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

class Data implements Serializable {
    private int n;
    public Data(int n) { this.n = n; }
    public String toString() { return Integer.toString(n); }
} // class Data

public class SerializationTest {
    public static void main(String[] args)
        throws ClassNotFoundException, IOException {

        Data d1 = new Data(17);
        Data d2 = new Data(4711);
        Data d3 = new Data(7);

        System.out.println("d1 = " + d1);
        System.out.println("d2 = " + d2);
        System.out.println("d3 = " + d3);

        ObjectOutputStream out =
            new ObjectOutputStream(new FileOutputStream("data.out"));
        out.writeObject(d1);
        out.writeObject(d2);
        out.writeObject(d3);
        out.close(); // Also flushes output

        ObjectInputStream in =
            new ObjectInputStream(new FileInputStream("data.out"));

        Data d4 = (Data)in.readObject();
        Data d5 = (Data)in.readObject();
        Data d6 = (Data)in.readObject();

        System.out.println("d4 = " + d4);
        System.out.println("d5 = " + d5);
        System.out.println("d6 = " + d6);
    }
} // class SerializationTest