CPSC-115 Lab 10 Fall 2008

CPSC-115 Fall 2008
Lab 10
November 4/5, 2008
Professor Heidi Ellis

Be sure that you hand in the printouts of your work before leaving!!!

Objectives:

To understand arrays.

In this lab, you will create a class that represents the Quicklist feature on YouTube. The Quicklist feature allows users to create a list of videos for later viewing. Videos may be added to the list and removed from the list and the list may be searched based on the tag of a video.

Prelab: Write a flowchart algorithm for the removeVideo algorithm. What do you need to do to remove a video from the list? Assume that you have the following videos entered in the array (the lower row simply represents the indices into the array):

123 Sam Spade 4509 10987 4.5 mystery	456 Cam Comedy 5609 9876 3.4 comedy	789 Doni Dancing 7323 9899 1.2 dance	987 Bobby Bin 9989 10900 3.2 comedy
0	1	2	3	4	5

Removing the video with id 456 should result in the following array configuration:

123 Sam Spade 4509 10987 4.5 mystery	789 Doni Dancing 7323 9899 1.2 dance	987 Bobby Bin 9989 10900 3.2 comedy
0	1	2	3	4	5

Your algorithm will not be long, but should provide sufficient detail so that you can write code from the algorithm. Hand the pre-lab into the instructor at the beginning of class.

Pair Programming:

Locate your partner and introduce yourself:

Tuesday Lab		Wednesday Lab
Kristen Anderson	Jake Elder	Corazon Irizarry	Catherine Doyle
Nick Dragu	Jeff Young	Chelsea Bainbridge-Donner	Jesse Vazquez
		Greg Vaughan	Ryan Ersland
		Jin Feng Liu	John Wilsterman

Select one person to start as "driver". This person will type at the keyboard for the first 20 mintues.
Proceed through the process of completing the lab as described below. Be very careful to ensure that every item for both programs is completed.
Swap pairs every 20 minutes.
When you are done, be sure to email a copy of the code to the person whose account you are not working in. In other words, make sure that both partners have a copy of the code.

The QuickList Functionality

In this lab, you are to create an application that supports the management of a list of videos similar to a Quicklist on Youtube. The UML diagram of the classes is shown below:

I have provided you with the Video.java class which represents a video such as those posted on Youtube. You are to implement the QuickList class. In order to aid in implementation, I have provided descriptions of each of the methods below:

QuickList(): The default constructor allocates space for the list of songs using the MAX_VIDEOS constant as the size of the array.
QuickList(int num): This constructor allocates space for the list of songs using the num parameter as the size of the array.
getSize(): Returns the number of videos that are in the list.
readInVideos(String fileName): This method is passed the name of a file that contains information on a series of videos. The readInSongs method checks to ensure that the file exists, and then reads in the information, creates an instance of a video for each set of information and adds the video to the array.
addVideo(Video video): This method is passed a video to be added to the list (array) of videos. The method checks to see if there is room in the array. If there isn't, an error message is displayed. If there is room, the video is added to the end of the array.
removeVideo(String id): The removeVideo method removes a video with a specific id. The method is passed the ID of the video to be removed. The method calls the search method to retrieve the location of the video to be removed. If the video is found, the video is removed and the remainder of the videos are shifted so that there is no empty space in the array.
retrieveVideos(String tag): The retrieveVideos method is passed a string that represents the tag of a video that a user is searching for. The method then returns an array of all videos that are tagged with the provided tag.
search(String id): The search method is passed a string that represents the id of a video. The method returns the location (index) in the array where the video with the provided id is found. If the id is not found, the method returns -1.
toString is inherited from the Object. You must override the method to construct a string that contains the information for all videos contained in the QuickList. If the QuickList object contains no videos, the toString method should return a string indicating that the list is empty.

You should also create a QuickListDriver class to test your QuickList class. The main method should do the following:

Create an instance of a QuickList (I created one of size four).
Prompt the user for a file name and read in a series of songs from file into the QuickList object.
Print out the contents of the QuickList.
Create a Video object and add it to the QuickList object.
Print out the contents of the QuickList.
Create another Video object and attempt to add it to the list (beyond the maximum size of the list).
Search for a video that has an ID that you know is contained in the QuickList
Remove a video with an ID that you know is contained in the QuickList object.
Print out the contents of the QuickList.
Attempt to remove a video with an ID that you know does not exist in the QuickList object.
Retrieve a list of videos with a tag that you know exists.
Print that list of videos. You will have to write a loop within your main method to accomplish this.

A sample execution of the main method might appear as below. The output below uses the videos.txt file that contains information for three videos.

Enter name of file that contains the video information: videos.txt

*** Original QuickList:
ID: 123 Author: Sam Spade Length: 75:9 Size: 10.747 MB Rating: 4.5 Tag: mystery
ID: 456 Author: Cam Comedy Length: 93:29 Size: 9.660 MB Rating: 3.4 Tag: comedy
ID: 789 Author: Doni Dancing Length: 122:3 Size: 9.683 MB Rating: 1.2 Tag: dance

*** QuickList after adding a video (888):
ID: 123 Author: Sam Spade Length: 75:9 Size: 10.747 MB Rating: 4.5 Tag: mystery
ID: 456 Author: Cam Comedy Length: 93:29 Size: 9.660 MB Rating: 3.4 Tag: comedy
ID: 789 Author: Doni Dancing Length: 122:3 Size: 9.683 MB Rating: 1.2 Tag: dance
ID: 888 Author: Sally Song Length: 72:23 Size: 96.1019 MB Rating: 3.0 Tag: dance

*** Adding a video that exceeds the size of the list.
Sorry, the list is full with 4 videos. You cannot add another video.

*** Searching for a video. Video 456 found at location: 1

*** Removing video 456.

*** QuickList after removing video with id 456:
ID: 123 Author: Sam Spade Length: 75:9 Size: 10.747 MB Rating: 4.5 Tag: mystery
ID: 789 Author: Doni Dancing Length: 122:3 Size: 9.683 MB Rating: 1.2 Tag: dance
ID: 888 Author: Sally Song Length: 72:23 Size: 96.1019 MB Rating: 3.0 Tag: dance

*** Removing a video that does not exist.
Video was not found.

*** Searching for dance videos.
*** Videos found: 
ID: 789 Author: Doni Dancing Length: 122:3 Size: 9.683 MB Rating: 1.2 Tag: dance
ID: 888 Author: Sally Song Length: 72:23 Size: 96.1019 MB Rating: 3.0 Tag: dance

Note that only the lines that begin with three asterisks are produced by the main method. The rest of the output is produced by methods in the QuickList or Video classes. Test your code carefully to make sure that it operates correctly under a variety of test cases. Your code should have good programming style and follow all Java conventions. Don't forget to use constants where appropriate.

You're done!! Don't forget to log out and hand in your printouts to the professor before you leave!!

CPSC-115 Fall 2008 Lab 10 November 4/5, 2008 Professor Heidi Ellis

Objectives:

The QuickList Functionality

CPSC-115 Fall 2008
Lab 10
November 4/5, 2008
Professor Heidi Ellis