Assignment 4

CSC 115 -- Fall 2002

Objectives

• Practice using object-oriented user interfaces
• Introduction to listeners and multiple views
• Practice with code reuse
• Extended practice with the Iterator interface
• Trees and manipulating trees
• Experience with Swing JTree objects
• Practice doing pair programming

Instructions 

Part I of the assignment is to be done with a fellow classmate.  Pair up with a partner during the lab or use the webboard.  Part II should be done alone.

Part I

As a first step, you should familiarize yourself with JTrees from the Java sun tutorial:

JTtrees:  http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html

You should explore and thoroughly understand the following examples from this tutorial (these examples will be described in detail in the lab, so do not miss your lab this week!):

• TreeDemo.java
• DynamicTreeDemo.java (see also the DynamicTree.java file)

You will also need to know how to use the following provided classes:

• DefaultMutableTreeNode
• JTree

You and your partner  should explore these built in classes and interfaces together, taking turns to explain the code to each other.  You should understand all of this code thoroughly before attempting any implementation.  While you explore, take turns editing the example code to explore it more deeply.  (Note:  you will need to describe how you worked with your partner for Part II of the assignment.)

Implementation requirements

For this assignment, you will learn how to use a graphical representation of a tree using the tree built in classes and interfaces in Java.    Using the DynamicTree and DynamicTreeDemo example classes mentioned above as a starting point, your graphical tree view will have controls which will allow  a user to add and remove nodes from the tree, as well as a button to empty the tree.  The user can also expand and collapse branches in the tree. 

You need to add a text area to  the bottom of the tree window that will display  preorder, inorder and postorder traversals of the visible parts of the tree.   Therefore, when the user changes  the tree by adding a node, removing a node, renaming a node or clearing the tree, the traversals should be updated.  The DynamicTree example already has listeners for when a user adds, removes or clears the tree.   You need to add code to these listeners to create your traversal display.   You will also need to add a listener for when the user collapses or expands a branch in the tree.

You are free to design the output style of the tree traversals (bonus marks will be awarded for outstanding displays of the traversals).  The only requirement is that your output is clear and that it is intuitive for the user to read the traversals and that they map correctly to the visible tree. 

Hints

• Make sure you understand the interactive examples we covered in class
• Implement this program incrementally.
• It is imperative you attend the labs this week and that you understand the code listed above before trying to do this assignment.  You should also attend the labs during the week of Nov 18th and Nov 25th for more help should you need it.
• The DynamicTreeDemo example above does most of what you need for this assignment -- start with this and add a text area for displaying output (the listeners will
• Hints:  for improving the text output of your tree traversals, see this link http://java.sun.com/docs/books/tutorial/uiswing/components/label.html in the Java tutorial.
• For tips on how to add the expansion listener, see http://java.sun.com/docs/books/tutorial/uiswing/events/treeexpansionlistener.html
• Develop this assignment in this order: 
  • First create a text area and write one of the traversals to this area.  At first just print out the entire tree even the nodes that are not visible.  Just get one traversal type working, and then add the others later.
  • Next add the listeners for tree contraction and expansion events.  Note -- these listeners should be attached to the DynamicTree class  (see the simpler TreeDemo example for a similar example).
  • Once you are sure your listeners are working correctly (just do prints to make sure they work),  then adapt your traversal text output so that it only shows nodes that are visible  (hint:  the JTree class has an isVisible() method.... see the API for JTree).

Part II

For Part II, you are to write a description of your experiences doing pair programming and design (one to two pages).    You should write this summary alone.  In your essay, you should discuss which aspects of pair programming you found useful, how it helped you learn (or how you helped your partner learn) and what you would do differently the next time you had to do pair programming.   Your short essay should be typed and spell checked.

Due dates

• The code for Part I should be submitted electronically on Thursday, 28th November by 3pm (you will need to hand in your edited versions of DynamicTree.java and DynamicTreeDemo.java).
• Part II should be handed in before class on Thursday, 28th November.  Also hand in a printout of your code from Part I on Thursday.
• Clearly print both student names and student numbers on the code that you hand in.

Remarks

• Part 1:
  • Correctness of your program.
  • Simplicity of your code.
  • Presentation style of your tree traversals.
  • Meaningful variable and method names.
  • Use of comments
• Part 2:
  • Clarity of writing
  • Quality and depth of your observations (if you don't do the exercise doing pair programming, this part will be hard to write!)