Reading an object via ObjectInputStream throws EOF exception

Question

I am trying to read an object via ObjectInputStream. However I retrieve the following stacktrace with an EOFException:

java.io.EOFException
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2325)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2794)
at
java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:801)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
at student.operations.StudentOperations.addStudentDetails(StudentOperations.java:46)
at student.

My code is the following:

FileInputStream fi = new        FileInputStream(file.getPath());
ObjIn = new ObjectInputStream(fi);

FileOutputStream fo = new FileOutputStream(file.getPath());
Objout = new ObjectOutputStream(fo);

//bo = new BufferedOutputStream(Objout);
//bi = new BufferedInputStream(ObjIn);

System.out.println("Enter the number of students to add");

number = in.nextInt();

System.out.println("Enter Student roll number:");
int rollno = in.nextInt();

try {
    HashMap<Integer, StudentModel> hs = (HashMap<Integer, StudentModel>) ObjIn
            .readObject();

    if (hs.containsKey(rollno)) {
        System.out.println("Duplicate values are not allowed ");
    } else {

        for (counter = 0; counter < number; counter++) {

            System.out.println("Enter Student name:");
            String name = in.next();

            System.out.println("Enter Student's Father name:");
            String fname = in.next();

            System.out.println("Enter Gender:");
            String gender = in.next();

            System.out.println("Enter Date of birth:");
            String date = in.next();

            SimpleDateFormat dateFormat = new SimpleDateFormat(
                    "dd-MM-yyyy");
            Date dateObj = null;

            try {
                dateObj = dateFormat.parse(date);
            } catch (ParseException e) {
                System.out.println(e);
            }

            Calendar birthday = Calendar.getInstance();

            birthday.setTimeInMillis(dateObj.getTime());

            Calendar current = Calendar.getInstance();

            long currentTime = System.currentTimeMillis();

            current.setTimeInMillis(currentTime);

            int age = current.get(Calendar.YEAR)
                    - birthday.get(Calendar.YEAR);

            System.out.println("Enter the AddressLine1:");
            String address1 = in.next();
            in.nextLine();

            System.out.println("Enter the AddressLine2:");
            String address2 = in.next();
            in.nextLine();

            System.out.println("Enter the city");
            String city = in.next();
            in.nextLine();

            System.out.println("Enter the state");
            String state = in.next();
            in.nextLine();

            System.out.println("Enter the country:");
            String country = in.next();
            in.nextLine();

            System.out.println("Enter the Zipcode");
            int code = in.nextInt();
            in.nextLine();

            StudentUtill.student.put(rollno, new StudentModel(name,
                    fname, rollno, age, gender, dateObj, address1,
                    address2, city, state, country, code));

            Objout.writeObject(StudentUtill.student.toString());


            Objout.flush();

        }// for loop ends here

tester.StudentTester.main(StudentTester.java:30)

Answer 1

• You're trying to read objects from an empty file. Look at the stack trace. End of file trying to read the header. There isn't even a header in the file, let alone an object. It's empty.

• Don't create a FileOutputStream until you have something to write to it, and don't forget to close it immediately afterwards.

• You're also incorrectly converting the map to a String before writing it to the file, but you haven't yet got to the point where that's a problem.