Homework 08 - Yelp

Homework 08 - Yelp
Oh no! You want to get lunch but there are so many restaurants to pick from and so many types of food to
try. After receiving a database of all the foods and restaurants in the area from the Mayor, you decide to
create a program to help you use the databse.
Purpose
The purpose of this assignment is to apply recursion, File I/O, Exceptions and ArrayLists to a working
Java Program. Additionally, you will be able to expand upon your knowledge of command line args to take
in arguments.
Overview
Your task is to implement methods for working with the Yelp “database” (which is given to you as
a set of nested folders). The structure is as follows: the outermost directory (or folder) is called
database_restaurants and contains further folders of types of food (such as fastfood, asian, etc.), then
within that, restaurants associated with that type of food. From there, each restaurant has multiple reviews
that are .txt files.
You task is to create methods for working with the database. One method will recursively traverse the
“database”, find all the restaurants, and return them through an ArrayList of Restaurant objects. Another
method will count the total number of reviews in all the restaurants. The final method will traverse the
folders to find a specific review in a specific restaurant to read and return the rating that the review gave.
Be sure to download database_restaurants.zip from Canvas, place it in the same directory as your code,
and unzip it. This will help you understand the file structure of the “database”.
Restaurant Database File Structure
You are given a directory called database_restaurants containing folders of several different types of
food. Those folders for food-type will contain either more folders of a more specific food-type or folders for
restaurants. Folders for restaurants always have reviews inside as .txt files.
Restaurant directories will be named restaurantName. For example, restaurantMoes, restaurantMcdonalds.
Restaurant directories contain only .txt files with reviews. Reviews are named with a prefix of review and
then a suffix of the reviewers name (such as reviewJohn or reviewSarah).
An example of the folder structure is:
database_restaurants
|____ food_type1
|____ restaurantName1
|____ reviewNeethu
|____ food_type2
|____ moreSpecificFoodType
|___restaurantName2
|____ reviewMaddy
|____ reviewFelipe
Keep in mind there could be several nested types of food, for example you could have a path to a review of:
database_restaurants -> asian -> sushi -> restaurantSatto -> reviewSusan
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Directions
Functionality: You will code the following functionality: * You will recurse through the nested folders
and create an ArrayList of all the Restaurants found in the folder. * You will also implement a method
that counts the total number of reviews in all the restaurants. * Finally, you will create a method to read
a specific review for a Restaurant in the database. * If the restaurant isn’t in the database, throw a
NotARestaurantException. * If the review is not in the database, throw a ReviewNotFoundException.
Class Details
Restaurant.java
Instance Data
• String name - the restaurant name
• int numReviews - the number of reviews in a restaurant
• Don’t add any other fields
Constructor
• 2-param constructor that creates a Restaurant object with the name and numReviews passed in
Methods
• getter for name
• getter for numReviews
NotARestaurantException.java
• unchecked exception that has a no-args constructor that uses the super class’s constructor to have
the message of “That is not a restaurant we know!”
ReviewNotFoundException.java
• checked exception that has a 1-args constructor that takes in a message of and when the exception
is printed, it should have the message you pass in (hint: use the super constructor)
YelpDB.java
This class will hold a number of static methods for working with the database. HINT Helper methods are
generally a key to recursion and can definitely help structure recursive functions (Remember encapsulation
- will any helper methods need to be called from outside the class?)
Methods in YelpDB.java
• Method main (this is your main method)
– Take in the restaurantName and reviewName using the command line argument
∗ To pass arguments to your program via command line, run YelpDB with java YelpDB
restaurantName reviewName instead of just java YelpDB. So for example, java YelpDB
Moes Shishir
∗ Make sure your commands are in that order - restaurantName, then reviewName.
∗ These arguments could be used later in the main method for readReview
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– Create a File object for the database_restaurants directory. The YelpDB class should expect the “database” folder (called database_restaurants) to be in the same directory as itself,
YelpDB.java. This File could be used later in the main method for testing code.
– Be sure to catch a ReviewNotFoundException or a NotARestaurantException from any
methods you may call in the main method and print out the message.
– Use this method as a tester to test your code!
• Static Method load:
– Take in a File object as the parameter
– Call the helper method loadHelper
– Return an ArrayList of Restaurant objects
• Static Method loadHelper:
– Take in a File object and an ArrayList of Restaurant objects as the parameters
– If the File is a directory and not a restaurant directory, recursively call the method on all
nested folders
– However if the directory is a restaurant (remember restaurant directories in the folders are
named restaurantName where the suffix ‘name’ is the name of the specific restaurant)
∗ create a Restaurant object with the restaurant name found and the number of reviews
in that restaurant (look at the File API for methods you could use to get the
number of files in a folder)
∗ add the Restaurant you created to the ArrayList
– Return the ArrayList of Restaurant objects
• Static Method countNumReviews:
– Take in the ArrayList of Restaurants
– Iterate through all the Restuarants in the ArrayList and find the cumulative sum of the number
of reviews in all the Restaurants
– Return the total number of reviews you found
• Static Method readReview:
– Takes in a File object to search inside, an ArrayList of Restaurants representing the
Restaurants in the database, a String restaurantName we are searching for, and a String
reviewName find which review from that restaurantName we want to read. Assume all inputs
are the correct - no validation needed
∗ the restaurantName parameter will not start with “restaurant”; i.e. restaurantName would
be “Mcdonalds”, not “restaurantMcdonalds”.
∗ the reviewName parameter will just be the name of the person who wrote the review; i.e. reviewName would be “John” not “reviewJohn”
∗ if that Restaurant is not in the database, throw a NotARestaurantException with the
message “That is not a restaurant we know!”. (Hint: How can you check if the Restaurant
is in the database using an ArrayList method?)
– If the Restaurant is in the database, find the Restaurant recursively
– Read the appropriate review based on the reviewName using a Scanner
∗ If the reviewName isn’t in the Restaurant, be sure to throw ReviewNotFoundException with
a message of “That is not a review!”
– Catch any FileNotFoundException that could occur
– Return the rating from the review you read!
-> Keep in Mind when reading reviews All reviews are written in the following format and are named
review{name} where ‘{name}” is the name of the reviewer:
Name: John
Date: 02/02/20
Rating: 1.0
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Review of Classes Involved:
• YelpDB.java
– This class holds static methods for accessing the database
– You will create a method to access the database and make an ArrayList of all the Restaurants
found in it
– You will create a method that counts the total number of reviews in an ArrayList of all the
Restaurants
– You will create a method to read a specific review from a specific Restaurant from the database
– You will create the main method, which will be calling the static methods to get the data returned
by them and use them for other methods
• Restaurant.java
– This class stores information about the restaurants you find in the database
– It holds the name of the restaurant and the number of reviews the Restaurant has
• NotARestaurantException.java
– This class is a user created unchecked exception that you will use when checking if a Restaurant
you want to read a review from is actually in the database
• ReviewNotFoundException.java
– This class is a user created checked exception that you will use when checking if a review you
want to read from a Restaurant is actually in the database
Allowed Imports
To prevent trivialization of the assignment, you may only import:
- java.util.Scanner
- java.util.ArrayList
- java.io.File
- java.io.IOException
- java.io.FileNotFoundException
Checkstyle and Javadocs
You must run checkstyle on your submission. The checkstyle cap for this assignment is 20 points. If you
don’t have checkstyle yet, download it from Canvas -> Files/Resources. Place it in the same folder as the
files you want checkstyled. Run checkstyle on your code like so:
$ java -jar checkstyle-8.28.jar yourFileName.java
Starting audit...
Audit done.
The message above means there were no Checkstyle errors. If you had any errors, they would show up above
this message, and the number at the end would be the points we would take off (limited by the checkstyle
cap mentioned above). The Java source files we provide contain no Checkstyle errors. In future homeworks
we will be increasing this cap, so get into the habit of fixing these style errors early!
Additionally, you must javadoc your code.
Run the following to only check your javadocs.
$ java -jar checkstyle-8.28.jar -j yourFileName.java
Run the following to check both javadocs and checkstyle.
$ java -jar checkstyle-8.28.jar -a yourFileName.java
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Feature Restrictions
There are a few features and methods in Java that overly simplify the concepts we are trying to teach or
breaks our auto grader. For that reason, do not use any of the following in your final submission: var (the
reserved keyword) System.exit
Collaboration
Collaboration Statement
To ensure that you acknowledge collaboration and give credit where credit is due, we require that you
place a collaboration statement as a comment at the top of at least one java file that you
submit. That collaboration statement should say either:
I worked on the homework assignment alone, using only course materials.
or
In order to help learn course concepts, I worked on the homework with [give the names of the people you
worked with], discussed homework topics and issues with [provide names of people], and/or consulted related
material that can be found at [cite any other materials not provided as course materials for CS 1331 that
assisted your learning].
Recall that comments are special lines in Java that begin with //.
Turn-In Procedure
Submission
To submit, upload the files listed below to the corresponding assignment on Gradescope:
• YelpDB.java
• Restaurant.java
• ReviewNotFoundException.java
• NotARestaurantException.java
Make sure you see the message stating “HW08 submitted successfully”. From this point, Gradescope will
run a basic autograder on your submission as discussed in the next section.
You can submit as many times as you want before the deadline, so feel free to resubmit as you make
substantial progress on the homework. We will only grade your last submission: be sure to submit every
file each time you resubmit.
Gradescope Autograder
For each submission, you will be able to see the results of a few basic test cases on your code. Each test
typically corresponds to a rubric item, and the score returned represents the performance of your code on
those rubric items only. If you fail a test, you can look at the output to determine what went wrong and
resubmit once you have fixed the issue.
The Gradescope tests serve two main purposes:
1. Prevent upload mistakes (e.g. forgetting checkstyle, non-compiling code)
2. Provide basic formatting and usage validation
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In other words, the test cases on Gradescope are by no means comprehensive. Be sure to thoroughly test
your code by considering edge cases and writing your own test files. You also should avoid using Gradescope
to compile, run, or checkstyle your code; you can do that locally on your machine.
Other portions of your assignment can also be graded by a TA once the submission deadline has passed, so
the output on Gradescope may not necessarily reflect your grade for the assignment.
Important Notes (Don’t Skip)
• You may add extra private variables or methods to facilitate your program, but you may not alter the
arguments in the constructor
• Take a look at the File API if you are stuck
• Check on Piazza for all official clarifications
• Non-compiling files will receive a 0 for all associated rubric items
• Do not submit .class files.
• Test your code in addition to the basic checks on Gradescope
• Submit every file each time you resubmit
• Read the “Allowed Imports” and “Restricted Features” to avoid losing points
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