StreamCorruptedException in ObjectInputStream

Question

Hello!! I have a problem with serialization and ObjectInputStream/ObjectOutputStream classes:
I have two programs. The first program writes objects in a file. Here is the code:
FileOutputStream f = new FileOutputStream ("filename", true);
ObjectOutputStream o = new ObjectOutputStream (f);
o.writeObject (objetTest);
f.close();
o.close();
The other program reads these objects:
FileInputStream f = new FileInputStream ("filename");
ObjectInputStream o = new ObjectInputStream (f);
TestClass objetTest = (TestClass)o.readObject();
f.close();
o.close();
The first program is executed and when it finishes the second program is executed. Imagine that the first program writes two object and the second program wants to read these two objects. The second program reading the first object runs ok, but when try to read the second object a java.io.StreamCorruptedException appears
Anybody can help me? Any ideas?
Cheers
Kike

Answer 1

A newly created ObjectOutputStream first writes a header to its encapsulated
OutputStream. From your code I see that you're using the FileOutputStream
in 'append mode'. So, if you write two objects, running the above code twice,
you basically get this in your file: <header><object><header><object>.
You're just using one ObjectInputStream; when it gets created it reads the
header and then attempts to read objects from the encapsulated InputStream.
It encounters another header when it attempts to read a second object,
hence the StreamCorruptedException.
kind regards,
Jos