序列化HashTable,Java

public class Test{

public static void main(String args[]){

    Store store = new Store();

    FileOutputStream fos;
    ObjectOutputStream oos = null;

    try{

        fos = new FileOutputStream(new File("table.obj"));
        oos = new ObjectOutputStream(fos);

    }catch(IOException e1){

        e1.printstacktrace();

    }

这继续包含一堆更多的代码,但我认为真正重要的是我的“Q”案例……

case "Q":

            System.out.println("Good-Bye!");

            try{

                oos.writeObject(store);
                oos.flush();
                oos.close();

            }catch(IOException e){

                e.printstacktrace();

            }

            System.exit(0);

            break;

当我尝试将所有数据保存到我的.obj文件并关闭流并退出我的程序时,我得到所有这些错误……

java.io.NotSerializableException：Item
at java.io.ObjectOutputStream.writeObject0(UnkNown Source)
at java.io.ObjectOutputStream.writeObject(UnkNown Source)
at java.util.Hashtable.writeObject(UnkNown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(UnkNown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(UnkNown Source)
at java.lang.reflect.Method.invoke(UnkNown Source)
at java.io.ObjectStreamClass.invokeWriteObject(UnkNown Source)
at java.io.ObjectOutputStream.writeSerialData(UnkNown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(UnkNown Source)
at java.io.ObjectOutputStream.writeObject0(UnkNown Source)
at java.io.ObjectOutputStream.defaultWriteFields(UnkNown Source)
at java.io.ObjectOutputStream.writeSerialData(UnkNown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(UnkNown Source)
at java.io.ObjectOutputStream.writeObject0(UnkNown Source)
at java.io.ObjectOutputStream.writeObject(UnkNown Source)
在Test.main(Test.java:143)

我不确定这些错误大多数意味着什么,或者为什么我会得到它们,甚至不知道如何修复它们.谁能帮我？

编辑：商店类

import java.io.Serializable;
import java.util.Hashtable;

 public class Store implements Serializable{

Hashtable<String,Item> stockedItems = new Hashtable<String,Item>();

public boolean addItem(String code){

    if(stockedItems.containsKey(code)){

        stockedItems.get(code).incrementQuantity();

        return true;

    }

    return false;

}

public boolean removeItem(String code){

    if(stockedItems.containsKey(code)){

        stockedItems.get(code).decrementQuantity();

        return true;

    }

    return false;


}

public boolean findItem(String code){

    if(stockedItems.containsKey(code)){

        return true;

    }

    return false;

}

 }

**我的HashTable包含不实现Serializable的Item对象.我现在修复了哪个.程序运行和Q案例工作正常！现在是我的U案不起作用,这里是……

case "U":

            try{

                FileInputStream fis = new FileInputStream("table.obj");
                ObjectInputStream ois = new ObjectInputStream(fis);

                store = (Store)ois.readobject();

                ois.close();

            }catch(IOException | ClassNotFoundException e){

                e.printstacktrace();

            }

            break;

这种情况的目的是允许用户选择是否要使用存储在我的.obj文件中的数据.我试图使用这种情况时得到这些错误

at java.io.ObjectInputStream $BlockDataInputStream.peekByte(UnkNown Source)
at java.io.ObjectInputStream.readobject0(UnkNown Source)
at java.io.ObjectInputStream.readobject(UnkNown Source)
在Test.main(Test.java:142)