Question

I basically have a similar problem as stated here: EOFexception in Java when reading objectinputstream, but I don’t find an answer with clean code.

The answer states that the ObjectInputStream#readObject will throw the exception when the reader reachs the End Of File. After looking in the web for a solution, I haven’t found a solution. Could be a good and clean solution for this case?

Note: I have tried this (but it looks ugly and is not clean code). I’m looking for a better solution:

ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file));
try {
    Object o;
    while ((o = ois.readObject()) != null) {
        if (o instanceof MyClass) {
            MyClass m = (MyClass)o;
            //use the object...
        }
    }
} catch (EOFException eofex) {
    //do nothing
}  catch (IOException ioex) {
    throw ioex;
    //I have another try/catch block outside to control the life of the ObjectInputStream
}
//later in the code...
ois.close();

Answer 1

That’s what’s supposed to happen. Your code is wrong. Check the Javadoc. readObject() only returns null if you wrote a null. It doesn’t say anything about returning a null at EOF. Looping until readObject() returns null will only stop if you ever wrote a null via writeObject(), and if you didn’t you will get an EOFException.