如何反序列化对象的哈希图？

Question

I have a hashmap of objects in java. I want to deserialize the objects but since the collection is dynamic, I'm confused on how I would read the objects back in (the number of objects is not known when deserializing). I tried to look around online but couldn't find much.

HashMap patron = new HashMap();
HashMap book = new HashMap();
public static void main(String args[]){

}
public void refresh(){
    try {
        FileInputStream fis = new FileInputStream("Books.ser");
        ObjectInputStream os = new ObjectInputStream(fis);
        Set set = book.entrySet();
        Iterator i = set.iterator();
        while(i.hasNext()){

        }
        os.close();

    }
}

I don't know how to complete the while loop where the deserialization takes place.

Answer 1

1. If you serialized the HashMap as a single object, just deserialize it the same way:

    HashMap hm = (HashMap)ois.readObject(); 

2. If you didn't serialize it as a single object, change it so you do.