15200: Advanced Programming Practicum

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15-200 Advanced Programming / Practicum

• Don Slater -- Lecturer
• School of Computer Science
• Phone x84370
• Office Wean Hall 5115
• dslater_at_andrew.cmu.edu
• Course Assistants
• Ben Naman bnaman_at_andrew.cmu.edu
• Dawn Day dday_at_andrew.cmu.edu

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15-200 Course Overview

• Java
• Object-Oriented Programming (OOP)
• Algorithm analysis
• Data Structures
• Collections
• Programming larger projects
• Problem solving skills
• Time management skills

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Extras

• Java Review
• Evening Sessions on Graphics
• The Campus

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Infrastructure

• Lectures in 7500 (at least to start)
• 5419 D
• Recitation at 430 pm
• Evening open hours from 700 pm to 1030 pm
• Explore possible afternoon hours from 300 to
  430
• Macintosh computers
• May bring your own laptop
• Wireless network
• Other places to work
• From your room
• Other campus clusters (may or may not have
  Eclipse)
• Learn to use the andrew network file system

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How to be Successful in this Course

• Attend class, attend recitation
• Do the homework
• Do the labs (programming assignments)
• They are designed to help you learn how to use
  the concepts covered in the text and discussed
  during lecture
• Start the labs early, programming assignments
  ALWAYS take longer than you think they will
• The material in each session builds on the
  material from the previous session
• Recognize that 70 of your grade is based on the
  exams

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Course Web Sites

• http//www.cmu.edu/blackboard/
• (log in using andrew id and password)
• Mirrored at http//www.andrew.cmu.edu/course/15-CS
  AP/
• Announcements All important updates about the
  course
• Course Information Syllabus and course policies
• Staff Information and Communication Contact
  information
• Assignments Links to labs and homework
• Course Documents Lectures and demo code
• External Links Extra support materials

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Programs and Models

• Almost all computer programs model some artifact
• Artifact product of civilization, either
  concrete or abstract, simple or complex
• Model a simplified representation of something
• It includes features that are considered
  important
• Neglects other features not considered important
• Characteristics of a model
• Elements of the model represent other, more
  complex things
• Model elements exhibit consistent behavior
• Model elements can be grouped into different
  categories, depending on their behaviors
• Actions external to the model element cause the
  behavior of the model element

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Object-Oriented Programming

• The Java programming language using an
  object-oriented programming approach to modeling
• Each model is defined as a class
• Java programs use multiple instances of different
  models or classes to solve a problem or perform a
  task
• These multiple instances are known as objects
• Object-Oriented Programming (OOP), then, is the
  process of solving problems or performing tasks
  with multiple, interacting objects.

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Collections

• There are four broad categories of collections
• Linear (strings, lists, stacks, queues)
• Hierarchical (trees or various types)
• Graphs (directed, undirected, weighted, and
  unweighted)
• Unordered (sets, bags, maps)
• Collections are
• A group of items we wish to treat as a conceptual
  unit
• Every non-trivial piece of software involves the
  use of collections
• Arrays are the most common and fundamental type
  of collections
• Dynamic structures are second
• But more typically, arrays and dynamic structures
  are used to implement other collections

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Types of Collections

• That we are studying
• Bags
• Sets
• Lists
• Stacks
• Queues
• Trees
• We will discuss briefly
• Graphs
• Heaps
• Priority Queues

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Multiple Implementations

• You should have studied arrays
• and you will be studying linked lists (and loving
  it!)
• We are learning that all of the other collections
  are generally implemented (put together) using
  either arrays or linked lists
• Using our understanding of complexity (Big-O) we
  will start thinking about which implementations
  make the most sense
• We will also see that many of the collections we
  discuss are already implemented as classes in the
  Java API

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Collections

• public interface Collection
• Root interface in the collection hierarchy
• A Collection represents a group of objects, known
  as elements
• Characteristics of Collections
• Some are ordered, some not
• Some contain duplicates, some not
• The Java API specifies the behavior of all
  Collections through the interface
• The SDK does not directly implement Collection
• It provides more specific implementations as
  sub-interfaces
• Interface typically used to pass collections
  around for manipulation
• THIS IS COOL!

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Collection hierarchy
Collections
Bags
MultiSets
Lists
Sets
SortedSets
ArrayList
LinkedList
TreeSets
HashSets
Actually implemented in Java Class Libraries
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Collection a Bag

• A Bag collection is a container that holds a
  collection of things that we place into it (See
  Bag.java, IntArrayBag.java)
• A Bag can be used by any program to store a
  collection of items for its own use
• The elements in a bag are unordered
• Their may be multiple instances of the same value
• The Bag is actually a MultiSet

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The conceptual view of a bag collection
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The operations on a bag collection
(See the Collections Interface)
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Interfaces

• Use of the term interface in Java can be
  confusing
• Dictionary definition, Object-Oriented
  Programming definition, Java reserved word for a
  special type of class
• Dictionary definition
• A system of devices, or mechanisms, or behaviors
  that enable two entities to interact with each
  other
• A vending machine or automobile
• A diplomat folloing an agrred upon protocol
• Object-Oriented Programming definition
• An objects interface those methods and data
  elements that can be used to communicate with and
  / or manipulate an object
• The public members (constants and methods) of a
  class
• The API (Application Programmers Interface) is a
  collection of interfaces for the Java Class
  Library

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Vending Machine class interface

• public interface VendingMachine
• public boolean isEmpty()
• public void refill()
• public void fill(int numItems)
• public boolean hasChange()
• public String displayItems()
• public boolean insertMoney(double value)
• public Object selectItem()
• public double makeChange()
• public void cancelTransaction()
• // this is all users need to know (with
  documentation)
• // about a class in order to use it

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A Java interface

• A Java interface is a class that contains only
  constants and method signatures.
• It does not have any instance variables
• None of the methods are defined
• It does not have constructors
• It cannot be instantiated
• The designer of an interface specifies the
  behavior of an object that implements the
  interface
• The user of an interface defines how that
  behavior is to be implemented
• There is a contract between the designer of the
  interface and the user of the interface in which
  all the behaviors will be implemented according
  to the specification of the designer
• All classes that implement an interface have the
  same behavior, but may be defined differently
  (with different data structures, for example)

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Comparable interface

• The Comparable interface is defined by the API
• There is exactly one method compareTo(Object)
  that will be implemented by any class that
  implements Comparable
• A class may define is own compareTo() method
  without implementing Comparable
• But by implementing Comparable, a contract is
  signed indicating to users of the class that
  compareTo(Object) will behave in a reasonable
  way, according to specifications
• See Comparable demo