Why do we need Serializable Interface since there is no method decl. inside

On working with Serialization in java
I could see that the Serializable Interface is empty without any method inside.
Also, the writeObject() and readObject() accepts only if the Serializable interface is implemented to a class.
What is the use of implementing an empty Interface?
Please clarify.
Thanks in advance.
Regards,
R.Mahendra Babu

The completely empty Serializable is only a marker interface -- it simply allows the serialization mechanism to verify that the class is able to be persisted.

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http://java.sun.com/javase/technologies/core/basic/serializationFAQ.jsp#whyserial
http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html
http://java.sun.com/j2se/1.5.0/docs/guide/serialization/spec/serial-arch.html#4539

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Why do we need Serializable Interface since there is no method decl. inside

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