子類可序列化為文件，但該文件不可反序列化

什么例外？（請考慮將其添加到帖子中，因為它看起來像是一個“重要的細節”）。

抱歉，無法re-produce/comprehend：

package com.example.serial;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class SerialTest {

  public static void main(String[] args) throws IOException, ClassNotFoundException {
    Car car = new Car();
    car.manufacturer = "Toyota";
    car.model = "Land Cruiser";
    
    // tmp memory:
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();

    // write object:
    ObjectOutputStream oos = new ObjectOutputStream(outStream);
    oos.writeObject(car);

    // input stream of "tmp memory":
    ByteArrayInputStream inStream = new ByteArrayInputStream(outStream.toByteArray());

    // read object:
    ObjectInputStream ois = new ObjectInputStream(inStream);
    Car c2 = (Car) ois.readObject();

    // print/verify:
    System.out.println(c2);
  }
}

class Vehicle implements Serializable {

  private static final long serialVersionUID = 0L;
  String manufacturer;
}

class Car extends Vehicle {

  String model;
}

Prints:

com.example.serial.Car@1ed6993a

我們還可以做到：

Vehicle car = new Car();
// ... same code, but without "model"

But not:

Vehicle car = new Vehicle();
...

…這將導致：

java.lang.ClassCastException: class com.example.serial.Vehicle cannot be cast to class com.example.serial.Car

在這一行：

Car c2 = (Car) ois.readObject();

Reference: https://docs.oracle.com/en/java/javase/17/docs/specs/serialization/serial-arch.html