2016-09-23 13:23:35 -06:00

79 lines
2.0 KiB
Java

// serialization/Blips.java
// (c)2016 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.
// Simple use of Externalizable & a pitfall
import java.io.*;
class Blip1 implements Externalizable {
public Blip1() {
System.out.println("Blip1 Constructor");
}
@Override
public void writeExternal(ObjectOutput out)
throws IOException {
System.out.println("Blip1.writeExternal");
}
@Override
public void readExternal(ObjectInput in)
throws IOException, ClassNotFoundException {
System.out.println("Blip1.readExternal");
}
}
class Blip2 implements Externalizable {
Blip2() {
System.out.println("Blip2 Constructor");
}
@Override
public void writeExternal(ObjectOutput out)
throws IOException {
System.out.println("Blip2.writeExternal");
}
@Override
public void readExternal(ObjectInput in)
throws IOException, ClassNotFoundException {
System.out.println("Blip2.readExternal");
}
}
public class Blips {
public static void
main(String[] args) throws IOException,
ClassNotFoundException {
System.out.println("Constructing objects:");
Blip1 b1 = new Blip1();
Blip2 b2 = new Blip2();
try(
ObjectOutputStream o = new ObjectOutputStream(
new FileOutputStream("Blips.serialized"))
) {
System.out.println("Saving objects:");
o.writeObject(b1);
o.writeObject(b2);
}
// Now get them back:
System.out.println("Recovering b1:");
try(
ObjectInputStream in = new ObjectInputStream(
new FileInputStream("Blips.serialized"))
) {
b1 = (Blip1)in.readObject();
}
// OOPS! Throws an exception:
//- System.out.println("Recovering b2:");
//- b2 = (Blip2)in.readObject();
}
}
/* Output:
Constructing objects:
Blip1 Constructor
Blip2 Constructor
Saving objects:
Blip1.writeExternal
Blip2.writeExternal
Recovering b1:
Blip1 Constructor
Blip1.readExternal
*/