CPE 102

Winter 2008

Lab 6

Objectives

• To gain experience developing several Comparator classes to use for sorting.
• To gain experience using Java Standard Library sort methods.

Resources

• The Java Standard Library

Ground Rules

• None

Orientation

You will be developing a class that represents a list of random Integer class objects.  The class will support sorting using the appropriate Java Standard Library sort methods found in the Arrays or Collections classes. The class will support natural ordering by using the compareTo method supported by the Integer class and other ordering by implementing three different classes that implement the Comparator interface.  The class will also have a method to determine whether or not the list is sorted in a particular order and will implement the toString method so the contents of the list can be examined easily.

Remember to implement all functionality in a test-driven development fashion; write a test case for each individual piece of functionality, followed by the implementation.

Specification

1. Implement a class called IntegerList that supports a specified number of randomly initialized Integer objects as follows:

1. The class should have the minimally necessary instance variable(s) to support the specified functionality.

2. Implement a single constructor that accepts an int-parameter specifying the number of Integer objects the list should contain and a long-parameter specifying the seed to use when generating random numbers to populate the list with.  The constructed object should contain the specified number of Integer objects that have been initialized with random integer values.

3. Implement a method called sort with no parameters and a return type of void.  The method will sort the list of Integer objects using the appropriate method from the Arrays or Collections class.

4. Implement a method called sort with one parameter of type Comparator<Integer> and a return type of void.  The method will sort the list of Integer objects using the appropriate method from the Arrays or Collections class.

5. Implement a method called isSorted with a single parameter of type Comparator<Integer> and a return type of boolean.  The method will check to see if the list is in the order specified by the provided Comparator.  If the Comparator parameter is null the method will check to see if the list is in the natural order specified by the compareTo method of the Integer class.  The method returns true if the list is in the specified order, otherwise false.

6. Override the toString method inherited from Object so that it returns a String containing each integer value on its own line.  If the list is empty the method should return an empty String.

2. Implement a class called Descending that implements the Comparator<Integer> interface so that it results in Integers being ordered in descending order.

3. Implement a class called OddEvenAscending that implement the Comparator<Integer> interface so that it results in Integers being ordered so that all odds come before all evens and within odds or evens the values are ascending.

4. Implement a class called OddEvenDescending that implement the Comparator<Integer> interface so that it results in Integers being ordered so that all odds come before all evens and within odds or evens the values are descending.

5. Implement JUnit tests that demonstrates that your implementation of the four classes above are complete and correct.