OnJava8-Examples/serialization/Worm.java

// serialization/Worm.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Demonstrates object serialization.
import java.io.*;
import java.util.*;

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

public class Worm implements Serializable {
  private static Random rand = new Random(47);
  private Data[] d = {
    new Data(rand.nextInt(10)),
    new Data(rand.nextInt(10)),
    new Data(rand.nextInt(10))
  };
  private Worm next;
  private char c;
  // Value of i == number of segments
  public Worm(int i, char x) {
    System.out.println("Worm constructor: " + i);
    c = x;
    if(--i > 0)
      next = new Worm(i, (char)(x + 1));
  }
  public Worm() {
    System.out.println("No-arg constructor");
  }
  @Override
  public String toString() {
    StringBuilder result = new StringBuilder(":");
    result.append(c);
    result.append("(");
    for(Data dat : d)
      result.append(dat);
    result.append(")");
    if(next != null)
      result.append(next);
    return result.toString();
  }
  public static void main(String[] args)
  throws ClassNotFoundException, IOException {
    Worm w = new Worm(6, 'a');
    System.out.println("w = " + w);
    try(ObjectOutputStream out = new ObjectOutputStream(
          new FileOutputStream("worm.dat"))) {
      out.writeObject("Worm storage\n");
      out.writeObject(w);
    }
    try(ObjectInputStream in = new ObjectInputStream(
          new FileInputStream("worm.dat"))) {
      String s = (String)in.readObject();
      Worm w2 = (Worm)in.readObject();
      System.out.println(s + "w2 = " + w2);
    }
    try(ByteArrayOutputStream bout =
          new ByteArrayOutputStream();
        ObjectOutputStream out2 =
          new ObjectOutputStream(bout)) {
      out2.writeObject("Worm storage\n");
      out2.writeObject(w);
      out2.flush();
      try(ObjectInputStream in2 = new ObjectInputStream(
          new ByteArrayInputStream(bout.toByteArray()))) {
        String s = (String)in2.readObject();
        Worm w3 = (Worm)in2.readObject();
        System.out.println(s + "w3 = " + w3);
      }
    }
  }
}
/* Output:
Worm constructor: 6
Worm constructor: 5
Worm constructor: 4
Worm constructor: 3
Worm constructor: 2
Worm constructor: 1
w = :a(853):b(119):c(802):d(788):e(199):f(881)
Worm storage
w2 = :a(853):b(119):c(802):d(788):e(199):f(881)
Worm storage
w3 = :a(853):b(119):c(802):d(788):e(199):f(881)
*/