CompSci 105 SS 2005 Principles of Computer Science

CompSci 105 SS 2005 Principles of Computer Science Please try to Understand All concepts involved. Lecture 9: Implementing ADTs Lecturer: Santokh Singh

Partitioning (Revision) ≥p p <p 0 1 2 3 4 8 3 9 1 7 3 1 7 8 9 1 3 7 8 9 Textbook, pp. 83

Built-in Data Types 14 int x = 14; 1110

Abstract Data Type A collection of data … combined with … a set of operations on that data Textbook, p. 108

The Wall ADT Operations Program that uses the ADT ADT Implementation Textbook, p. 110

List ADT • Milk • Eggs • Butter • Apples • Bread • Chicken Operations? Textbook, p. 111ff

List ADT • createList() • isEmpty() • size() • add( index, item) • remove(index) • removeAll() • get(index) Operations Textbook, p. 113

List ADT • createList() • isEmpty() • size() • add( index, item) • remove(index) • removeAll() • get(index) aList.createList() aList.add(1, milk) aList.add(2, eggs) aList.add(3, butter) aList.remove(3) Using the ADT Operations Textbook, p. 114

List ADT • createList() • isEmpty() • size() • add( index, item) • remove(index) • removeAll() • get(index) for i=1 to aList.size() { data = aList.get(i) println(data) } Using the ADT Operations Textbook, p. 115

Abstract Data Types (ADTs) Examples Specifying ADTs Combining ADTs Implementing ADTs Interfaces Classes Private vs. Public Constructors Other Methods Exceptions and Inheritance

Defining ADTs • What needs to be stored? • What are the valid operations? Textbook, p. 119

Combining ADTs Dropbox ADT Implementation Program that uses the DropBox DropBox ADT Operations

Combining ADTs Dropbox ADT Implementation List ADT Implementation Program that uses the DropBox DropBox ADT Operations List ADT Operations

Object Oriented Programming

Circle ADT • setX() • setY() • setRadius() • getX() • getY() • getRadius() • getArea() Operations

Java Interface public interface Circle { void setX ( float x ); void setY ( float y ); void setRadius( float r ); float getX (); float getY (); float getRadius(); float getArea (); }

A method that uses Circle public boolean isBigger( Circle A, Circle B) { if ( A.getArea() > B.getArea() ) return(true); else return(false); }

Creating Circles? Circle A = new Circle(); Circle B = new Circle(); boolean b = isBigger( A, B );

public Class MyCircle implements Circle { float x, y, radius; void setRadius( float newRadius ) { radius = newRadius; } void getArea() { return ( Math.PI * radius * radius ); } }

public Class MyCircle implements Circle { // Constructors MyCircle() { x = 0.0; y = 0.0; radius = 1.0; } MyCircle(float newX, newY, newR ) { x = newX; y = newY; radius = newR; }

A method that uses Circle public boolean isBigger( Circle A, Circle B) { if ( A.getArea() > B.getArea() ) return(true); else return(false); }

Creating Circles Circle A = new MyCircle(); Circle B = new MyCircle(1, 1, 2); boolean x = isBigger( A, B );

public Class MyCircle implements Circle { : : printCircle( ) { System.out.println( x, y, radius ); } : :

public Class AreaCircle implements Circle { float x, y, radius, area; void setRadius( float newRadius ) { radius = newRadius; area = Math.PI * radius * radius ); } void getArea() { return ( area ); } }

Creating Circles Circle A = new MyCircle (); Circle B = new AreaCircle(1, 1, 2); boolean x = isBigger( A, B );

CompSci 105 SS 2005 Principles of Computer Science