類別與方法 (Classes and Methods)

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1 類別與方法 (Classes and Methods)
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 程式 UsingObject (1/2) using System; namespace UsingObject {
class Program /* 示範類別的宣告與物件的使用 * 3/17/2007 */ static void Main(string[] args) Hello hello = new Hello(); hello.showMessage(); Console.WriteLine(hello.accessMessage); hello.accessMessage = "測試訊息";

3 程式 UsingObject (2/2) Console.ReadLine(); } public class Hello {
string message = "Hello! 原始測試訊息"; public void showMessage() Console.WriteLine(message); public string accessMessage get { return message; } set { message = value; }

4 類別(Class)觀念 類別 File 資料變數(欄位成員 field) fileName 方法函式(函式成員 function)
Open() Read() Create() Write() Delete()

5 物件(Object)觀念 file1 file1.fileName 記憶體地址1 函式Open進入地址 file2
記憶體地址2 函式Open進入地址 函式成員Open進入點

6 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();

7 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)

8 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,

9 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);

10 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;

11 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;

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

13 程式 PassByReferenceAndOut (1/4)
using System; namespace PassByReferenceAndOut { /* * 示範傳址參數與out參數的使用方法 * 3/17/2007 */ class Program static void Main(string[] args) double length = 100.0; Square s = new Square(); s.acessLength = length;

14 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(); }

15 程式 PassByReferenceAndOut (3/4)
/* * 正方形 * 3/17/2007 */ public class Square { double a; public double acessLength get { return a; } set { a = value; } }

16 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)

17 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

18 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);

19 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 */

20 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; }

21 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;

22 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

23 UML 的類別符號 Time hour : int min : int sec : int SetTime() GetTime()

24 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;

25 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;

26 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 */

27 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);

28 程式 UsingRecursive (1/4) using System; namespace UsingRecursive { /*
* 利用階乘說明遞迴函式的用法 * 3/17/2007 * * 測試: * 以遞迴及非遞迴兩種方式計算!, 結果應相同 */ class Program static void Main(string[] args)

29 程式 UsingRecursive (2/4) int factorialNonRecursive =
int factorialRecursive = FactorialRecursive(10); Console.WriteLine("(迴圈) 10! = " + factorialNonRecursive); Console.WriteLine("(遞迴) 10! = " + } /* * 不用遞迴計算階乘 * 3/17/2007 */

30 程式 UsingRecursive (3/4) static int FactorialNonRecursive(int n) {
int result = 1; for (int i = 1; i <= n; i++) result *= i; } return result; /* * 利用遞迴計算階乘 * 3/17/2007 */

31 程式 UsingRecursive (4/4) static int FactorialRecursive(int n) {
if (n == 1 || n == 0) return 1; int result = n * FactorialRecursive(n - 1); return result; }

32 遞迴的觀念

33 二分搜尋法 (Binary Search) Alice Bob Carol David Elaine Fred George Harry
Irene John Kelly Larry Mary Nancy Oliver Harry Irene John Kelly Larry Mary Nancy Oliver Irene John Kelly

34 二分搜尋法虛擬碼 *J. G. Brookshear, Computer Science – An Overview, 8th edition, Addison-Wesley, 2005

35 類別 NameList NameList list : string[] min : int sec : int AccessList()
Search()

36 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

37 程式 BinarySearch.Program (1/4)
using System; namespace BinarySearch { /* 實作二分搜尋法 * skj 3/20/2007 * * 測試規劃 * 名單: * 0: Abe * 1: Bob * 2: Carol' * 3: David * 4: Eve

38 程式 BinarySearch.Program (2/4)
* target: Carol ==> 第3名 * target: Bob ==> 第2名 * target: Abe ==> 第1名 * target: David ==> 第4名 * target: Eve ==> 第5名 * target: Mary ==> 不在名單中 * target: Aaron ==> 不在名單中 * target: Brown ==> 不在名單中 */ class Program { static void Main(string[] args)

39 程式 BinarySearch.Program (3/4)
string[] list = new string[5]; list[0] = "Abe"; list[1] = "Bob"; list[2] = "Carol"; list[3] = "David"; list[4] = "Eve"; NameList nameList = new NameList(); nameList.AccessList = list; int index; Console.Write("輸入欲搜尋的名字: "); string target = Console.ReadLine(); bool success = nameList.Search(target, 0, 4, out index);

40 程式 BinarySearch.Program (4/4)
if (success) { Console.WriteLine(target + "為名單中的第" + (index + 1) + "名"); } else Console.WriteLine(target + "不在名單中");

41 程式 BinarySearch.NameList (1/3)
using System; namespace BinarySearch { /* * 排序好的名單類別 * skj 3/20/2007 */ class NameList string[] list; // 儲存之名單 public string[] AccessList get { return list; } set { list = value; } }

42 程式 BinarySearch.NameList (2/3)
/* * 檢查字串target是否在list之中 * 3/20/2007 */ public bool Search(string target,// 欲搜尋之字串 int low, // 檢查註標之下限 int high, // 檢查註標之上限 out int index // 最後檢查的註標 ) { index = (low + high) / 2; if (low > high ) return false; int result = target.CompareTo(list[index]);

43 程式 BinarySearch.NameList (3/3)
if (result == 0) { return true; } else if (result < 0) high = index - 1; return Search(target, low, high, out index); else low = index + 1;

44 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

45 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

46 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

47 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

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

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

50 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