Deserialising unable to cast

[samtaylor08]

Hi All,

I have a class that I have put [Serializable] above the constructor.

This class has an Arraylist of other objects of a different class which also has this heading.

I have a form that holds an ArrayList of objects that are the first class.

I can serialise using this:

 FS = new FileStream("C:/pop_queries.dat", FileMode.Create, FileAccess.Write);
                BinaryFormatter b = new BinaryFormatter();
                b.Serialize(FS, common.ToArray());
                FS.Close();

And try to deserialise using this:

 
Query[] queriesFromFile;
FS = new FileStream("C:/pop_queries.dat", FileMode.Open, FileAccess.Read);
                BinaryFormatter b = new BinaryFormatter();
                queriesFromFile = (Query[])b.Deserialize(FS);
                FS.Close();

Query is the same type as the items held in the ArrayList common, which I convert array in the serialisation!

When I try to deserialise, I get the error:

Unable to cast object of type 'System.Object[]' to type 'ClassifyGUI.Query[]'.

Can anybody see where I have gone wrong?

Sam

[techgnome]

Yup... when you serialized it... you serialized it as an array[] object....
common.ToArray() <<< --- right there....

Try just common....


Also... why an ArrayList and not a List<T> ? what version of the FW are you using?

-tg

[jmcilhinney]

The ArrayList.ToArray method returns an Object[]. If you want a Query[] when you call ToArray then, as tg says, you should be using List<Query> rather than an ArrayList. If that's not possible for some reason, like you're using .NET 1.x, then you will have to manually create a Query[] and copy the elements from the Object[] before serializing.