OnJava8-Examples/serialization/MyWorld.java

// serialization/MyWorld.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
import java.io.*;
import java.util.*;

class House implements Serializable {}

class Animal implements Serializable {
  private String name;
  private House preferredHouse;
  Animal(String nm, House h) {
    name = nm;
    preferredHouse = h;
  }
  @Override public String toString() {
    return name + "[" + super.toString() +
      "], " + preferredHouse + "\n";
  }
}

public class MyWorld {
  public static void main(String[] args) {
    House house = new House();
    List<Animal> animals = new ArrayList<>();
    animals.add(
      new Animal("Bosco the dog", house));
    animals.add(
      new Animal("Ralph the hamster", house));
    animals.add(
      new Animal("Molly the cat", house));
    System.out.println("animals: " + animals);
    try(
      ByteArrayOutputStream buf1 =
        new ByteArrayOutputStream();
      ObjectOutputStream o1 =
        new ObjectOutputStream(buf1)
    ) {
      o1.writeObject(animals);
      o1.writeObject(animals); // Write a 2nd set
      // Write to a different stream:
      try(
        ByteArrayOutputStream buf2 =
          new ByteArrayOutputStream();
        ObjectOutputStream o2 =
          new ObjectOutputStream(buf2)
      ) {
        o2.writeObject(animals);
        // Now get them back:
        try(
          ObjectInputStream in1 =
            new ObjectInputStream(
              new ByteArrayInputStream(
                buf1.toByteArray()));
          ObjectInputStream in2 =
            new ObjectInputStream(
              new ByteArrayInputStream(
                buf2.toByteArray()))
        ) {
          List
            animals1 = (List)in1.readObject(),
            animals2 = (List)in1.readObject(),
            animals3 = (List)in2.readObject();
          System.out.println(
            "animals1: " + animals1);
          System.out.println(
            "animals2: " + animals2);
          System.out.println(
            "animals3: " + animals3);
        }
      }
    } catch(IOException | ClassNotFoundException e) {
      throw new RuntimeException(e);
    }
  }
}
/* Output:
animals: [Bosco the dog[Animal@19e0bfd], House@139a55
, Ralph the hamster[Animal@1db9742], House@139a55
, Molly the cat[Animal@106d69c], House@139a55
]
animals1: [Bosco the dog[Animal@1ee12a7], House@10bedb4
, Ralph the hamster[Animal@103dbd3], House@10bedb4
, Molly the cat[Animal@167cf4d], House@10bedb4
]
animals2: [Bosco the dog[Animal@1ee12a7], House@10bedb4
, Ralph the hamster[Animal@103dbd3], House@10bedb4
, Molly the cat[Animal@167cf4d], House@10bedb4
]
animals3: [Bosco the dog[Animal@a987ac], House@a3a380
, Ralph the hamster[Animal@1453f44], House@a3a380
, Molly the cat[Animal@ad8086], House@a3a380
]
*/