1、北京信息職業(yè)技術(shù)學(xué)院 | 范美英Java中繼承與多態(tài)的實(shí)現(xiàn)舉例2基類的定義public class Person private String name; private Integer bornYear; private Integer diedYear; public Person(String name, Integer bornYear, Integer diedYear) = name; this.bornYear = bornYear; this.diedYear = diedYear; public Person(String name, Integer bo

2、rnYear) = name; this.bornYear = bornYear; public String getName() return name; public void setName(String name) = name; public Integer getBornYear() return bornYear; public void setBornYear(Integer bornYear) this.bornYear = bornYear; public Integer getDiedYear() return diedYear;

3、public void setDiedYear(Integer diedYear) this.diedYear = diedYear; Java中的繼承與多態(tài)舉例| 基類 3PersonDemo.javapublic class PersonDemo public static void main(String args) Person edison = new Person(Thomas Edison, 1847, 1931); Person billGates = new Person(Bill Gate, 1955); Java中的繼承與多態(tài)舉例| Java中類的應(yīng)用4類之間的繼承關(guān)系圖

4、Java中的繼承與多態(tài)舉例| 類圖5Animal.javaJava中的繼承與多態(tài)舉例| Animal類的定義Animal 類是抽象類，它的方法沒有方法體，這種方法是一個(gè)抽象方法，在子類中，你需要聲明和實(shí)現(xiàn)這個(gè)方法。Animal 類如果有一個(gè)以上抽象方法，它必須聲明為抽象的類。抽象類有構(gòu)造函數(shù)，但不能用它創(chuàng)建的實(shí)例。類的定義如下：public abstract class Animal private String name;public Animal() = this.getAnimalName();public Animal(String name)

5、= name;public String getName() return name; public void setName(String name) = name;public abstract String getAnimalName(); 6Cat.javaJava中的繼承與多態(tài)舉例| Cat.java的定義Cat還具有構(gòu)造函數(shù)，也有自己的字段。在構(gòu)造函數(shù)中的第一行必須調(diào)用super(.)，這意味著調(diào)用父類的構(gòu)造函數(shù)，給父類的字段賦值。如果不調(diào)用super() ，JAVA在編譯時(shí)構(gòu)造函數(shù)的第一行會自動插入super() 。類的定義如下：public class Ca

6、t extends Animal private int age; private int height; public Cat(int age, int height) super();this.age = age; this.height = height; public Cat(String name, int age, int height)super(name);this.age = age; this.height = height; public int getAge() return age; public void setAge(int age) this.age = age

7、; public int getHeight() return height; public void setHeight(int height) this.height = height;Override public String getAnimalName() return Cat; 7Java中的繼承與多態(tài)舉例| Cat.java的定義創(chuàng)建一個(gè)Cat對象，會發(fā)生什么？8Mouse.javaJava中的繼承與多態(tài)舉例| Mouse.java的定義public class Mouse extends Animal private int weight; public Mouse() thi

8、s(100); public Mouse(int weight) this.weight = weight; public Mouse(String name, int weight) super(name); this.weight = weight; public int getWeight() return weight; public void setWeight(int weight) this.weight = weight; Override public String getAnimalName() return Mouse; 9InstanceofDemo.javaJava中

9、的繼承與多態(tài)舉例| 類的應(yīng)用public class InstanceofDemo public static void main(String args) Animal tom = new Cat(Tom, 3, 20); (name: + tom.getName(); boolean isMouse = tom instanceof Mouse; boolean isCat = tom instanceof Cat; boolean isAnimal = tom instanceof Animal;); 10InheritMethodDemo.javapublic class Inheri

10、tMethodDemo public static void main(String args) Cat tom = newCat(Tom, 3, 20);(name: + tom.getName(); (animalName: + tom.getAnimalName(); (Age: + tom.getAge(); (Height: + tom.getHeight(); Java中的繼承與多態(tài)舉例| 類的應(yīng)用11Java中的繼承與多態(tài)舉例| 類的繼承AsianCat.javapublic class AsianCat extends Cat public AsianCat(String name, int age, int height) super(name, age, height); Override public String getAnimalName() return Asian Cat; 假設(shè)你有一只貓AsianCat,，你可以作為一只貓或者作為一種動物調(diào)用是多態(tài)的體現(xiàn)。下面的例子說明了如何聲明和實(shí)現(xiàn)行為。12Java中的繼承與多態(tài)舉例| 類