These Magercises illustrate how to use the essential capabilities of the Collection Framework. When you finish these Magercises, you will be able to effectively use the Map and Collection capabilities of the framework.

Magercise Outline

• About Magercises
  • The Anatomy of a Magercise
  • Magercise Design Goals
  • Magercises, Introduction to the Collections Framework
  1. Using a HashSet for a Sparse Bit Set
  2. Using a TreeSet to provide a sorted JList
  3. Using an ArrayList with a JComboBox
  4. Using a Map to Count Words

About Magercises

The Anatomy of a Magercise

• Help: Gives you help or hints on the current Magercise (an annotated solution). For ease of use, the task information is duplicated on the help page with the actual help information indented beneath it.
• Solution: The <applet> tag and Java™ source resulting in the expected behavior.
• API Documentation: A link directly to any necessary online API documentation.

Magercise Design Goals

"Blank screen"

You are confronted with a "blank screen" and you create the entire desired functionality yourself.

Extension

You extend the functionality of an existing, correctly-working program.

Repair

You repair undesirable behavior in an existing program.

To make learning easier, Magercises, where possible, address only the specific technique being taught in that Magercise. Irrelevant, unrelated, and overly complex materials are avoided.

Where possible, Magercises execute via the web. However, Magercises that must access Java features or library elements that could cause security violations are not executed on the web.

Magercises, Introduction to the Collections Framework

1. Using a HashSet for a Sparse Bit Set

   This Magercise has you extend the BitSet class to be a collection backed by a HashSet instead of an array of long values where individual bits are used to store the state of individual boolean values.

   Educational goal(s):

   • Extend the use of BitSet
   • Work with set algebra
   • Use a HashSet

2. Using a TreeSet to provide a sorted JList

   This Magercise has you create a sorted data model for a JList, storing the data within an TreeSet.

   Educational goal(s):

   • Work with the SortedSet interface
   • Use a TreeSet
   • Use a Iterator

3. Using an ArrayList with a JComboBox

   This Magercise has you create a mutable data model for a JComboBox, storing the data within an ArrayList.

   Educational goal(s):

   • Work with the List interface
   • Use a ArrayList

4. Using a Map to Count Words

   This Magercise has you count the individual words in the contents specified by a URL. Then, you format the output for a JTextArea.

   Educational goal(s):

   • Work with the Map interface
   • Use a HashMap and TreeMap
   • Use a custom Comparator
   • Use the Map.Entry interface

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