Question

I have a series of different object serialized into a binary file.How can I read the file until the end?

    try {
        ObjectInputStream reader = new ObjectInputStream(new FileInputStream(fname));

        Object obj = reader.readObject(); 

        if (obj instanceof Azienda) {
            Azienda a = (Azienda) obj;
            company.put(a.getCod(), a);
        } else if (obj instanceof Privato) {
            Privato p = (Privato) obj;
            privato.put(p.getCod(), p);
        }
    } catch (ClassNotFoundException cnfe) {
        cnfe.printStackTrace();
    } catch (FileNotFoundException ffe) {
        System.err.println("Error: the file was not found!");
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }

in this way I read only once object per read.

when I read a text file I use null

Answer 1

try{
    while(true) {
       Object obj=reader.readObject()
     // do sth with object
    }
}catch(EOFException e){
//we expect it so ignore
}

there is no EOF check besides the exception when you read past it for ObjectInputStream so you’ll have to use the code smell called exceptions for control flow