Due: 2024-02-08 23:59:00EDT
In this assignment, you will practice object-oriented design with inheritance.
You will be building on top of your Homework 0 which parsed zipcodes from uszipcodes.csv
.
You will use the csv file as well as your implementation of Place.java
and LookupZip.java
You will also use the ExpandableArray.java
implementation you wrote in Lab2.
Copy all four to your hw1 directory.
In this assignment, we’ll also use a second input file ziplocs.csv
. Download it with this command:
wget https://raw.githubusercontent.com/BMC-CS-151/BMC-CS-151.github.io/main/hws/hw01/ziplocs.csv ziplocs.csv
which gives information about zipcodes and their associated latitudes and longitudes (as decimal numbers), among other things (but not
population). Your task this week is to weave these two files together and organize
the data into classes stored in an ExpandableArray
that allows us to perform similiar
lookups as those in Homework 0.
All programming assignments will go through an autograder on Gradescope. The autograder will test for correctness. We are providing you some public tests that you can use on your own.
In this assignment, your driver program should be called
Driver01.java
.
In addition, please read the program design principles and code formatting standards carefully. You are expected to adhere to all stated standards. Violations will result in deductions.
Requirement: You can ONLY include the following import statements:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
You are NOT ALLOWED to include any other import statements in your solutions. That means you cannot use any built-in java data structures.
The file ziplocs.csv
contains a header line at the top with column names.
The following rows contain 12
comma-separated fields that look like this:
"07677","STANDARD","WOODCLIFF LAKE","NJ","PRIMARY",41.02,-74.05,"NA-US-NJ-WOODCLIFF LAKE","false",2945,5471,325436960
We will only use three of these fields, the zipcode (1st column), the latitude (6th column) and the longitude (7th column). In the sample line notice that 07677 is in quotes, but 41.02 and -74.05 are not.
In your last assignment, you only read the zipcode, town and state fields from
uszipcodes.csv
, but ignored the population information. In this homework, you’ll use the
total population field in uszipcodes.csv
as well. Note that some fields are missing in the csv, and not every row has an entry for the population.
By using the data between uszipcodes.csv
and ziplocs.csv
, we
can categorize all zipcodes into one of three categories:
PopulatedPlace
- zipcodes with a population and location,LocatedPlace
- zipcodes with a location only,Place
- zip codes without either.These types naturally form an inheritance hierarchy. Think about what the hierarchy should be before you click the answer. Hint: The top-most parent (superclass) should be the most abstract.
Write a new class LocatedPlace
that is a subclass of Place
.
Remember that a subclass inherits all the public
or protected
fields and methods in the superclass (except the constructor).
Include a constructor and any necessary instance variables and getters.
The LocatedPlace
class must have an overridden toString
method that
includes the location information in the string returned. For example, a
LocatedPlace
representing Bryn Mawr would return the string
Bryn Mawr, PA 40.02 -75.31
Write a new class PopulatedPlace
that is a subclass of LocatedPlace
.
Include a constructor and any necessary instance variables and getters.
The PopulatedPlace
class must also override the toString
method to include the place’s population in the string. A PopulatedPlace
representing
Bryn Mawr should return the string
Bryn Mawr, PA 40.02 -75.31 21103
Modify the readZipCodes
method from LookupZip
to read both data files,
constructing an ExpandableArray
of Places
and returns it.
The method will be modified to take two arguments:
/**
* @param filename The name of the uszipcodes file
* @param filename2 The name of the second csv file with location info
* @return An ExpandableArray of Places
*/
Assume that we don’t know how many entries are in the csv files.
If a place’s population is known, it should be represented by a PopulatedPlace
object.
Otherwise, if a place’s location is known, it should be represented by a LocatedPlace
object.
otherwise it will be represented by a Place
object.
Note that the return value is an ExapndableArray
of Place
s.
Since both LocatedPlace
s and PopulatedPlace
s are Place
s, all types can be in the return value;
This new version returns an ExpandableArray
, not an array.
This will cause compiler type errors with your old code that used arrays.
You need to adapt your old parseLine
or lookupZip
accordingly.
Requirement: One restriction is that
readZipCodes
should read each file only once: that is, you should create a newScanner
for each file only once, not repeatedly. You should also not reset theseScanners
. You should read in one file first, create objects to accumulate the partial data in that file, and then read the other file, combining the entries appropriately. Note that the zipcodes in the files are not in the same order.
You can copy the driver from your last homework assignment
into a new file called Driver01.java
Update the main
method to work with your new methods. It will now take as command line input two Strings: one for each filename.
I would recommend compiling all your java files with:
javac *.java
at this point. In general, compiling as you code, rather than once at the end is a good debugging strategy.
Many of the compiler errors will be regarding type mismatches since we are now using ExpandableArray<Place>
instead of Place[]
.
Once you’ve fixed the compiler errors, you can run the code with:
java Driver01 uszipcodes.csv ziplocs.csv
You’ll see the same output you had in the previous homework.
At this point, you’ve created version of HW0 which does not assume anything about the length of the input csv files.
This is because we are using the ExpandableArray
data structure instead of a fixed length array.
Now, your task will be to modify the functionality to practice inheritance.
Recall that the appropriate toString()
will be used when you print your three different
objects of the Place
type hierachy.
Here’s a sample session of running your driver:
zipcode: 19010
Bryn Mawr, PA 40.02 -75.31 21103
zipcode: 99400
No such zipcode
zipcode: 91729
Rancho Cucamonga, CA 34.09 -117.56
zipcode: 97252
Portland, OR
zipcode: 00000
Good Bye!
As you start implementing the functionality, you should think about these design questions and come up with answers for them:
Currently, your parseLine
function in LookupZip.java
returns a Place
.
Consider the following:
PopulatedPlace
, a LocatedPlace
, or
just a Place
?uszipcodes.csv
is not filled out for some lines.
How do you detect that it is missing? Hint: research split
and learn about
the overloaded version with a second parameter limit.uszipcodes.csv
,
what object do you construct? And if the field is not empty, what object do you construct?Currently, your readZipCodes
only scans a single file. You must create two Scanners
(one for each file).
Read in one entire file first, then read in the second. Consider the following:
Place
s (or the appropriate subclass).ziplocs.csv
has double quotes around it. You should
remove the quotes (after reading in - don’t modify the input file!) or you will
not be able to match them with the zipcodes found in uszipcodes.csv
. I
recommend using replace
from the Java String
library (use the Java API
reference to find out how).In a text file called README.txt
answer the following questions:
Before submitting to the autograder, make sure you conform to the following format:
LocatedPlace
constructor should take the following types: (String, String, String, double, double)PopulatedPlace
constructor should take the following types: String zip, String town, String state, double latitude, double longitude, int population)Submit the following files to the assignment called HW01
on Gradescope:
Driver01.java
Place.java
LocatedPlace.java
PopulatedPlace.java
LookupZip.java
ExpandableArray.java
README.txt
Make sure to name these files exactly what we specify here. Otherwise,
our autograders might not work and we might have to take points off.
DO NOT submit a .docx or .pdf file.
DO NOT submit any .class
files or any of the csv
files.
You will likely want to submit the files from your own laptop/computer.
To copy the files from goldengate
to your own machine,
open up a terminal on your own computer. If you have a mac or linux, you can use the
Terminal application, if you have a windows you can use the Powershell app.
Run the following command:
$ scp <username>@goldengate.cs.brynmawr.edu/home/<username>/cs151/homeworks/hw00/*
Make sure to replace <username>
with your username. scp
is a command to secure-copy files
from one server to another. In this case, from goldengate
to your own machine.