1.9 Sometimes it is useful to measure the length of time it takes for a piece of code to run. (For example, it may help determine where optimizations of your code would be most effective.) Design a Stopwatch class to support tim- ing of events. You should consider use of the nanosecond clock in the Java environment, System. nanoTime (). Like many stopwatches, it should support starting, temporary stopping, and a reset. The design of the protected section of the stopwatch should hide the implementation details.

The implementation of a queue in an array, as given in this chapter, uses the variable count to determine whether the queue is empty or full. You can also use the variable count to return the number of elements in the queue. On the other hand, class linkedQueueType does not use such a variable to keep track of the number of elements in the queue. Redefine the class linkedQueueType by adding the variable count to keep track of the number of elements in the queue. Modify the definitions of the functions addQueue and deleteQueue as necessary. Add the function queueCount to return the number of elements in the queue. Also, write a program to test various operations of the class you defined.

a. Write a FractionDemo program that instantiates several Fraction objects and demonstrates that their methods work correctly. Create a Fraction class with fields that hold a whole number, a numerator, and a denominator. In addition: Create properties for each field. The set access or for the denominator should not allow a 0 value; the value defaults to 1. Add three constructors. One takes three parameters for a whole number, numerator, and denominator. Another accepts two parameters for the numerator and denominator; when this constructor is used, the whole number value is 0. The last constructor is parameterless; it sets the whole number and numerator to 0 and the denominator to 1. (After construction, Fractions do not have to be reduced to proper form. For example, even though 3/9 could be reduced to 1/3, your constructors do not have to perform this task.) Add a Reduce() method that reduces a Fraction if it is in improper form. For example, 2/4 should be reduced to 1/2. Add an operator+() method that adds two Fractions. To add two fractions, first eliminate any whole number part of the value. For example, 2 1/4 becomes 9/4 and 1 3/5 becomes 8/5. Find a common denominator and convert the fractions to it. For example, when adding 9/4 and 8/5, you can convert them to 45/20 and 32/20. Then you can add the numerators, giving 77/20. Finally, call the Reduce() method to reduce the result, restoring any whole number value so the fractional part of the number is less than 1. For example, 77/20 becomes 3 17/20. Include a function that returns a string that contains a Fraction in the usual display format—the whole number, a space, the numerator, a slash (D, and a denominator. When the whole number is 0, just the Fraction part of the value should be displayed (for example, 1/2 instead of 0 1/2). If the numerator is 0, just the whole number should be displayed (for example, 2 instead of 2 0/3). b. Add an operator*() method to the Fraction class created in Exercise 11a so that it correctly multiplies two Fractions. The result should be in proper, reduced format. Demonstrate that the method works correctly in a program named FractionDemo2. c. Write a program named FractionDem03 that includes an array of four Fractions. Prompt the user for values for each. Display every possible combination of addition results and every possible combination of multiplication results for each Fraction pair (that is, each type will have 16 results).

Create an application for Ninas Cookie Emporium named CookieDemo that declares and demonstrates objects of the CookieOrder class and its descendants. The CookieOrder class includes auto-implemented properties for an order number, recipients name, and cookie type (for example, chocolate chip), and fields for number of dozens ordered and price. When the field value for number of dozens ordered is set, the price field is set as $15 per dozen for the first two dozen and $13 per dozen for each dozen over two. Create a child class named Special Cookieorder, which includes a field with a description as to why the order is special (for example, gluten-free). Override the method that sets a CookieOrders price as described in part a, but also to include special handling, which is SIO for orders up to $40 and $8 for higher-priced orders. Create an application named CookieDem02 that demonstrates using several Special CookieOrder objects.