Homework 10: SimLaundry 2010
Due 1 Friday, 9 April 2009 2010 at 11:00 A.M. (Wednesday before class)
Preface
This assignment has a long description but the coding involved is straightforward. Most of the code for the full application has been written as support code by the course staff. In the our solution written by the course staff, the remaining code remaining for that you to must write (excluding test code) consists of approximately 175 250 lines (including some terse comments and whitespace lines).
...
Acker never discards clothing, no matter how threadbare, but does, on rare occasions, lose some. Not even only does Acker loses lose clothes being worn, but they can be lost from anywhere else, including the closet shelf, the dirty laundry pile, and the laundry room.
...
The course staff is providing a framework for writing this program that includes many classes and interfaces. The framework is packaged as a zipped DrJava project file laundry.zip. This file will unzip into a self-contained file tree with root directory laundry
. This directory contains the source tree for the laundry framework with root directory edu
, a DrJava project profile file laundry.drjava
and two text files sampleIn}
and {{sampleOut
used by the sample laundry test class edu.rice.comp211.laundry.tests.LaundryTest
. Given the text input in sampleIn}
, your program should generate the text in {{sampleOut
. The provided framework compiles but LaundryTest
will fail because most of the members in two the key classes class DoCommandVisitor
and Student
have been stubbed out.
After unzipping the laundry.zip
file, you can open the DrJava laundry project by starting DrJava, setting the Language Level
to Full Java
, pulling down the Project
menu and selecting the Open
command. In the file chooser that pops up, select the project profile file laundry.drjava
embedded in the file in the unzipped file tree for laundry.zip
. You can save the project state at any point during a DrJava session using the Save
command in the Project
menu. You can also save individual files within the project using the Save
button on command file or the File
menu.
The Test Project Test
commands runs all of the JUnit test files in the project.
Your assignment is to fill in the stubbed out members of the DoCommandVisitor
and Student
(members with degenerate bodies (either return;
or return null;
). In the process you may choose to define some new classes to support your Student
DoCommandVisitor
class implementation. The Student
class which repeatedly invokes DoCommandVisitor
models the laundry habits of Acker. In our test simulations, we will typically only create a single instance of Student
representing Acker, but your code should support multiple students (e.g., Acker and his brothers) at a time. Since these students do not interact with each other, supporting this form of multiplicity is a trivial consequence of OO coding style used in the framework.
...
- the name of the student,
- the closet shelf with its piles of clean clothes,
- the dirty laundry pile, and
- the laundry room with its piles of laundered garmets sitting on tables.
- and methods to manipulate those data representations to perform the specified simulation
...
When the simulation begins, Acker is wearing _white_ pants, _white_ socks, and a _white_ shirt. The closet shelf, dirty laundry pile, and laundry facilities are all initially empty. Your program should start execution using the special method {{public static void The program starts execution using the special method public static void main(String
\[
\]
args)
}} in class {{Main
}}. The {{main
}} method interface is the only vehicle for executing Java programs directly from the command line. (_DrJava _ has a {{main
}} method for this reason.)
Form of Event Commands
Your program executes a loop that repeatedly reads input from an input "process" that returns Command
objects. The input process (provided by our supporting framework) reads a series of event description commands, one to a line, either from the console or from a file. The input process converts a stream of characters to Command
objects which are passed to your program.
In addition to performing the specified command, your program should output a brief description of for each command that it performs in the exact format described below. In the following list of commands, the output line specifies what your program should print.
Code Block |
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receive <adjective> <article>
|
means Acker received a gift of the specified article (<adjective> <article>) of clothing. In response, the simulation outputs
Code Block |
---|
received adjective article
|
and updates the state of the StudentEnvironment
. For example,
Code Block |
---|
receive argyle socks
|
generates
Code Block |
---|
received argyle socks
|
and adds the argyle socks
to the top of the socks
pile on the shelf.
Code Block |
---|
lose <adjective> <article>
|
means Acker misplaced the specified article of clothing. If the item exists and Acker is not wearing it, the simulation outputs
Code Block |
---|
lost <adjective> <article>
|
and updates the state of the StudentEnvironment
accordingly. If Acker is wearing it, the simulation outputs
Code Block |
---|
Acker is wearing adjective article
|
...
Your solution will be graded using the textual interface. Graphical interfaces are notoriously difficult to test and all of the graphical interface code is part of our support code anyway. Your correctness and testing scores (which each count 25% of your grade) will be based on how well your implementation of each command complies with the given specifications and on how well you demonstrate this compliance with test cases. You can test your DoCommandVisitor using the same approach given in our LaundryTest.java
class. These tests use the simulate
method in Student
to drive the execution of DoCommandVisitor
. If you write some utility methods fopr BiLists
you should separately test these methods. You are NOT responsible for testing any of our support code in laundry.zip
including the BiList
class.
A major portion of your grade (35%) will be based on your program style. If you write your code in the OO style practiced in this course, you should do very well on this aspect of the assignment. The remaining 15% of your grade is based on your documentation, particularly your javadoc
comments for classes and methods.
Form of Event Commands
Your program executes a loop that repeatedly reads input from an input "process" that returns Command
objects. The input process (provided by our supporting framework) reads a series of event description commands, one to a line, either from the console or from a file. The input process converts a stream of characters to Command
objects which are passed to your program.
In addition to performing the specified command, your program should output a brief description of for each command that it performs in the exact format described below. In the following list of commands, the output line specifies what your program should print.
- The command
means Acker received a gift of the specified article (<adjective> <article>) of clothing. In response, the simulation outputsCode Block receive <adjective> <article>
Code Block
...
received
...
and<adjective> <article>
...
- updates the state of the
StudentEnvironment
...
- . For example,
generatesCode Block receive argyle socks
Code Block
...
received argyle
...
socks
means Acker doffed the specified article of clothing, discarding it in the dirty laundry pile, and donned a replacement article using the protocol described above. In response, the simulation outputs
...
- and adds the
argyle socks
to the top of thesocks
pile on the shelf. - The command
Code Block lose <adjective> <article>
...
- means Acker misplaced the
...
- specified article of clothing. If the item exists and Acker is not wearing it, the simulation outputs
Code Block
...
lost <adjective> <article>
...
- and updates the state of the
StudentEnvironment
accordingly. If Acker is wearing it, the simulation outputsCode Block
...
Acker
...
is wearing <adjective> <article>
...
- and leaves the
StudentEnvironment
unchanged. If the item does not exist, the simulation outputsCode Block
...
and leaves the<adjective> <article> does not exist
StudentEnvironment
unchanged.- The command
Code Block
...
means Ackerchange <article>
...
- doffed the specified article of clothing, discarding it in the dirty laundry pile, and donned a replacement article using the protocol described above. In response, the simulation outputs
Code Block
...
doffed <adjective> <article>,
...
donned <adjective> <article>
...
- describing the article doffed and the article donned.
- The command
means Acker washed and dried a load of laundry. If the dirty clothes pile is not empty, the simulation outputsCode Block {{launder}}
listing the clothes in the order they were removed from the dirty clothes pile. If the dirty clothes pile is empty, the simulation outputsCode Block washed <adjective> <article>, ..., <adjective> <article>
Code Block nothing to wash
- The command
Code Block fold
...
- means Acker retrieved a load of laundry, folded it, and put it on the closet shelf. If a load of laundry is available, the simulation outputs
Code Block folded
...
Code Block |
---|
outfit
|
...
for the oldest unfolded load. List the clothes in the order they are placed on the shelf. Hence the top garment on the shelf should be the last one listed. If no load of laundry has been washed and dried, then the simulation outputs<adjective> <article>, ..., <adjective> <article>
Code Block
...
nothing
...
If the oldest load is empty (because all items in it were lost), the simulation outputsto fold
Code Block folded empty load
- The command
asks "what is Acker wearing?" The simulation outputsCode Block outfit
Code Block wearing <adjective> <shirt>, <adjective> pants, <adjective> socks
Supporting Code and Programming Details
...
All of our supporting code is included in the unzipped project. Each file resides in a package that is identified by a package
statement at the beginning of the file. Most support classes are public
so that they can be accessed anywhere. Classes without
a visibility modifier have "default" visibility, which means that they can only be accessed from classes within the same package.
...
The input processor class TerminalIO
implements the IOProcess
interface. You are welcome to inspect the code of TerminalIO
but it relies heavily on the Java I/O library, particularly the class StreamTokenizer
. To understand this code, you will need to read Chapter 11 of JLS (or similar reference). The framework also includes implementations of EnumI
and ReadIteratorI
as part of a BiList
(mutable circular doubly linked list) class implementation.
Your The Student
class must implement implements the StudentEnvironment
interface, which includes the simulate
method supporting the laundry simulation. Within this The simulate method contains a loop that reads commands from its IOProcess
and invokes DoCommandVisitor
on each command. Within the DoCommandVistor
class you must implement methods that return values of type EnumI and ReadIteratorI, the remaining two interfacesprocess the various possible commands.
The IOProcess
interface that provides your program with a command input stream introduces program includes two class definitions defining unions (composites without recursion): Garment
, specifying the representation of garments that appear in the input stream, and Command
, specifying the representation of event description commands. Both classes include the hooks required to support the visitor pattern.
The data definition for Garment
is important because we will subsequently provide you with an graphical IOProces
that the graphical version of the user interface included in the framework animates the state of your implementation before each command. This IOProcess
will expect graphical user interface (GUI) expects the garments that appear as elements in lists (as revealed by the EnumI
and ReadIteratorI
interfaces) to be instances of the Garment
class. Hence, you must use the representation of garments that our class Garment
provides.
The file StudentDoCommandVisitor.java
contains comments describing all of the members that you need to write. In fact, you only need to define the member methods of the inner class DoCommandVisitor
. Early next week, we will upload a GraphicalIO
class implementing IOProcess
that supports a graphics window with buttons that generate input commands, a screen that animates the simulation, and a text output buffer that shows conventional terminal output. this input processor supports exactly the same IOProcess
interface as the TerminalIO
process provided herein.This class could have been defined as an inner class of Student
but we made it a top level class to simplify debugging.
The IOProcess
interface includes a method PrintStream open(StudentEnvironment a, boolean debug)
which initializes an IOProcess
object for a laundry simulation of the specified environment and returns the PrintStream
object to be used for terminal output. (Up to now you have implicitly used the PrintStream
object System.out
.) The PrintStream
method println(String s)
prints the string s
followed by a newline character to the PrintStream
. The boolean debug
argument indicates whether or not debugging output should be produced. The IOProcess
interface also includes a method nextCommand
which reads the next command from the input channel supported by the IOProcess
object.
Each call on nextCommand
returns the next command in the stream provided by the IOProcess
object, until it reaches an end-of-file ({<control>-d
} from the keyboard). End-of-file is reported as a null reference of type Command
.
The nextCommand
method in TerminalIO
processes character strings consisting of words separated by ``space'' characters such as ' '
and '\n'
. A word
is any sequence of printable characters other than space, '\n'
(newline), and '\r'
. (return). An adjective
must be a single word. An article
must be one the words shirt
, pants
, or socks
. The same adjective, say argyle
may be applied to garments of different types, but there are no duplicate items of clothing.
Your The program must pass passes a boolean debug flag
to the IOProcess
it is using (TerminalIO
(TerminalIO
). The value of the flag sould be is true iff the command line argument -d
or -debug
is passed to main
. When we upload the graphics version of the {{IOProcess}}, your {{main}} method in the {{Main}} class should accept a command line argument, a file-name string, (passed in the {{String\[\] arguments}} array to {{main}}) indicating that the command stream
should be read from the specified file.
The default should be the GUI {{IOProcess}} which also supports console input. If you are interested in implementation details of these interfaces and classes, please read relevant source files Wiki Markup
The Graphical User Interface (GUI)
The initialization of the GUI creates an Acker Student object and associated DoCommandVisitor. Each GUI event triggers the execution of DoCommandVisitor; in some cases, such as reading input from a file, it triggers the execution of DoCommandVisitor on a stream of Commands. In essence, the event-handling loop built-in to the Java Swing framework is used to drive the computation rather than a separate loop in the main thread such as the one in the simulate method in Student.
The GUI could also have been written as an implementation of the IOProcess interface. This approach, which conforms to the classic "model-view-controller" (MVC) pattern, is more flexible because it decouples the GUI (the view in MVC terminology) from the model, but it is also more complex because it involves the cooperative execution of
two loops in separate threads--a main program loop in the simulate method of Student and the loop driving the event-handling thread supporting the processing of GUI inputs. The SimLaundryApplication dispenses with the main program loop by absorbing the application (the model) into the GUI (the view).
Efficiency
For this assignment, you should be concerned about relevant asymptotic efficiency. Choose the simplest representation that yields good performance on inputs of plausible size.
Changing an article of clothing should take constant time (i.e., no searching should be done) provided there's an appropriate garment on the shelf. If the shelf contains no clothing of that type, then in the common case we expect to find one of those near the bottom of the pile, no matter how big the pile is: make that case fast. Infrequent operations need not be particularly fast, because they have little impact on the running time of the entire system. (Suppose one operation accounts for 5% of the runtimerunning time, and
we can make it run 10 times as fast. How does that compare to making an operation that accounts for 25% of the runtime running time twice as fast?)
Example
With Acker initially wearing white shirt, socks, and pants, given the input:
...
The sample input and output files tinyin
and tinyout
are a good starting point for testing your program but they are far from exhaustive.
You are responsible for testing your own program. Since your class containing main
is called Student
, the terminal commandcalled edu.rice.comp211.laundry.Main
, you can enter the line
Code Block |
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java Student < infile > outfile
|
will take input from file infile
and direct output to file outfile
. If you omit outfile
, output will appear in the standard output stream.
edu.rice.comp211.laundry.Main -t <infile>
|
in the DrJava Interactions Pane to run the program on input from file <infile>
. Output will be displayed in the DrJava console. If you simply hit the Run Project
button, this action is equivalent to entering the lineYou can run the main method from within DrJava by typing
Code Block |
---|
java Student infile
|
DrJava does not recognize command line input or output redirection, so there is no way to redirect output to a file, but it is printed to the console tab. The infile
command argument is supported by the skeleton code we have provided in the Student
class.
Addendum
edu.rice.comp211.laundry.Main
|
which runs the program with terminal input as the input file. In this case, the program will prompt you for the input of each command in a box within the Interactions Pane.
You can also run the program from the command line (a terminal) in the laundry
directory of the program file tree.
The input line
Code Block |
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java edu.rice.comp211.laundry.Main -t <infile>
|
should produce exactly the same results as executing the same line in the DrJava Interactions Pane. You can redirect the output to a the file <outfile>
by typing
Code Block |
---|
java edu.rice.comp211.laundry.Main -t <infile> > <outfile>
|
DrJava does not support output redirection but you can copy the text printed in the console and paste it into a file using your editor of choiceThe graphical interface code was written on the assumption that your program resides in a package named laundry
and that numerous fields of classes in your program are public. It also relies on deprecated library classes and has no supporting test code. It is a major project to rewrite it to work with the current problem specification. The course staff may succeed in getting a version working later in the term, but not before Wednesday. You can ignore all references to "graphics" in the assignment.