Servlet constructor and init() method

Question

Why do we need an init() method in servlet? Can't we use the constructor to initialization?

Answer 1

Because Servlet is an interface, not an abstract class. Constructor arguments cannot be specified on an interface, so the ServletContext needs to be specified on a normal method signature.

This allows the application server to know how to initialize any Servlet implementation properly.

Another solution would have been to require, but not enforce at compile time, a constructor taking ServletContext. The application server would then call the constructor via reflection. However, the designers of the Servlet specification did not chose this path.