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COMPSCI 230 Assignment
Bounce: part III/III
Introduction
This is the final instalment of the Bounce project, and perhaps the most challenging. The emphasis of
Bounce III is on working with design patterns. You are required to complete and extend the application
in a way that makes appropriate use of design patterns. Bounce III is a model/view application that
presents three views of a shared model. Such applications are commonplace and introduce the need
for views to be mutually consistent and synchronised with a model whose state changes at run‐time.
Once you have completed the assignment tasks, you should have an application that looks similar to
that shown in Appendix 1.

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COMPSCI 230 Assignment
Bounce: part III/III
Introduction
This is the final instalment of the Bounce project, and perhaps the most challenging. The emphasis of
Bounce III is on working with design patterns. You are required to complete and extend the application
in a way that makes appropriate use of design patterns. Bounce III is a model/view application that
presents three views of a shared model. Such applications are commonplace and introduce the need
for views to be mutually consistent and synchronised with a model whose state changes at run‐time.
Once you have completed the assignment tasks, you should have an application that looks similar to
that shown in Appendix 1.
Assessment criteria
Each task is associated with assessment criteria. To test that you have met the criteria, each task is
associated with CodeRunner tests. The tests include a mix of:
 tests that run your compiled code to check that it is functionally correct and,
 other tests that examine your source to ensure that conforms to object‐oriented principles.
CR3 submissions carry 90% of the marks, whereas the ADB submission carry the rest 10%.
Marking scheme  for CR3 questions is mentioned against each task. ADB submission will be marked
based on whether your entire submitted code compiles and runs successfully to show the expected GUI
as per specifications given in assignment brief. As such, if your code passes all four CR3 tests, and your
code is showing the expected GUI in your IDE, submitting the full iteration code should work fine at
marker’s end too. You can ensure this by carefully packaging, zipping and submitting the verified code
to ADB as per the submission instructions given below.
Bonus for Task 3:
 For CR3 only, 50% bonus marks will be added to Task 3 marks before adding them to the total
marks (9). E.g. if you earn 2 marks each in the first two tasks, and earn 2 marks in the third
task, then your total marks will be 7 [2 + 2 + 2 + 1 (50% of Task 3 marks)]. This will further be
added to your ADB submission mark. If this total exceeds 10, then the exceeding marks will
be added to your previous (A3 Bounce II) assignment marks, only up to the point where it does
not exceed the maximum marks for A3.
Submission
For part 3 of the assignment (A4 – Bounce III), you must:
 (9 marks) pass the CodeRunner tests by Week 10 (Friday 9:00pm, 12 June 2020)
o visit coderunner3.auckland.ac.nz.
o under ‘Assignments’, you should access ‘A4 – Bounce III’ Quiz.
o the quiz has a total of four questions, each of which would require you to paste the
source code of one or more of your classes’ that you wrote in your IDE to complete
each task.
o Task 1 and Task 2 have one CR question each, and Task 3 has two CR questions.
o You may click on ‘Check’ for each question multiple times without any penalty.
o You may however make only one overall CR submission for the whole quiz.
 (1 mark)  submit your source  code  (including  the original Canvas code)  to  the Assignment
Drop Box (ADB – adb.auckland.ac.nz) by Week 10 (Friday 10:00pm, 12 June 2020).
o The code submission must  take the  form of one zip  file  that maintains  the Bounce
package structure.
o You must name your zip file as “YourUPI_230a4_2020.zip”.
o You may make more than one ADB submission, but note that every submission that
you make replaces your previous submission.
o Submit ALL your files in every submission.
o Only your most recent submission will be marked.
o Please double check that you have included all the files required to run your program
in the zip file before you submit it. Your program must compile and run (through Java
1.8) to gain any marks.
o Include  the code  for creating and showing all  required shapes in AnimationViewer
class.
NOTE: It is highly recommended to first complete all tasks (that you are able to complete) in an IDE
like Eclipse, and then only proceed to answer CR3 questions once you have finished writing working
code for this iteration in your IDE. However, if you did not complete at least one of the previous
Bounce assignments, then this may not be advisable. Read the preparation section below for more.
Constraints
For all 3 parts of the of the assignment, any changes you make to the Shape class hierarchy must not
break  existing  code  (e.g.  the AnimationViewer  class).  In  particular,  class  Shape  must  provide  the
following public interface (note this is not the Java “interface”; here the term “interface” refers to the
set of public methods in a class  that may act as entry points  for  the objects of other classes) at all
times:
 void paint(Painter painter)
 void move(int width, int height)
Preparation
You will need to download the bounce‐3.zip file from Canvas. The zip file includes the source code and
a properties file. The properties file allows you to specify application properties that are read by the
application.
You  are  strongly  advised  to  construct  a  model  of  the  application  that  captures  the  key  classes,
instances and their interactions. The model need not be “proper” UML – informal diagrams that allow
you to discover, document and visualise the application’s structure would be sufficient to obtain the
required understanding. It is common in industry to work on existing software projects, and an ability
to understand their structure is an important skill.
You should copy all the files from the bounce package that you have developed for Bounce I and II
into the bounce package of Bounce III. Specifically, these  (Java)  files are:  Shape, RectangleShape,
OvalShape, DynamicRectangleShape, ImageRectangleShape and NestingShape. You should replace
your ImageRectangleShape class with that contained in the bounce‐III.zip download.
For  students  who  did  not  complete  Bounce  I  and  II:‐    You  can  still  proceed  with  Bounce  III  by
implementing the required Bounce III classes, and then testing and submitting them using CodeRunner.
However, without the classes from Bounce I and II, your Bounce application won’t compile outside of
CodeRunner. Also, without the classes for Bounce I and II, you won’t be able to develop an executable
Bounce application. This means that you may potentially have deductions in your ADB submissions.
However, if you are able to resolve those compilation issues, you have every chance to avoid those
deductions.  Another  indirect  way  of  avoiding  this  deduction  would  be  to  target  the  bonus  marks
associated with Task 3. Note that ADB weightage is just 1 out of 10 marks for this assignment.
If you did not complete any of the  first two assignments, and you intend to write code to include
those previous shapes:
 You should study the A2 and A3 review lectures (Lecture 24 and Lecture 30 respectively) on
Canvas pages, along with the code for ImageRectangleShape classes provided in the Bounce
II code, for assistance.
The specific learning material required to complete each task is mentioned under the Hint section of
each task. Still the starting point should be the Week 10 material on writing Java GUI programs, and
how event handling works. This along with lectures on observer pattern (L26), adapter pattern (L29),
MVC pattern (L31) and multithreading (L32) should be helpful.
Supplied code
The Bounce III project is organised around five packages:
 bounce:  This  includes  the Shape  hierarchy  classes, Painter  and  the  classes  and  interfaces
concerned with the Shape model: ShapeModel, ShapeModelListener and ShapeModelEvent.
 bounce.bounceApp:  This  package  contains  the  main  Bounce  application  class  and
BounceConfig, which provides a convenient way of accessing application properties.
 bounce.forms: Package bounce.forms contains GUI form classes that allow the user to specify
Shape attribute  values. These  include ColourFormElement  for  specifying a Shape’s  colour,
ImageFormElement for specifying a Shape’s image file, and ShapeFormElement for specifying
general  Shape  attributes  such  as  width  and  height.  In  addition,  this  package  contains
FormHandler implementations  that  read  form  data and which  instantiate  particular Shape
subclasses.
 bounce.forms.util: This contains application‐independent artefacts for building forms. Form,
FormElement and FormHandler are  basic interfaces  for  representing  forms,  form elements
containing  data  fields,  and  form  processing  respectively.  FormComponent  and
FormElementComponent are Swing component implementations of Form and FormElement.
FormUtility is convenience class for laying out forms. Of the five Bounce packages, this is the
one that you need to be least familiar with.
 bounce.views: This package includes the view classes for this application and their associated
adapters that link them to a ShapeModel.
Other than that your code has passed all tests for the included Bounce I and II code of this assignment
(only for IDE submission), the supplied code (both for CR3 and IDE) makes the following assumptions
about your bounce package code:
 Class Shape and all shape subclasses (other than ImageRectangleShape) have a 7‐argument
constructor that takes the following parameters in order: x, y, deltaX, deltaY, width, height and
text. The first 6 parameters are of type int, while text is of type String.
 Class  DynamicRectangleShape  has  an  8‐argument  constructor  that  takes  the  following
parameters in order: x, y, deltaX, deltaY, width, height, text and colour. The first 6 parameters
are of type int, text is a String and colour’s type is java.awt.Color.
Once your code conforms to the above expectations, the project will still contain compilation errors
because  the  tasks have yet  to be completed. Specifically,  the  following units will have compilation
errors:
 bounce.bounceApp.Bounce.  This  is  the  main  application  class.  It  requires
bounce.views.TreeModelAdapterWithShapeModelListener to be implemented.
 bounce.forms.TestImageShapeFormHandler. This test case requires you to implement class
bounce.forms.ImageShapeFormHandler in Task 3.
 bounce.views.TreeViewer requires that bounce.views.TreeModelAdapter is implemented.
Task 1: implement class bounce.views.TreeModelAdapter
A key part of a ShapeModel object is its composite structure of Shapes. When completed, the Bounce
application should include a hierarchical view of this composition structure. Rather than reinvent the
wheel, it makes sense to reuse Swing’s JTree component that is tried and tested and which is intended
for visualising hierarchical structures. However, there is an interface mismatch problem in that a JTree
component is not able to render ShapeModel objects directly. Rather, a JTree component can render
any TreeModel object. This problem – of wanting  to make incompatible objects work together – is
common  in  object‐oriented  software  development  and  can  be  solved  using  the  Adapter  design
pattern (Lecture 29) with which you are familiar. Apply this design pattern so that you can display a
ShapeModel’s shape composition using a JTree component.
Once  you  have  completed  this  task,  you  can  run  the  demo  program bounce.views.TreeViewer.
Assuming  your TreeModelAdapter  class  is  correct,  this  program  will  display  a ShapeModel’s  shape
composition.
Hints
 Carefully study the API documentation for Swing’s TreeModel interface. You will spend less
time on this task overall if you invest in some up‐front activity to understand the TreeModel
interface.
 Many of the TreeModel methods have arguments of type Object that you will need to cast to
Shape  and  NestingShape.  In  implementing  class  TreeModelAdapter,  be  sure  to  use  the
instanceof operator so that only safe casts are performed.
 Class TreeModelAdapter should define one constructor that takes as argument – a reference
to an object of type ShapeModel.
 TreeModel’s valueForPathChanged()  method  can  simply  be  implemented  with  an  empty
method body. This method is an event notification method that can safely be implemented
like this in the context of this task.
 Lecture  on  MVC  pattern  (Lecture  32)  is  helpful  for  understanding  most  concepts  under
implementation.
Testing
From the CodeRunner quiz named Bounce III, complete the first question:
 (3  marks)  Bounce  III  TreeModelAdapter,  which  runs  a  series  of  tests  on  your
TreeModelAdapter class.
Your code will need to pass all tests.
Task 2: Implement class ‐
bounce.views.TreeModelAdapterWithShapeModelListener
Your TreeModelAdapter class has leveraged the Swing framework, and with very little effort you have
a  robust  means  of  visualising  a  ShapeModel’s  shape  composition.  Awesome.  However,  the
TreeModelAdapter class suffers from a limitation that prevents the Bounce application from working
correctly.  Bounce  is  a  model/view  application,  with  the  GUI  showing  three  different  views  of  a
ShapeModel  instance.  The  problem  is  that  while  the  AnimationView  and  TableViewAdapter  views
respond to changes in the state of ShapeModel, an instance of the TreeModelAdapter class does not.
Consequently, when a new Shape instance is added or an existing Shape object is removed from the
ShapeModel, the change is not reflected in the JTree component. Obviously, this is most undesirable
as all views should offer consistent representations of a common model.
Introduce  a  new  class,  TreeModelAdapterWithShapeModelListener,  that  extends  your
TreeModelAdapter  class  such  that  a  TreeModelAdapterWithShapeModelListener  instance  can  both
render a ShapeModel’s shape composition and  respond  to changes  that occur in  the ShapeModel.
Using  a  TreeModelAdapterWithShapeModelListener  instance,  its  connected  JTree  component  will
update  its  display  whenever  the  ShapeModel  changes.  It  is  helpful  to  think  of  a
TreeModelAdapterWithShapeModelListener object as follows:
 A TreeModelAdapterWithShapeModelListener  object  plays  two  roles:  the model  of a  JTree
component, and the (non‐visual) view (listener) of a ShapeModel.
 A  TreeModelAdapterWithShapeModelListener  object  essentially  transforms  ShapeModel
events that is hears about into TreeModel events that it fires to its TreeModelListeners. In the
case of the Bounce application there is one such listener, the JTree component.
Implement  class  TreeModelAdapterWithShapeModelListener  to  do  the  necessary.  Once  completed
you  should  have  a  functioning  Bounce  application.  Once  you  have  edited  and  deployed  the
application’s properties file, discussed below, run the application and enjoy the fruits of your labour.
On startup the Bounce application attempts to read configuration information from the file named
bounce.properties.  You  should  locate  this  file  within  your  login  directory.  For  home  PCs  running
Windows,  the  login  directory  is  C:/Users/<username,  where  <username  is  replaced  with  your
username. You should ensure that the shape classes property lists the fully qualified names of Shape
subclasses that you want the application to use. Essentially, the combo box on the GUI is populated
with  the  names  of  the  classes  you  specify  for  the shape  classes  property.  Hence,  when  using  the
application you can specify the kind of shape you want to add to the animation. In specifying class
names for this property, each name should be separated by whitespace; note however that if names
are spread across multiple lines a \ character should end each line except the last. For example, the
following specifies that two classes should be loaded:
shape classes = bounce.RectangleShape \
bounce.NestingShape
Hints
 Carefully study the Java 8.0 API documentation for Swing’s TreeModelListener interface and
classes TreeModelEvent and TreePath.  Similarly  to  before,  you will  spend  significantly  less
time on  this  task if you  study  the API pages first  rather  than  rushing in and  trying  to  hack
something together.
 There is a  reasonable amount of complexity in the TreeModelListener and TreeModelEvent
entities. Some of this complexity lies in the ability for a TreeModelEvent to describe multiple
node  additions/removals/changes  in  a  TreeModel.  Note  that  your
TreeModelAdapterWithShapeModelListener class need only generate TreeModel events that
describe a single addition or removal of a Shape at a time. Hence, the childIndices and children
arrays that form part of the state of a TreeModelEvent will always have a length of 1.
 Each node shown in  the Bounce application’s JTree component  represents a composite or
simple shape instance within the ShapeModel object. Each node is labelled with the name of
the Shape subclass that the node is an instance of. The JTree acquires the label value for each
node  by  calling  method  toString()  on  each  Shape  instance  it  discovers  through  making
TreeModel calls on its model. Given that these label values are not subject to change in the
Bounce application, your TreeModelAdapterWithShapeModelListener class need not make any
treeNodesChanged()  calls  on  registered  TreeModelListeners.  In  other  words,  your
TreeModelAdapterWithShapeModelListener class  has only  to make treeNodesInserted() and
treeNodesRemoved() calls on registered listeners, thereby communicating new and removed
nodes, respectively.
 Class TreeModelAdapterWithShapeModelListener should define one constructor that takes as
argument a reference to an object of type ShapeModel.
 In addition to Lectures 29 and 32, Lecture 26 on Observer pattern will be helpful.
Testing
From the CodeRunner quiz named Bounce III, complete the second question:
 (3 marks) Bounce III TreeModelAdapterWithShapeModelListener, which runs a series of tests
on your class.
Your code will need to pass all tests.
Task 3: add class bounce.forms.ImageShapeFormHandler
The Bounce III application allows images to be loaded and added to the animation. Key classes are:
 bounce.ImageRectangleShape. This is a Shape subclass that paints a given image.
 bounce.forms.ImageFormElement.  An  ImageFormElement  allows  the  user  to  select  a
particular image from disk that is to be displayed by an ImageRectangleShape.
 bounce.forms.SimpleImageShapeFormHandler.  An  instance  of
SimpleImageShapeFormHandler  processes  data  entered  in  form  elements
ShapeFormElement  and  ImageFormElement  and  uses  this  to  instantiate  an
ImageRectangleShape object.
Class  SimpleImageShapeFormHandler  scales  the  image  selected  by  a  user  based  on  the
ShapeFormElement’s width field value. ShapeFormElement’s height is ignored as the scaling operation
maintains the image’s aspect ratio.
The problem with SimpleImageShapeFormHandler is that the loading and scaling operations – which
are expensive for large images – are performed by the Event Dispatch thread. The image processing
thus causes the application to freeze and become unresponsive when working with large images.
For  this  task,  you  should  create  a  new  class  (bounce.forms.ImageShapeFormHandler)  to  more
appropriately  load  and  scale  the  image  using  a  background  thread,  and  make  the  new
ImageRectangleShape  instance  available  to  the  Event  Dispatch  thread.  Like
SimpleImageShapeFormHandler,  ImageShapeFormHandler  should  have  a  constructor  that  takes
ShapeModel and NestingShape parameters and should implement the FormHandler interface.
Specific requirements
 Class ImageShapeFormHandler must use class SwingWorker as part of its implementation.
 Class ImageShapeFormHandler must implement the FormHandler interface.
Once you  have implemented ImageShapeFormHandler, you  should edit  the FormResolver class  to
change  method  getFormHandler()  to  return  an  ImageShapeFormHandler  rather  than  a
SimpleImageShapeFormHandler.  You  can  then  run  the  Bounce  application  and  have  large  images
loaded and scaled in the background when creating ImageRectangleShape objects.
Hints
 The  logic  for  acquiring  form  data,  loading  and  scaling  the  image,  and  instantiating
ImageRectangleShape is provided in the existing SimpleImageShapeFormHandler class. You
can reuse this without modification in ImageShapeFormHandler. Don’t consider this to be a
case  of  duplicating  code  –  in  reality  you  would  discard  the  naive
SimpleImageShapeFormHandler class.
 You  will  need  a  large  image  file  (greater  than  20MB)  to  effectively  demonstrate  your
ImageShapeFormHandler  implementation.  One  source  of  suitable  images  is
https://effigis.com/en/solutions/satellite‐images/satellite‐image‐samples/
 Lecture 33 material on multithreading and especially the part on SwingWorker class is helpful.
Testing (See the Assessment Criteria section for provision for bonus marks)
From the CodeRunner quiz named Bounce III, complete the remaining questions:
 (2 marks) Bounce III ImageShapeFormHandler, which runs a series of tests on your class.
 (1 mark) Bounce III ImageShapeFormHandler (static analysis), which analyses your code.
Your code will need to pass all tests.
Debugging
I strongly recommend that you use Eclipse for all assignments, and use Eclipse debugging feature for
your assistance.

Appendix 1 Screen shot of final Bounce application