Java Generics in GWT-RPC

[Ramon Salla]

We are having a SerializationException error when sending a list of objects using RPC and Java Generics.

I'm creating this widget to show the error:

public class Test<T> {

    ListDataProvider<T> ldp = new ListDataProvider<T>();

    public void setItems(List<T> list){
        for(T t :list){
            ldp.getList().add(t);
        }
    }

    public List<T> getItems(){
        return ldp.getList();

    }

}

This is the code for creating the Test widget and passing a list of POJOs (where ExporterFormKey is the POJO object)

List<ExporterFormKey> list = new ArrayList<ExporterFormKey>();
ExporterFormKey key = new ExporterFormKey();
key.setKey("key1");
list.add(key);

Test<ExporterFormKey> test = new Test<ExporterFormKey>();
test.setItems(list);

At the end the next code throws a SerializationException:

service.sendList(test.getList(), new AsyncCallback...);

While the next one does fine:

service.sendList(list, new AsyncCallback...);

I found that doing the next code also works

List<ExporterFormKey> newList = new ArrayList<ExporterFormKey>(test.getItems());

[Ramon Salla]

This change on Test works!! It seems a problem with the ListDataProvider object.

public List<T> getItems(){
    return new ArrayList<T>(ldp.getList());
}

El dimecres 19 de desembre de 2012 10:35:14 UTC+1, Ramon Salla va escriure:

[Paul Robinson]

ListDataProvider.getList() returns a list implementation that is not GWT-serializable.

https://developers.google.com/web-toolkit/doc/latest/DevGuideServerCommunication#DevGuideSerializableTypes

If you look at the exception you received, it should tell you (in its own idiosyncratic way) that this class is not serializable.

Paul

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[Aldin Habibović]

check if your model class implements Serializable (or IsSerializable) and check if you have non-construcotra in your model class.