Understanding Java Inheritance and Interfaces in Vehicle Class Hierarchies

Vehicle Car 類別的繼承

Vehicle Car Motorcycle Truck SportsCar Jeep 類別的繼承

類別的繼承 class Car { private int engineNum; private int color; public void setNum(int num){engineNum = num;} public void setColor(int color){ this.color = color;} public void printVehicle(){ } }

類別的繼承 class 子類別名稱 extends 父類別名稱 { ....//額外的成員資料和方法 } class Nissan extends Car { private double price; public Nissan (int num, int color , double price) { } public void printNissan() { } }

類別的繼承 • 子類別不能存取父類別宣告成private 的成員資料和方法。 • 父類別的建構子不屬於類別的成員，所以子類別並不能繼承父類別的建構子，只能呼叫父類別的建構子。

類別的繼承 class Car { ....... public static void printName(){...}//隱藏 ....... public void printCar(){...}//覆寫 } class Nissan extends Car { ....... public Static void printName(){....} ....... public void printCar() {....} } 覆寫(override)與隱藏(hide)父類別的方法

類別的繼承 隱藏父類別的成員資料 class Car { ….. public int color; ….. } class Nissan extends Car { private String color; ….. }

類別的繼承 使用父類別的建構子 class Car extends Vehicle // Car類別宣告 { private String name; // 隱藏父類別的成員變數 private int engineNo; private int doors; // 幾門 public Car(String name, int no, int doors) { super(name, no); // 呼叫父類別的建構子 ……… } public void printVehicle() { ………. super.printVehicle(); System.out.println("名稱(父): " + super.name); System.out.println("引擎號碼(父): " + super.engineNo); ……….. } } class Vehicle // Vehicle類別宣告 { // 成員資料 public static int count; // 車輛數 public int engineNo; // 引擎號碼 public String name; // 名稱 // 建構子 public Vehicle(String name, int no) {…………………} // 成員方法: 顯示車輛資料 public void printVehicle() {…………………} }

常數與抽象類別 • final class Customer extends Person • { • ..... • } • class Person • { • ..... • final char getName(){return nmae;} • final int getAge(){return age;} • final void setName(char c){ name = c; } • final void setAge(int age) { this.age = age; } • }

<<abstract>> Shape +x:double +y:double area() 常數與抽象類別 • abstract class Shape • { • public double x; • public double y; • abstract void area(); • } • class Circle extends Shape • { • public double r; • public Circle(double x, double y, double r) { ..... } • public void area() • { System.out.println("圓面積： " + 3.1416*r); } • } Circle +r:double +area()

多形 • class Circle extends Shape • { • ....... • public void area(){.....} • ....... • } • class Rectangle extends Shape • { • ....... • public void area(){.....} • ....... • } • class Triangel extends Shape • { • ....... • public void area(){.....} • ....... • } Circle Shape.area() ch6_3 Shape.area() Rectangle Shape.area() Triangle

隨堂練習 Abstract<<Test>> MidTerm +max : int +min : int +avg : float MidTerm m = new MideTerm(90, 45, 67.8); Quiz q = new Quiz(70, 34, 78.5); Final f = new Final(87, 64, 76.3); Test t = m; t.print(); t = q; t.print(); t = f; t.print(); print() print() Quiz Final print() print()

隨堂練習 Abstract<<Triangle>> T1 +a : int +b : int +c : int T1 t1 = new T1(6, 6, 6); T2 t2 = new T2(3, 4, 5); T3 t3 = new T3(8, 8, 12); T t = t1; t.area(); t = t2; t.area(); t = t3; t.area(); +area : float area() T3 T2 +area : float +area : float

import java.lang.*; • public class Ch1_4_1 • { // 主程式 • public static void main(String[] args) • { // 顯示訊息 • System.out.println(Math.sqrt(9)); • } • }

<<interface>> IPrice Car getPrice():double -price:double -name:String +getPrice():double +getName():String 類別的繼承 Java的介面

類別的繼承 介面的宣告 public interface 介面名稱 { final 資料型態常數值 ; ….. 傳回值型態介面方法(參數列) ; ….. } Interface IArea { final double PI=3.1415926; void area(); }

類別的繼承 類別實作介面 Class 類別名稱 implements 介面名稱1、介面名稱2 { ….. //實作介面的方法 } Class Circle implements IArea { …… public void area() { System.out.println(“圓面積 :”+PI*r*r); } }

<<interface>> IArea Circle -x:double -y:double -r :double area() +area() 類別的繼承 Ch_9_2_2

<<interface>> IArea <<interface>> IShow area() show() 類別的繼承 Ch_9_2_3 在類別實作多個介面 Circle -x:double -y:double -r :double +area() +show()

Vehicle -engineNo:int -name:String -price:double Car +print() <<interface>> IPrint print() -door:int +print() 類別的繼承類別架構與介面 Ch_9_2_4

<<interface>> IArea <<interface>> IShape area() perimeter() 類別的繼承 Ch9_3 Circle -x:double -y:double -r :double +area() +perimeter()

類別的繼承 介面的多重繼承 interface 介面名稱 extends 繼承介面1,繼承介面2 { …..//額外的常數和方法 } interface Ishape extends IArea, IShow { void perimeter(); }

<<interface>> IShow <<interface>> IArea <<interface>> IShape show() perimeter() area() Circle -x:double -y:double -r :double +area() +show() +perimeter() 類別的繼承 Ch_4_2

Student Class Student { private int stdNo; … public float score; public Student(…) { ….} public int getNo() {…..} public String getName() {…..} public String getAddress() {…..} } Class GraduateStudent { private String department; public GraduateStudent(…) { super.stdNo = no; …… } public int getNo() { System.out.println(“No” + super.getNo()); …… } }

<<interface>> I1 <<interface>> I2 sum() printout() IArray FloatArray -buf: int [] -no : int -buf: float[] -no : int +sum() +printout() +sum() 練習

<<interface>> IArea area() Triangle Triangle1 Triangle2 Triangle3 -a: Point -b : Point -c: Point +area() +printout() +area() +area() +area() 練習

Understanding Java Inheritance and Interfaces in Vehicle Class Hierarchies

Understanding Java Inheritance and Interfaces in Vehicle Class Hierarchies

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