Comment résoudre ce cas "n'a pas de sous-types instanciables"

Question

Ceci est mon code pour l'offre de classe, quand je compile cette partie du code j'ai eu une erreur .. s'il vous plaît aidez-moi. Thx u gars

import java.io.Serializable; 

public class Offer implements Comparable<Object>, Serializable { 

    private static final long serialVersionUID = 1L; 
    private Product product; 
    private RegisteredUser user; 
    private float amount; 

    //stati dell'offerta 
    private OfferState bestOffer; 
    private OfferState overtakenOffer; 
    private OfferState winnerOffer; 
    private OfferState loserOffer; 

    //stato attuale dell'offerta 
    private OfferState state; 

    public Offer(){} 

    public Offer(Product product, RegisteredUser user, float amount) 
    { 
     this.user = user; 
     this.amount = amount; 
     this.product = product; 

     bestOffer = new BestOffer(this); 
     overtakenOffer = new OvertakenOffer(this); 
     winnerOffer = new WinnerOffer(this); 
     loserOffer = new LoserOffer(this); 

     state = bestOffer; 
    } 


    public RegisteredUser getUser() { 
     return user; 
    } 


    public float getAmount() { 
     return amount; 
    } 


    public void setAmount(float amount) { 
     this.amount = amount; 
    } 

    @Override 
    public int compareTo(Object arg0) { 

     return Float.compare(amount, ((Offer) arg0).getAmount()); 
    } 


    public OfferState getBestOffer() { 
     return bestOffer; 
    } 


    public OfferState getOvertakenOffer() { 
     return overtakenOffer; 
    } 


    public OfferState getWinnerOffer() { 
     return winnerOffer; 
    } 


    public OfferState getLoserOffer() { 
     return loserOffer; 
    } 

    public OfferState getState() { 
     return state; 
    } 

    public void setState(OfferState state) { 
     this.state = state; 
    } 

    public void reciveOffer() 
    { 
     try 
     { 
      state.reciveOffer(); 
     } 
     catch (UnsupportedOperationException e) { 
     } 
    } 

    public void deadline() 
    { 
     try 
     { 
      state.deadline(); 
     } 
     catch (UnsupportedOperationException e) { 

     } 
    } 

    public Product getProduct() { 
     return product; 
    } 

} 

Error gwt

Answer 1

Tous les membres comme produit, RegisteredUser, OfferState doivent être sérialisables trop ou transitoire marquée. Je cas, ils ne sont pas vous devez les faire. Il y a un bon exemple ici: Serialization - readObject writeObject overrides