Java三大面向对象特性及实现方法

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        if (age > 0) {
            this.age = age;
        }
    }
}

public class Person {
    protected String name;

    public void eat() {
        System.out.println(name + " 在吃饭");
    }
}

public class Teacher extends Person {
    private String subject;

    public void teach() {
        System.out.println(name + " 教授 " + subject);
    }
}

public class Animal {
    public void makeSound() {
        System.out.println("动物叫");
    }
}

public class Dog extends Animal {
    @Override
    public void makeSound() {
        System.out.println("汪汪汪");
    }
}

public class Cat extends Animal {
    @Override
    public void makeSound() {
        System.out.println("喵喵喵");
    }
}

// 测试
Animal a1 = new Dog();
Animal a2 = new Cat();
a1.makeSound(); // 输出：汪汪汪
a2.makeSound(); // 输出：喵喵喵