python plus java in a three course sequence!taming the tiger -- teaching the next generation of...

Python Plus Java in a Three Course Sequence

David RanumBrad Miller

Luther College

We’d like them to look like this

But many look more like this

Want To Avoid This

Why do they end up this way?

! Taxonomy of Problems in Teaching Java -- The Java Task Force Difficulties Teaching Java in CS1 and How We Aim to Solve Them! Taming the Tiger -- Teaching the next generation of Java! The Dream of a Common Language: The search for Simplicity and Stability in

Computer ScienceThe original Pascal book by Wirth had 266 Pages, Dietel and Dietel has 1536There are more public methods in the java and javax package heirarchies than there are words in Wirth's book.

! Taming Java for the Classroom! Java is the Canonical Lanuage for teaching introductory programming, but...

! Lots of Papers on help for teaching objects early! BlueJ! ObjectDraw! Karel J Robot

! Java Task Force Libraries


! Taxonomy of Problems in Teaching Java -- The Java Task Force! Taming the Tiger -- Teaching the next generation of Java! The Dream of a Common Language: The search for Simplicity and Stability in

Computer ScienceThe original Pascal book by Wirth had 266 Pages, Dietel and Dietel has 1536There are more public methods in the java and javax package heirarchies than there are words in Wirth's book.

! Taming Java for the Classroom

!Java is the Canonical Lanuage for teaching introductory programming, but...



! Taxonomy of Problems in Teaching Java -- The Java Task Force! Taming the Tiger -- Teaching the next generation of Java! The Dream of a Common Language: The search for Simplicity and Stability in

Computer Science

The original Pascal book by Wirth had 266 Pages, Dietel and Dietel has 1536There are more public methods in the java and javax package heirarchies than there are words in Wirth's book.

! Taming Java for the Classroom! Java is the Canonical Lanuage for teaching introductory programming, but...




The Java Magic Spell?

Increasingly, people seem to misinterpret complexity as sophistication, which is baffling - the incomprehensible should cause suspicion rather than admiration. (Niklaus Wirth)

What Can We Do?

Join the folks trying to fix Java or...

Use a Language that encourages students to focus on problem solving and computer science

As Moti-Ben Ari put it in SIGCSE 2005 Keynote: “Its OK to teach introductory Physics students about levers and pulleys”

Its OK to start out on the Green Runs

Hello World

public class Hello { public static void main(String[] args) { System.out.println("Hello Java World"); }}





Hello World

>>>print "Hello Python World"Hello Python World

Hello World

>(print "Hello Scheme World")“Hello Scheme World”>

Our Courses and Goals

Our Students:

Very little programming experience

Bright

Enthusiastic

Our Courses and GoalsLearn Computer Science

Problem Solving

Patterns

Techniques

Algorithms

Data Structures

Prepare for Upper Level Courses

CS-1

Basic problem solving approaches.

Programming is presented as a notation

Want to encourage not frustrate

Practice Practice Practice

CS-2

Students are still beginners!

Classic Algorithms and Data Structures

Problem solving patterns

Analysis

CS-3Software Design and Development

2 Parallel TracksJava

ExceptionsInterfacesInner Classes.GUI and Event Driven ProgrammingThreading

Preparing Students for Upper Level CS

CS1Case Studies

Accumulator

Iteration Over a Collection of Objects

Nested Loops and Functions

Conditionals

Classes

Python Data Model

Consistency!

1 + 2 == 3

A = 1 + 2

(1).__add__(2) == 3

3A

CS2Case Studies

Insertion Sort(Pseudocode)

Insertion-Sort(A)for j 2 to length[A] key A[j] i j - 1 while i > 0 and A[i] > key A[i+1] A[i] i i - 1 A[i + 1] key

Insertion Sort(Python)

def insertionSort(A): for j in range(1,len(A)): key = A[j] i = j while i>0 and A[i-1]>key: A[i]=A[i-1] i = i-1 A[i]=key

Comparing Python to Pseudocode

Insertion-Sort(A)for j 2 to length[A] key A[j] i j - 1 while i > 0 and A[i] > key A[i+1] A[i] i i - 1 A[i + 1] key

def insertionSort(A): for j in range(1,len(A)): key = A[j] i = j while i>0 and A[i-1]>key: A[i]=A[i-1] i = i-1 A[i]=key

Running and Testingcray:MICS2005> python -i insertion.py>>> A = [9, 4, 2, 10, 7, 22, 1]>>> insertionSort(A)>>> A[1, 2, 4, 7, 9, 10, 22]>>> B = ['dog', 'cat', 'ape', 'eel']>>> insertionSort(B)>>> B['ape', 'cat', 'dog', 'eel']>>> C = [3.14, 2.78, 9.80, 3.8]>>> insertionSort(C)>>> C[2.78, 3.14, 3.8, 9.8]>>>

Sorting Objectsclass student: def __init__(self,lname,fname,gpa): self.fname = fname self.lname = lname self.gpa = gpa def __cmp__(self,other): if self.gpa < other.gpa: return -1 elif self.gpa == other.gpa: return 0 else: return 1

Knights Tour

20 21 22 23 24

15 16 17 18 19

10 11 13 14

5 6 7 8 9

0 1 2 3 4

21 23

15 19

12

9

3

5

1

Graphclass Graph: def __init__(self): self.vertList = {} self.numVertices = 0 def addVertex(self,key): self.numVertices = self.numVertices + 1 newVertex = Vertex(key) self.vertList[key] = newVertex return newVertex def addEdge(self,f,t,cost=0): if not self.vertList.has_key(f): nv = self.addVertex(f) if not self.vertList.has_key(t): nv = self.addVertex(t) self.vertList[f].addNeighbor(self.vertList[t],cost) def __iter__(self): return self.vertList.itervalues()

for node in graph: print node.color

Vertexclass Vertex: def __init__(self,num): self.id = num self.adj = [] self.color = 'white' self.dist = sys.maxint self.pred = None self.disc = 0 self.fin = 0 self.cost = {}

def addNeighbor(self,nbr,cost=0): self.adj.append(nbr) self.cost[nbr] = cost

Depth First Searchdef knightTour(n,path,u,limit): u.setColor('gray') path.append(u) if n < limit: nbrList = u.getAdj() i = 0 done = False while i < len(nbrList) and not done: if nbrList[i].getColor() == 'white': done = knightTour(n+1,path,nbrList[i],limit) i = i + 1 if not done: # prepare to backtrack path.remove(u) u.setColor('white') else: done = True return done

orderByAvail(u)

Complete Tour

CS3Case Studies

First Few Weeks

2 weeks Java Basics (Using Collections)

Command Line then IDE

Building Classes

Testing -- jUnit

Interfaces and Inheritance

River Crossings

Graphpublic class Graph implements Iterable { public Graph() { this.vertList = new HashMap(); this.numVertices = 0; } private HashMap vertList; private int numVertices = 0;

class Graph:

def __init__(self): self.vertList = {} self.numVertices = 0

addVertex

def addVertex(self,key): self.numVertices = self.numVertices + 1 newVertex = Vertex(key) self.vertList[key] = newVertex return newVertex

public Vertex addVertex(int key) { this.numVertices = this.numVertices + 1; Vertex newVertex = new Vertex(key); this.vertList.put(key,newVertex); return newVertex; }

Iteration

public Iterator iterator() { return vertList.values().iterator(); }

def __iter__(self): return self.vertList.itervalues()

for (Vertex v : g) { System.out.println(node.color);}

Event Driven Programming

Java Swing

Java 2D Graphics Programming

Model View Controller Pattern

Listeners and Event Handling

What is left?

Swing components

Threading

Simple Network Programming

Source Control

Database Access (JDBC)

XML

Next Project jPhoto

SummaryPut the focus back on Computer Science and Problem SolvingBy Using Python early we can:

Solve interesting problems that motivateLearn important problem solving patterns

By Moving to Java at the right time we can:Prepare students for successencourage good software development habits

[In a programming language] Simple things should be simple and complex things should be

possible. (Alan Kay)

python plus java in a three course sequence!taming the tiger -- teaching the next generation of...

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