Question

The GWT tutorial says

As of GWT 1.5, it must have a default (zero argument) constructor (with any access modifier) or no constructor at all.

So, when the default constructor is only used by the Serialization mechanism, wouldn’t it be useful to make it private? This way, clients of the class don’t accidentally call the default constructor, and the visible interface becomes smaller.

Or does it somehow affects the Serialization mechanism in any other way?

Answer 1

**WARNING THIS ANSWER IS NOT ABOUT HOW THE GWT COMPILER HANDLES ITS REQUIRED DEFAULT NO-ARG CONSTRUCTOR**
If you put it private, Serialization won’t work.

From Javadoc :
“The subtype may assume this responsibility only if the class it extends has an accessible no-arg constructor to initialize the class’s state. It is an error to declare a class Serializable if this is not the case. The error will be detected at runtime.”

So yes, it will affect the Serialization process.

You could deprecate or comment this constructor indicating it is only used for Serialization purpose.

See here for details about serialization.