java - How to initialize a Servlet during startup with parameters?

Question

Can we write an argument constructor in a Servlet? If yes, how can you call?

Answer 1

Can we write an argument constructor in a Servlet?

Yes, you can but it is useless since the servlet container won't invoke it.

The proper way to do it is to use the init() method:

@Override
public void init() throws ServletException {
    String foo = getInitParameter("foo");
    String bar = getServletContext().getInitParameter("bar");
    // ...
}

In this example, getInitParameter("foo") returns the value of the <init-param> of the specific <servlet> entry in web.xml, and getServletContext().getInitParameter("bar") returns the value of the independent <context-param> in web.xml.