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).
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When doing laundry, Acker removes fifteen (or fewer, if the pile isn't that large) items from the top of the dirty clothes pile. In the simulation, a load of clothes is laundered and dried instanteously instantaneously and placed on a table for clean clothes reserved for Acker in the laundry room. Acker changes clothes so infrequently that the washing and drying time is negligible, so our simulation is a good approximation. The garments in each load of clean clothes are piled in exactly the same order they appeared in the dirty pile. Acker fills the washer and dryer so full that the clothing doesn't get jumbled up.
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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.
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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.
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
class implementation. The Student
class 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 Student
class includes:
- 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
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
commands runs all of the JUnit test files in the project.
Your assignment is to fill in the stubbed out members of the DoCommandVisitor
(members with degenerate bodies (either return;
or return null;
). In the process you may choose to define some new classes to support your 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 Student
class includes:
- 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. 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.)
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. 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 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.) Wiki Markup
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 commoncommand, 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
Code Block
...
means Acker received a gift of the specified article (<adjective> <article>) of clothing.receive <adjective> <article>
...
- In response, the simulation outputs
Code Block received
...
<adjective>
...
and updates the state of the<article>
StudentEnvironment
.
...
- For example,
generatesCode Block receive argyle socks
and adds theCode Block received argyle socks
argyle socks
to the top of thesocks
pile on the shelf. - The command
Code Block
...
means Acker misplaced the specified article of clothing.lose <adjective> <article>
...
- If the item exists and Acker is not wearing it, the simulation outputs
Code Block lost
...
<adjective>
...
and updates the state of the<article>
StudentEnvironment
accordingly.
...
- If Acker is wearing it, the simulation outputs
Code Block Acker is wearing
...
<adjective>
...
and leaves the<article>
StudentEnvironment
unchanged.
...
- If the item does not exist, the simulation outputs
Code Block
...
<adjective>
...
and leaves the<article> does not exist
StudentEnvironment
unchanged.
...
- The command
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.Code Block change <article>
...
- In response, the simulation outputs
Code Block doffed
...
<adjective>
...
<article>, donned
...
<adjective>
...
describing the article doffed and the article donned.<article>
- The command
means Acker washed and dried a load of laundry.Code Block {{launder}}
...
- If the dirty clothes pile is not empty, the simulation outputs
Code Block washed
...
<adjective>
...
<article>, ...,
...
<adjective>
...
listing the clothes in the order they were removed from the dirty clothes pile.<article>
...
- If the dirty clothes pile is empty, the simulation outputs
Code Block nothing to wash
- The command
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 outputsCode Block fold
Code Block folded
...
<adjective>
...
<article>, ...,
...
<adjective>
...
for the oldest unfolded load.<article>
...
- 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
If the oldest load is empty (because all items in it were lost), the simulation outputsCode Block nothing to 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 resides in the default package and none of the 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 all of the code that they can be placed in a single file. We are providing multi-file version of the source so that you can (optionally) gain experience with code bases where every public
class resides in a separate file. All subsequent assignment will use the package system where most classes are public
and reside in separate filesaccessed anywhere. Classes without a visibility modifier have "default" visibility, which means that they can only be accessed from classes within the same package.
Our supporting framework includes an input processor that reads event commands from the input stream and returns high level data representations for these commands. The input processor can also print debugging output describing the state of your simulation before each command is performed. To communicate with your code, the input processor uses four interfaces:
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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 simulation. 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 that return values of type EnumI and ReadIteratorI, the remaining two interfacesmethods that process the various possible commands.
The IOProcessinterface 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 IOProcess 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 Student.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 DoCommandVisitor.java
contains comments describing all of the members that you need to write. 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<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 program must pass a boolean debug {{ flag to the =IOProcess}} it is using ( TerminalIO
for now ). The value of the flag sould be is true iff the command line argument -d
or -debug
is passed to main
.
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.
The program passes a boolean debug flag
to (TerminalIO
). The value of the flag is true iff the command line argument -d
or -debug
is passed to main
.
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) When we upload the graphics version of the {{IOProcess}} , your main method in the {{Student}} class should accept a command line argument {{\-graphics}} (passed in the {{String\[\] arguments}} array to =main=) indicating that the graphics version of the {{IOProcess}} should be used instead of the terminal version.
The default should be the terminal {{IOProcess}} . If you are interested in implementation details of these interfaces and classes, please read relevant source files. Wiki Markup
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 command edu.rice.comp211.laundry.Main
, you can enter the line
Code Block |
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java Student < infile > outfile
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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>
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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 |
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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.