Methods and containment arrows (lập TRÌNH cơ bản SLIDE)

Basic Programming Course Methods and Containment Arrows Week 4,5,6 Date example • Develop a program that helps you keep track of daily One date is described with three pieces of information: a day, a month, and a Class year Date Data type - int day - int month - int year Property or field Method Define Class, Constructor and test Constructor public class Date { private int day; private int month; private int year; public Date(int day, int month, int year) { this.day = day; this.month = month; this.year = year; } } import junit.framework.*; public class TestDate extends TestCase { public void testConstrutor(){ new Date(5, 6, 2003); // denotes June 5, 2003 new Date(6, 6, 2003); // denotes June 6, 2003 new Date(23, 6, 2000); // denotes June 23, 2000 } GPS Location example • Develop a GPS navigation program for cars The physical GPS unit feeds the program with the current location Each such location consists of two pieces of information: the latitude and the longitude Class GPSLocation - double latitude - double longitude Data type Property or field Method Define Class, Constructor and test Constructor public class GPSLocation { private double latitude /* degrees */; private double longitude /* degrees */; public GPSLocation(double latitude, double longitude) { this.latitude = latitude; this.longitude = longitude; } } import junit.framework.*; public class TestGPSLocation extends TestCase { public void testConstrutor(){ new GPSLocation (33.5, 86.8); new GPSLocation (40.2, 72.4); new GPSLocation (49.0, 110.3); } Class A class is a generic description of a “thing” It has: Attribute: describes the “thing” Attributes = Properties = Information = Fields = Data = Variables Behavior: describes what the “thing” does Behaviors = Methods = Functions = Operations State: describes the state that “thing” belongs to A “thing” in a computer system ‘come alive – they have behavior Car example With a Car • Attributes which we concern: manufacturer, color, speed,… • Behaviors can happen with a car: how to start up, how to speed up, • States: – when a car in good shape, it is in use state, – When it is damaged, it becomes not workable state, Book example A Book in library has: • Attributes that we concern : name, author, publisher, price,… • Behaviors can modeled with this book: borrow, payback,… • States: – If it is ready to be borrow, it in ready state – if it is borrowed, it becomes busy state – when it is old, damaged and taken stock of, it is in out of stock (thanh lý) state –… Room example A Room in hotel has: • Attributes we concern: name, kind (may be: usual, deluxe, VIP,…), price per day,… • Behavior can happen with a room: rent,… • States: – If it is ready to be rent, it is in ready state – if it is rent, it becomes busy state – when it is damaged, it is in-correct (sửa chữa) state –… Point example A point in monitor has: • Attributes: x coordinate, which tells us where the pixel is in the horizontal direction, and y coordinate, which tells us where the pixel is located in the downwards vertical direction and color • Behaivors: – Computes how far some pixel is from the origin – Computes the distance between pixels,… • State: ? So, some real-life objects not have state 10 Solution 3.1.3: inThisCity() way • Method implementation public boolean inThisCity(String city) { return this.address.getCity().equals(city); }// class House pubilc String getCity(){ return this.city; } //class Address • Unit testing public void testThisCity() { House house1 = new House("Ranch", 7, new Address("23", "Mapple Street", "Brooklyn"), 375000); House house2 = new House("Colonial", 9, new Address("5", "Jove Road", "Newton"), 450000); House house3 = new House("Cape", 6, new Address("83", "Winslow Road", "Waltham"), 235000); Assert.assertTrue(house1.inThisCity("Brooklyn")); Assert.assertFalse(house1.inThisCity("Newton")); } 102 Solution 3.1.3: inThisCity() way public boolean inThisCity(String city){ return this.address.inThisCity(city); }// class House public boolean inThisCity(String thatCity) { return this.city.equals(thatCity); }//class Address 103 Solution 3.1.3: sameCity() way • Method implementation public boolean sameCity(House that) { return this.address.getCity().equals(that.address.getCity()); } • Unit testing public void testSameCity() { House house1 = new House("Ranch", 7, new Address("23", "Mapple Street", "Brooklyn"), 375000); House house2 = new House("Colonial", 9, new Address("5", "Jove Road", "Newton"), 450000); House house3 = new House("Cape", 6, new Address("83", "Winslow Road", "Waltham"), 235000); Assert.assertTrue(house1.sameCity(house1)); Assert.assertFalse(house1.sameCity(house2)); } 104 Solution 3.1.3: sameCity() way public boolean sameCity(House that){ return this.address.sameCity(that.address); } //class House public boolean sameCity(Address that) { return this.city.equals(that.city); }// class Address Back 105 Ranch • A ranch is a large farm used for raising animals, especially cattle, horses or sheep 106 Back Colonial • A colonial building or piece of furniture was built or made in a style that was popular in American in the 17th and 18th centuries 107 Cape • A cape is a large piece of land that sticks out into the sea from the coast 108 Solution 4.1.1 109 currentBook() • Method implementation public boolean currentBook() { int currentYear = 2004; return (this.year == currentYear) || (this.year == currentYear - 1); } • Unit testing public void testCurrentBook() { Author felleisen = new Author("Matthias Felleisen", 1960); Book htdch = new Book(felleisen, "How to Design Class Hierarchies", 0.0, 2004); Assert.assertTrue(htdch.currentBook()); } Author friedman = new Author("Daniel P Friedman", 1939); Book aljafp = new Book(friedman, "A Little Java, A Few Pattern", 25.9, 1998); Assert.assertFalse(aljafp.currentBook()); 110 currentAuthor() • Method implementation public boolean currentAuthor() { // in class Book.java return this.author.currentAuthor(); } public boolean currentAuthor() { // in class Author.java return this.birthYear >= 1940; } • Unit testing public void testCurrentAuthor() { Author felleisen = new Author("Matthias Felleisen", 1960); Book htdch = new Book(felleisen, "How to Design Class Hierarchies", 0.0, 2004); Assert.assertTrue(htdch.currentAuthor()); } Author friedman = new Author("Daniel P Friedman", 1939); Book aljafp = new Book(friedman, "A Little Java, A Few Pattern", 25.9, 1998); Assert.assertFalse(aljafp.currentAuthor()); 111 thisAuthor() • Method implementation public boolean thisAuthor(Author that) { // in class Book.java return this.author.thisAuthor(that); } public boolean thisAuthor(Author that) { // in class Author.java return (this.name.equals(that.name)) && (this.birthYear == that.birthYear); } • Unit testing public void testThisAuthor() { Author felleisen = new Author("Matthias Felleisen", 1960); Book htdch = new Book(felleisen, "How to Design Class Hierarchies", 0.0, 2004); Assert.assertTrue(htdch.thisAuthor(felleisen)); } Author friedman = new Author("Daniel P Friedman", 1939); Assert.assertFalse(htdch.thisAuthor(friedman)); 112 sameAuthor() • Method implementation public boolean sameAuthor(Book that) { // in class Book.java return this.author.thisAuthor(that.author); } • Unit testing public void testSameAuthor() { Author felleisen = new Author("Matthias Felleisen", 1960); Book htdch = new Book(felleisen, "How to Design Class Hierarchies", 0.0, 2004); Book htdp = new Book(felleisen, "How to Design Programs", 0.0, 2002); Assert.assertTrue(htdch.sameAuthor(htdp)); } Author friedman = new Author("Daniel P Friedman", 1939); Book aljafp = new Book(friedman, "A Little Java, A Few Pattern", 25.9, 1998); Assert.assertFalse(aljafp.sameAuthor(htdch)); 113 sameGeneration() • Method implementation public boolean sameGeneration(Book that) { // in class Book.java return this.author.sameGeneration(that.author); } public boolean sameGeneration(Author that) { // in class Author.java return Math.abs(this.birthYear - that.birthYear) = thatPrecipitation; } } public boolean recordDay() { return ! this.today.within(this.record); } public class TemperatureRange { private double low; private double high; … } public boolean within(TemperatureRange that) { return (this.low >= that.low) && (this.high