Stream closed and not reopened - Java

Question

I have an easy \'homework\' to do, but I have found a little problem with the closure of the input stream. To put it simply, I have to make a contact \'list\' application in Jav

Answer 1

You could still use try-with-resources if you wrap System.in with a CloseShieldInputStream.

I would also recommend using a Scanner instead of the InputStreamReader and BufferedReader, because of it's simplicity:

import java.util.Scanner;
import org.apache.commons.io.input.CloseShieldInputStream;

public class Contact {

    protected String name;
    protected String surname;
    protected String email;

    public void modify() throws IOException {
        System.out.println("Previously name: " + name);
        System.out.println("Insert new name");
        try (Scanner sc = new Scanner(new CloseShieldInputStream(System.in))) {
            name = sc.nextLine();
            System.out.println("You've changed the name to: " + name);
            System.out.println("Previously surname: " + surname);
            System.out.println("Insert new surname");
            surname = sc.nextLine();
            System.out.println("You've changed the surname to: " + surname);
            System.out.println("Previously e-mail: " + email);
            System.out.println("Insert new e-mail");
            email = sc.nextLine();
            System.out.println("You've changed the e-mail to: " + email);
        }
    }
}

public class Private extends Contact {

    private String cell;
    private String skype;

    @Override
    public void modify() throws IOException {
        super.modify();
        System.out.println("Numero di cellulare precedente: " + cell);
        System.out.println("Inserire nuovo numero");
        try (Scanner sc = new Scanner(new CloseShieldInputStream(System.in))) {
            cell = sc.nextLine();
            System.out.println("Hai cambiato il numero in: " + cell);
            System.out.println("Contatto skype precedente: " + skype);
            System.out.println("Inserire nuovo contatto");
            skype = sc.nextLine();
            System.out.println("Hai cambiato il contatto in: " + skype);
        }
    }
}

See also: Closing BufferedReader and System.in

Answer 2

Your problem is indeed due to the try-with-resource statement that closes new InputStreamReader(System.in) which behind the scene closes also the underlying input stream that is System.in (in is a public static field of System) such that in your modify method System.in is already closed and then cannot be read anymore this is why you get this exception.