为什么序列化无需实现Serializable就可以工作

Question

Is it mandatory to implement Serializable class when serializing a class .I tried to put object data into file with and without serializable implementation and found absolutely no difference.

snippet -1

import java.io.*;
import java.net.*;
public class SerializableTest {

    int a= 10;
    String test="Serialize test";

    public static void main(String [] args){

        SerializableTest test =new SerializableTest();
        test.save();
    }

    public void save(){

        try{

            FileOutputStream fs = new FileOutputStream("save.res");
            ObjectOutputStream os = new ObjectOutputStream(fs);
            os.writeObject(test);
            os.close();

        }
        catch (Exception ex ){
            System.out.println("Error in opening or saving file");

        }
        System.out.println("Complete");
    }
}

---

snippet -2

    import java.io.*;
    import java.net.*;
    public class SerializableTest **implements Serializable**{

    int a= 10;
    String test="Serialize test";

    public static void main(String [] args){

        SerializableTest test =new SerializableTest();
        test.save();
    }

    public void save(){

        try{

            FileOutputStream fs = new FileOutputStream("save.res");
            ObjectOutputStream os = new ObjectOutputStream(fs);
            os.writeObject(test);
            os.close();

        }
        catch (Exception ex ){
            System.out.println("Error in opening or saving file");

        }
        System.out.println("Complete");
    }
}

In both cases program ran fine and contents of save.res looked absolutely similar.

1. What is the advantage of implementing Serializable when I can do things without implementing.

Answer 1

Serializable should ideally be implemented by the object that needs to be serialized. String implements Serializable . You are serializing a String object. You are not serializing SerializableTest .

In other words, it does not matter if SerializableTest implements Serializable or not since SerializableTest is not the object that is being serialized.