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  1. 1. Data Structures Using Java 1 Chapter 1 Software Engineering Principles and Java Classes
  2. 2. Data Structures Using Java 2 Chapter Objectives • Learn about software engineering principles • Discover what an algorithm is and explore problem-solving techniques • Become aware of structured design and object- oriented design programming methodologies • Learn about user-defined classes • Learn about private, protected, and public members of a class
  3. 3. Data Structures Using Java 3 Chapter Objectives • Explore how classes are implemented • Become aware of Unified Modeling Language (UML) notation • Examine constructors and destructors • Learn about the abstract data type (ADT) • Explore how classes are used to implement ADT
  4. 4. Data Structures Using Java 4 Software Life Cycle • Life cycle: the many phases a program goes through from the time it is conceived until the time it is retired • Three fundamental stages of a program – Development – Use – Maintenance
  5. 5. Data Structures Using Java 5 Software Development Phase • Analysis – Understand problem – Requirements analysis – Data analysis – Divide problem into subproblems and perform analysis
  6. 6. Data Structures Using Java 6 Software Development Phase • Design – Algorithm – Structured design • Divide problem into subproblems and analyze each subproblem – Object-oriented design • Identify components (objects) which form the basis of solution • Determine how these objects interact with one another
  7. 7. Data Structures Using Java 7 Software Development Phase • Three basic principles of object-oriented design (OOD) – Encapsulation: ability to combine data and operations in a single unit – Inheritance: ability to create new data types from existing data types – Polymorphism: ability to use the same expression to denote different operations
  8. 8. Data Structures Using Java 8 Software Development Phase • Implementation – Write and compile programming code to implement classes and functions discovered in design phase
  9. 9. Data Structures Using Java 9 Software Development Phase • Testing and Debugging – Test the correctness of the program to make sure it does what it is supposed to do – Find and fix errors – Run program through series of specific tests, test cases
  10. 10. Data Structures Using Java 10 Software Development Phase • Testing and Debugging – Black-box testing: test based on inputs and outputs not the internal working of the algorithm or function – White-box testing: relies on the internal structure and implementation of a function or algorithm; ensures that every part of the function or algorithm executes at least once
  11. 11. Data Structures Using Java 11 Algorithm Analysis: The Big-O Notation
  12. 12. Data Structures Using Java 12 Algorithm Analysis: The Big-O Notation
  13. 13. Data Structures Using Java 13 Algorithm Analysis: The Big-O Notation
  14. 14. Data Structures Using Java 14 Algorithm Analysis: The Big-O Notation
  15. 15. Data Structures Using Java 15 Algorithm Analysis: The Big-O Notation • Definition: Let f be a function of n.The term “asymptotic” means the study of the function f as n becomes larger and larger without bound.
  16. 16. Data Structures Using Java 16 Algorithm Analysis: The Big-O Notation
  17. 17. Data Structures Using Java 17 Classes • class: reserved word; collection of a fixed number of components • Components: member of a class • Members accessed by name • Class categories/modifiers – Private – Protected – public
  18. 18. Data Structures Using Java 18 Classes • private: members of class not accessible outside class • public: members of class accessible outside class • Class members: can be methods or variables • Variable members declared like any other variables
  19. 19. Data Structures Using Java 19 Syntax • General syntax for defining a class: modifier(s) class ClassIdentifier modifier(s) { classMembers } • General syntax for using the operator new: new className() or new className(argument1, argument2, ..., argumentN)
  20. 20. Data Structures Using Java 20 Classes • Syntax to access data member of class object or method: referenceVariableName.memberName • Shallow copying: two or more reference variables of the same type point to the same object • Deep copying: each reference variable refers to its own object
  21. 21. Data Structures Using Java 21 Constructors • Guarantee that data members are initialized when object is declared • Automatically execute when class object created • Name of constructor is name of class • More than one constructor can be present in one class • Default constructor: constructor without parameters
  22. 22. Data Structures Using Java 22 The Copy Constructor • Executes when an object is instantiated • Initialized using an existing object • Syntax public ClassName(ClassName otherObject)
  23. 23. Data Structures Using Java 23 UML Diagram
  24. 24. Data Structures Using Java 24 UML Diagram • Top box: Name of class • Middle box: data members and their data types • Bottom box: member methods’ names, parameter list, return type of method • + means public method • - means private method • # means protected method
  25. 25. Data Structures Using Java 25 Example: class Clock myClock = new Clock(); yourClock = new Clock(9,35,15);
  26. 26. Data Structures Using Java 26 Example: class Clock
  27. 27. Data Structures Using Java 27 Example: class Clock
  28. 28. Data Structures Using Java 28 The Method toString • Public value-returning method • Takes no parameters • Returns address of String object • Output using print and println methods • Default definition creates String with name of object’s class name followed by hash code of object
  29. 29. Data Structures Using Java 29 The Modifier Static • In method heading, specifies that method can be invoked by using name of class • If used to declare data member, data member invoked by using class name • Static data members of class exist even when no object of class type instantiated • Static variables are initialized to their default values
  30. 30. Data Structures Using Java 30 static Data Members of a Class Illustrate illusObject1 = new Illustrate(3); Illustrate illusObject2 = new Illustrate(5);
  31. 31. Data Structures Using Java 31 Finalizers • Automatically execute when class object goes out of scope • Have no parameters • Only one finalizer per class • Name of finalizer: finalize
  32. 32. Data Structures Using Java 32 Creating Packages • Can create packages using reserved word package – Define the class to be public (If class not public it can only be used within package) – Choose name for package. Organize package (create subdirectories)
  33. 33. Data Structures Using Java 33 The Reference this • Refers to instance variables and methods of a class • Used to implement cascaded method calls
  34. 34. Data Structures Using Java 34 Inner Classes • Defined within other classes • Can be either a complete class definition or anonymous inner class definition • Used to handle events
  35. 35. Data Structures Using Java 35 Abstract Data Types • Definition: A data type that specifies the logical properties without the implementation details
  36. 36. Data Structures Using Java 36 Programming Example: Candy Machine (Problem Statement) • A common place to buy candy is from a candy machine. A new candy machine is bought for the gym, but it is not working properly. The machine sells candies, chips, gum, and cookies. You have been asked to write a program for this candy machine so that it can be put into operation. • The program should do the following: 1. Show the customer the different products sold by the candy machine. 2. Let the customer make the selection. 3. Show the customer the cost of the item selected. 4. Accept money from the customer. 5. Release the item.
  37. 37. Data Structures Using Java 37 Programming Example: Candy Machine (Input and Output) • Input – Item Selection – Cost of Item • Output – The selected item
  38. 38. Data Structures Using Java 38 Programming Example: Candy Machine • Components – Cash Register – Several Dispensers
  39. 39. Data Structures Using Java 39 Programming Example: Candy Machine
  40. 40. Data Structures Using Java 40 Programming Example: Candy Machine
  41. 41. Data Structures Using Java 41 Programming Example: Candy Machine Object chips
  42. 42. Data Structures Using Java 42 Programming Example: Candy Machine Sample Run: In this sample run, the user input is shaded. *** Welcome to Shelly's Candy Shop *** To select an item, enter 1 for Candy 2 for Chips 3 for Gum 4 for Cookies 9 to exit 1 Please deposit 50 cents 50 Collect your item at the bottom and enjoy.
  43. 43. Data Structures Using Java 43 Object-Oriented Design • Simplified methodology 1. Write down detailed description of problem 2. Identify all (relevant) nouns and verbs 3. From list of nouns, select objects 4. Identify data components of each object 5. From list of verbs, select operations
  44. 44. Data Structures Using Java 44 Object-Oriented Design Example • Problem Statement – Write a program to input the dimensions of a cylinder and calculate and print the surface area and volume • Nouns – Dimensions, surface area, volume, cylinder
  45. 45. Data Structures Using Java 45 Chapter Summary • Software Life Cycle – Development, Use, Maintenance • Algorithm Analysis: The Big-O Notation • Classes • UML Diagram • Constructors, Destructors • Abstract Data Types
  46. 46. Data Structures Using Java 46 Chapter Summary • Software Development Phase – Analysis – Design • Structured design • Object-oriented design – Encapsulation, Inheritance, Polymorphism – Implementation – Testing and Debugging