Updates to UW CSE's 142143 Courses

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Updates to UW CSE's142/143 Courses

• Craig Chambers
• UW CSE
• (Planned and executed withHal Perkins, Ben
  Dugan, and Martin Dickey)

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Quick Summary

• Revisions to UW CSE intro courses
• CSE142 (CS1) switched to Java in Summer, 2001
• CSE143 (CS2) switched to Java in Fall, 2001
• C version of CSE143 also offered through Winter
  2002, then no more
• Not just about Java other improvements to both
  courses

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Outline

• Motivation
• Overview of changes
• CSE 142 content (in some detail)
• CSE 143 content (briefly)
• Textbooks, programming tools
• Open issues

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Problems with old 142/3 versions

• C C are complicated unsafe
• Pointers are particularly nasty
• No interesting data structures in 142
• Objects/classes delayed until middle of 143
• Programming environments are complicated
• Too much focus on detail
• Skewed view of programming and CS?

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Changes

• Switched to Java for both courses
• Smaller, cleaner, safer language
• Extensive, portable libraries
• Simple programming environments available
• Focus remains on programming fundamentals, not
  Java language or libraries per se
• Java enables us to teach the fundamentals better,
  without distractions or complications

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CSE 142

• Use objects from the beginning
• Allows interesting data structures throughout
• Supports a view of programming as building new
  things from existing things
• Most of the usual topics are still covered
• Conditionals, loops, functions, variables, arrays
  (sequences), classes (i.e., structs or records)

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In more detail

• Start with using some existing objects
• Used our home-grown library of graphical shape
  objects that can be added (drawn on) windows
• Nice immediate feedback for students
• Use Jeva a simple Java command-line interpreter

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• Then build new classes from existing classes
• Composite shape classes,e.g., House, Tree,
  Landscape
• Instance variables, constructors, methods,
  parameter passing, returns
• Use BlueJ a simple development environment

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• Then do conditionals, console I/O
• Draw decision trees
• Use home-grown Input class
• Inputting and analyzing weather data
• Then do assignment state change
• BankAccount class

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• Then introduce collections
• Use ArrayList
• Store weather data in a list
• Then introduce iteration over collections
• Use Iterators and while loops, initially
• Use indexing and for loops, later
• Draw flow charts

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• Then introduce interfaces and interface
  inheritance
• Home-grown animation frameworkStage class,
  Actor interface, Prop interface
• Examples asteroid field, quaking landscape, gas
  particle simulation

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• Then teach other collections
• Arrays a lower-level variation on ArrayList
• HashMaps a different kind of collection
• Then teach collections of collections
• Includes multidimensional arrays
• Board games

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• Other possible topics
• Exceptions
• Some algorithms, e.g. searching sorting

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Some Philosophy

• Teach uniformly reference-based data model
• Use primitive data, but describe like objects
• Mention "warts" late
• Avoid static methods, wrapper classes
• Use only classes with real instance variables
• No code inheritance
• Interface inheritance late, for animations

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CSE 143

• Main topics
• Object-oriented programming, specifications
• Data structures, algorithms, complexity
• Recursive functions and data
• Streams, networks
• Exceptions
• Builds on framework from CSE 142
• No language, environment, or paradigm transition
  needed
• Basics of classes, methods, heap data already
  learned

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Textbooks

• CSE 142
• An Introduction to Programming in Java, Ben
  Dugan, course notes required
• Introduction to Computer Science via Software
  Development in Java, David Riley, Addison Wesley
  recommended
• CSE 143
• An Introduction to Programming and
  Object-Oriented Design using Java, Jaime Nino
  and Frederick Hosch, Wiley required
• Probably replacing Riley with Nino in 142 too

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Programming Tools

• Jeva interpreter, from MIT
• Easy to get started a sandbox
• Good for experimenting with messages, expression,
  and statement evaluation
• Cannot define classes no debugger
• BlueJ editor, compiler, debugger, from Monash
  University
• No interpreter

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UW Resources

• Regular CSE 142/143 web sites
• Slides, outlines, course software, materials from
  previous quarters
• Source code for slides and course software
  available upon request

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Some Issues

• Learn programming at a higher level of
  abstraction where do students learn lower-level
  programming knowledge?
• Lower-level data, pointer, memory model
• A later course using C or C
• How do students with prior programming background
  enter the UW CSE 142/143 sequence?

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Conclusion

• Switch to Java enables us to
• focus on important programming ideas
• avoid distracting detail and complexity
• instill a higher-level approach to thinking about
  programming
• Still a work in progress