Binary output

readandwrite.java

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

public class StudentAppBinary {
	public static void main(String [] args) throws IOException {

		Scanner input = new Scanner(System.in);

		
		System.out.println("Introduce  ID of the student");
		String id = input.nextLine();

		System.out.println("Introduce  name of the student");
		String name = input.nextLine();

		System.out.println("Introduce the gpa of the student");
		double gpa = input.nextDouble();

		System.out.println("Introduce the courses taken of the student");
		int coursesTaken = input.nextInt();

		input.nextLine();


		Student alumni = new Student(id, name, gpa, coursesTaken);

		System.out.println("What would you like to do?");
		System.out.println("0 to Exit Application");
		System.out.println("1 to Read File");
		System.out.println("2 to Modify Information");
		System.out.println("3 to Store Information");

		String estring = input.nextLine();
		char operation = estring.charAt(0);

		switch(op) {

			case '0': 
					System.out.println("See you later.");
					break;

			case '1':
			try{

				FileInputStream inputFile = new FileInputStream("studentbinary.bin");
				ObjectInputStream file = new ObjectInputStream(inputFile);

				String datid = file.readLine();
				String datname = file.readLine();
				double datgpa = file.readDouble();
				int datcoursestaken = file.readInt();

				System.out.println(theid);
				System.out.println(thename);
				System.out.println(thegpa);
				System.out.println(thecoursesTaken);

			} catch (FileNotFoundException e ) {
				System.err.println("A FileNotFoundException happened" + e.getMessage());
			}
					break;

			case '2':
					System.out.println("What would you like to modify?");
					System.out.println("1 to id");
					System.out.println("2 to name");
					System.out.println("3 to gpa");
					System.out.println("4 to courses taken");


					int mod = input.nextInt();
					input.nextLine();

					if(modify==1){
						datid = input.nextLine();
					} else if(modify==2) {
						datname = input.nextLine();
					} else if(modify==3){
						datgpa = input.nextDouble();
					} else {
						datcoursestaken = input.nextInt();
					}
					break;

			case '3':
			try{
					FileOutputStream fstream = new FileOutputStream("studentbinary.bin");
					DataOutputStream outputFile = new DataOutputStream(fstream);

					outputFile.write(coursesTaken);
					outputFile.close();
				} catch (FileNotFoundException e) {
					System.err.println("Some FileNotFoundException happened: " + e.getMessage());
				}
					break;
		}

	}
}