Lab Assignment #9 Activities Solution

1. Answer the questions in the spaces provided or attach a sheet with your answers (be sure to label questions for proper credit) (2 points each, unless noted otherwise):
Question
Answer
a. The private accessor type is used for an abstract class constructor method.
True or False (circle one)
b. An abstract class must have at least one abstract method.
True or False (circle one)
c. An abstract class can be inherited from a concrete class.
True or False (circle one)
d. Abstract classes can be used to create object reference variables.
True or False (circle one)
e. Instance variables of a concrete subclass can be assigned to reference variables of the abstract superclass type.
True or False (circle one)
f. Interfaces can have instance data fields.
True or False (circle one)
g. A class can implement more than one interface.
True or False (circle one)
CIS 2571: Introduction to Java
Lab Assignment
College of DuPage 2 CREngland
h. When a class implements an interface, it must implement all the methods defined in the interface with the exact signature and return type.
True or False (circle one)
i. The private accessor type is used for an interface constructor method.
True or False (circle one)
j. What is the method header of the abstract method to be overridden when the Comparable interface is implemented? (4 points)
k. What is the method header of the abstract method to be overridden when the Cloneable interface is implemented? (4 points)
l. Interfaces can extend other interfaces.
True or False (circle one)
m. Wrapper classes are immutable.
True or False (circle one)
2. You will modify a version of the Account class from previous labs to incorporate interfaces and use a generic sorting algorithm. The Account.java file will be given to you to modify. The modified class should be called AccountWithInterface.
a) The AccountWithInterface class should implement the following interfaces: (20 points)
• Cloneable  deep copy should be done for the dateCreated field.
• Comparable  balance field should be used for comparison.
b) Create a TestAccountWithInterface class with a main method that accomplishes the following program requirements: (14 points)
o Create an object called accountTemplate of the AccountWithInterface class type. Use your own data for the annualInterestRate, id, and name fields. Create an array of three (3) AccountWithInterface objects called accountArray that have been cloned from the accountTemplate object.
CIS 2571: Introduction to Java
Lab Assignment
College of DuPage 3 CREngland
o Set the balances for the accountArray elements as follows:
accountArray[0]  85900.32
accountArray[1]  3250.99
accountArray[2]  6200.56
o Use a loop to print out all the elements of the array using the class toString() method.
o Sort the accountArray using any sort method that takes advantage of the implemented compareTo() method of the AccountWithInterface class.
o Use a loop to print out all the elements of the sorted array using the class toString() method.
c) Add a block comment at the top of each file to identify your name, file, date, class, assignment, and short description of the included class. Use proper code alignment for full credit. (2 points total, 1 point each)
d) Compile the source code until no errors are found.
• Common Errors: http://www.cs.armstrong.edu/liang/intro9e/debug.html
e) Run the Java bytecode and observe the results.
f) Attach a hardcopy printout of your source code files.
g) Attach a hardcopy printout of your sample output. (2 points)
h) Create a .zip file containing only your .java source code files. Upload a copy of this .zip file to the appropriate assignment in Blackboard (this will be demonstrated during class, if necessary). (2 points)
• See the following link for a video on submitting assignment in Blackboard:
http://ondemand.blackboard.com/r91/movies/bb91_student_submit_assignment.htm
• See the following link for a video on creating .zip files in Windows XP:
http://www.youtube.com/watch?v=3xqF56OZo_k
• See the following link for instructions on creating .zip files: