This assignment has four objectives. You will:

1. Learn about software design reuse by studying a provided framework for problem solving that has abstracted the general features of the bridge crossing program from the previous assignment.
2. Adapt your bridge crossing program to work with the framework.
3. Apply the framework to allow users to solve a new problem, the "Water Jug" problem.
4. Write your own test classes for unit testing of the water jug problem program.

Upon completion, this assignment will have two working programs:

• A revision of the previous program that allows its user to solve the bridge crossing problem in exactly the same was as before
• A new program that allows its user to solve the water jug problem

Applets showing the behavior of these programs follow.

(Note: to restart the applet below, simply reload this page and select Bridge from the menu on the left.)

(Note: to restart the applet below, simply reload this page and select Water Jug from the menu on the left.)

Frameworks consist of generally useful code that can be used with more than one application.

This section briefly describes the motivation behind frameworks, the elements typically contained in frameworks, and how frameworks contribute to code reuse.

Frameworks often arise from the realization that separate program applications have similar structure.

For example, in both the bridge crossing and water jug problems,

• There is a fixed number of problem states.
• There is a fixed number of well-defined possible moves.
• The problem is to transform the current state into a goal

Examining two separate implementations of these problems would reveal repeated code.

A framework manages repeated code so that it can be shared among multiple applications.

The problem solving framework you will use consists of an interface, two abstract classes, and a concrete class.

• The concept of an interface type in Java is not taken up in our text book until chapter 4 (relevant pages: 137—144), but it is like a C++ class with:
  • No state
  • Only pure virtual methods (ones with no implementation)
• An interface is intended to be implemented.
• The concept of an abstract class in Java is not taken up in our text book until chapter 6 (relevant pages: 215—222), but it is like a C++ class that has at least one pure virtual method.
• An abstract class is intended to be extended (subclassed).
• A concrete class is not abstract. All classes in the previous assignment were concrete.

• We will present a general framework of code that is "abstracted" out of your bridge crossing problem solution in such a way that the framework code does not depend on specific classes like BridgeState, BridgeMove, etc.
• The advantage of this is that the framework code can be applied to the water jug problem.
• Since frameworks are meant to be reused, they must never be altered by application programmers.
• Reimplementing the bridge crossing problem does not require new code, since the framework is designed to use code that's already written.
• Adapting code to a more general design in this way is called refactoring the design.

1. Study the provided framework classes to understand their function
2. Refactor your bridge crossing code to work with the framework
3. Develop classes to implement the water jug problem
4. Develop classes to test the water jug implementation classes

The implementation and test classes have been started for you.

The source code for the implementation packages is described in this section.

• The NetBeans project for you to use is here: CS_2511_Framework.zip.
• The project folder is CS_2511_Framework.
• Java documentation for the package APIs can be viewed here (will generate a new tab): Javadoc.

This section describes the tests to be used in unit testing for this assignment.

• The bridge crossing test classes are provided for you.
• They are the same as or essentially the same as those for the first assignment.
• As in the first assignment, test the overall program by running the BridgeConsole class.

• The water jug test classes are started for you but you must complete them.
• Use the corresponding bridge crossing test classes as models.
• Test the overall program by running the WaterJugConsole class.