Java 04

XiaoXianYue原创2024年6月9日大约 3 分钟

1.定义狗类

public class Dog {
    private int age;
    private String color;

    public Dog() {}

    public Dog(int age, String color) {
        this.age = age;
        this.color = color;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public void eat(String something) {
        System.out.println(age + "岁的" + color + "颜色的狗两只前腿死死的抱住" + something + "猛吃");
    }

    public void lookHome() {
        System.out.println("狗正在看家");
    }
}

2. 定义猫类

public class Dog {
    private int age;
    private String color;

    public Dog() {}

    public Dog(int age, String color) {
        this.age = age;
        this.color = color;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public void eat(String something) {
        System.out.println(age + "岁的" + color + "颜色的狗两只前腿死死的抱住" + something + "猛吃");
    }

    public void lookHome() {
        System.out.println("狗正在看家");
    }
}

3. 定义Person类

public class Person {
    private String name;
    private int age;

    public Person() {}

    public Person(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;
    }

    public void keepPet(Dog dog, String something) {
        System.out.println("年龄为" + age + "岁的" + name + "养了一只" + dog.getColor() + "颜色的" + dog.getAge() + "岁的狗");
        dog.eat(something);
    }

    public void keepPet(Cat cat, String something) {
        System.out.println("年龄为" + age + "岁的" + name + "养了一只" + cat.getColor() + "颜色的" + cat.getAge() + "岁的猫");
        cat.eat(something);
    }
}

4. 定义测试类

public class Test {
    public static void main(String[] args) {
        Dog dog = new Dog(2, "黑");
        Cat cat = new Cat(3, "灰");

        Person person1 = new Person("老王", 30);
        Person person2 = new Person("老李", 25);

        person1.keepPet(dog, "骨头");
        person2.keepPet(cat, "鱼");
    }
}

5. 思考

问题：

Dog和Cat都是Animal的子类，以上案例中针对不同的动物，定义了不同的keepPet方法，过于繁琐，能否简化，并体会简化后的好处？
Dog和Cat虽然都是Animal的子类，但是都有其特有方法，能否想办法在keepPet中调用特有方法？

简化 keepPet 方法: 可以通过定义一个 Animal 基类，并在 Person 类中使用多态来简化 keepPet 方法。

调用特有方法: 可以通过类型检查和强制类型转换在 keepPet 方法中调用特有方法。

public abstract class Animal {
    private int age;
    private String color;

    public Animal() {}

    public Animal(int age, String color) {
        this.age = age;
        this.color = color;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public abstract void eat(String something);
}

public class Dog extends Animal {
    public Dog(int age, String color) {
        super(age, color);
    }

    @Override
    public void eat(String something) {
        System.out.println(getAge() + "岁的" + getColor() + "颜色的狗两只前腿死死的抱住" + something + "猛吃");
    }

    public void lookHome() {
        System.out.println("狗正在看家");
    }
}

public class Cat extends Animal {
    public Cat(int age, String color) {
        super(age, color);
    }

    @Override
    public void eat(String something) {
        System.out.println(getAge() + "岁的" + getColor() + "颜色的猫眯着眼睛侧着头吃" + something);
    }

    public void catchMouse() {
        System.out.println("猫正在逮老鼠");
    }
}

public class Person {
    private String name;
    private int age;

    public Person() {}

    public Person(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;
    }

    public void keepPet(Animal pet, String something) {
        System.out.println("年龄为" + age + "岁的" + name + "养了一只" + pet.getColor() + "颜色的" + pet.getAge() + "岁的" + pet.getClass().getSimpleName().toLowerCase());
        pet.eat(something);

        if (pet instanceof Dog) {
            ((Dog) pet).lookHome();
        } else if (pet instanceof Cat) {
            ((Cat) pet).catchMouse();
        }
    }
}

public class Test {
    public static void main(String[] args) {
        Dog dog = new Dog(2, "黑");
        Cat cat = new Cat(3, "灰");

        Person person1 = new Person("老王", 30);
        Person person2 = new Person("老李", 25);

        person1.keepPet(dog, "骨头");
        person2.keepPet(cat, "鱼");
    }
}

简化后的好处

代码复用: 通过继承和多态，keepPet 方法得以简化，避免了重复代码。
扩展性强: 以后添加新的宠物类型时，无需修改 Person 类，只需继承 Animal 并实现相应方法即可。
更简洁: 简化代码逻辑，使代码更易读易维护。