The ServletConfig interface in Java is used to provide configuration information to a servlet. It is a part of the Servlet API and provides methods for getting initialization parameters and the context in which the servlet is running.

A ServletConfig object is created by the web container for each servlet and is passed to the init method of the servlet during initialization. The ServletConfig object can be used to get initialization parameters specified in the web.xml file for the servlet.

The ServletConfig interface provides the following methods:

• String getServletName(): Returns the name of the servlet.
• ServletContext getServletContext(): Returns a reference to the ServletContext in which the servlet is running.
• String getInitParameter(String name): Returns the value of the initialization parameter with the given name, or null if the parameter does not exist.
• Enumeration<String> getInitParameterNames(): Returns an Enumeration of the names of the initialization parameters.

Here is an example of how the ServletConfig interface can be used:

public class MyServlet extends HttpServlet {
    private String myParam;

    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        myParam = config.getInitParameter("myParam");
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        // use the myParam value here
    }
}

In this example, the init method is called with the ServletConfig object, which is used to get the value of an initialization parameter called myParam. The value is stored in a private member variable for later use in the doGet method.