ASSIGNMENT 8 file input/output and strings

COMPUTER SCIENCE 11A 
PROGRAMMING IN JAVA
PROGRAMMING ASSIGNMENT 8
Overview
This assignment focuses on file input/output and strings.
"Mad Libs" are short stories that have blanks called placeholders to be filled in. In the noncomputerized version of this game, one person asks a second person to fill in each of the
placeholders without the second person knowing the overall story. Once all placeholders are filled
in, the second person is shown the resulting story, often with humorous results.
In this assignment, you present a menu to the user with three options: create a new mad lib, view a
previously created mad lib, or quit. These are shown as C, V, and Q, case-insensitively. If any
other command is typed, the user is re-prompted.
When creating a new mad lib, the program prompts the user for input and output file names. Then
the program reads the input file, prompting the user to fill in any placeholders that are found without
showing the user the rest of the story. As the user fills in each placeholder, the program is writing
the resulting text to the output file. The user can later view the mad lib that was created or quit the
program. The log below shows one sample execution of the program.
Notice that if an input file is not found, either for creating a mad lib or viewing an existing one, the
user is re-prompted. No re-prompting occurs for the output file. If it does not already exist, it is
created. If it already exists, overwrite its contents. (These are the default behaviors in Java.) You
may assume that the output file is not the same file as the input file.
Welcome to the game of Mad Libs.
I will ask you to provide various words
and phrases to fill in a story.
The result will be written to an output file.
(C)reate mad-lib, (V)iew mad-lib, (Q)uit? c Input file name: oops.txt
File not found. Try again: mabldib1.txt
File not found. Try again: madlib1.txt
Output file name: out1.txt
Please type an adjective: silly
Please type a plural noun: apples
Please type a noun: frisbee
Please type an adjective: hungry
Please type a place: Tacoma, WA
Please type a plural noun: bees
Please type a noun: umbrella
Please type a funny noise: burp
Please type an adjective: shiny
Please type a noun: jelly donut
Please type an adjective: beautiful
Please type a plural noun: spoons
Please type a person's name: Keanu Reeves
Your mad-lib has been created!
(C)reate mad-lib, (V)iew mad-lib, (Q)uit? X
(C)reate mad-lib, (V)iew mad-lib, (Q)uit? I don't understand.
(C)reate mad-lib, (V)iew mad-lib, (Q)uit? V
Input file name: OUT001.txt
File not found. Try again: i forget the file name
File not found. Try again: something.DOC
File not found. Try again: out1.txt
One of the most silly characters in fiction is named
"Tarzan of the apples ." Tarzan was raised by a/an
frisbee and lives in the hungry jungle in the
heart of darkest Tacoma, WA . He spends most of his time
eating bees and swinging from tree to umbrella . Whenever he gets angry, he beats on his chest and says,
" burp !" This is his war cry. Tarzan always dresses in
shiny shorts made from the skin of a/an jelly donut
and his best friend is a/an beautiful chimpanzee named
Cheetah. He is supposed to be able to speak to elephants and
spoons . In the movies, Tarzan is played by Keanu Reeves .
(C)reate mad-lib, (V)iew mad-lib, (Q)uit? Q
Input'Data'Files:
You will need to download the example input files and save them to the same folder as your
program. Mad lib input files are mostly just plain text, but they may also contain placeholders.
Placeholders are represented as input tokens that begin with < and end with >. For example, the
file madlib1.txt used in the previous log contains:
One of the most <adjective> characters in fiction is named
"Tarzan of the <plural-noun> ." Tarzan was raised by a/an
<noun> and lives in the <adjective> jungle in the
heart of darkest <place> . He spends most of his time
eating <plural-noun> and swinging from tree to <noun> .
Whenever he gets angry, he beats on his chest and says,
" <funny-noise> !" This is his war cry. Tarzan always dresses in
<adjective> shorts made from the skin of a/an <noun>
and his best friend is a/an <adjective> chimpanzee named
Cheetah. He is supposed to be able to speak to elephants and
<plural-noun> . In the movies, Tarzan is played by <person's-name> .
Your program should break the input into lines and into tokens using a Scanner so that you can
look for all its placeholders. Normal non-placeholder word tokens can be written directly to the
output file as-is, but placeholder tokens cause the user to be prompted. The user's response to the
Console
Interaction
Input'File
madlib1.txt
prompt is written to the output file, rather than the placeholder itself. You should accept whatever
response the user gives, even a multi-word answer or a blank answer.
You may assume that each word/token from the input file is separated by neighboring words by a
single space. In other words, when you are writing the output, you may place a single space after
each token to separate them. You do not need to worry about blank spaces at the end of lines of the
output file. It's okay to place a space after each line's last token.
Sometimes a placeholder has multiple words in it, separated by a hyphen ( - ), such as <propernoun>. As your program discovers a placeholder, it should convert any such hyphens into spaces.
Any hyphens that appear outside of a placeholder, such as in the other text of the story, should be
retained and not converted into spaces.
When prompting the user to fill in a placeholder, give a different prompt depending on whether the
placeholder begins with a vowel (a, e, i, o, or u, case-insensitively). If so, prompt for a response
using "an". If not, use "a". For example:
Placeholder Resulting Prompt
<noun> Please type a noun:
<adjective> Please type an adjective:
<plural-noun> Please type a plural noun:
<Emotional-Actor's-NAME> Please type an Emotional Actor's NAME:
Do not make unnecessary assumptions about the input. For example, an input file could have <
and > characters in it that are not part of placeholders, and these should be retained and included in
the output. You may assume that a placeholder token will contain at least one character between
its < and > (in other words, no file will contain the token < >). You may assume that a placeholder
will appear entirely on a single line; no placeholder will ever span across multiple lines.
Your output mad lib story must retain the original placement of the line breaks from the input story.
When you are viewing an existing mad lib story, you are simply reading and echoing its contents
to the console. You do not need to do any kind of testing to make sure that the story came from a
mad lib input file; just output the file's contents.
Your program's menu should work properly regardless of the order or number of times its
commands are chosen. For example, the user should be able to run each command (such as C or
V) many times if so desired. The user should also be able to run the program again later and choose
the V option without first choosing the C option on that run. The user should be able to run the
program and immediately quit with the Q option if so desired. And so on.
Implementation'and'Development'Strategy:
Read/write files using Scanners and PrintStreams, passing File parameters. Remember to
import java.io.*; Read all console user input using the Scanner's nextLine method
(not next, which permits only one-word answers). When reading files, you may need a mixture
of line-based and token-based processing.
To re-prompt for input file names, you need to know whether a file with a given name exists. You
can do this by using methods from File objects as shown in class.
You will need to use several String methods to search for and replace characters. In particular
you may use the replace method to replace occurrences of one character with another. For
example:
String str = "mississippi";
str = str.replace("s", "*"); // str = "mi**i**ippi"
Incorrect file input often leads to exceptions. If you get an InputMismatchException, you
are trying to read the wrong type of value from a Scanner. If you get a
NoSuchElementException, you are trying to read past the end of a file or line. If you get an
exception, look at the exception's text to find the relevant line number in your file. For example:
Exception in thread "main" java.util.NoSuchElementException: No line found
 at java.util.Scanner.nextLine(Scanner.java:1516)
 at MadLibs.myMethodName(MadLibs.java:73)
 at MadLibs.main(MadLibs.java:20)
After finding the line number, use println statements to see the values of each variable as it is
read. A common bug is calling next, nextLine, etc. on the wrong Scanner, so examine those
calls carefully.
Style'Guidelines:
Structure your solution using static methods that accept parameters and return values as
appropriate. It is okay to have methods that return objects, such as a File or Scanner or
PrintStream. Objects (such as a File or Scanner or PrintStream) can also be passed
as parameters.
For full credit, you must have at least 4 non-trivial methods other than main in your program. It
is okay for some println statements and code to be in main, as long as you use good structure
and main is a concise summary. It is also okay for the main UI menu loop to be in main, as long
as the code inside that loop is short and elegant.
For this assignment, you are limited to the language features in Chapters 1 through 6 of the
textbook. In particular, you are not allowed to use arrays on this assignment.
Grading:'
You will be graded on
o External Correctness: The output of your program should match exactly what is expected.
Programs that do not compile will not receive points for external correctness.
o Internal Correctness: Your source code should follow the stylistic guidelines shown in
class. Also, remember to include the comment header at the beginning of your program.
Submission:
Create a folder named PA8 containing all your files. Zip the folder, named
PA8_USERNAME.zip (where USERNAME is your Brandeis username – your email
address without the @brandeis.edu), and submit it via Latte the day it is due, Friday, Dec
9 at 11:00pm.
NOTE: Make sure that your submission is in the correct format, and that all your files work
as you intend them to before submitting. Additionally, make sure you are submitting the .java
files, not the .class files. Any submissions not in a zip file will receive a zero, and any
assignments that don’t compile or that don’t have .java files will receive a zero. There will be
no exceptions to this rule.