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CS200 - Class Overview 1
CS200 Fall 2009
Instructor: Wim Bohm
Teaching Assistant: Artem Sokolov
CS200 - Class Overview 2
CS200 structure
Quizzes & Class Participation:
“are you with us?”
Tests:
“what have you learned?”
Programming assignments:
“can you implement it?”
Written assignments:
“do you understand the underlying theory?”
Check the CS200 webpage
CS200 - Class Overview 3
Class meetings
Lectures
Programming: algorithms, data structures
Theory: complexity
Recitation (in Lab hours)
L04 has been cancelled (sorry!)
L04 people need to drop the class and reregister for
another lab.
Help you with programming and homework
assignments, reinforce material from lecture.
you get credit for attending and participating in
recit!
CS200 - Class Overview 4
Difference from CS160/
More freedom in how to structure your
program
Larger programs, continuing assignments
Team programming
CS200 - Class Overview 5 Grading Programming assignments 30% Written assignments 10% Quizzes 10% Recitation (attendance + completion) 5% Midterms (2) 20% Final 25% You need to have a passing grade on the exams to get a passing grade in the course CS200 - Class Overview 6 Policies “Trust men and they will be true to you; treat them greatly and they will show themselves great.” Ralph Waldo Emerson Be professional. We are all here to learn. CS200 - Class Overview 7 Course Goals
To understand programs at different levels
Logical view Program = Algorithms + Data Structures Understand their relationship and use them correctly, efficiently Implementation Program = Objects + Methods Practice design and implementation of object-oriented programs in Java Analysis Study the complexity of programs, deriving Order of Magnitude expressions for their time and space use CS200 - Class Overview 8 Course Goals An understanding of a variety of common data structures A practical understanding of where they are applicable
Implementing ADTs Interface : Java construct that specifies method headers, constants What does it mean to implement an interface? How do you express it? Which interfaces did you meet in cs161? Which interface does an ArrayList implement? Do you remember some methods? CS200 - Class Overview 13 CS200 - Class Overview 14 ADT for a List
A list: a collection of elements indexed by an
integer
What methods should be included?
CS200 - Class Overview 15 ADT for a List, e.g. … Create
createList()
Add
add(index:integer, item:ListItemType)
Remove
remove(index:integer)
removeAll()
Ask
isEmpty():boolean
size():integer
get(index):ListItemType
Let’s play CS200 - Class Overview 16 Specifying ADT Describe: Methods that are visible (public)
Parameters
Return values
Pre condition: what they expect
Post condition: what they deliver
What must the method do if pre holds?
What must the method do if pre does not hold?
CS200 - Class Overview 17 Specifications: example
createList() // creates an empty list
isEmpty():boolean // returns true if list is empty
size():integer // returns # of items in list
add(index:integer, item:ListItemType)
// Inserts item at position index of a list, if
// 1<=index<=size()
// When inserted, elements with position >=index are
// renumbered to position + 1.
// Throws an exception when index is out of range or
// list is full.
CS200 - Class Overview 18 Specifications example (cont.)
remove(index:integer)
// Removes the item at position index, if 1<=index<=size(). // After removal, elements with position >= index are // renumbered to position-1. // Throws an exception when index is out of range or // list is empty.
removeAll() // Removes all elements from list
get(index):ListItemType
// Returns the item at position index if 1<=index<=size(). // List is not changed. // Throws an exception if index is out of range. CS200 - Class Overview 19 An Array Based Implementation Public class ListArrayBased implements ListInterface { private static final int MAX_LIST = 50; private Object items[]; private int numItems; public ListArrayBased() { items = new Object[MAX_LIST]; numItems = 0; } public boolean isEmpty() { return (numItems == 0); } CS200 - Class Overview 20 Implementation (cont) public int size() { return numItems; } public void removeAll() { items = new Object[MAX_LIST]; numItems = 0; } public Object get (int index) throws ListIndexOutOfBoundsException { if (index >=1 && index <= numItems) { return items[index - 1]; } else { // index out of range throw new ListIndexOutofBoundsException(); } }
