【Java】继承练习

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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