Doubt on Serialization

[jami siva]

I am reading SCJP Book, In that they given like this. when you deserialize an object, the non-serializable superclass must run its
constructor. Remember, constructors don't run on deserialized classes that implement Serializable.
As per above statement i guessed output for the below one is p only. But the correct output is pcp. Can any one explain why this is?

import java.io.*;

class Player {
	Player() {
		System.out.print("p");
	}
}

class CardPlayer extends Player implements Serializable {
	CardPlayer() {
		System.out.print("c");
	}

	public static void main(String[] args) {
		CardPlayer c1 = new CardPlayer();
		try {
			FileOutputStream fos = new FileOutputStream("play.txt");
			ObjectOutputStream os = new ObjectOutputStream(fos);
			os.writeObject(c1);
			os.close();
			FileInputStream fis = new FileInputStream("play.txt");
			ObjectInputStream is = new ObjectInputStream(fis);
			CardPlayer c2 = (CardPlayer) is.readObject();
			is.close();
		} catch (Exception x) {
		}
	}
}

[lokesh sree]

Hi,

In line 15, when we do a new CardPlayer(), since CardPlayer extends Player, first Player's constructor and then CardPlayer's constructors will be invoked. Making the output "pc". This is irrespective of whether serialization is in picture or not.
Now, coming to the question, the statement posted itself explains the output. CardPlayer implements Serializable but not Player class.
So, when the serialized object c1 is read back/deserialized, it realizes that its parent Player does not implement Serializable. Hence, Player's constructor will be run. So, the additional "p" at the end making the output "pcp". And, yes, as you have mentioned constructors will not run during deserialization for classes that implement serializable. Hence, constructor of CardPlayer is not invoked while deserializing c1. Hope this clarifies your question.

[Devendra Mahra]

Just to clarify a bit more,

"constructors don't run on deserialized classes that implement Serializable."

is applicable to the process of deserialization.
At line 15 in the code, a new instance is being created hence the constructor and super class constructors are being called.