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解析java多态经典习题

萌宠菠菠乐园
2024-12-25 00:18

解析java多态经典习题

1 题目一

1.1 题目内容

编写程序实现乐手弹奏乐器。乐手可以弹奏不同的乐器从
而发出不同的声音。
可以弹奏的乐器包括二胡、钢琴和琵琶。
实现思路及关键代码：
①定义乐器类Instrument，包括方法makeSound()
②定义乐器类的子类：二胡Erhu、钢琴Piano和
小提琴Violin
③定义乐手类Musician，可以弹奏各种乐器
play(Instrument i)
④定义测试类,给乐手不同的乐器让他弹奏

1.2 示例代码 Instrument类

package Work03; public class Instrument { public void makeSound(){ System.out.println("乐器在奏乐"); } } 1234567 Erhu类

package Work03; public class Erhu extends Instrument{ @Override public void makeSound() { System.out.println("二胡,弹奏的曲目是二泉映月"); } } 123456789 Piano类

package Work03; public class Piano extends Instrument{ @Override public void makeSound() { System.out.println("钢琴,弹奏的曲目是致爱丽丝"); } } 123456789 Violin类

package Work03; public class Violin extends Instrument{ @Override public void makeSound() { System.out.println("小提琴,弹奏的曲目是沉思"); } } 123456789 Muscian类

package Work03; public class Musician { private String name; public Musician() { } public Musician(String name) { this.name = name; } public void play(Instrument i){ System.out.print(name+"弹奏的乐器是"); i.makeSound(); } }

1234567891011121314151617 Test类

package Work03; public class Test { public static void main(String[] args) { Musician m=new Musician("张三"); m.play(new Piano()); m.play(new Erhu()); m.play(new Violin()); } } 123456789 1.3 示例代码运行截图

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2 题目二

2.1 题目内容

编写程序实现主人喂养宠物和跟宠物玩耍的场景
定义宠物类Pet，宠物都需要吃东西,跟主人玩。
定义狗类Dog、猫类Cat、Dolphin海豚类继承Pet宠物类。
狗狗吃骨头、猫咪吃老鼠、海豚吃乌贼。

主人和宠物的玩耍是每个宠物都独有一份

主人跟狗狗完抓飞盘，主人跟猫咪玩抓老鼠、主人跟海豚玩转圈圈。

2.2 示例代码 Pet类

package Work03; //上课练习 public class Pet { private String name; public Pet() { } public Pet(String name) { this.name = name; } //吃的方法 public void eat(){ } public String getName() { return name; } public void setName(String name) { this.name = name; } }

1234567891011121314151617181920212223242526 Dog类

package Work03; public class Dog extends Pet{ public Dog() { } public Dog(String name) { super(name); } public void catchDisc() { System.out.println("玩抓飞盘"); } @Override public void eat() { System.out.println("狗狗在啃骨头"); } }

1234567891011121314151617181920 Cat类

package Work03; public class Cat extends Pet{ public Cat() { } public Cat(String name) { super(name); } public void catchMouse() { System.out.println("玩抓老鼠"); } @Override public void eat() { System.out.println("猫咪吃老鼠"); } }

1234567891011121314151617181920 Dolphin类

package Work03; public class Dolphin extends Pet{ public Dolphin() { } public Dolphin(String name) { super(name); } public void runningCircle() { System.out.println("玩转圈圈"); } @Override public void eat() { System.out.println("海豚吃乌贼"); } }

1234567891011121314151617181920 Master类

package Work03; public class Master { private String name; public Master() { } public Master(String name) { this.name = name; } public void feed(Pet pet){ //得出喂食的宠物是什么名字,是狗还是猫还是海豚 if(pet instanceof Dog){ System.out.println(name+"喂食的宠物是一只叫"+ ((Dog)pet).getName()+"的狗狗"); }else if(pet instanceof Cat){ System.out.println(name+"喂食的宠物是一只叫"+ ((Cat)pet).getName()+"的猫咪"); }else if(pet instanceof Dolphin){ System.out.println(name+"喂食的宠物是一只叫"+ ((Dolphin)pet).getName()+"的海豚"); } //吃的方法都是被重写的,无需进行类型的判断 pet.eat(); } public void play(Pet pet){ //每个宠物的玩耍方法都是其独有的方法,因此需要向下转型,向下转型前需要对类型进行判断 if(pet instanceof Dog){ System.out.print(name+"是和一只叫"+ ((Dog)pet).getName()+"的狗狗"); ((Dog)pet).catchDisc(); }else if(pet instanceof Cat){ System.out.print(name+"是和一只叫"+ ((Cat)pet).getName()+"的猫咪"); ((Cat)pet).catchMouse(); }else if(pet instanceof Dolphin){ System.out.print(name+"是和一只叫"+ ((Dolphin)pet).getName()+"的海豚"); ((Dolphin)pet).runningCircle(); } } }

123456789101112131415161718192021222324252627282930313233343536373839 Test类

package Work03; public class Test { public static void main(String[] args) { Master master=new Master("张三"); Dog dog=new Dog("德福"); Cat cat=new Cat("叮当"); Dolphin dolphin=new Dolphin("祥云"); master.feed(dog); master.feed(cat); master.feed(dolphin); master.play(dog); master.play(cat); master.play(dolphin); } }

12345678910111213141516 2.3 示例代码运行截图

在这里插入图片描述