Creating a Java Interface

<%! javax.servlet.jsp.JspWriter jw; interface Add { int add() throws java.io.IOException; } class Addition implements Add { int a = 10; int b = 20; public int add() throws java.io.IOException { jw.println("The addition of " + a + " and " + b + " is equal to "); return (a+b); } } %> <% jw = out; Addition addition = new Addition(); int a = addition.add(); out.println(a); %>