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分别使用继承、多态、抽象类和接口方式实现动物类需求

萌宠菠菠乐园
2024-10-20 02:55

文章目录继承实现解决了啥？多态实现解决了啥？存在的问题抽象实现解决了啥？接口实现解决了啥？

继承

实现

package jicheng; public class Animal { private String name; private int age; public Animal() { } public Animal(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } }

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package jicheng; public class Cat extends Animal { public Cat() { } public Cat(String name, int age) { super(name, age); } public void catchMouse() { System.out.println("猫抓老鼠"); } }

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package jicheng; public class Dog extends Animal { public Dog() { } public Dog(String name, int age) { super(name, age); } public void lookDoor() { System.out.println("狗看门"); } } 123456789101112131415

package com.itheima_11; /* 测试类 */ public class AnimalDemo { public static void main(String[] args) { //创建猫类对象并进行测试 Cat c1 = new Cat(); c1.setName("加菲猫"); c1.setAge(5); System.out.println(c1.getName() + "," + c1.getAge()); c1.catchMouse(); Cat c2 = new Cat("加菲猫", 5); System.out.println(c2.getName() + "," + c2.getAge()); c2.catchMouse(); } }

12345678910111213141516171819 解决了啥？

使用继承可以有效实现代码复用，避免重复代码的出现。例如get、set方法就是大家通用的。

多态

实现

package duotai03; public class Animal { private int age; private String name; public Animal() { } public Animal(int age, String name) { this.age = age; this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public void eat(){ System.out.println("动物吃东西"); } }

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package duotai03; public class Cat extends Animal{ public Cat() { } public Cat(int age, String name) { super(age, name); } @Override public void eat() { System.out.println("猫吃鱼"); } } 123456789101112131415

package duotai03; public class Dog extends Animal{ public Dog() { } public Dog(int age, String name) { super(age, name); } @Override public void eat() { System.out.println("狗吃骨头"); } } 123456789101112131415

package duotai03; public class AnimalDemo { public static void main(String[] args) { //无参构造方法 Animal a = new Cat(); a.setAge(10); a.setName("英短"); a.eat(); System.out.println(a.getAge()+a.getName()); //使用带参构造方法 a = new Cat(10,"加菲"); a.eat(); System.out.println(a.getAge()+a.getName()); } }

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可以增强程序的可扩展性及可维护性，使代码更加简洁。

存在的问题

父类本身可能是一个具体事务，例如动物类。所以上面的多态的实现是有问题的。下面使用抽象方式实现。

抽象

实现

package chouxiang02; public abstract class Animal { private int age; private String name; public Animal() { } public Animal(int age, String name) { this.age = age; this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } //提供抽象方法 public abstract void eat(); }

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package chouxiang02; public class Cat extends Animal { public Cat() { } public Cat(int age, String name) { super(age, name); } @Override public void eat() { System.out.println("猫吃鱼"); } } 123456789101112131415

package chouxiang02; public class Dog extends Animal{ public Dog() { } public Dog(int age, String name) { super(age, name); } @Override public void eat() { System.out.println("狗吃骨头"); } } 123456789101112131415

package chouxiang02; public class AnimalDemo { public static void main(String[] args) { Animal a = new Cat(); a.setAge(6); a.setName("测试猫"); System.out.println(a.getAge()+a.getName()); a.eat(); System.out.println("------------"); a = new Cat(10,"英短"); System.out.println(a.getAge()+a.getName()); a.eat(); } }

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父类本身可能是一个具体事务，例如动物类。抽象类的实现解决了这个问题。

接口

实现

package interface02; public interface Jumpping { public abstract void jump(); } 12345

package interface02; public abstract class Animal{ private int age; private String name; public Animal() {} public Animal(int age, String name) { this.age = age; this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public abstract void eat(); }

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package interface02; public class Cat extends Animal implements Jumpping{ public Cat() { } public Cat(int age, String name) { super(age, name); } @Override public void eat() { System.out.println("猫吃鱼"); } @Override public void jump() { System.out.println("猫可以跳高了"); } }

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package interface02; public class AnimalDemo { public static void main(String[] args) { Jumpping j = new Cat(); j.jump(); System.out.println("---------"); Animal a = new Cat(); a.setAge(10); a.setName("英短"); System.out.println(a.getAge()+a.getName()); a.eat(); //向下转型，把一个父类对象转为子类对象 ((Cat)a).jump();//由于Animal中没有jump，所以要强转 a = new Cat(10,"加菲"); System.out.println(a.getAge()+a.getName()); a.eat(); System.out.println("---------"); //一般使用这个方式 Cat c = new Cat(); c.setAge(10); c.setName("英短"); c.jump(); c.eat(); } }

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接口的出现可以很方便的实现程序的拓展。