invalidClassException: please help getting these errors

Question

I am getting this error when i run the program:

java.io.InvalidClassException: Food; local class incompatible: stream classdesc serialVersionUID = -1986042743597353721, local class serialVersionUID = -2452322360924937818
    at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:570)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1599)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1494)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1599)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1494)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1748)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1327)
    at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1683)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1321)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:349)
    at GroceryStore.readInventory(GroceryStore.java:16)
    at GroceryStore.main(GroceryStore.java:39)

I tried so many things but not really sure where im going wrong, im new to this thing.

    import java.io.Serializable;

    public abstract class Food implements Serializable {
    String Type, Name;
    double Price;
    private static final long serialVersionUID = -2452322360924937818L;

    public Food(String Type, String Name, double Price){
            this.Type = Type;
        this.Name = Name;
        this.Price = Price;
    }
    public String getType(){
        return Type;
    }
    public String getName(){
        return Name;
    }
    public double getPrice(){
        return Price;
    }
    public String toString(){
        return (Type + " " + Name + " " + Price);
    }
    public abstract double getQuantity();
}



    import java.io.Serializable;

    public class FoodItem extends Food implements Serializable {

     private static final long serialVersionUID = -2452322360924937818L;
     private double quantity;
     int bestBeforeMonth;
     int bestBeforeDay;


     public FoodItem(String Type, String Name, double Price, double quantity, int        bestBeforeMonth, int bestBeforeDay) {
        super(Type, Name, Price);
        this.quantity = quantity;
        this.bestBeforeDay = bestBeforeDay;
        this.bestBeforeMonth = bestBeforeMonth;
     }


     @Override
     public double getQuantity() {
        return quantity;
     }
     public void removeQuantity(double quantity){
        this.quantity = this.quantity - quantity;
     }

    }


    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectInputStream.GetField;
    import java.io.ObjectOutputStream;


    public class GroceryStore {
     static FoodItem[] inventory = null; 
     public static void readInventory(){

    try {
        ObjectInputStream in = new ObjectInputStream(new FileInputStream("grocery.bin"));
        inventory[0] =  (FoodItem) in.readObject();



    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
     }

public static void main(String[] args){
    readInventory();
}
}

Answer 1

This message is coming due to version mismatch between serialized version of the class and current class.

The message is saying the class you have serialized with object stream has version id -1986042743597353721, but your class version id is -2452322360924937818L.

So you have 2 options:

• Get the class with serial version id -1986042743597353721, or ...
• Write a custom deserializer which understands the old format and can construct a new object.

Here is the full documentation.