Write an interface called Shape, inside, there is a method double area(); write a class called Box which implements the Shape. In Box, there are two data members: a double called length, and a double called width. Also implements constructor, and the method area() which calculates the area by multiplying the length and width. Then write a Tester class, which has a main method and creates a box object and displays the area.

Explanation:

The following code is written in Java. It contains the interface Shape, the class Box, and a tester class called with the main method. Box implements the Shape interface and contains, the instance variables, the constructor which takes in the inputs for length and width, getter methods for length and width, and the defines the area() method from the interface. Then the object is created within the tester class' main method and the area() method is called on that object. Output can be seen in the image attached below. Due to technical difficulties, I have added the code as a txt file below.