teacher class must have a phone variable of type int to store only the 4-digit postfix of the phone number.

Method getName has to be implemented by both Student and Teacher classes in the same way. Class Student must implement getID in a way that it returns the StudentID and ignores the TeacherID given by the input. Class Teacher must implement getID in a way that it returns the TeacherID and ignores the StudentID given by the input. Class TA must override the Student implementation of getID so that it returns the maximum value of StudentID and TeacherID.

Method csvPrintln has to be implemented by Student and Teacher classes (and overridden by TA class) so that it writes the following string followed by a new line on the output stream out:

getName() + “,” + getID() + “,” + phone

Output .csv File

The program must store the personal information of students, teachers and TAs in a commaseparated values (.csv) file called “out.csv”. You need to construct the output file by repetitively calling the csvPrintln method of every CSVPrintable object instantiated in your program. The output .csv file stores the information of every individual in a separate row; while each column of the file stores different type of information regarding the students and teachers (i.e. Name, ID and phone columns). Please note that you should be able to open the output file of your program using MS-Excel and view it as a table.

Sample Input/Output

Assume that the user enters the following four lines in console:

Teacher Alex,Martinez 0 98765 3053489999

Student Rose,Gonzales 56789 0 9876543210

TA John,Cruz 88888 99999 1234567890

The program must write the following content in the out.csv file.

Alex Martinez,98765,9999

Rose Gonzales,56789,9876543210

John Cruz,99999,1234567890

Answer 1

CSVPrintable.java
-------------------------------------------------------
// import necessary classes 
import java.io.IOException;
import java.io.PrintWriter;

// interface ( defines some abstract methods )
public interface CSVPrintable {

    String getName();
    int getID();
    void csvPrintln(PrintWriter out) throws IOException;

} // END of interface

-----------------------------------------------------------------------------------------------------------------------

file-name :     Student.java
-------------------------------------------
import java.io.PrintWriter;
// Student class implementing CSVPrintable interface
public class Student implements CSVPrintable{
    // members of Student class
    String studentName;
    int studentID;
    long studentMobile;

    // Constructor
    Student(String name , int id, long mobile) {
        studentID = id;
        studentName = name;
        studentMobile = mobile;
    }
    public String getName() {
        return studentName;
    }

    public int getID() {
        return studentID;
    }
    // this method takes PrintWriter as argument and writes the data in String format to the file ( append mode)
    public void csvPrintln(PrintWriter out) {
        String data = getName()+","+getID()+","+studentMobile+"\n";
        out.write(data);
        out.flush();
        out.close();

    }
}

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

file-name;    TA.java
// TA class extends Student class
// TA is the child and Student is parent
// So, TA inherits all the members of Student class 
public class TA extends Student {
    
    // constructor
    TA(String name, int id, long mobile) {
        super(name, id, mobile);
    }

    @Override
    public int getID() {
        return super.getID();
    }
}

-----------------------------------------------------------------------------------------------------------------------------------------

file-name :   Teacher.java
-------------------------------------------
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

// Teacher class implements the interface CSVPrintable
public class Teacher implements CSVPrintable {

    // members 
    String teacherName;
    int teacherID;
    int teacherMobile;

    // constructor
    Teacher(String name, int id, int mobile) {
        teacherName = name;
        teacherID = id;
        teacherMobile = mobile;
    }
    public String getName() {
        return teacherName;
    }
    
    public int getID() {
        return teacherID;
    }

    // this method takes PrintWriter as argument and writes the data in String format to the file ( append mode)
    public void csvPrintln(PrintWriter out) throws IOException {
        String data = getName()+","+getID()+","+teacherMobile+"\n";
        out.write(data);
        out.flush();
        out.close();
    }
}

==========================================================

file-name : Main.java
----------------------------------------------------------
import java.util.*;
import  java.io.*;
import java.lang.Math;

// Main class ( creates objects of all classes and calls thier methods )
public class Main {

    // main( ) method:
    public static void main(String[] args) throws IOException{
        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the total number of lines:");
        int n = sc.nextInt();sc.nextLine();
        // while loop to take user input
        while(n > 0) {

            // reads the entire line
            String str = sc.nextLine();
            // split that line based on space in between
            String[] input = str.split(" ");

            // checks that if first word is Teacher or not
            if(input[0].equals("Teacher")) {

                Teacher t;

                String[] firstLastName = null;
                // if the required conditions are not satisfied it raises an exception
                try {
                    // splitting the name ( second parameter in input line ) , using "," 
                    firstLastName = input[1].split(",");
                    
                    // checking all the conditions
                    if(!(input[1].equals(firstLastName[0]+","+firstLastName[1])) || (input[3].length()!=5) ||(input[4].length()!=10)) {
                        throw new IllegalArgumentException();
                    }
                int ID = Integer.parseInt(input[3]);
                int mobile = Integer.parseInt(input[4].substring(6));
                
                // creating a Teacher object
                t = new Teacher(firstLastName[0]+" "+firstLastName[1], ID, mobile);

                // file path( address ) -- change it according to your computer
                    // if not working properly , create that file in the required location and then give as input
                String file_location = "/home/rahul/Pictures/school.csv";
                // opening file in append mode
                FileWriter fw = new FileWriter(file_location,true);

                // calling method csvPrintln( ) to append into file
                t.csvPrintln(new PrintWriter(fw));

                }
                catch(IllegalArgumentException e) {
                    System.out.println("Enter the input in correct format");
                }
                catch(ArrayIndexOutOfBoundsException e) {
                    System.out.println("Enter the input in correct format");
                }


            }

            // checks that if first word is TA or not
            else if(input[0].equals("TA")) {

                TA ta ;
                String[] firstLastName = null;

                // if the required conditions are not satisfied it raises an exception
                try {
                    // splitting the name ( second parameter in input line ) , using "," 
                    firstLastName = input[1].split(",");
                    if(!(input[1].equals(firstLastName[0]+","+firstLastName[1])) || (input[2].length()!=5) ||(input[4].length()!=10))
                        throw new IllegalArgumentException();

                int sid = Integer.parseInt(input[2]);
                int tid = Integer.parseInt(input[3]);
                int ID = (Math.max(sid,tid));
                long mobile = Long.parseLong(input[4]);
                ta = new TA(firstLastName[0]+" "+firstLastName[1], ID, mobile);

                // // file path( address ) -- change it according to your computer
                String file_location = "/home/rahul/Pictures/school.csv";
                FileWriter fw = new FileWriter(file_location,true);

                ta.csvPrintln(new PrintWriter(fw));

                }
                catch(IllegalArgumentException e) {
                    System.out.println("Enter the input in correct format");
                }
                catch(ArrayIndexOutOfBoundsException e) {
                    System.out.println("Enter the input in correct format");
                }

            }
            // checks that if first word is Student or not
            else if(input[0].equals("Student")) {

                Student s;
                String[] firstLastName = null;
                // if the required conditions are not satisfied it raises an exception
                try {
                    // splitting the name ( second parameter in input line ) , using "," 
                    firstLastName = input[1].split(",");

                    if(!(input[1].equals(firstLastName[0]+","+firstLastName[1])) || (input[2].length()!=5) ||(input[4].length()!=10))
                        throw new IllegalArgumentException();

                int ID = Integer.parseInt(input[2]);
                long mobile = Long.parseLong(input[4]);
                s = new Student(firstLastName[0]+" "+firstLastName[1], ID, mobile);

                    // file path( address ) -- change it according to your computer
                String file_location = "/home/rahul/Pictures/school.csv";
                FileWriter fw = new FileWriter(file_location,true);

                s.csvPrintln(new PrintWriter(fw));
                }
                catch(IllegalArgumentException e) {
                    System.out.println("Enter the input in correct format");
                }
                catch(ArrayIndexOutOfBoundsException e) {
                    System.out.println("Enter the input in correct format");
                }
            }

            // if it is neither Student nor Teacher nor TA  
            else {
                System.out.println("Re enter the above values in correct format");
                // incrementing 'n ' because , if user entered wrong values , that n decrease by 1 in the below updation step
                 // So I am incrementing by 1 here
                n++;
            }

            n--; // updation for while loop
        } // END of while loop

    } // END of main( ) method
} // END of Main class

========================================================================================================================================

========================================================================================================================================

INPUT ( ON CONSOLE )

OUTPUT:

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