類別與物件 I (Classes and Objects I)

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1 類別與物件 I (Classes and Objects I)
鄭士康 國立台灣大學 電機工程學系/電信工程研究所/ 資訊網路與多媒體研究所

2 結構化程式設計/逐步細分法 序列/分支/迴圈 虛擬碼 Magic number 7 加減 2 逐層分解工作 函式 軟體危機

3 物件導向程式設計 (Object-Oriented Programming)
軟體IC/程式碼重覆使用( Code Reuse) 封裝(Encapsulation) 狀態、行為 模擬 繼承(Inheritance) 多型(Polymorphism)

4 程式 DiceSimulation (1/4) using System; namespace DiceSimulation { /*
* 模擬擲骰子示範類別的宣告與物件的使用 * 3/16/2008 * * 測試規畫: * 六個點數出現次數應該大約相同 */ class Program static void Main(string[] args)

5 程式 DiceSimulation (2/4) int[] count = new int[6]; // 累計點數出現次數
for (int i = 0; i < 6; ++i) { count[i] = 0; } const int N = 12000; // 總擲骰次數 int faceValue; Dice dice = new Dice(); // 擲骰N次 for (int i = 0; i < N; ++i) dice.Toss(); faceValue = dice.FaceValue; ++count[faceValue-1];

6 程式 DiceSimulation (3/4) // 印出結果 for (int i = 0; i < 6; ++i) {
Console.WriteLine(" {0} appears {1} times ", i + 1, count[i]); }

7 程式 DiceSimulation (4/4) public class Dice { int faceValue = 1;
Random rand = new Random(); public int FaceValue get { return faceValue; } set { faceValue = value; } } public void Toss() faceValue = rand.Next() % 6 + 1;

8 函式呼叫流程 static void Main(string[] args) { public class Dice { . . .
public void Toss() faceValue = rand.Next() % 6 + 1; } dice.Toss(); } public class Random { . . . public int Next() }

9 類別(Class)觀念 類別 Dice 資料變數(欄位成員 field) faceValue, rand
方法函式(函式成員 function, 屬性 attribute) FaceValue Toss()

10 堆疊(Stack)與堆積(Heap) Heap . Stack

11 實值型別儲存方式 堆疊(Stack) int x = 100; x 100

12 參考型別儲存方式 堆積(Heap) 堆疊(Stack) string x = “abc”; x 參考 ‘a’ ‘b’ ‘c’

13 物件(Object)觀念 dice1 dice1.faceValue 記憶體地址1 dice1.rand 函式Toss進入地址 dice2
dice2.fileName 記憶體地址2 dice2.rand 函式Toss進入地址 函式成員Toss進入點

14 物件的設定(Assignment) dice2 = dice1; dice1 dice1.faceValue 記憶體地址1
dice1.rand 函式Toss進入地址 dice2 dice2 = dice1; dice2.fileName 記憶體地址2 dice2.rand 函式Toss進入地址 函式成員Toss進入點

15 UML 的類別符號 Dice faceValue : int rand: Random FaceValue Toss() : void

16 練習1 宣告並測試以下類別 Car speed : int driver : string Speed Driver
Accelerate() PutOnBrakes()

17 程式 CalculatorTest (1/6) using System; namespace CalculatorTest {
* 3/17/2007 */ class Program static void Main(string[] args) int op = 0; int operand1; int operand2; int result; Calulator calculator = new Calulator();

18 程式 CalculatorTest (2/6) do { Console.Write(
"指定運算: 0. 結束; 1. 加; 2. 減; 3. 乘; 4. 除: "); op = int.Parse(Console.ReadLine()); if (op == 0) break; if (op > 4) continue; Console.Write("輸入第一個數字: "); operand1 = int.Parse(Console.ReadLine()); Console.Write("輸入第二個數字: "); operand2 = int.Parse(Console.ReadLine()); switch (op)

19 程式 CalculatorTest (3/6) case 1: result = calculator.Add(operand1,
Console.WriteLine("{0} + {1} = {2} ", operand1, operand2, result); break; case 2: result = calculator.Subtract(operand1, Console.WriteLine("{0} - {1} = {2} ", case 3: result = calculator.Multiply(operand1,

20 程式 CalculatorTest (4/6) Console.WriteLine("{0} * {1} = {2} ",
operand1, operand2, result); break; case 4: result = calculator.Divide(operand1, operand2); Console.WriteLine("{0} / {1} = {2} ", default: Console.WriteLine( "Should not appear this message. Debug!!!"); } } while (true);

21 程式 CalculatorTest (5/6) /* * 計算器 * 3/17/2007 */ public class Calulator
{ public int Add(int a, int b) int result = a + b; return result; } public int Subtract(int a, int b) int result = a - b;

22 程式 CalculatorTest (6/6) public int Multiply(int a, int b) {
int result = a * b; return result; } public int Divide(int a, int b) int result = a / b;

23 函式傳回值 Program.Main() result calculator.Add() result return value

24 程式SwapIntegers (1/2) using System; namespace SwapIntegers {
/* 交換兩個整數變數 * 以說明傳值呼叫與傳址呼叫 * skj 4/5/2008 */ class Program static void Main(string[] args) int x = 3; int y = 5; Console.WriteLine("x = {0}, y = {1}", x, y); Swap(ref x, ref y); }

25 程式SwapIntegers (2/2) static void Swap(ref int x, ref int y) {
int temp = x; x = y; y = temp; }

26 程式 PassByReferenceAndOut (1/4)
using System; namespace PassByReferenceAndOut { /* * 示範傳址參數與out參數的使用方法 * 3/31/2008 */ class Program static void Main(string[] args) double length = 100.0; Square s = new Square(); s.Side = length;

27 程式 PassByReferenceAndOut (2/4)
double area1 = 0.0; double perimeter1 = 0.0; s.GetAreaAndPerimeter(ref area1, ref perimeter1); Console.WriteLine( "正方形邊長: {0}, 面積: {1}, 周長: {2}", length, area1, perimeter1); double area2; double perimeter2; s.GetAreaAndPerimeterUsingOut(out area2, out perimeter2); "正方形邊長: {0}, 面積: {1}, 周長: {2}", length, area2, perimeter2); Console.ReadLine(); }

28 程式 PassByReferenceAndOut (3/4)
/* * 正方形 * 3/16/2008 */ public class Square { double a; public double Side get { return a; } set { a = value; } }

29 程式 PassByReferenceAndOut (4/4)
public void GetAreaAndPerimeter(ref double area, ref double perimeter) { area = Math.Pow(a, 2); perimeter = 4.0 * a; } public void GetAreaAndPerimeterUsingOut( out double area, out double perimeter)

30 傳值, 傳址, out 參數 傳值參數傳遞( Pass by value ) 傳址參數傳遞( Pass by reference )
初值設定問題

31 類別Time Time hour : int min : int sec : int SetTime() GetTime()

32 程式 UsingThis (1/4) using System; namespace UsingThis { /* * 說明this的使用
* 3/17/2007 */ class Program static void Main(string[] args) Time t = new Time(); t.SetTime(11, 30, 52);

33 程式 UsingThis (2/4) int hour; int min; int sec;
t.GetTime(out hour, out min, out sec); Console.WriteLine("現在時間{0} : {1} : {2}", hour, min, sec); Console.ReadLine(); } /* * 以時,分,秒表示時間 */

34 程式 UsingThis (3/4) public class Time { int hour; int min; int sec;
public void SetTime(int hour, int min, int sec) bool error = ( hour < 0 || hour > 24 || min < 0 || min > 59 || sec < 0 || sec > 59 ); if (!error) this.hour = hour; this.min = min; this.sec = sec; }

35 程式 UsingThis (4/4) else { Console.WriteLine(
"Time.SetTime>>參數值不合理"); } public void GetTime(out int hour, out int min, out int sec) hour = this.hour; min = this.min; sec = this.sec;

36 物件自我參考 this t 記憶體地址 hour min sec this SetTime()進入地址 函式成員SetTime進入點

37 極端化程式設計 (Extreme Programming)
撰寫一個簡單的測試程式 編譯執行程式，看它失敗 增添恰能通過測試之程式碼並編譯偵錯 重整及消除冗餘程式碼並編譯偵錯 反覆進行上述步驟

38 練習(1/4) 寫主程式 以傳值參數參照下一頁虛擬碼，寫一個函式Swap交換兩張牌位置
宣告陣列 Card[] deck = new Card[2] 在deck中放入兩張撲克牌Card物件 呼叫函數Swap交換兩張牌位置 以傳值參數參照下一頁虛擬碼，寫一個函式Swap交換兩張牌位置

39 練習(2/4) 函式Swap虛擬碼 Procedure Swap( card1, card2 ) 1. temp = card1;
return card1 temp card2

40 練習(3/4) 宣告並實作以下類別 Card suit : char faceValue : int SetCard() GetCard()

41 練習(4/4) 根據完成之Card類別修正主程式 測試兩張牌能否交換 將Swap函式之參數改為傳址參數，再試一次
利用偵錯器找出結果差異之原因

42 程式 OverloadingDemo (1/4)
using System; namespace OverloadingDemo { /* * 示範多載之應用 * 3/17/2007 */ class Program static void Main(string[] args) Adder adder = new Adder(); int i = 0;

43 程式 OverloadingDemo (2/4)
do { Console.Write( "指定運算數值型態: 0. 結束; 1. 整數; 2. 浮點數: "); i = int.Parse(Console.ReadLine()); if (i == 0) break; if (i > 2) continue; switch (i) case 1: Console.Write("輸入第一個整數"); int a = int.Parse(Console.ReadLine()); Console.Write("輸入第二個整數"); int b = int.Parse(Console.ReadLine()); adder.AddAndDisplay(a, b); break;

44 程式 OverloadingDemo (3/4)
case 2: Console.Write("輸入第一個浮點數"); double ad = double.Parse(Console.ReadLine()); Console.Write("輸入第二個浮點數"); double bd = adder.AddAndDisplay(ad, bd); break; } } while (true); /* 模擬加法器 * 3/17/2007 */

45 程式 OverloadingDemo (4/4)
public class Adder { public void AddAndDisplay(int a, int b) int result = a + b; Console.WriteLine("{0} + {1} = {2}", a, b, result); } public void AddAndDisplay(double a, double b) double result = a + b; Console.WriteLine("{0} + {1} = {2}", a, b, result);

46 物件導向思維 什麼是程式要完成的功能? 需要那些物件/類別才能完成程式功能? 物件/類別需要那些行為才能合作完成程式功能?
例: Mission Impossible, RPG

47 範例問題 假設有一N_ROW列、N_COL欄的整數表格，寫一程式計算每列總和、每欄總和、及全部總和。以如下2列3欄表格為例：
其每列總和為 9、18，每欄總和為8、11、8，全部總和為27。利用一個二維陣列儲存表格資料，兩個一維陣列分別儲存每列總和及每欄總和。 3 4 2 5 7 6

48 演算法主要虛擬碼 1. 取得資料 2. 計算每列總和 3. 計算每欄總和 4. 計算全部總和 5. 輸出答案

49 物件識別 表格 計算全部總和 列 計算全列之和 欄 計算全欄之和

50 類別 Table Table content: int[, ] nRow : int nCol : int Content
GetRowSum() GetColSum() GetTotalSum()

51 程式 ClassDemo.Program (1/5)
using System; namespace ClassDemo { /* * 假設有一N_ROW列、N_COL欄的整數表格， * 計算每列總和、每欄總和、及全部總和 * 利用物件導向 * * 主要虛擬碼: * 1. 取得資料 * 2. 計算每列總和 * 3. 計算每欄總和 * 4. 計算全部總和 * 5. 輸出答案

52 程式 ClassDemo.Program (2/5)
* 測試: 2 X 3 表格 * * | | | | * | | | | * * 每列總和 * * | | | * 每欄總和 * | | | |

53 程式 ClassDemo.Program (3/5)
* 全部總和 * 27 * */ class Program { static void Main(string[] args) const int N_ROW = 2; const int N_COL = 3; int[,] table = new int[N_ROW, N_COL]; table[0, 0] = 3; table[0, 1] = 4; table[0, 2] = 2; table[1, 0] = 5;

54 程式 ClassDemo.Program (4/5)
table[1, 1] = 7; table[1, 2] = 6; Table t = new Table(); t.Content = table; int[] rowSum = t.GetRowSum(); int[] colSum = t.GetColSum(); int totalSum = t.GetTotalSum(); for (int i = 0; i < N_ROW; ++i) { Console.WriteLine("Sum of row " + i + " is " + rowSum[i]); }

55 程式 ClassDemo.Program (5/5)
for (int j = 0; j < N_COL; ++j) { Console.WriteLine("Sum of column " + j + " is " + colSum[j]); } Console.WriteLine("Total sum is " + totalSum); Console.ReadLine();

56 程式 ClassDemo.Table (1/5) using System; namespace ClassDemo { /* * 表格
* skj 3/31/2008 */ public class Table private int[,] content; int nRow; int nCol;

57 程式 ClassDemo.Table (2/5) public int[,] Content {
get { return content; } set content = value; nRow = content.GetUpperBound(0) + 1; nCol = content.GetUpperBound(1) + 1; }

58 程式 ClassDemo.Table (3/5) { int[] rowSum = new int[nRow];
public int[] GetRowSum() { int[] rowSum = new int[nRow]; for (int i = 0; i < nRow; ++i) rowSum[i] = 0; for (int j = 0; j < nCol; ++j) rowSum[i] += content[i, j]; } return rowSum;

59 程式 ClassDemo.Table (4/5) public int[] GetColSum() {
int[] colSum = new int[nCol]; for (int j = 0; j < nCol; ++j) colSum[j] = 0; for (int i = 0; i < nRow; ++i) colSum[j] += content[i, j]; } return colSum;

60 程式 ClassDemo.Table (5/5) public int GetTotalSum() { int totalSum = 0;
for (int i = 0; i < nRow; ++i) for (int j = 0; j < nCol; ++j) totalSum += content[i, j]; } return totalSum;

61 物件/類別之識別 程式功能敘述中的名詞、代名詞、名詞片語可能需要轉換為物件/類別(CRC卡)
類別之間的關係可以畫UML類別圖表示 主程式及類別的方法可以用虛擬碼進一步描述

62 物件 CRC 卡 Object Name: withdrawManager Collaborators Responsibilities
Ask user for amount to withdraw Verify amount with AccountManager Tell cash dispenser to release cash accountManager cashDispenser

63 類別 CRC卡 Class Name: WithdrawManager Collaborators Responsibilities
Ask user for amount to withdraw Verify amount with AccountManager Tell CashDispenser to release cash AccountManager CashDispenser

64 UML 類別圖( Class Diagram )
* G. Booch, J. Rumbaugh, and I. Jacobson, The Unified Modeling Language User Guide, Addison Wesley, 1999.

65 構成(Aggregation)之實作 class Company { //…… Department[] department;
// created by Company objects Office[] office; }

66 關連(Association)之實作 class Department { //……
Person manager; // created outside Department Person[] member; // created outside Department } class Person { Department department; // created outside Person

67 延伸閱讀：系統分析與設計 F. P. Brooks, Jr., The Mythical Man-Month – Essays on Software Engineering, Addison-Wesley, 1975 G. Booch, J. Rumbaugh, and I. Jacobson, The Unified Modeling Language User Guide, Addison Wesley, 1999. I. Jacobson, G. Booch, and J. Rumbaugh, The Unified Software Development Process, Addison Wesley, 1999. R. C. Lee and W. M. Tepfenhart, UML and C++, A Practical Guide to Object-Oriented Development, 2nd ed., Prentice Hall, 2001. 李潛瑞譯, W. C. Wake 原著, 極端軟體製程--探索篇, 碁峰, 2002.

68 練習 (1/2) 模擬兩輛車的直線賽道競速比賽, 先擬好測試規畫 track1 track2

69 練習 (2/2) 主程式虛擬碼 while(true) { 擲骰子決定兩部車的加減速或維持速率; 計算各車前進距離(等於速率乘以時間);
更新兩部車在賽道上的位置; if 有車衝過終點, 記下駕駛員; break; } 印出勝利者姓名;