CIS 211 Blog

CIS 211 Assignment#6: part two

lpfuller86 — Sun, 16 May 2010 21:40:33 +0000

To incorporate the state pattern into your design follow these steps:

1) Carefully consider what you are trying to model and determine the different states that an object would have in your model.

2) Now consider how these states would interact with each other

3) Decide how you want the state transitions to function. If you want states to be able to change the state of their parent. If you want the states to be publicly setable. If you want the states to have the ability to change themselves.

4) Now the class that defines your object will contain a variable of type State where State is an abstract class and each state that appears in your model is a class that extends State. All of the methods in the class that defines your object should delegate their function to the instance of the State that is in the class. Unless the function does not depend on the state of the object. Essentially, all of the intelligentence will be concentrated in the different states. All that remains is to do the coding or implementation

CIS 211 Assignment#6: Part One

lpfuller86 — Sun, 16 May 2010 21:25:34 +0000

My design was to modify the code that I had so that each type of animal became a state that had a moveBehavior, chaseBehavior,eatBehavior, and escapeBehavior. I had some trouble integrating the state pattern with the observer pattern, but I was eventually able to work that problem out. However, I eventually want to make it so that the type of movement an animal makes is actually a state so that there would be a chase state, flee state, and travel state, as well as possibly a chase,capture, and eat state for predators. I am still working on the design for this though.

CIS 211: Assignment#5_Part3

lpfuller86 — Sun, 09 May 2010 17:30:40 +0000

Creating a singly linked list class and using an iterators was fairly straight forward. When I used iterators in my project the code was cleaner and I didn’t have as much code that was duplicated as before. After using iterators I think that it is useful to seperate the data structure from the actual iteration and creates cleaner and more efficent code.

CIS 211: Answer to Assignment#4_part2

lpfuller86 — Sun, 25 Apr 2010 12:47:30 +0000

To Use the Decorator Pattern Follow these steps:

1. Determine what class you want to attach additional responsabilities to.

2. Determine now create an abstract class that extends the class you want to attach additional responsabilities to. Include any methods that you want every additional behavior type or attribute type to include in this class.

3. Determine the different types of the attribute or behavior you are adding to the class that will have added responsabilities. Create a class for each type that extends the abstract class you made in step 2 and has an instance variable of type (class you are adding responsabilities to).

CIS 211: Answer to Assignment#4_part1

lpfuller86 — Sun, 25 Apr 2010 12:32:16 +0000

I wanted to use the decorator pattern to create different sizes of different features in my simulation of the coral reef. At the moment I have two different features in the coral reef that are locations they are rock features and underwater caves. I wanted to be able to have small rock features and underwater caves, medium sized rock features and underwater caves, and large rock features and underwater caves. In order to do this I used the decorator pattern by creating an abstract class that extends the abstract class location and having the three classes Small, Medium, and Large contain their own versions of the draw method which scales the size of the image I used for either a rock feature or a underwater cave. I had some problems related to having the PImage that is in either of the three classes be the same as the location that was passed in. To solve this problem I created a field in the abstract class location with the modifier protected and added a getter method and then I was able to acess the PImage from the class location in the classes Small,Large, and Medium.

CIS 211: Guide to driver for part three of Assignment#3

lpfuller86 — Sun, 18 Apr 2010 07:08:43 +0000

3. The driver creates several locations in the setup method and instances of three types of animates whale sharks, manta rays, and tiger sharks. In the setup method a whale shark adds itself as an observer and sets its hunger level to above 100 and notifies itself of the change in its hunger state. When the hunger level reaches 100 the whale calls the method dive which does not yet have graphics attached to it. It uses a simple print statement. The tiger shark adds the manta ray as an observer, and the manta ray adds the tiger shark as an observer. Every time the tiger shark moves the manta ray is notified and increases its speed. Every time the manta ray moves the tiger shark is notified and it implements its chase behavior which does not yet have graphics yet. It uses a simple print statement. The Driver is the java file Driver.java .

CIS 211: Answer to Question#2 for Assignment#3

lpfuller86 — Sun, 18 Apr 2010 06:54:55 +0000

2. To adopt the observer pattern follow these steps

First determine in your program what is the observer adn what is the observable. For example, in my project in one application of the observer pattern the Tiger Shark is the observer of the manta ray.
Second determine what information from the observed the observer wants to be notified of.
Third the class that is the observed must extend the java class Observable(Note this class is in the Java API). Ant the class must have the import statements: import java.util.Observer and import java.util.Observable
Fourth a method needs to be defined that calls the setChanged() method in the class Observable and calls the notifyObserver() method in the class Observable. You now need to decide whether to use the push or pull strategy. If you want to use the push strategy the notifyObserver() will take a data object as an argument. If you want to use the pull strategy the method will not take any arguments.
Fifth you need to call the method defined in step four where the information you want sent to the observer might change. This may be done in a setter method or in another method.
Sixth the class that is the observer must implement the interface Observer (Note this interface is in the Java API). And the class must have the import statements: import java.util.Observer and import java.util.Observable
Seventh the observer must create an instance variable of type observable and the constructor must pass a reference to an observable object. The constructor must set the instance variable of type observable to the reference to an observable object passed in and add this object as an Observer.
Eighth the observer must implement the method update from the Observer interface. The method update should check to see if an instance of the Class Observable is of the type of the observed class. Then if the object is an instance of the observed class it should be cast to the observed class.Any information about the state of the observed object should be pulled from that object.
Ninth determine how the observer should react to any updates from the subject. Implement the reaction in the update method after the needed information concerning the state of the subject is retrieved.

CIS 211: Assignment#3 part 1

lpfuller86 — Sun, 18 Apr 2010 06:16:52 +0000

I used the observer pattern to simulate a predator watching its prey in this case a shark watching a manta ray. In order to do this I had to solve the problem that the tiger shark class already extended class fish and so did class manta ray. I solved this problem by having Animate extend Observable and implement Observer. I also used the observer pattern to have the whale shark observe what its own hunger level and at a certain level dive further down to feed. To do this I had to have the whale shark be both the observer and the observed. I had the whale shark class implement the Observer interface and created an instance of the Observable class so that the whale shark class could add and remove observers.

CIS 211: Answer to Question#9 from Assignment#2

lpfuller86 — Sun, 11 Apr 2010 05:38:51 +0000

9. I have decided to focus on four core types of animals which will be animated in my project for now they are Sharks, Fish, Birds, and Dolphins. I have two main locations for my project the coral reef and surface of the ocean. The coral reef has the sublocations of underwater caves and rock features. I may add more locations later in the term. I am using the strategy pattern for the behaviors eat and chase at the moment. I have defined three different possible implementations of the chase behavior and three different possible implementations of the eating behavior. The three kinds of chases are circle chase, does not chase, and fast chase. The three kinds of eating are swallows whole prey, does not eat prey, and eats prey in bites. The design principle is to seperate the hunting behaviors of predators from the actual base classes of the different types of animals. I am struggling with the animation of the animals. I think that I may need to actually refactor what I turned this week and rethink the design of the current incarnation of my project.

CIS 211: Answer to Question#4 from Assignment#2

lpfuller86 — Sun, 11 Apr 2010 05:24:02 +0000

4. Oliver is a cat that is referenced on page vi of the book or the page where all the copyright information for the book is given. He appears on the page after the word Observer which is in bold.