Java Serialisation : reading and writing to a file

Question

I have a class called item which has a few Strings like price, stock etc.

I write these to a file as such:

item[] data = new item[numberofitems]; 

The array is then filled then:

ObjectOutputStream outinv = new ObjectOutputStream(outinvstream);

    outinv.writeInt(numberofitems);

    for (int i = 0; i < numberofitems; i++)
    {

        outinv.writeObject(data[i]);
    }

This all works fine. The trouble comes when I try reading it in:

FileInputStream fin = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fin);
inventory = (item[]) ois.readObject();

where f is the file (it definitely finds it) and inventory is an item[] . However I get a OptionalDataException

Any hints are appreciated!

Answer 1

您必须按照与编写顺序相同的顺序进行读取。首先要写入数组大小，因此需要先读取int，然后再读取Objects。