Download jtf-ap-cs-reading - Stanford Computer Science

Resources to Support the Use of Java
in Introductory Computer Science
The ACM Java Task Force
Eric Roberts, Stanford University (chair)
Kim Bruce, Williams College
Susan Rodger, Duke University
James Cross, Auburn University
Fran Trees, Drew University
Scott Grissom, GVSU
Ian Utting, University of Kent
Karl Klee, Alfred State College
Frank Yellin, Sun Microsystems
http://www.sigcse.org/topics/javataskforce/
AP CS Reading
Clemson, South Carolina
June 14-20, 2004
The Current Situation
• Since its introduction in 1995, Java has grown in popularity
as a language for introductory computer science.
• The importance of Java, particularly for high schools, has
been increased by its adoption by the College Board for the
Computer Science Advanced Placement (CSAP) program.
• There is a growing sense that Java may become a virtual
standard for computer science education in the sense that
Pascal was for so many years.
We should shift our attention from the whether Java
question to the if Java, then how question.
— Chris Wallace, Peter Martin, and Bob Lang
Java in the Computing Curriculum, 1997
• But there are some difficulties . . .
Not Everyone Is Happy
• Several papers have identified problems in the use of Java:
—
—
—
—
Java as first programming language: a critical evaluation [Hadjerrouit98]
Java pitfalls for beginners [Biddle98]
Java, the good, the bad and the ugly [Martin98]
. . . and many more . . .
• High-school teachers find themselves unprepared for Java:
At present 79% of high school computer science teachers rated
their current knowledge of Java as poor to fair and only 3%
rating their knowledge as excellent. At the same time, 86% rated
their personal need to learn Java as very important to critical and
89% indicated that they needed to do so within one year.
— Chris Stephenson, JETT proposal, 2002
• At ITiCSE 2002, Niklaus Wirth assailed Java’s complexity:
I have yet to see a manual on UNIX/C++/Java that I can dare to
read in about a week. Their manuals are unreadable, they expect
you to belong to a cult whose incantations are not public, and
you are not to expect much in terms of reliability, coherence or
general elegance.
And Stuart Reges’s Wonderful Observation
Now I find myself sitting
in on Java intro courses
and I almost can’t watch.
It’s like staring at a traffic
accident. I have a morbid
curiosity to know what’s
going on, but it’s almost
too painful to witness.
— Owen Astrachan’s keynote address, SIGCSE 2004
AP Computer Science
• AP Java Subset
– “The AP Java subset is intended to outline the
features of Java that may appear on AP Computer
Science Examinations. The AP Java subset is NOT
intended as an overall prescription for computer
science courses—the subset itself will need to be
supplemented in order to cover a typical introductory
curriculum.”
— AP CS Course Description
The CS AP Dilemma:
• How do AP CS teachers “supplement” the AP CS Java
subset so that it parallels what is done in the introductory
courses in colleges and universities?
• Some paths taken:
– Follow the textbook.
– Find out what other AP CS teachers are teaching.
– Find out what some universities are teaching.
Problem Taxonomy
High-Level Issues
H1.
H2.
H3.
H4.
Scale
Instability
Speed of execution
Lack of textbooks and environments
(remains a concern)
(remains a concern)
(improving over time)
(improving over time)
Problem Taxonomy
Language Issues
L1.
L2.
L3.
L4.
L5.
L6.
L7.
L8.
L9.
Static methods (including main)
Exceptions
Interface/implementation separation
Wrapper classes
Lack of parameterized classes
Lack of enumerated types
Inability to code preconditions
Lack of an iterator syntax
Low-level concerns
(remains a concern)
(remains a concern)
(addressed by tools)
(fixed in Java 1.5)
(fixed in Java 1.5)
(fixed in Java 1.5)
(fixed in Java 1.4)
(fixed in Java 1.5)
(disposition varies)
Problem Taxonomy
API Issues
A1.
A2.
A3.
A4.
Difficulty of the graphics model
GUI components hard for novices
Support for event-driven code
Lack of a simple input mechanism
(remains a concern)
(remains a concern)
(remains a concern)
(largely fixed in Java 1.5)
The Critical Problems
• Complexity. The number of programming details that
students must master has grown much faster than the
corresponding number of high-level concepts.
• Instability. The languages, libraries, and tools on which
introductory computer science education depends are
changing more rapidly than they have in the past.
More background on these problems and the sources from
which they arise can be found in the background paper in the
SIGCSE 2004 proceedings:
Eric Roberts. The Dream of a Common Language: The Search
for Simplicity and Stability in Computer Science Education.
SIGCSE 2004.
A Dramatic Example of Complexity
There are more public methods in the java and javax
package hierarchies than there are words in Jensen and Wirth.
The amount of text once deemed sufficient to teach the
standard introductory programming language is thus no longer
sufficient for a full index of the operations available today.
— SIGCSE Proceedings
The ACM Java Task Force
In October 2003, the ACM Education Board approved the
formation of a new task force with the following charter:
To review the Java language, APIs, and tools from the perspective of
introductory computing education and to develop a stable collection
of pedagogical resources that will make it easier to teach Java to
first-year computing students without having those students
overwhelmed by its complexity.
The Java Task Force held its first meeting at the end of January
2004. It proposes to issue its final report in June 2005, in time
for use in the following fall.
Deliverables
1. A definition of a subset of the standard Java APIs
appropriate for first-year computer science
2. A public web site containing an updated javadoc
reference manual for the approved Java subset
3. A collection of pedagogically oriented APIs that have
been evaluated and approved by the task force
4. A survey of existing noncommercial materials and tools
for teaching Java
5. A proposal for sustaining the activity begun by this task
force
Principles
1. Object-oriented approach. In our work, the Java Task
Force will design around an objects-first approach to the
introductory curriculum. At the same time, we will seek
to ensure that the resources we provide will be usable
with other approaches wherever possible.
2. Backward compatibility. In order to be forward-looking
and to ensure that our resources remain current for as
long as possible, our baseline version of Java will be
J2SE 1.5. However, we anticipate that some institutions
will not be in a position to adopt Java 1.5, even by the
time at which the Task Force materials are released. For
this reason, we will make every effort to ensure that
those resources work in Java releases from Java 1.2
forward.
Principles
(continued)
3. Minimalism. To avoid the proliferation of a complex
collection of tools that does little to address the scale
problems of Java, the Task Force will seek to define
tools that are, as Einstein put it, “as simple as possible,
but no simpler.”
4. Conformance. Insofar as possible, the Task Force will
work within the standard frameworks provided by Sun
Microsystems and avoid the development of new APIs.
To the extent that we do endorse additional APIs, we
will ensure that there is a work-around that remains
within the standard. Thus, anyone who chooses to use
the resources provided by the Task Force should be able
to do so without being forced to adopt nonstandard
packages.
Principles
(continued)
5. Multiple environments. The Task Force will not enforce
the use of any particular programming environment but
will instead seek to ensure that the resources work with
all major integrated development environments (IDEs).
Milestones
Jan 04
Mar 04
Convene initial meeting of full task force
Introduce the project at a SIGCSE special session
Call for submissions of proposed pedagogical APIs
Publish taxonomy of issues identified in the literature
Apr-Nov 04 Conduct series of working meetings
Undertake review of existing resources
Review submissions of pedagogical APIs
Refine definition of Java teaching subset
Dec 05
Publish draft of Java teaching subset on the web
Present complete draft report at SIGCSE 2005
Feb 05
Mar-May 05 Review and incorporate feedback from SIGCSE
Construct website
Jun 05
Publish final report and website in time for fall
The Task Force Call for Proposals
At SIGCSE 2004, the Java Task Force issued a call for two-page
submissions in the following two categories:
1. A description of any additional challenges you have
beyond those identified in our taxonomy.
2. A description of any solutions you have developed in
response to these challenges.
We received a total of 32 proposals, which we reviewed in May.
Proposed Extensions to the Standard APIs
Based on our analysis of the problems instructors have reported
in teaching Java and our review of the submissions we received
in response to our call for proposals, we believe that the ACM
Java Task Force needs to develop the following extended APIs:
1. A simple, object-oriented graphics package for which the
underlying metaphor is that of a felt board. Under this
model, students create pictures by instantiating graphical
objects and adding them to a component.
2. A set of GUI-based interactors that simplify I/O. We
believe that the use of these interactors should involve
method invocations on interactor objects as opposed to
the static method calls typically used for JOptionPane.
3. A Console class that provides a traditional, interactive,
text-based console.
Planned Extensions to the Standard API
At SIGCSE 2004, the Java Task Force issued a call for two-page
submissions in the following two categories:
1. A description of any additional challenges you have
beyond those identified in our taxonomy.
2. A description of any solutions you have developed in
response to these challenges.
We received a total of 32 proposals, which we reviewed in May.