[Class] Add a class

[coreybasden]

As a user, I want to add a class to the diagram with a unique name, So that I can later add fields/methods and relationships to it.

[Lantzer]

[1] valid class name
From the home screen of the program. When I type “add class testClass” There is a message saying that the class “testClass” was created And the UML diagram shows the class “testClass”

[2] invalid class name From the home screen of the program, When I type “add class testClass”, when there is already a class named “testClass”, There is a message saying that the name “testClass” is invalid, I am then returned to the home screen of the program.

[Lantzer]

Tasks: Implement input checking: ensuring valid user names Acceptance Criteria: name should be unique.

Create logic : Check name if valid, add class object to internal data structure.

Display success message: when name is valid, print "The class 'testClass' was created" when name is invalid, print "The class 'testClass' was not created"

Unit Testing: create unit tests

[Lantzer]

Initialized fieldItems and methodItems lists as ArrayLists for now.