Getting an exception(Serialization)

[Amit Batra]

The code below is from the k&B.

 
import java.io.*;
class Dog implements Serializable{
private transient Collar theCollar;
int dogSize;
 
private void WriteObject(ObjectOutputStream os)throws IOException{
try{
os.defaultWriteObject();
os.writeInt(theCollar.getCollarSize());
}catch(Exception e){e.printStackTrace();}
}
 
private void ReadObject(ObjectInputStream is)throws IOException,ClassNotFoundException{
try{
is.defaultReadObject();
theCollar=new Collar(is.readInt());
}catch(Exception e){}
}
 
public Dog(Collar collar,int size){theCollar=collar; size=dogSize;}
 
public Collar getCollar(){return theCollar;}
}
 

class Collar /*implements Serializable*/{
private int collarSize;
 
public Collar(int size){collarSize=size;}
 
public int getCollarSize(){return collarSize;}
}
 

class SerializeDog1{
public static void main(String[] args){
Collar c=new Collar(3);
Dog d=new Dog(c,5);
System.out.println("before collar size is"+d.getCollar().getCollarSize());
 
try{
FileOutputStream fs=new FileOutputStream("test1.ser");
ObjectOutputStream oos=new ObjectOutputStream(fs);
oos.writeObject(d);
oos.close();
}catch(Exception e){e.printStackTrace();}
 
try{
FileInputStream fis=new FileInputStream("test1.ser");
ObjectInputStream ois=new ObjectInputStream(fis);
d=(Dog)ois.readObject();
ois.close();
}catch(Exception e){e.printStackTrace();}
System.out.println("After:   collar size is"+d.getCollar().getCollarSize());
}
}

Why am I getting an exception when I deserialize?. Ive run through this code but still cant see what im doing wrong. Please help.

[Gowher Naik]

import java.io.*;
class Base implements Serializable{
 transient int x=100;
}
public class FileTest extends Base implements Serializable{
private void writeObject(ObjectOutputStream os)throws Exception{
os.defaultWriteObject();
os.writeInt(x);
}
private void readObject(ObjectInputStream os)throws Exception{
os.defaultReadObject();
x=os.readInt();
}
    public static void main(String argv[]) throws Exception{
FileOutputStream f=new FileOutputStream("SerFile.txt");
ObjectOutputStream o=new ObjectOutputStream(f);
o.writeObject(new FileTest());
o.close();
FileInputStream f1=new FileInputStream("SerFile.txt");
ObjectInputStream o1=new ObjectInputStream(f1);
FileTest c=(FileTest)o1.readObject();
o1.close();
    System.out.println("transient variable x After Deserilization : "+c.x);
    }
}

Above code serilize and deserilize a transient variable.
comment and uncomment private writeObject and readObject methods and see the output.
I hope it will help You.

[Patrick Patel]

Transient variables are not Serializable. If transient variable is a primitive and you try to deserialize it, java will initialize the primitive with the default value, for an Object it will be null.

[Burkhard Hassel]

G'day mates!

Three errors, the wrong version is outcommented:
// -->private void WriteObject(ObjectOutputStream os) throws IOException {
private void writeObject(ObjectOutputStream os) throws IOException {try {


//private void ReadObject(ObjectInputStream is) throws IOException,
private void readObject(ObjectInputStream is) throws IOException,ClassNotFoundException {


this method names must be lower case, and the third in the constructor:


public Dog(Collar collar, int size) {
theCollar = collar;
//size = dogSize;
dogSize=size;
}
just the other way round.

Yours,
Bu.