继承的思想实现猫和狗的案例，并在测试类中进行测试

猫和狗——共同特性都是属于动物

1. 定义动物类（Animal）

• 成员变量：姓名，年龄
• 构造方法：无参，带参
• 成员方法：get/set 方法

2. 定义猫类（Cat），继承动物类

• 构造方法：无参，带参
• 成员方法：抓老鼠（catchMouse）

3. 定义狗类（Dog）, 继承动物类

• 构造方法：无参，带参
• 成员方法：看门（lookDoor）

4. 定义测试类（AnimalDemo）, 写代码测试

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示例代码：

AnimalParent.java

package com.面向对象.Demo14;public class AnimalParent {private String name; // 名称private int age; // 年龄public AnimalParent() {}public AnimalParent(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;}
}

Cat.java

package com.面向对象.Demo14;public class Cat extends AnimalParent {public Cat() {}public Cat(String name, int age) {super(name, age);}public void catchMouse() {System.out.println("抓老鼠");}
}

Dog.java

package com.面向对象.Demo14;public class Dog extends AnimalParent {public Dog() {}public Dog(String name, int age) {super(name, age);}public void lookDoor() {System.out.println("看门");}
}

AnimalDemo01.java

package com.面向对象.Demo14;public class AnimalDemo01 {/*** 使用有参构造方法给我们成员属性 赋值*/public static void main(String[] args) {Cat catA = new Cat("小猫A", 3);Cat catB = new Cat("小猫B", 3);System.out.print(catA.getName() + "," + catA.getAge() + ",");catA.catchMouse();System.out.print(catB.getName() + "," + catB.getAge() + ",");catB.catchMouse();Dog dogA = new Dog("小狗A", 2);Dog dogB = new Dog("小狗B", 2);System.out.print(dogA.getName() + "," + dogA.getAge() + ",");dogA.lookDoor();System.out.print(dogB.getName() + "," + dogB.getAge() + ",");dogB.lookDoor();}
}

AnimalDemo02.java

package com.面向对象.Demo14;public class AnimalDemo02 {/*** 使用 set 方法给成员属性 赋值*/public static void main(String[] args) {Cat cat1 = new Cat();cat1.setName("小猫A");cat1.setAge(2);Cat cat2 = new Cat();cat2.setName("小猫B");cat2.setAge(2);System.out.print(cat1.getName() + "," + cat1.getAge() + ",");cat1.catchMouse();System.out.print(cat2.getName() + "," + cat2.getAge() + ",");cat2.catchMouse();Dog dog1 = new Dog();Dog dog2 = new Dog();dog1.setName("小狗A");dog2.setName("小狗B");dog1.setAge(3);dog2.setAge(3);System.out.print(dog1.getName() + "," + dog1.getAge() + ",");dog1.lookDoor();System.out.print(dog2.getName() + "," + dog2.getAge() + ",");dog2.lookDoor();}
}

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综上：使用有参构造方法给成员属性赋值的 代码量要比 使用set方法给成员属性赋值要少，∴一般推荐使用有参构造方法给成员属性赋值。

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