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Java throwing exceptions Exercise
    Throwing exceptions
In this exercise, the square root program written earlier will be extended to detect when the answer might be an imaginary number. (An imaginary number is the square root of a negative number.)
Here is some partially implemented code that will need to be completed: 
class SqRoot2 {

  public static void main(String[] args) {
    try {
      double d = getInput(args[0]);
      double root = Math.sqrt(d);
      System.out.println(
        "The square root of " + d + " is " + root);
    } 
    catch (NumberFormatException e) {
      System.out.println("Be sure to enter a number.");
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Enter number as first parameter.");
    }
    catch (ImNumberException e) {
      System.out.println("Result will be imaginary number.");
    } 
  }

  static double getInput(String s) throws ImNumberException {
    double d = new Double(s).doubleValue();

    // Throw an ImNumberException if d is less than 0
    return d;
  }

}
// Define an ImNuberException class
Handle exceptions
As the bold portions of the above listing illustrate, you should define a new class called ImNumberException that is capable of acting like an exception. Then, if the value for what the user has supplied is a negative number, throw an instance of this exception.

Place your code into the text area below once it is working smoothly.