* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CS 340 Data Structures
Survey
Document related concepts
Join-pattern wikipedia , lookup
Design Patterns wikipedia , lookup
Reactive programming wikipedia , lookup
Name mangling wikipedia , lookup
Falcon (programming language) wikipedia , lookup
Stream processing wikipedia , lookup
Structured programming wikipedia , lookup
Abstraction (computer science) wikipedia , lookup
Java (programming language) wikipedia , lookup
String literal wikipedia , lookup
Index of robotics articles wikipedia , lookup
Class (computer programming) wikipedia , lookup
String (computer science) wikipedia , lookup
Java ConcurrentMap wikipedia , lookup
Java performance wikipedia , lookup
C Sharp syntax wikipedia , lookup
Transcript
CS 340 DATA STRUCTURES Instructor: Xenia Mountrouidou Course Objectives 2 At the end of this class you will be able to: Make design decisions on which data structure is best to use regarding performance, memory, and implementation efficiency. Devise or use the most efficient algorithm in your projects. Understand algorithmic complexity. Think analytically and identify complexity of a program. Course Objectives (cont.) 3 At the end of this class you will be able to: Apply object oriented programming principles when you develop software. Use and understand third party code. Detect inefficiency of data structures and algorithms of third party code. Develop projects using agile test driven approach (Junit). Employ the Java API. CS 340 Why do you need CS 340? 4 Scenario: You are a senior developer for e-bay. You are working on their e-commerce application server! You drop code, you are a java guru, OO programming is second nature to you… but you do not understand data structures and algorithms. BIG DEAL! Everything runs perfectly. Until one day… You need to use a sorting algorithm to sort all potential sellers of a product based in price or ranking. CS 340 Why do you need CS 340? 5 Scenario (cont.): On every click for a product search, your sorting algorithm will be used. You choose bubble sort. After all, it has a cool name! Let’s see what happens: http://www.cs.bu.edu/teaching/alg/sort/demo Software is not just coding… It is design, performance, memory consumption It is an art, a riddle to be solved with every project CS 340 Lectures 6 We meet at 15:00-16:45, every Tues/Thurs, at Merritt Penticoff Science Bld, Room 130 Attendance will have a part in your grade. Attendance means: active participation! Check the schedule in our webpage Reading and examples will be posted online. Check the webpage for news frequently. CS 340 How to get help 7 Join my office hours! Join the conversation on Piazza. Check our website frequently. Use the textbook: “Data Structures: Abstraction and Design Using Java”, Second Edition by Elliot B. Koffman, Paul A. T. Wolfgang Experiment with code. It’s fun… CS 340 Grading 8 Midterm exam Final exam Homeworks Programming projects Class participation Total Homework online CS 340 20% 20% 25% 25% 10% 100% and Programming projects will be posted Programming Projects 9 They involve Design Coding Testing Debugging Some of these can be done in pairs Both team members will need to answer detailed questions about the implementation Each team member will evaluate his/her team mate CS 340 Principles of Pair Programming 10 CS 340 Principles of Pair Programming 12 All I Really Need to Know about pair programming I Learned in Kindergarten Share everything. Play fair. Don’t hit people. Put things back where you found them. Clean up your own mess. Don’t take things that aren’t yours. Say you’re sorry when you hurt somebody. CS 340 Principles of Pair Programming 13 Wash your hands before you eat. Flush. Warm cookies and cold milk are good for you. Live a balanced life – learn some and think some and draw and paint and sing and Dance and play and work every day some. Take a nap every afternoon. When you go out into the world, watch out for traffic, hold hands and stick together. Be aware of wonder. CS 340 Policies 14 Read the collaboration policy carefully. Late policy: 1st day late: 10% off 10% is reduced by every day the homework is late CS 340 15 Java… a bit of history CS 340 Java timeline 16 http://www.youtube.com/watch?v=WAy9mgEYb6o CS 340 Java Design Goals 17 Simple, object oriented, and familiar Robust and secure Architecture neutral and portable High performance Interpreted, threaded, and dynamic CS 340 Java abbreviations 17 JDK: Java Development Kit JSDK: Java Servlet Development Kit JVM: Java Virtual Machine J2EE: Java Platform, Enterprise Edition. A widely used platform for server programming. CS 340 18 OOP or… Object Oriented Programming CS 340 Object-Oriented Programming 19 Object-oriented programming (OOP) is popular because: enables reuse of previous code saves time If a new class is similar to an existing class, the existing class can be extended This is called inheritance CS 340 Java is object oriented 20 Old programming languages: code was executed line by line and accessed variables or records Java objects that come with their own methods When coding in Java one is always thinking about “which object is running this code?” CS 340 Inheritance 21 Meat is a Food Meat has all the data fields and methods defined by Food Food is the superclass of Meat Meat is a subclass of Food Meat may define other variables and methods that are not contained in Food CS 340 Food expirationDate() Meat percentageOfProtein() A Superclass and Subclass Example 22 Robot A robot has a manufacturer processor disk parts processor speed Write the robot class CS 340 A Superclass and Subclass Example (cont.) 23 Robot A robot has a manufacturer processor disk Robot parts processor CS 340 speed String manufacturer String processor int diskSize int numberOfParts double processorSpeed A Superclass and Subclass Example (cont.) 24 Robot String manufacturer String processor int diskSize int numberOfParts double processorSpeed int getDiskSize() double getProcessorSpeed() int getParts() String toString() CS 340 A Superclass and Subclass Example (cont.) 254 Cylon A Cylon has all the properties of Robot, manufacturer processor disk parts processor speed plus, vision (pixels) hands (battle speed) What is a Cylon class? CS 340 A Superclass and Subclass Example (cont.) 26 Robot String manufacturer String processor int diskSize int numberOfParts double processorSpeed int getDiskSize() double getProcessorSpeed() int getParts() String toString() Cylon double pixels double battleSpeed CS 340 A Superclass and Subclass Example (cont.) 27 The constructor of a subclass begins by initializing the data fields inherited from the superclass(es) super(man, proc, parts, disk, procSpeed); which invokes the superclass constructor with the signature Robot(String man, String processor, int parts, int disk, double procSpeed) CS 340 A Superclass and Subclass Example (cont.) 28 /** Class that represents a robot */ public class Robot { private String manufacturer; private String processor; private int numParts; private int diskSize; private double processorSpeed; public Robot(String man, String processor, int numParts, int disk, double procSpeed) { //constructor manufactuer = man; this.processor = processor; this.numParts = numParts; diskSize = disk; processorSpeed = procSpeed; } } Write the methods’ code A Superclass and Subclass Example (cont.) 29 public double getProcessorSpeed() { return processorSpeed; } public int getDiskSize() { return diskSize; } public int getParts() { return numParts; } public String toString() { String result = "Manufacturer: " + manufacturer + "\nCPU: " + processor + "\nBody parts: " + numParts + "\nDisk: " + diskSize + " gigabytes" + "\nProcessor speed: " + processorSpeed + " gigahertz"; return result; } } CS 340 A Superclass and Subclass Example (cont.) 30 public class Cylon extends Robot { private double pixels; private double battleSpeed; public Cylon(String man, String processor, int parts, int disk, double procSpeed, double pix, double bSpeed) { super(man, proc, parts, disk, procSpeed); pixels = pix; battleSpeed = bSpeed; } } CS 340 Protected Visibility for Superclass Data Fields 31 Variables with private visibility (defined by the keyword private) cannot be accessed by a subclass Variables with protected visibility (defined by the keyword protected) are accessible by any subclass or any class in the same package By default variables are public, i.e., they can be accessed by any package CS 340 Is-a versus Has-a Relationships 32 In an is-a or inheritance relationship, one class is a subclass of the other class In a has-a or aggregation relationship, one class has the other class as an attribute CS 340 Is-a versus Has-a Relationships (cont.) 33 public class Robot { private Memory mem; ... } public class Memory { private int size; private int speed; private String kind; ... } A Robot has only one Memory But a Robot is not a Memory (i.e. not an is-a relationship) If a Cylon extends Robot,then the Cylon isa Robot CS 340