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Starting Out with Java: From Control Structures through Objects 5 th edition By Tony Gaddis

Starting Out with Java: From Control Structures through Objects 5 th edition By Tony Gaddis Source Code: Chapter 8. Code Listing 8-1 (Countable.java) 1 /** 2 This class demonstrates a static field . 3 */ 4 5 public class Countable 6 {

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Starting Out with Java: From Control Structures through Objects 5 th edition By Tony Gaddis

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  1. Starting Out with Java:From Control Structures through Objects 5th edition By Tony Gaddis Source Code: Chapter 8

  2. Code Listing 8-1 (Countable.java) 1 /** 2 This class demonstrates a static field. 3 */ 4 5 public class Countable 6 { 7 private staticint instanceCount = 0; // What category of variable? 8 // What is it’s scope? 9 /** 10 The constructor increments the static 11 field instanceCount. This keeps track 12 of the number of instances of this 13 class that are created. 14 */ 15 16 public Countable() 17 { 18 instanceCount++; 19 } 20 (Continued)

  3. 21 /** 22 The getInstanceCount method returns 23 the number of instances of this class 24 that have been created. 25 @return The value in the instanceCount field. 26 */ 27 28 public intgetInstanceCount() 29 { 30 return instanceCount; 31 } 32 }

  4. Code Listing 8-2 (StaticDemo.java) 1 /** 2 This program demonstrates the Countable class. 3 */ 4 5 public class StaticDemo 6 { 7 public static void main(String[] args) 8 { 9 int objectCount; 10 // Create three instances 13Countable object1 = new Countable(); 14 Countable object2 = new Countable(); 15 Countable object3 = new Countable(); 16 17 18 19 objectCount = object1.getInstanceCount(); 20 System.out.println(objectCount + 21 "instances of the class " + 22 "were created."); 23 } 24 } Program Output 3 instances of the class were created.

  5. Code Listing 8-3 (Metric.java) 1 /** 2 This class demonstrates static methods. 3 */ 4 5 public class Metric 6 { 7 /** 8 The milesToKilometers method converts a 9 distance in miles to kilometers. 10 @param m The distance in miles. 11 @return The distance in kilometers. 12 */ 13 14 public staticdouble milesToKilometers( double m ) 15 { 16 return m * 1.609; 17 } 18 (Continued)

  6. (Continued) Code Listing 8-3 (Metric.java) 19 /** 20 The kilometersToMiles method converts 21 a distance in kilometers to miles. 22 @param k The distance in kilometers. 23 @return The distance in miles. 24 */ 25 26 public static double kilometersToMiles(double k ) 27 { 28 return k / 1.609; 29 } 30 }

  7. Code Listing 8-4 (MetricDemo.java) 1 import javax.swing.JOptionPane; 2 import java.text.DecimalFormat; 3 4 /** 5 This program demonstrates the Metric class. 6 */ 7 8 public class MetricDemo 9 { 10 public static void main(String[] args) 11 { 12 String input; 13 double miles; 14 double kilos; 15 16 17 DecimalFormatfmt =new DecimalFormat("0.00"); 19 20 21 input = JOptionPane.showInputDialog("Enter" + "a distance in miles."); 23 miles = Double.parseDouble(input); (Continued)

  8. kilos =Metric.milesToKilometers(miles); // Invoked thru? 27 JOptionPane.showMessageDialog(null, 28 fmt.format(miles) + "miles equals " + 29 fmt.format(kilos) + " kilometers."); 30 32 input =JOptionPane.showInputDialog("Enter " + 33 "a distance in kilometers:"); 34 kilos =Double.parseDouble(input); 35 37 miles =Metric.kilometersToMiles(kilos); // Invoked thru? 38 JOptionPane.showMessageDialog(null, 39 fmt.format(kilos) + " kilometers equals " + 40 fmt.format(miles) + " miles."); 41 42 System.exit(0); 43 } 44 }

  9. Code Listing 8-5 (PassObject.java) 1 /** 2 This program passes an object as an argument. 3 */ 4 5 public class PassObject 6 { 7 public static voidmain(String[] args) 8 { 9 10 Rectangle box = new Rectangle(12.0, 5.0); 11 12 // Pass a reference to the object to // the displayRectangle method. 14 displayRectangle(box); // Where defined? 15 } 16 17 /** 18 The displayRectangle method displays the 19 length and width of a rectangle. 20 @param r A reference to a Rectangle 21 object. 22 */ (Continued)

  10. 23 24 public static void displayRectangle(Rectangle r) 25 { 26 // Display the length and width. 27 System.out.println("Length : " +r.getLength() + // Calls an Instance Method 28 " Width : " +r.getWidth()); // from a static method 29 } } Program Output Length : 12.0 Width : 5.0

  11. Code Listing 8-6 (PassObject2.java) 1 /** 2 This program passes an object as an argument. 3 The object is modified by the receiving method. 4 */ 5 6 public class PassObject2 7 { 8 public static void main(String[] args) 9 { 10 11 Rectangle box = new Rectangle(12.0, 5.0); 12 13 14 System.out.println("Contents of the box object:"); 15 System.out.println("Length : " + box.getLength() + 16 " Width : " +box.getWidth()); 17 18 // Pass a reference to the object to the // changeRectangle method. 20 changeRectangle(box); (Continued)

  12. 23 System.out.println("\nNow the contents of the " + 24 "box object are:"); 25 System.out.println("Length : " + box.getLength() + 26 " Width : " + box.getWidth()); 27 } 28 29 /** 30 The changeRectangle method sets a Rectangle 31 object's length and width to 0. 32 @param r The Rectangle object to change. 33 */ 34 35 publicstaticvoid changeRectangle( Rectangle r ) 36 { 37 r.setLength(0.0); 38 r.setWidth(0.0); 39 } 40 } Program Output Contents of the box object: Length : 12.0 Width : 5.0 Now the contents of the box object are: Length : 0.0 Width : 0.0

  13. Code Listing 8-7 (ReturnObject.java) 1 import javax.swing.JOptionPane; 2 3 /** 4 This program demonstrates how a method 5 can return a reference to an object. 6 */ 7 8 public class ReturnObject 9 { 10 public static voidmain(String[] args) 11 { 12 BankAccount account; 13 14 15 account = getAccount(); // Returns what? 16 17 18 JOptionPane.showMessageDialog(null, 19 "The account has a balance of $" + 20 account.getBalance()); 21 22 System.exit(0); 23 } (Continued)

  14. 24 25 /** 26 The getAccount method creates a BankAccount 27 object with the balance specified by the 28 user. 29 @return A reference to the object. 30 */ 31 32 public staticBankAccountgetAccount() 33 { 34 String input; // To hold input 35 double balance; // Account balance 36 37 38 input= JOptionPane.showInputDialog("Enter " + 39 "the account balance."); 40 balance = Double.parseDouble(input); 41 42 43 44 returnnewBankAccount(balance); 45 } 46 }

  15. Code Listing 8-8 (Stock.java) 1 /** 2 The Stock class holds data about a stock. 3 */ 4 5 public class Stock 6 { 7 private Stringsymbol; // Trading symbol of stock 8 private doublesharePrice; // Current price per share 9 10 /** 11 Constructor 12 @param sym The stock's trading symbol. 13 @param price The stock's share price. 14 */ 15 16 publicStock( String sym, double price ) 17 { 18 symbol = sym; 19 sharePrice = price; 20 } 21 (Continued)

  16. 22 /** 23 getSymbol method 24 @return The stock's trading symbol. 25 */ 26 27 public String getSymbol() 28 { 29 return symbol; 30 } 31 32 /** 33 getSharePrice method 34 @return The stock's share price 35 */ 36 37 public double getSharePrice() 38 { 39 return sharePrice; 40 } 41 (Continued)

  17. 42 /** 43 toString method 44 @return A string indicating the object's 45 trading symbol and share price. 46 */ 47 48 public String toString() // EXPLICIT toString() 49 { // Create a string describing the stock. 51 Stringstr="Trading symbol: " + symbol + 52 "\nShare price: " + sharePrice; 53 54 55 return str; 56 } 57 }

  18. Code Listing 8-9 (StockDemo1.java) 1 /** 2 This program demonstrates the Stock class's 3 toString method. 4 */ 5 6 public class StockDemo1 7 { 8 public static voidmain(String[] args) 9 { 10 // Create a Stock object for the XYZ Company. 11 Stock xyzCompany = new Stock ("XYZ", 9.62); 14 // Display the object's values. 16 System.out.println(xyzCompany); // What method is called? 17 } 18 } // Auto call under what 2 // conditions? Program Output Trading symbol: XYZ Share price: 9.62

  19. Code Listing 8-10 (StockCompare.java) 1 /** 2 This program uses the Stock class's equals method to compare two Stock objects. See 514-515 for “equals”. 4 */ 5 6 public class StockCompare 7 { 8 public static voidmain(String[] args) 9 { 11 Stock company1 = new Stock("XYZ", 9.62); 12 Stock company2 = new Stock("XYZ", 9.62); 13 14 15 if (company1.equals(company2)) 16 System.out.println("Both objects are the same."); 17 else 18 System.out.println("The objects are different."); 19 } } Program Output Both objects are the same.

  20. Code Listing 8-11 (ObjectCopy.java) 1 /** 2 This program uses the Stock class's copy method 3 to create acopy of a Stock object. ( see pg. 517) 4 */ 5 6 public class ObjectCopy 7 { 8 public static void main(String[] args) 9 { 11 Stockcompany1 = new Stock("XYZ", 9.62); 12 14 Stock company2; 15 16 // copy()- makes a new stock object-uses IV’s of company1. // returns addr of new object company2 = company1.copy(); 19 20 // Display the contents of both objects. 21 System.out.println("Company 1:\n" + company1); // Calls toString() // implicitly 22 System.out.println(); 23 System.out.println("Company 2:\n" + company2); (Continued)

  21. 24 25 // Confirm that we actually have two objects. 26 if (company1 == company2) 27 { 28 System.out.println("The company1 and company2 " + 29 "variables reference the same object."); 30 } 31 else 32 { 33 System.out.println("The company1 and company2 " + 34 "variables reference different objects."); 35 } 36 } 37 } Program Output Company 1: Trading symbol: XYZ Share price: 9.62 Company 2: Trading symbol: XYZ Share price: 9.62 The company1 and company2 variables reference different objects.

  22. Code Listing 8-12 (Instructor.java) 1 /** 2 This class stores data about an instructor. 3 */ 4 5 public class Instructor 6 { 7 private String lastName; // Last name 8 private String firstName; // First name 9 private String officeNumber; // Office number 10 11 /** 12 This constructor initializes the last name, 13 first name, and office number. 14 @param lname The instructor's last name. 15 @param fname The instructor's first name. 16 @param office The office number. 17 */ 18 19 publicInstructor(String lname, String fname, 20 String office) (Continued)

  23. 21 { 22 lastName = lname; 23 firstName = fname; 24 officeNumber = office; 25 } 26 27 /** 28 The copy constructor initializes the object 29 as a copy of another Instructor object. 30 @param object2 The object to copy. 31 */ 32 33 publicInstructor(Instructor object2) 34 { 35 lastName = object2.lastName; 36 firstName = object2.firstName; 37 officeNumber = object2.officeNumber; 38 } 39 40 /** 41 The set method sets a value for each field. 42 @param lname The instructor's last name. (Continued)

  24. 43 @param fname The instructor's first name. 44 @param office The office number. 45 */ 46 47 public void set(String lname, String fname, 48 String office) 49 { 50 lastName = lname; 51 firstName = fname; 52 officeNumber = office; 53 } 54 55 /** 56 toString method 57 @return A string containing the instructor 58 information. 59 */ 60 (Continued)

  25. 61 public String toString() 62 { // Create a string representing the object. 64 String str = "Last Name: " + lastName + 65 "\nFirst Name: " +firstName + 66 "\nOffice Number: " + officeNumber; 67 68 69 return str; 70 } 71 }

  26. Code Listing 8-13 (TextBook.java) 1 /** 2 This class stores data about a textbook. 3 */ 4 5 public class TextBook 6 { 7 private String title; // Title of the book 8 private String author; // Author's last name 9 private String publisher; // Name of publisher 10 11 /** 12 This constructor initializes the title, 13 author, and publisher fields 14 @param textTitle The book's title. 15 @param auth The author's name. 16 @param pub The name of the publisher. 17 */ 18 19 public TextBook(String textTitle, String auth, 20 String pub) 21 { 22 title= textTitle; 23 author = auth; (Continued)

  27. 24 publisher = pub; 25 } 26 27 /** 28 The copy constructor initializes the object 29 as a copy of another TextBook object. 30 @param object2 The object to copy. 31 */ 32 33 public TextBook( TextBook object2 ) 34 { 35 title = object2.title; 36 author = object2.author; 37 publisher = object2.publisher; 38 } 39 40 /** 41 The set method sets a value for each field. 42 @param textTitle The book's title. 43 @param auth The author's name. 44 @param pub The name of the publisher. 45 */ 46 47 public void set(String textTitle, String auth, (Continued)

  28. 48 String pub) 49 { 50 title = textTitle; 51 author = auth; 52 publisher = pub; 53 } 54 55 /** 56 toString method 57 @return A string containing the textbook 58 information. 59 */ 60 61 public String toString() 62 { 63 // Create a string representing the object. 64 String str = "Title: " + title + 65 "\nAuthor: " + author + 66 "\nPublisher: " + publisher; 67 68 69 return str; 70 } 71 }

  29. Code Listing 8-14 (Course.java) 1 /** 2 This class stores data about a course. Aggregate data. 3 */ 4 5 public class Course 6 { 7 private String courseName; // Name of the course 8 private Instructorinstructor; // Course “has an” instructor 9 private TextBooktextBook; // Course “has a” textbook 10 11 /** 12 This constructor initializes the courseName, 13 instructor, and text fields. 14 @param name The name of the course. 15 @param instructor An Instructor object. 16 @param text A TextBook object. 17 */ 18 19 public Course(String name, Instructorinstr, 20 TextBooktext) 21 { 22 // Assign the courseName. 23 courseName = name; (Continued)

  30. 24 25 // Init IV with a “deep copy” of the parameter object. 26 27 instructor = new Instructor(instr); 28 29 // Init IV with a “deep copy” of the parameter object. 30 31 textBook =newTextBook(text); 32 } 33 34 /** 35 getName method 36 @return The name of the course. 37 */ 38 39 public String getName() 40 { 41 return courseName; 42 } 43 44 /** 45 getInstructor method 46 @return A reference to a copy of this course's (Continued)

  31. 47 Instructor object. 48 */ 49 50 public Instructor getInstructor() 51 { 52 // Return a copy of the instructor object. 53 return new Instructor(instructor); // Returns a copy of object, not 54 } // reference to the object. 55 // See 527-529, “Shallow” copy and security 56 /** 57 getTextBook method 58 @return A reference to a copy of this course's 59 TextBook object. 60 */ 61 62 public TextBook getTextBook() 63 { 64 // Return a copy of the textBook object. 65 return new TextBook(textBook); // Same as comments above. 66 } 67 68 /** 69 toString method (Continued)

  32. 70 @return A string containing the course information. 71 */ 72 73 public String toString() 74 { 75 // Create a string representing the object. 76 String str = "Course name: " + courseName + 77 "\nInstructor Information:\n" + 78 instructor + 79 "\nTextbook Information:\n" + 80 textBook; 81 // “courseName” - String IV // “instructor” -Instructor class toString() //“textBook” - Textbook class toString() 83 return str; 84 } 85 }

  33. Code Listing 8-15 (CourseDemo.java) 1 /** 2 This program demonstrates the Course class. 3 */ 4 5 public class CourseDemo 6 { 7 public static void main(String[] args) 8 { 9 // Create an Instructor object. 10 Instructor myInstructor = new Instructor("Kramer", "Shawn", "RH3010"); 12 13 // Create a TextBook object. 14 TextBook myTextBook = new TextBook("Starting Out with Java", 16 "Gaddis", "Addison-Wesley"); 17 18 // Create a Course object. 19 CoursemyCourse =new Course("Intro to Java", myInstructor,myTextBook); 22 23 // Display the course information. (Continued)

  34. 24 System.out.println(myCourse); // Implicit call to ? 25 } 26 Program Output Course name: Intro to Java Instructor Information: Last Name: Kramer First Name: Shawn Office Number: RH3010 Textbook Information: Title: Starting Out with Java Author: Gaddis Publisher: Addison-Wesley

  35. Code Listing 8-16 (FullName.java) 1 /** 2 This class stores a person's first, last, and middle 3 names. The class is dangerous because it does not prevent operations on null reference fields. NOTE:No explicit constructor 5 */ 6 7 public class FullName 8 { 9 private String lastName; // Last name 10 private String firstName; // First name 11 private String middleName; // Middle name 12 13 /** 14 The setLastName method sets the lastName field. 15 @param str The String to set lastName to. 16 */ 17 18 public void setLastName(String str) 19 { 20 lastName = str; 21 } 22 23 /** (Continued)

  36. 24 The setFirstName method sets the firstName field. 25 @param str The String to set firstName to. 26 */ 27 28 public void setFirstName(String str) 29 { 30 firstName = str; 31 } 32 33 /** 34 The setMiddleName method sets the middleName field. 35 @param str The String to set middleName to. 36 */ 37 38 public void setMiddleName(String str) 39 { 40 middleName = str; 41 } 42 43 /** 44 The getLength method returns the length of the 45 full name. 46 @return The length. (Continued)

  37. 47 */ 48 49 public int getLength() 50 { 51 return lastName.length() + firstName.length() 52 + middleName.length(); 53 } 54 55 /** 56 The toString method returns the full name. 57 @return A reference to a String. 58 */ 59 60 public String toString() 61 { 62 return firstName + " " + middleName + " " 63 + lastName; 64 } 65 }

  38. Code Listing 8-17 (NameTester.java) 1 /** 2 This program creates a FullName object, and then 3 calls the object's getLength method before values 4 are established for its reference fields. As a 5 result,this program will crash. 6 */ 7 8 public class NameTester 9 { 10 public static voidmain(String[] args) 11 { 12 int len; // To hold the name length 13 14 // Create a FullName object. 15 FullName name = new FullName(); 16 // Get the length of the full name. 18 len = name.getLength(); // Will cause crash! Why? 19 } 20 }

  39. Code Listing 8-18 (EnumDemo.java) 1 /** 2 This program demonstrates an enumerated type. 3 */ 4 5 public class EnumDemo 6 { 7 8 enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, 9 THURSDAY, FRIDAY, SATURDAY } 10 11 public static void main(String[] args) 12 { 13 14 Day workDay = Day.WEDNESDAY; 15 16 17 System.out.println(workDay); 18 20 21 System.out.println("The ordinal value for " + 22 Day.SUNDAY + " is " + 23 Day.SUNDAY.ordinal()); (Continued)

  40. 24 27 System.out.println("The ordinal value for " + 28 Day.SATURDAY + " is " + 29 Day.SATURDAY.ordinal()); 30 31 32 if (Day.FRIDAY.compareTo(Day.MONDAY) > 0) 33 System.out.println(Day.FRIDAY + " is greater than " + 34 Day.MONDAY); 35 else 36 System.out.println(Day.FRIDAY + " is NOT greater than " + 37 Day.MONDAY); 38 } 39 } Program Output WEDNESDAY The ordinal value for SUNDAY is 0 The ordinal value for SATURDAY is 6 FRIDAY is greater than MONDAY

  41. Code Listing 8-19 (CarType.java) 1 /** 2 CarType enumerated data type 3 */ 4 5 enum CarType { PORSCHE, FERRARI, JAGUAR }

  42. Code Listing 8-20 (CarColor.java) 1 /** 2 CarColor enumerated data type 3 */ 4 5 enum CarColor { RED, BLACK, BLUE, SILVER }

  43. Code Listing 8-21 (SportsCar.java) 1 import java.text.DecimalFormat; 2 3 /** 4 SportsCar class 5 */ 6 7 public class SportsCar 8 { 9 private CarTypemake; // The car's make 10 private CarColor color; // The car's color 11 private double price; // The car's price 12 13 /** 14 The constructor initializes the car's make, 15 color, and price. 16 @param aMake The car's make. 17 @param aColor The car's color. 18 @param aPrice The car's price. 19 */ 20 21 public SportsCar( CarType aMake, CarColor aColor, 22 doubleaPrice) 23 { (Continued)

  44. 24 make = aMake; 25 color = aColor; 26 price = aPrice; 27 } 28 29 /** 30 getMake method 31 @return The car's make. 32 */ 33 34 public CarType getMake() 35 { 36 return make; 37 } 38 39 /** 40 getColor method 41 @return The car's color. 42 */ 43 44 publicCarColor getColor() 45 { 46 return color; (Continued)

  45. 47 } 48 49 /** 50 getPrice method 51 @return The car's price. 52 */ 53 54 public double getPrice() 55 { 56 return price; 57 } 58 59 /** 60 toString method 61 @return A string indicating the car's make, 62 color, and price. 63 */ 64 65 public String toString() 66 { 67 // Create a DecimalFormat object for 68 // dollar formatting. 69 DecimalFormat dollar = new DecimalFormat("#,##0.00"); (Continued)

  46. 70 // Create a string representing the object. 72 String str = "Make: " + make + 73 "\nColor: " + color + 74 "\nPrice: $" + dollar.format(price); 75 // Return the string. 77 return str; 78 } 79 }

  47. Code Listing 8-22 (SportsCarDemo.java) 1 /** 2 This program demonstrates the SportsCar class. 3 */ 4 5 public class SportsCarDemo 6 { 7 public static voidmain(String[] args) 8 { // Create a SportsCar object. 10 SportsCar yourNewCar = new SportsCar (CarType.PORSCHE, 11 CarColor.RED, 100000); 12 14 System.out.println(yourNewCar); 15 } 16 } Program Output Make: PORSCHE Color: RED Price: $100,000.00

  48. Code Listing 8-23 (SportsCarDemo2.java) 1 /** 2 This program shows that you can switchon an 3 enumerated type. 4 */ 5 6 public class SportsCarDemo2 7 { 8 public static void main(String[] args) 9 { 10 11 SportsCar yourNewCar = new SportsCar(CarType.PORSCHE, 12 CarColor.RED, 100000); 13 14 15 switch ( yourNewCar.getMake() ) 16 { 17 case PORSCHE : 18 System.out.println("Your car was made in Germany."); 19 break; 20 case FERRARI : 21 System.out.println("Your car was made in Italy."); 22 break; 23 case JAGUAR :

  49. 24 System.out.println("Your car was made in England."); 25 break; 26 default: 27 System.out.println("I'm not sure where that car " 28 + "was made."); 29 } 30 } } Program Output Your car was made in Germany.

  50. Code Listing 8-24 (StockPurchase.java) 1 /** The StockPurchase class represents a stock purchase. Class collaboration. Uses Stock class. 3 */ 4 5 public class StockPurchase 6 { 7 private Stockstock; // The stock that was purchased 8 private intshares; // Number of shares owned 9 10 /** 11 Constructor 12 @param stockObject The stock to purchase. 13 @param numShares The number of shares. 14 */ 15 16 publicStockPurchase(Stock stockObject, intnumShares) 17 { 18 // Create a copy of the object referenced by // stockObject. stock = newStock(stockObject); //CreatesStockobject copy. shares = numShares; 22 } 23 (Continued)

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