Simple use of Externalizable and a pitfall

      

// : c12:Blips.java
// Simple use of Externalizable & a pitfall.
// {Clean: Blips.out}
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.

import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;

class Blip1 implements Externalizable {
  public Blip1() {
    System.out.println("Blip1 Constructor");
  }

  public void writeExternal(ObjectOutput out) throws IOException {
    System.out.println("Blip1.writeExternal");
  }

  public void readExternal(ObjectInput in) throws IOException,
      ClassNotFoundException {
    System.out.println("Blip1.readExternal");
  }
}

class Blip2 implements Externalizable {
  Blip2() {
    System.out.println("Blip2 Constructor");
  }

  public void writeExternal(ObjectOutput out) throws IOException {
    System.out.println("Blip2.writeExternal");
  }

  public void readExternal(ObjectInput in) throws IOException,
      ClassNotFoundException {
    System.out.println("Blip2.readExternal");
  }
}

public class Blips {
  // Throw exceptions to console:
  public static void main(String[] args) throws IOException,
      ClassNotFoundException {
    System.out.println("Constructing objects:");
    Blip1 b1 = new Blip1();
    Blip2 b2 = new Blip2();
    ObjectOutputStream o = new ObjectOutputStream(new FileOutputStream(
        "Blips.out"));
    System.out.println("Saving objects:");
    o.writeObject(b1);
    o.writeObject(b2);
    o.close();
    // Now get them back:
    ObjectInputStream in = new ObjectInputStream(new FileInputStream(
        "Blips.out"));
    System.out.println("Recovering b1:");
    b1 = (Blip1) in.readObject();
    // OOPS! Throws an exception:
    //! System.out.println("Recovering b2:");
    //! b2 = (Blip2)in.readObject();
  }
} ///:~

Related examples in the same category

1.	Serialization with ObjectInputStream and ObjectOutputStream
2.	Object Serialization
3.	Serial Demo
4.	Create a serialized output file
5.	Reconstructing an externalizable object
6.	Serializable
7.	Serializer class
8.	This program shows how to use getSerialVersionUID
9.	Working with Serialization
10.	Assists with the serialization process and performs additional functionality based on serialization.
11.	Computes all the class serialVersionUIDs under the jboss home directory.
12.	Serializable Enumeration
13.	Serialization Utilities
14.	This program demonstrates the transfer of serialized objects between virtual machines
15.	A class whose clone method uses serialization
16.	Writes a serialized version of obj to a given file, compressing it using gzip.
17.	Reads a serialized object from a file that has been compressed using gzip.
18.	Serialized File Util
19.	Serializes an object to a file, masking out annoying exceptions.

Simple use of Externalizable and a pitfall : Serialization « File Input Output « Java

Related examples in the same category