Date: 04 Jun 1999 08:06:03 -0700
From: "Scott Violet" <###@###.###>
Subject: Re: Serializing ArrayTables
To: "Georges Saab" <###@###.###>
Cc: ###@###.###

Georges Saab <###@###.###> writes:
> I noticed that you (and I) are both serializing ArrayTables
> by hand. It occurs to me that perhaps we should move the
> serialization code for these into ArrayTable itself and then
> just not declare the fields transient.
>
> What do you think?

Pro: we don't have to duplicate serialization code.
Con: we are locked down to the ArrayTable implementation.

When I had talked to Hans about this (when doing InputMap/ActionMap)
he thought the con outweighted the pro, which is why InputMap/ActionMap
have the exact same code in it for serializing the ArrayTable.
Perhaps we could add a package private method to ArrayTable that does
the serializing/unserializing (not readObject/writeObject), that way
we aren't locked into using ArrayTable. I'm thinking something
like the following:
public class InputMap ....

    private void writeObject(ObjectOutputStream s) throws IOException {
        ArrayTable.write(s, arrayTable);
    }

    private void readObject(ObjectInputStream s) throws ClassNotFoundException,
IOException {
        arrayTable = ArrayTable.read(s);
    }

class ArrayTable ...

    static void write(ObjectOutputStream s, ArrayTable table) {
        if (table == null) {
s.writeInt(0);
        }
else {
int size = table.size();
Object[] keys = new Object[table.size()];
table.getKeys(keys);
int validCount = 0;
for (int counter = 0; counter < size; counter++) {
if ((keys[counter] instanceof Serializable) &&
(table.get(keys[counter]) instanceof Serializable)) {
validCount++;
}
else {
keys[counter] = null;
}
}
s.writeInt(validCount);
for (int counter = 0, gCount = 0; counter < size; counter++) {
if (keys[counter] != null) {
s.writeObject(keys[counter]);
s.writeObject(table.get(keys[counter]));
if (++gCount == validCount) {
break;
}
}
}
}
    }

Notice the handling of null. If InputMap.read was invoked, and their
was no valid entries (readInt() == 0) I would say it should return
null.
Additionaly we could make the methods that call write on ArrayTable
write and int, or string, indicating that ArrayTable is being
used. That way, if we decide not to use ArrayTables in the future we
have a way of knowing it is a serialized ArrayTable.

What do you think?

-Scott