CODEWITHSUNDEEP
gwtserializationsubclass
czupe
czupe

Reputation: 4919

GWT + Serialization

I am having hard time trying to serialize my class (literally 3-4 hour to find a solutio). I add a subclass to an existing serializable and functioning class, and than get the following error message:

 [ERROR] com.google.gwt.user.client.ui.DelegatingChangeListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingClickListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingFocusListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingKeyboardListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.view.client.ListDataProvider<T>.ListWrapper<> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.client.rpc.ItemRecRpc.LogCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.client.rpc.ItemRecRpc.LogCollection has no available instantiable subtypes. (reached via com.client.rpc.ItemRecRpc)
                 [ERROR]    subtype com.client.rpc.ItemRecRpc.LogCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.AbstractList.SubList<E> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.Collections.UnmodifiableList<T> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.Collections.UnmodifiableRandomAccessList<T> is not default instantiable (it must have a zero-argument

My class looks like:

public class ItemRecRpc implements Serializable {

    private static final long serialVersionUID = -5828108890651522661L;
        .
        .

        private String rId;
    private LogCollection logColl;//if i comment this, no error message...

    public class LogCollection{ 

        public LogCollection(){

        }
        //public long creationTime = System.currentTimeMillis();
        //public LongVector times = new LongVector();
        //public ArrayList<Object> messages = new ArrayList<Object>();
        //public int nSkipped = 0; 
        //public int nExceptions = 0; 
        //public Exception firstException = null; 
        //public long endGcTime=0;
        public long endTime;
    }
.
.
.
}

When i comment the "private LogCollection logColl" line it is ok, but when i uncomment i again get the error mesage. I tried with static keyword, as you see i comment every subclass variable, but can not help... Anyway if i create a new class:

public class LogCollectionRpc implements Serializable {

    public LogCollectionRpc() {
        //
    }
    public long creationTime = System.currentTimeMillis();
    public LongVector times = new LongVector();
    public ArrayList<Object> messages = new ArrayList<Object>();
    public int nSkipped = 0; // due to reaching the limit
    public int nExceptions = 0; // due to MyAppender-s
    public Exception firstException = null; // due to MyAppender-s
    public long endGcTime = 0;
    public long endTime;

}

And than try to use this as my functioning class, it is ok... But this thing is really bugging my mind...

Any idea? Gwt dont support subclass serialization? Or am i miss something. Aprreciate any answer.

Best Regards, Peter

Upvotes: 2

Views: 7386

Answers (1)

jusio
jusio

Reputation: 9920

This error:

subtype com.client.rpc.ItemRecRpc.LogCollection is not default instantiable

Says that it can't create and instance of LogCollection by default. And it is true. Because to create an instance of LogCollection, you first need to have an instance of ItemRecRpc. Declaring LogCollection as static class should have helped.

Basically, when you want to send some object over gwt-rpc, all the classes used as fields in such object should be instantiable by default. (e.g. no special tricks to create it, just new and empty constructor). Also you can define a custom field serializer for any class, which can be instantiated by default.

Upvotes: 7

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