⌛ Shapes¶

The remote material repository (the round6/shapes directory) has supplementary files for this question.

The exercise is returned as a Maven project. Place the pom.xml file in the round6/shapes directory of your local repository and create to this directory the src/main/java subdirectory. Create class files Circle.java, Rectangle.java and IShapeMetrics.java and attach them to the fi.tuni.prog3.shapes package. Your files should be in the round6/shapes/src/main/java/fi/tuni/prog3/shapes directory. We use here the convention of naming interfaces with an I-prefix. This is a common practice especially in the C# programming language, but some use it in Java too.

In this exercise, you should write the following interface and two classes:

• Interface IShapeMetrics that has:

  • Member variable double PI that defines pi using 5 decimals of precision.

  • Abstract member functions String name(), double area() and double circumference().

• Class Circle that implements the interface IShapeMetrics and stores the radius of a circle as a value of the double type. Public members:

  • Constructor Circle(double radius) that initializes the radius.

  • Member function String toString() that overrides the default version inherited from Object. The function returns a String of form “Circle with radius: x”, where x is the radius with 2 decimals of precision. Please, note that point is used as the decimal separator. The format member function of the String class is convenient helper in this task.

  • Member function String name() that returns the String “circle”.

  • Member function double area() that returns the area of the circle, computed using PI as the value of pi.

  • Member function double circumference() that returns the circumference of the circle, computed using PI as the value of pi.

• Class Rectangle that implements the interface IShapeMetrics and stores the height and width of a rectangle as values of the double type. Public members:

  • Constructor Rectangle(double height, double width) that initilizes height and width.

  • Member function String toString() that overrides the default version inherited from Object. Function returns a String of form “Rectangle with height x and width y”, where x is the height and y the width of the rectangle, both with 2 decimals of precision. Please, note that point is used as the decimal separator. The format member function of the String class is convenient helper in this task.

  • Member function String name() that returns the String “rectangle”.

  • Member function double area() that returns the area of the rectangle.

  • Member function double circumference() that returns the circumference of the rectangle.

The automatic tests, and the ones given below, assume that you make the following definitions in your pom.xml project file:

• The value of artifactId is shapes.

• The value of version is 1.0.

• The values of the maven.compiler.source and maven.compiler.target elements are 17 or lower. The grader uses Java 17, so any newer versions won’t work.

• A Onejar plugin definition where the value of mainClass is InterfaceTest which is the name of the given test class (see below).