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class Key implements Serializable {
  //overrides hashcode and equals methods
}

class HashSer {
  public static void main(String[] args) throws IOException, ClassNotFoundException {
    Hashtable<Key,String> ht = new Hashtable<Key, String>();
    Key key = new Key();
    ht.put(key, "Value");
    System.out.println("Entry: " + ht.get(key)); // retrieve using the key, works
	 
    // Serialize the Hashtable object
    FileOutputStream fos = new FileOutputStream("hashdata.ser");
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(ht);
    oos.close();
	 
    // Deserialize the Hashtable object
    FileInputStream fis = new FileInputStream("hashdata.ser");
    ObjectInputStream ois = new ObjectInputStream(fis);
    Hashtable<Key, String> ht_in = (HashtableHashtable<Key, String>)(ois.readObject());
    ois.close();
	 
    if(ht_in.contains("Value")) // check if the object actually exists in the Hashtable
      System.out.println("Value was found in deserialized object.");
	 
    if (ht_in.get(key) == null) // gets printed
      System.out.println("Object was not found when retrieved using the key.");	 
  }
}

class HashSer {
  public static void main(String[] args) throws IOException, ClassNotFoundException {
    Hashtable<Integer,String> ht = new Hashtable<Integer, String>();
    ht.put(new Integer(1), "Value");
    System.out.println("Entry: " + ht.get(1)); // retrieve using the key
	 
    // Serialize the Hashtable object
    FileOutputStream fos = new FileOutputStream("hashdata.ser");
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(ht);
    oos.close();
	 
    // Deserialize the Hashtable object
    FileInputStream fis = new FileInputStream("hashdata.ser");
    ObjectInputStream ois = new ObjectInputStream(fis);
    Hashtable<Integer, String> ht_in = (HashtableHashtable<Integer, String>)(ois.readObject());
    ois.close();
	 
    if(ht_in.contains("Value")) // check if the object actually exists in the Hashtable
      System.out.println("Value was found in deserialized object.");
	 
    if (ht_in.get(1) == null)  // does not get printed
      System.out.println("Object was not found when retrieved using the key.");	 
  }
}