Week 12 Exercise

Overview

In this exercise, you will gain practice with using Exceptions in different contexts.

Resources

• Accept the GitHub Classroom assignment invitation in Canvas and then, in IntelliJ, create a new project from Version Control using the repository URL.

Circle

Create a Circle class that contains the following:

• A single instance attribute called circumference.
• A single argument constructor that takes in a circumference. If the circumference is non-positive, this method should throw an IllegalArgumentException.
• A toString() method that prints out "Circle" and the circle's circumference. See the sample output.

Exercise12

This driver class must contain the following methods:

• makeCircle
  • This method takes in a radius as a double and creates and returns a new Circle.
• fillList
  • This method takes in an ArrayList of Circle objects, a Scanner for user input, and an int for the number of tries to create and add a Circle to the list.
  • If the number of tries is non-positive, this method should throw an IllegalArgumentException.
  • This method should ask the user for the radius of a circle, create a new Circle with the makeCircle() method, and then add that new Circle to the passed-in list. If there is an error anywhere in this process, you should print an error message to the user and move onto making the next Circle if any.
    • You should be using catches for InputMismatchException (or NumberFormatException if you are using next() and Integer.parseInt() and IllegalArgumentException to detect the errors.
• main
  • This method creates the Scanner used for the user input and an empty ArrayList of Circle references called circles.
  • It then asks the user for a non-negative number for the number of circles to create and uses the fillList() method to fill the ArrayList of Circles. It then prints out the ArrayList of Circles.
    • If there is an error with the user's input of a whole number or an error is thrown by fillList(), print a descriptive warning message to the user.
    • You should be detecting errors through the catching of the relevant exceptions.

Sample Output

Example 1

Enter a non-negative number for how many times you want to make a Circle.
3
Enter the radius for the Circle.
1
Enter the radius for the Circle.
2
Enter the radius for the Circle.
3
Circles entered: 
[Circle{circumference=6.28}, Circle{circumference=12.57}, Circle{circumference=18.85}]

Example 2

Enter a non-negative number for how many times you want to make a Circle.
3
Enter the radius for the Circle.
no
Error radius must be a valid double. Skipping this input.
Enter the radius for the Circle.
-1
Error radius must be positive. Skipping this input.
Enter the radius for the Circle.
3
Circles entered:
[Circle{circumference=18.85}]

Example 3

Enter a non-negative number for how many times you want to make a Circle.
no
Error, number of Circles must be a whole number.

Example 4

Enter a non-negative number for how many times you want to make a Circle.
-1
Error, number of Circles must not be negative number.

Submission Instructions

Commit and push your code to your repository.