Practice Problems: Creating Classes and Objects

1 Problems Involving Interfaces

• Assume you want to capture shapes, which can be either circles (with a radius and a color) or rectangles (with a length, width, and color). You also want to be able to create signs (to post in the campus center, for example), each of which has a shape (for the background of the sign) and the text (a String) to put on the sign.

  Create classes and interfaces for circles, rectangles, shapes, and signs.

• In order to make signs, we need to make shapes that are large enough to fit the text for the sign. Write a method on shapes fitsText that takes the text as an argument and determines whether the length of the text is shorter than the length/radius of the shape. You can get the length of a String by calling the method length on the string.

• Practice making errors with your shapes: omit the interface, make typos in the names of the fitsText method, and so on. This will help you get familiar with the errors messages that Java produces in various situations.